Transgenic mice having a human major histocompatibility complex (MHC) phenotype, experimental uses and applications
09986721 · 2018-06-05
Assignee
- Institut Pasteur (Paris, FR)
- Institut National De La Sante Et De La Recherche Medicale (Inserm) (Paris, FR)
Inventors
- Claude Auriault (Juan les Pins, FR)
- Véronique Pancre (Orchies, FR)
- Yu-Chun Lone (Paris, FR)
- Anthony Pajot (Paris, FR)
- François Lemonnier (Bourg la Reine, FR)
Cpc classification
A01K67/0275
HUMAN NECESSITIES
A61P31/00
HUMAN NECESSITIES
A61K49/0008
HUMAN NECESSITIES
C12N15/8509
CHEMISTRY; METALLURGY
A01K67/0278
HUMAN NECESSITIES
A01K2217/05
HUMAN NECESSITIES
International classification
G01N33/00
PHYSICS
A01K67/00
HUMAN NECESSITIES
Abstract
The present invention relates to transgenic mice and isolated transgenic mouse cells, the mice and mouse cells comprising a disrupted H2 class I gene, a disrupted H2 class II gene, a functional HLA class I transgene, and a functional HLA class II transgene. In embodiments, the transgenic mouse or mouse cells are deficient for both H2 class I and class II molecules, wherein the transgenic mouse comprises a functional HLA class I transgene and a functional HLA class II transgene. In embodiments, the transgenic mouse or mouse cell has the genotype HLA-A2.sup.+HLA-DR1.sup.+2mIA. The invention also relates to methods of using a transgenic mouse of the invention.
Claims
1. A method of simultaneously identifying the presence of one or more epitopes in a candidate antigen or group of antigens, wherein the epitope elicits a specific humoral response, a TH HLA-DR1 restricted response, and/or a CTRL HLA-A2 restricted response, the method comprising: a) administering the candidate antigen or group of candidate antigens to a transgenic mouse comprising: 1) a disrupted H2 class I gene; 2) a disrupted H2 class II gene; 3) a functional HLA-A2 transgene; and 4) a functional HLA-DR1 transgene, wherein the transgenic mouse has the genotype HLA-A2.sup.+HLA-DR1.sup.12mIA and the phenotypes of (i) complete restriction by the HLA transgenes, and (ii) complete absence of immune responses restricted by the H2 genes; b) assaying for a specific humoral response in the mouse to the antigen; c) assaying for a TH HLA-DR1 restricted response in the mouse to the antigen; and d) assaying for a CTRL HLA-A2 restricted response in the mouse to the antigen; wherein, observation of a specific humoral response in the mouse to the antigen identifies an epitope in the antigen that elicits a humoral response; observation of a TH HLA-DR1 restricted response in the mouse to the antigen identifies an epitope in the antigen that elicits a TH HLA DR1 restricted response; and observation of a CTRL HLA-A2 restricted response in the mouse to the antigen identifies an epitope in the antigen that elicits a CTRL HLA-A2 restricted response.
2. The method of claim 1, further comprising assaying for a Th1-specific response in the mouse to the antigen and assaying for a Th2-specific response in the mouse to the antigen; wherein observation of a Th1-specific response in the mouse to the antigen identifies an epitope that elicits a Th1-specific response in the mouse to the antigen; and observation of a Th2-specific response in the mouse to the antigen identifies an epitope that elicits a Th2-specific response in the mouse to the antigen.
3. A method of identifying the presence of an HLA DR1-restricted T helper epitope In a candidate antigen or group of candidate antigens, the method comprising: a) administering the candidate antigen or group of candidate antigens to a transgenic mouse comprising: 1) a disrupted H2 class I gene; 2) a disrupted H2 class II gene; 3) a functional HLA-A2 transgene; and 4) a functional HLA-DR1 transgene, wherein the transgenic mouse has the genotype HLA-A2.sup.+HLA-DR1.sup.12mIA and the phenotypes of (i) complete restriction by the HLA transgenes, and (ii) complete absence of immune responses restricted by the H2 genes; and b) assaying for a TH HLA-DR1 restricted T helper epitope response in the mouse to the antigen; wherein, observation of a TH HLA-DR1 restricted T helper epitope response in the mouse to the antigen identifies an epitope in the antigen that elicits a TH HLA-DR1 restricted T helper epitope response.
4. A method of Identifying the presence of an HLA-A2-restricted T cytotoxic (CTL) epitope in a candidate antigen or group of candidate antigens, the method comprising: a) administering the candidate antigen or group of candidate antigens to a transgenic mouse comprising: 1) a disrupted H2 class I gene; 2) a disrupted H2 class II gene; 3) a functional HLA-A2 transgene; and 4) a functional HLA-DR1 transgene, wherein the transgenic mouse has the genotype HLA-A2.sup.+HLA-DR1.sup.12mIA and the phenotypes of (i) complete restriction by the HLA transgenes, and (ii) complete absence of immune responses restricted by the H2 genes; and b) assaying for an HLA-A2-restricted T cytotoxic (CTL) response in the mouse to the antigen or group of antigens; wherein, observation of an HLA-A2-restricted T cytotoxic (CTL) response in the mouse to the antigen or group of antigens identifies an epitope in the antigen group of antigens that elicits an HLA-A2-restricted T cytotoxic (CTL) response.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The invention will be more fully described with reference to the drawings in which:
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SEQUENCES
(9) SEQ ID NO:1 contains the following subparts: Nucleotides 1-1205 comprise the HLA-A2 promoter; nucleotides 1206-1265 the HLA-A2 leader sequence; nucleotides 1266-1565 the human 2 microgobulin cDNA; nucleotides 1566-1610 a (Gly4Ser).sub.3 linker; nucleotides 1611-2440 a segment containing exon 2 and part of intron 3 of HLA-A2; and nucleotides 2441-4547 a segment containing part of intron 3, exons 4 to 8, and part of the 3 non-coding region of the H.sub.2D.sup.b gene.
(10) SEQ ID NO:2 is the nucleotide sequence of the DRA*0101 gene. Nucleotides 1-15279 are the promoter located 5 to the HLA-DR alpha gene, nucleotides 15280-15425 are exon 1, nucleotides 15344-15346 are the ATG start codon, nucleotides 17838-18083 are exon 2, nucleotides 18575-18866 are exon 3, nucleotides 19146-19311 are exon 4, and nucleotides 20008-20340 are exon 5.
(11) SEQ ID NO:3 is the nucleotide sequence of the DRB1*010101 gene. Nucleotides 7391-7552 are exon 1, nucleotides 7453-7455 are the ATG start codon, nucleotides 15809-16079 are exon 2, nucleotides 19536-19817 are exon 3, nucleotides 20515-20624 are exon 4, nucleotides 21097-21121 are exon 5, and nucleotides 21750-22085 are exon 6.
DETAILED DESCRIPTION OF THE INVENTION
(12) The practice of the present invention will employ, unless otherwise indicated, conventional techniques of cell biology, cell culture, molecular biology, transgenic biology, microbiology, recombinant DNA, and immunology, which are within the skill of the art. Such techniques are explained fully in the literature. See, for example, Molecular Cloning A Laboratory Manual, 2nd Ed., ed. by Sambrook, Fritsch and Maniatis (Cold Spring Harbor Laboratory Press: 1989); DNA Cloning, Volumes I and II (D. N. Glover ed., 1985); Oligonucleotide Synthesis (M. J. Gait ed., 1984); Mullis et al. U.S. Pat. No. 4,683,195; Nucleic Acid Hybridization (B. D. Hames & S. J. Higgins eds. 1984); Transcription And Translation (B. D. Hames & S. J. Higgins eds. 1984); Culture Of Animal Cells (R. I. Freshney, Alan R. Liss, Inc., 1987); Immobilized Cells And Enzymes (IRL Press, 1986); B. Perbal, A Practical Guide To Molecular Cloning (1984); the series, Methods In ENZYMOLOGY (J. Abelson and M. Simon, eds.-in-chief, Academic Press, Inc., New York), specifically, Vols. 154 and 155 (Wu et al. eds.) and Vol. 185, Gene Expression Technology (D. Goeddel, ed.); Gene Transfer Vectors For Mammalian Cells (J. H. Miller and M. P. Calos eds., 1987, Cold Spring Harbor Laboratory); Immunochemical Methods In Cell And Molecular Biology (Mayer and Walker, eds., Academic Press, London, 1987); Handbook Of Experimental Immunology, Volumes I-IV (D. M. Weir and C. C. Blackwell, eds., 1986); and Manipulating the Mouse Embryo, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1986).
(13) This invention provides mice comprising (1) mutated H-2 class I and class II molecules; and (2) expressing HLA class I transgenic molecules, or HLA class II transgenic molecules, or HLA class I transgenic molecules and HLA class II transgenic molecules. Mice of the invention, which comprise a knock-out for both H-2 class I and class II molecules, and express HLA class I transgenic molecules and HLA class II transgenic molecules represent a completely humanized experimental mouse that can be used to simultaneously detect the presence of antigen-specific antibodies, an antigen-specific HLA-DRI restricted T cell response, and an antigen-specific HLA-A2 restricted T cell response. These mice are useful to study how mutual coordination operates between a CTL response, a TH response (in particular a TH.sub.1 or TH.sub.2 response), and, optionally, a humoral response. These mice represent an optimized tool for basic and applied vaccinology studies.
(14) The invention provides transgenic mouse comprising a disrupted H2 class I gene, a disrupted H2 class II gene, and a functional HLA class I or class II transgene. In some embodiments, the transgenic mouse comprises a disrupted H2 class I gene, a disrupted H2 class II gene, a functional HLA class I transgene, and a functional HLA class II transgene. Such a mouse can be said to be a completely humanized experimental mouse, because it can be used to simultaneously detect the presence of antigen-specific antibodies, an antigen-specific HLA-DRI restricted T cell response, and an antigen-specific HLA-A2 restricted T cell response.
(15) As shown, in part, in the Examples provided herein, and as is generally clear to one of skill in the art from the disclosure, HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-KO mice have the capacity to develop HBsAg-specific antibody, CD4.sup.+ helper and CD8.sup.+ cytolytic T cell responses following DNA immunization. These responses, observed in every single mouse tested, were directed at the same immunodominant epitopes as human responses and conferred to the immunized animals specific protection against a HBsAg recombinant vaccinia virus.
(16) T helper cells are essential for full maturation of antibody responses (Katz, D. H. & Benacerraf, B., Adv Immunol 15, 1-94 (1972)) CTL priming against many epitopes (von Boehmer, H. & Haas, W., J Exp Med 150, 1134-1142 (1979); Keene, J. A. & Forman, J., J Exp Med 155, 768-782 (1982)) and CTL long-term maintenance (Matloubian, M., Concepcion, R. J. & Ahmed, R., J Virol 68, 8056-8063 (1994)). Both antibodies (Lefrancois, L., J Virol 51, 208-214 (1984)) and CTL (Zinkernagel, R. M. & Welsh, R. M., J Immunol 117, 1495-1502 (1976)) are critical components of protective immunity against viral infections. Potent HBsAg-specific antibody and CTL responses were in fact observed in HLA-A2.1-/HLA-DR1-double transgenic, H-2 class I-/class II-KO mice, but not in HLA-A2.1-single transgenic, H-2 class I-/class II-KO mice. Thus, HBsAg-specific CD4.sup.+ T cell help is essential for generating efficient HBsAg-specific CTL and antibody responses. These results are consistent with studies on HBsAg-immunized mice (Milich, D. R., Semin Liver Dis 11, 93-112 (1991)) and HBsAg-vaccinated humans (Celis, E., Kung, P. C. & Chang, T. W., J Immunol 132, 1511-1516 (1984)), which suggest that production of an anti-HBs antibody response is dependent on CD4.sup.+ T cells.
(17) Transgenic mice expressing both HLA-A2.1 class I and HLA-DR1 class II molecules have already been derived (BenMohamed, L. et al. Hum Immunol 61, 764-779 (2000)). The authors reported that both the HLA-A2.I and HLA-DR1 molecules are functional restriction elements in vivo and that the product of the HLA-DR1 transgene enhances the HLA-A2.1-restricted antigen-specific CTL responses. However, the human relevance of the immune responses in these mice is dwarfed by the fact that they still expressed their own H-2 class I and class II molecules, which are usually preferentially and often exclusively used as restricting elements in response to antigens (Ureta-Vidal, A., Firat, H., Perarnau, B. & Lemonnier, F. A., J Immunol 163, 2555-2560 (1999); Rohrlich, P. S. et al., Int Immunol 15, 765-772 (2003)) (A. Pajot, unpublished results). The invention described herein overcomes this limitation by providing HLA-A2.1/HLA-DR1-transgenic, H-2 class I-/class II-KO mice.
(18) In some embodiments the HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice express, in a 2m-KO context, a HLA-A2.1 monochain in which the human 2m is covalently linked by a peptidic arm to the HLA-A2.1 heavy chain. They further lack cell surface expression of conventional H-2 IA and IE class II molecules as a result of the inactivation of the H-2 IA.sup.b gene, since H-2 IE is a pseudogene in the H-2.sup.b haplotype. The results provided herein demonstrate that such mice are deprived of cell surface expression of H-2 class I and class II molecules. However, it was reported in one case that a free class I heavy chain, in particular H-2 D.sup.b, may exist on the surface of a 2m-KO mouse, and could induce an alloreactivity response. Even if this is so, because such mice are empty of peptide, they should not interfere in antigen-specific immune response (Bix, M. & Raulet, D., J Exp Med 176, 829-834 (1992)). This is supported by the report of Allen et al (Allen, H., Fraser, J., Flyer, D., Calvin, S. & Flavell, R., Proc Natl Acad Sci USA 83, 7447-7451 (1986)), in which they confirmed that H-2 D.sup.b is expressed at the cell surface even when there is no 2m present within the cell, but that such D.sup.b antigen is recognized by neither D.sup.b-allospecific or D.sup.b-restricted cytotoxic T lymphocytes. Furthermore, D.sup.b antigens are not recognized by most monoclonal antibodies of the native D.sup.b.
(19) Nonetheless, in HLA-DR single transgenic mice, it was reported that unconventional HLA-DR/H-2 IE.sup.b hybrid complexes may be expressed to some extent on the cell surface, at least in the absence of the HLA-DR chain (Lawrance, S. K. et al., Cell 58, 583-594 (1989)). In spite of this observation, these unconventional molecules were not detected serologically on cell surfaces in HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice, even with mAb (17-3-3S), which is known to react with such hybrid molecules (Ozato, K., Mayer, N. & Sachs, D. H., J Immunol 124, 533-540 (1980)) (
(20) The peripheral CD8.sup.+ T lymphocytes of HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice, compared to parental HLA-A2.1-transgenic H-2 class I-KO mice, are quantitatively and qualitatively similar with full diversification, at least in terms of BV segment usage, of the TCR repertoire. Partial restoration compared to wild-type animals, especially of the CD8.sup.+ T cell pool, has been a constant observation in single HLA-transgenic mice expressing a chimeric (a3 domain of mouse origin) HLA-A2.1 molecule (Pascolo, S. et al., J Exp Med 185, 2043-2051 (1997)). Regardless of the 3 domain substitution, the interaction remains suboptimal between mouse CD8 and HLA-A2.1 molecules, since co-crystal analysis has documented that human CD8 also contacts the HLA-A2.1 heavy chain 2 domain (Gao, G. F. et al., Nature 387, 630-634 (1997)). Suboptimal cooperation might also occur in the endoplasmic reticulum where many molecules (TAP, tapasine, ERp 57) assist MHC class I molecule biosynthesis. However, at this stage, the only documented functional difference between these mice and human endoplasmic reticulum molecules, namely the efficient transport by human but not mouse TAP of COOH-terminus positively charged cytosolic peptides (Momburg, F., Neefjes, J. J. & Hammerling, G. J., Curr Opin Immunol 6, 32-37 (1994)), is not relevant for HLA-A2.1 molecules which bind peptides with a hydrophobic C-terminus, since these peptides are transported efficiently by mouse and human TAP. Even though the number of CD8.sup.+ T lymphocytes is lower in both single HLA-A2.1-transgenic, H-2 class I-KO mice and in HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-KO mice, they respond efficiently against HBsAg and, importantly, the latter mice develop antibody, helper and cytolytic cell responses similar to humans.
(21) One of the difficulties hampering the design of T-epitope-based vaccines targeting T lymphocytes is HLA class I/class II molecule polymorphism. HLA-A2.1 and HLA-DR1 molecules are expressed by a significant proportion of individuals in human populations (30 to 50% for HLA-A2.1, 6 to 18% for HLA-DR1). Even though the functional clustering of HLA class I molecules in superfamilies is based on significant redundancy of the presented sets of peptides.sup.34, individual analysis of the responses elicited by each HLA class I isotypic or allelic variant remains desirable to identify the optimal epitopes they present. This is particularly important to devise a new reagent, such as tetramer (HLA-class I or HLA-class II) to monitor the immune response. For the same reason, it would be helpful to obtain strains of mice co-expressing HLA-A2.1 with other HLA class II molecules, even if the binding of peptides to HLA class II molecules is less restrictive than to class I molecules. Based on the disclosure herein, additional HLA class I-/class II-transgenic, H-2 class I-/class II-KO mice can be constructed for these and other purposes.
(22) Whereas HLA-transgenic H-2-KO mice enable a detailed analysis and optimization of the immunogenicity of antigenic peptides with excellent transposability to humans (Rohrlich, P. S. et al., Int Immunol 15, 765-772 (2003); Loirat, D., Lemonnier, F. A. & Michel, M. L., J Immunol 165, 4748-4755 (2000); Scardino, A. et al., Eur J Immunol 31, 3261-3270 (2001)) this is less evident for vaccine adjuvant-formulation studies. This could be due to differences between the two species in the various effectors that are mobilized early in response to an antigenic challenge. Increasing fundamental knowledge of innate immunity might, in the future, lead to a more complete humanization of the mouse immune system.
(23) In conclusion, the disclosure herein describes an optimized, humanized transgenic mouse model, whose H-2 class I (mouse 2m) and class II (H-2 IA.sup.b) genes have been deleted and replaced with equivalent human genes HHD (HLA-A*0201), HLA-DRA*0101 and HLA-DRB1*0101. Cellular immunity in the HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-KO mice is completely restricted by the human HLA molecules, with a complete absence of immune responses restricted by the murine MHC molecules. The absence of competition between murine MHC and human (transgenic) HLA immune responses allows for use of these mice to characterize epitopes in human vaccines that require collaboration between HLA-restricted CD4.sup.+ T helper and HLA-restricted CD8.sup.+ T cytolytic cells.
(24) HLA is the human MHC complex, and H-2 the mouse MHC complex. The human complex comprises three class I -chain genes, HLA-A, HLA-B, and HLA-C, and three pairs of MHC class II - and -chain genes, HLA-DR, -DP, and -DQ. In many haplotypes, the HLA-DR cluster contains an extra -chain gene whose product can pair with the DR chain, and so the three sets of genes give rise to four types of MHC class II molecules. In the mouse, the three class I -chain genes are H-2-L, H-2-D, and H-2-K. The mouse MHC class II genes are H-2-A and H-2-E.
(25) It is known in the art that genetic diversity exists between the HLA genes of different individuals as a result of both polymorphic HLA antigens and distinct HLA alleles. Accordingly, embodiments of the invention disclosed herein may substitute one polymorphic HLA antigen for another or one HLA allele for another. Examples of HLA polymorphisms and alleles can be found, for example, at http://www.anthonynolan.org.uk/HIG/data.html and http://www.ebi.ac.uk/imgt/hla, and in Genetic diversity of HLA: Functional and Medical Implication, Dominique Charon (Ed.), EDK Medical and Scientific International Publisher, and The HLA FactsBook, Steven G. E. Marsh, Peter Parham and Linda Barber, AP Academic Press, 2000.
(26) A disrupted gene is one that has been mutated using homologous recombination or other approaches known in the art. A disrupted gene can be either a hypomorphic allele of the gene or a null allele of the gene. One of skill in the art will recognize that the type of allele to be used can be selected for any particular context. In many embodiments of the invention, a null allele is preferred.
(27) Homologous recombination is a general approach for targeting mutations to a preselected, desired gene sequence of a cell in order to produce a transgenic animal (Mansour, S. L. et al., Nature 336:348-352 (1988); Capecchi, M. R., Trends Genet. 5:70-76 (1989); Capecchi, M. R., Science 244:1288-1292 (1989); Capecchi, M. R. et al., In: Current Communications in Molecular Biology, Capecchi, M. R. (ed.), Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989), pp. 45-52; Frohman, M. A. et al., Cell 56:145-147 (1989)).
(28) It is now be feasible to deliberately alter any gene in a mouse (Capecchi, M. R., Trends Genet. 5:70-76 (1989); Frohman, M. A. et al., Cell 56:145-147 (1989)). Gene targeting involves the use of standard recombinant DNA techniques to introduce a desired mutation into a cloned DNA sequence of a chosen locus. That mutation is then transferred through homologous recombination to the genome of a pluripotent, embryo-derived stem (ES) cell. The altered stem cells are microinjected into mouse blastocysts and are incorporated into the developing mouse embryo to ultimately develop into chimeric animals. In some cases, germ line cells of the chimeric animals will be derived from the genetically altered ES cells, and the mutant genotypes can be transmitted through breeding.
(29) Gene targeting has been used to produce chimeric and transgenic mice in which an nptII gene has been inserted into the .sub.2-microglobulin locus (Koller, B. H. et al., Proc. Natl. Acad. Sci. (U.S.A.) 86:8932-8935 (1989); Zijlstra, M. et al., Nature 342:435-438 (1989); Zijlstra, M. et al., Nature 344:742-746 (1989); DeChiaba et al., Nature 345:78-80 (1990)). Similar experiments have enabled the production of chimeric and transgenic animals having a c-abl gene which has been disrupted by the insertion of an nptII gene (Schwartzberg, P. L. et al., Science 246:799-803 (1989)). The technique has been used to produce chimeric mice in which the en-2 gene has been disrupted by the insertion of an nptII gene (Joyner, A. L. et al., Nature 338:153-155 (1989)).
(30) In order to utilize the gene targeting method, the gene of interest must have been previously cloned, and the intron-exon boundaries determined. The method results in the insertion of a marker gene (e.g., an nptII gene) into a translated region of a particular gene of interest. Thus, use of the gene targeting method results in the gross destruction of the gene of interest.
(31) Significantly, the use of gene targeting to alter a gene of a cell results in the formation of a gross alteration in the sequence of that gene. The efficiency of gene targeting depends upon a number of variables, and is different from construct to construct.
(32) The chimeric or transgenic animal cells of the present invention are prepared by introducing one or more DNA molecules into a cell, which may be a precursor pluripotent cell, such as an ES cell, or equivalent (Robertson, E. J., In: Current Communications in Molecular Biology, Capecchi, M. R. (ed.), Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989), pp. 39-44). The term precursor is intended to denote only that the pluripotent cell is a precursor to the desired (transfected) pluripotent cell, which is prepared in accordance with the teachings of the present invention. The pluripotent (precursor or transfected) cell can be cultured in vivo in a manner known in the art (Evans, M. J. et al., Nature 292:154-156 (1981)) to form a chimeric or transgenic animal.
(33) Any ES cell can be used in accordance with the present invention. It is, however, preferred to use primary isolates of ES cells. Such isolates can be obtained directly from embryos, such as the CCE cell line disclosed by Robertson, E. J., In: Current Communications in Molecular Biology, Capecchi, M. R. (ed.), Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989), pp. 39-44), or from the clonal isolation of ES cells from the CCE cell line (Schwartzberg, P. A. et al., Science 246:799-803 (1989), which reference is incorporated herein by reference). Such clonal isolation can be accomplished according to the method of E. J. Robertson (In: Teratocarcinomas and Embryonic Stem Cells: A Practical Approach, (E. J. Robertson, Ed.), IRL Press, Oxford, 1987), which reference and method are incorporated herein by reference. The purpose of such clonal propagation is to obtain ES cells, which have a greater efficiency for differentiating into an animal. Clonally selected ES cells are approximately 10-fold more effective in producing transgenic animals than the progenitor cell line CCE. For the purposes of the recombination methods of the present invention, clonal selection provides no advantage.
(34) An example of ES cell lines, which have been clonally derived from embryos, are the ES cell lines, AB1 (hprt.sup.+) or AB2.1 (hprt.sup.). The ES cells are preferably cultured on stromal cells (such as STO cells (especially SNC4 STO cells) and/or primary embryonic fibroblast cells) as described by E. J. Robertson (In: Teratocarcinomas and Embryonic Stem Cells: A Practical Approach, (E. J. Robertson, Ed., IRL Press, Oxford, 1987, pp 71-112), which reference is incorporated herein by reference. Methods for the production and analysis of chimeric mice are disclosed by Bradley, A. (In: Teratocarcinomas and Embryonic Stem Cells: A Practical Approach, (E. J. Robertson, Ed.), IRL Press, Oxford, 1987, pp 113-151), which reference is incorporated herein by reference. The stromal (and/or fibroblast) cells serve to eliminate the clonal overgrowth of abnormal ES cells. Most preferably, the cells are cultured in the presence of leukocyte inhibitory factor (lif) (Gough, N. M. et al., Reprod. Fertil. Dev. 1:281-288 (1989); Yamamori, Y. et al., Science 246:1412-1416 (1989), both of which references are incorporated herein by reference). Since the gene encoding lif has been cloned (Gough, N. M. et al., Reprod. Fertil. Dev. 1:281-288 (1989)), it is especially preferred to transform stromal cells with this gene, by means known in the art, and to then culture the ES cells on transformed stromal cells that secrete lif into the culture medium.
(35) As used herein, the term transgene refers to a nucleic acid sequence, which is partly or entirely heterologous, i.e., foreign, to the transgenic animal or cell into which it is introduced, or, is homologous to an endogenous gene of the transgenic animal or cell into which it is introduced, but which is designed to be inserted, or is inserted, into the animal's genome in such a way as to alter the genome of the cell into which it is inserted (e.g., it is inserted at a location which differs from that of the natural gene or its insertion results in a knockout). A transgene can be operably linked to one or more transcriptional regulatory sequences and any other nucleic acid, such as introns, that may be necessary for optimal expression of a selected nucleic acid. Exemplary transgenes of the present invention encode, for instance an H-2 polypeptide. Other exemplary transgenes are directed to disrupting one or more HLA genes by homologous recombination with genomic sequences of an HLA gene.
(36) A functional transgene is one that produces an mRNA transcript, which in turn produces a properly processed protein in at least one cell of the mouse comprising the transgene. One of skill will realize that the diverse set of known transcriptional regulatory elements and sequences directing posttranscriptional processing provide a library of options from which to direct the expression of a transgene is a host mouse. In many embodiments of the invention, expression of an HLA transgene under the control of an H-2 gene regulatory element may be preferred.
(37) In some embodiments, the HLA class I transgene is an HLA-A2 transgene and the HLA class II transgene is an HLA-DR1 transgene. An example of an HLA-A2 transgene is one that comprises the HLA-A2 sequence provided in the sequence listing. An example of an HLA-DR1 transgene is one that comprises the HLA-DR1 sequence provided in the sequence listing.
(38) In an embodiment, the invention provides a transgenic mouse deficient for both H2 class I and class II molecules, wherein the transgenic mouse comprises a functional HLA class I transgene and a functional HLA class II transgene. In some embodiments, the mouse has the genotype HLA-A2.sup.+HLA-DR1.sup.+2mIA. In other embodiments the HLA-A2 transgene comprises the HLA-A2 sequence provided in the sequence listing and the HLA-DR1 transgene comprises the HLA-DR1 sequence provided in the sequence listing.
(39) The invention also provides isolated transgenic mouse cells. In some cases the cell comprises a disrupted H2 class I gene, a disrupted H2 class II gene, and a functional HLA class I or class II transgene. In others, the cell comprises a disrupted H2 class I gene, a disrupted H2 class II gene, a functional HLA class I transgene, and a functional HLA class II transgene. The HLA class I transgene can be an HLA-A2 transgene and the HLA class II transgene can be an HLA-DR1 transgene. In some cases, the HLA-A2 transgene comprises the HLA-A2 sequence provided in the sequence listing and the HLA-DR1 transgene comprises the HLA-DR1 sequence provided in the sequence listing.
(40) In an embodiment, the invention provides an isolated transgenic mouse cell deficient for both H2 class I and class II molecules, wherein the transgenic mouse comprises a functional HLA class I transgene and a functional HLA class II transgene. The isolated transgenic mouse cells can have the genotype HLA-A2.sup.+HLA-DR1.sup.+2mIA. The HLA-A2 transgene can comprise the HLA-A2 sequence provided in the sequence listing and the HLA-DR1 transgene can comprise the HLA-DR1 sequence provided in the sequence listing.
(41) The isolated transgenic mouse cells of the invention can have the genotype of any mouse of the invention. However, the set of genotypes of the isolated transgenic mouse cells of the invention, and the set of genotypes of the mice of the invention are not necessarily entirely overlapping.
(42) The isolated mouse cells of the invention can be obtained from a mouse or mouse embryo. In one embodiment, the mouse or mouse embryo has the same genotype as the cell to be obtained. In another embodiment, the mouse or mouse embryo has a different genotype than the cell to be obtained. After the cell is obtained from the mouse or mouse embryo, a gene of the cell can be disrupted by, for example, homologous recombination. Additionally, a functional transgene can be introduced into the genome of the cell by, for example, transfection. One of skill in the art will recognize that any suitable method known in the art can be applied to modify the genome of the cell to thereby obtain an isolated mouse cell having the desired genotype.
(43) An additional object of the invention is an isolated transgenic mouse cell deficient for both H2 class I and class II molecules, wherein the transgenic mouse cell comprises a functional HLA class I transgene and a functional HLA class II transgene. In some embodiments, the transgenic mouse cell has the genotype HLA-A2.sup.+HLA-DR1.sup.+2mIA. In other embodiments, the HLA-A2 transgene comprises the HLA-A2 sequence provided in the sequence listing and the HLA-DR1 transgene comprises the HLA-DR1 sequence provided in the sequence listing.
(44) T cells play a central role in many aspects of acquired immunity, carrying out a variety of regulatory and defensive functions. When some T cells encounter an infected or cancerous cell, they recognize it as foreign and respond by acting as killer cells, killing the host's own cells as part of the cell-mediated immune response. Other T cells, designated helper T cells, respond to perceived foreign antigens by stimulating B cells to produce antibodies, or by suppressing certain aspects of a humoral or cellular immune response.
(45) T helper cells (Th) orchestrate much of the immune response via the production of cytokines. Although generally identifiable as bearing the CD4 cell surface marker, these cells are functionally divided into Th1 or Th2 subpopulations according to the profile of cytokines they produce and their effect on other cells of the immune system.
(46) The Th1 cells detect invading pathogens or cancerous host cells through a recognition system referred to as the T cell antigen receptor. Termed cellular immunity, Th1-related processes generally involve the activation of non-B cells and are frequently characterized by the production of IFN-. Nevertheless, although the Th1 system is primarily independent from the production of humoral antibodies, Th1 cytokines do promote immunoglobulin class switching to the IgG.sub.2a isotype.
(47) Upon detection of a foreign antigen, most mature Th1 cells direct the release of IL-2, IL-3, IFN-, TNF-, GM-CSF, high levels of TNF-, MIP-1, MIP-1, and RANTES. These cytokines promote delayed-type hypersensitivity and general cell-mediated immunity. IL-2, for instance, is a T cell growth factor that promotes the production of a clone of additional T cells sensitive to the particular antigen that was initially detected. The sensitized T cells attach to and attack cells or pathogens containing the antigen.
(48) In contrast, mature Th2 cells tend to promote the secretion of IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, GM-CSF, and low levels of TNF-. In addition, the Th2 response promotes humoral immunity by activating B cells, stimulating antibody production and secretion, and inducing class switching to IgA, IgG.sub.1 and IgE isotypes.
(49) As used herein, an antigen comprises: 1) at least one HTL epitope, or 2) at least one CTL epitope or, 3) at least one B cell epitope, or 4) at least one HTL epitope and at least one CTL epitope, or 5) at least one HTL epitope and at least one B cell epitope, or 6) at least one CTL epitope and at least one B cell epitope, or 7) at least one HTL epitope and at least one CTL epitope and at least one B cell epitope. A candidate antigen is a molecule that is under investigation to determine whether it functions as an antigen.
(50) A humoral immune response is antibody-mediated specific immunity.
(51) An epitope is a site on an antigen that is recognized by the immune system. An antibody epitope is a site on an antigen recognized by an antibody. A T-cell epitope is a site on an antigen that binds to an MHC molecule. A TH epitope is one that binds to an MHC class II molecule. A CTL epitope is one that binds to an MHC class I molecule.
(52) The antigen can comprise a polypeptide sequence or a polynucleotide sequence, which can comprise RNA, DNA, or both. In one embodiment, the antigen comprises at least one polynucleotide sequence operationally encoding one or more antigenic polypeptides. Used in this context, the word comprises intends that at least one antigenic polypeptide is provided by the transcription and/or translation apparatus of a host cell acting upon an exogenous polynucleotide that encodes at least one antigenic polypeptide, as described, for example in U.S. Pat. Nos. 6,194,389 and 6,214,808.
(53) Antigens of the invention can be any antigenic molecule. Antigenic molecules include: proteins, lipoproteins, and glycoproteins, including viral, bacterial, parasitic, animal, and fungal proteins such as albumins, tetanus toxoid, diphtheria toxoid, pertussis toxoid, bacterial outer membrane proteins (including meningococcal outer membrane protein), RSV-F protein, malarial derived peptide, B-lactoglobulin B, aprotinin, ovalbumin, lysozyme, and tumor associated antigens such as carcinoembryonic antigen (CEA), CA 15-3, CA 125, CA 19-9, prostrate specific antigen (PSA), and the TAA complexes of U.S. Pat. No. 5,478,556, which is incorporated herein by reference in its entirety; carbohydrates, including naturally-occurring and synthetic polysaccharides and other polymers such as ficoll, dextran, carboxymethyl cellulose, agarose, polyacrylamide and other acrylic resins, poly (lactide-co-glycolide), polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, polyvinylpryrolidine, Group B Steptococcal and Pneumococcal capsular polysaccharides (including type III), Pseudomonas aeruginosa mucoexopolysaccharide, and capsular polysaccharides (including fisher type I), and Haemophilus influenzae polysaccharides (including PRP); haptens, and other moieties comprising low molecular weight molecules, such as TNP, saccharides, oligosaccharides, polysaccharides, peptides, toxins, drugs, chemicals, and allergens; and haptens and antigens derived from bacteria, rickettsiae, fungi, viruses, parasites, including Diphtheria, Pertussis, Tetanus, H. influenzae, S. pneumoniae, E. coli, Klebsiella, S. aureus, S. epidermidis, N. meningiditis, Polio, Mumps, measles, rubella, Respiratory Syncytial Virus, Rabies, Ebola, Anthrax, Listeria, Hepatitis A, B, C, Human Immunodeficiency Virus I and II, Herpes simplex types 1 and 2, CMV, EBV, Varicella Zoster, Malaria, Tuberculosis, Candida albicans, and other candida, Pneumocystis carinii, Mycoplasma, Influenzae virus A and B, Adenovirus, Group A streptococcus, Group B streptococcus, Pseudomonas aeryinosa, Rhinovirus, Leishmania, Parainfluenzae, types 1, 2 and 3, Coronaviruses, Salmonella, Shigella, Rotavirus, Toxoplasma, Enterovirusses, and Chlamydia trachomatis and pneumoniae.
(54) As used herein, a pharmaceutical composition or vaccine comprises at least one immunological composition, which can be dissolved, suspended, or otherwise associated with a pharmaceutically acceptable carrier or vehicle. Any pharmaceutically acceptable carrier can be employed for administration of the composition. Suitable pharmaceutical carriers are described in Remington's Pharmaceutical Sciences, 18th Edition (A. Gennaro, ed., 1990) Mack Pub., Easton, Pa., which is incorporated herein by reference in its entirety. Carriers can be sterile liquids, such as water, polyethylene glycol, dimethyl sulfoxide (DMSO), oils, including petroleum oil, animal oil, vegetable oil, peanut oil, soybean oil, mineral oil, sesame oil, and the like. Carriers can be in the form of mists, sprays, powders, waxes, creams, suppositories, implants, salves, ointments, patches, poultices, films, or cosmetic preparations.
(55) Proper formulation of the pharmaceutical composition or vaccine is dependent on the route of administration chosen. For example, with intravenous administration by bolus injection or continuous infusion, the compositions are preferably water soluble, and saline is a preferred carrier. For transcutaneous, intranasal, oral, gastric, intravaginal, intrarectal, or other transmucosal administration, penetrants appropriate to the barrier to be permeated can be included in the formulation and are known in the art. For oral administration, the active ingredient can be combined with carriers suitable for inclusion into tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like. Time-sensitive delivery systems are also applicable for the administration of the compositions of the invention. Representative systems include polymer base systems, such as poly(lactide-glycoside), copolyoxalates, polycaprolactones, polyesteram ides, polyorthoesters, polyhydroxybutyric acid and polyanhydrides. These and like polymers can be formulated into microcapsules according to methods known in the art, for example, as taught in U.S. Pat. No. 5,075,109, which is incorporated herein by reference in its entirety. Alternative delivery systems appropriate for the administration of the disclosed immunostimulatory compounds of the invention include those disclosed in U.S. Pat. Nos. 6,194,389, 6,024,983, 5,817,637, 6,228,621, 5,804,212, 5,709,879, 5,703,055, 5,643,605, 5,643,574, 5,580,563, 5,239,660, 5,204,253, 4,748,043, 4,667,014, 4,452,775, 3,854,480, and 3,832,252 (each of which is incorporated herein by reference in its entirety).
(56) Aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable or aerosol solutions. For administration by aerosol, as by pressurized spray or nebulizer, suitable propellants can be added as understood by those familiar with the art. The immunological composition can also be formulated with solubilizing agents; emulsifiers; stabilizers; dispersants; flavorants; adjuvants; carriers; topical anesthetics, such as lidocaine, xylocaine, and the like; antibiotics; and known or suspected anti-viral, anti-fungal, anti-parasitic, or anti-tumor compounds.
(57) An adjuvant is a composition that promotes or enhances an immune response to a target antigen. One of skill in the art can select an appropriate adjuvant for use in practicing the present invention in view of the disclosure herein.
(58) The present invention encompasses methods of treating a patient in need of immune stimulation by administering a composition comprising one or more antigens of the invention. As used herein, treatment encompasses corrective, restorative, ameliorative, and preventive methods relating to any disease, condition, abnormality, or symptom. Treatment further encompasses the elicitation or suppression of an immune response in an experimental animal or ex vivo.
(59) Thus, treatment comprises administering an immunostimulatory amount of any of the immunostimulatory compositions of the invention by any method familiar to those of ordinary skill in the art, commonly including oral and intranasal routes, and intravenous, intramuscular, and subcutaneous injections, but also encompassing, intraperitoneal, intracorporeal, intra-articular, intraventricular, intrathecal, topical, tonsillar, mucosal, transdermal, intravaginal administration and by gavage.
(60) As is recognized by the skilled practitioner, choosing an appropriate administration method may contribute to the efficacy of a treatment, and local administration may be preferred for some applications. Acceptable routes of local administration include subcutaneous, intradermal, intraperitoneal, intravitreal, inhalation or lavage, oral, intranasal, and directed injection into a predetermined tissue, organ, joint, tumor, or cell mass. For example, mucosal application or injection into mucosal lymph nodes or Peyer's patches may promote a humoral immune response with substantial IgA class switching. Alternatively, targeted injection into a lesion, focus, or affected body site may be applicable for the treatment of solid tumors, localized infections, or other situs requiring immune stimulation.
(61) Alternatively, cells of the immune system (e.g., T cells, B cells, NK cells, or oligodendrocytes) can be removed from a host and treated in vitro. The treated cells can be further cultured or reintroduced to a patient (or to a heterologous host) to provide immune stimulation to the patient or host. For example, bone marrow cells can be aspirated from a patient and treated with an HDR to stimulate global or specific immunity. High-dose radiation, or comparable treatments, can then be used to destroy the remaining immune cells in the patient. Upon re-implantation, the autologous stimulated cells will restore normal immune function in the patient. Alternatively, NK and/or T cells isolated from a patient suffering from cancer may be exposed in vitro to one or more antigens specific to the patient's cancer. Upon re-implantation into the patient, the antigen-stimulated cells will deploy a vigorous cellular immune response against the cancerous cells.
(62) An immunostimulatory (efficacious) amount refers to that amount of vaccine that is able to stimulate an immune response in a patient, which is sufficient to prevent, ameliorate, or otherwise treat a pathogenic challenge, allergy, or immunologic abnormality or condition. An immunostimulatory amount is that amount, which provides a measurable increase in a humoral or cellular immune response to at least one epitope of the antigen as compared to the response obtained if the antigen is administered to the patient without prior treatment with the vaccine. Thus, for example, an immunostimulatory amount refers to that amount of an antigen-containing composition that is able to promote the production of antibodies directed against an antigenic epitope of interest or stimulate a detectable protective effect against a pathogenic or allergenic challenge or to promote a protective CTL response against an antigenic epitope of interest.
(63) Treatment with an immunostimulatory amount of an antigen-containing composition of the invention comprises effecting any directly, indirectly, or statistically observable or measurable increase or other desired change in the immune response in a host, specifically including an ex vivo tissue culture host, comprising at least one cell of the immune system or cell line derived therefrom. Host cells can be derived from human or animal peripheral blood, lymph nodes or the like. Preferred tissue culture hosts include freshly isolated T cells, B cells, macrophages, oligodendrocytes, NK cells, and monocytes, each of which can be isolated or purified using standard techniques. Observable or measurable responses include, B or T cell proliferation or activation; increased antibody secretion; isotype switching; increased cytokine release, particularly the increased release of one or more of IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12, IL-13, GM-CSF, IFN-, TNF-, TNF-, GM-CSF, MIP-1, MIP-1, or RANTES; increased antibody titer or avidity against a specific antigen; reduced morbidity or mortality rates associated with a pathogenic infection; promoting, inducing, maintaining, or reinforcing viral latency; suppressing or otherwise ameliorating the growth, metastasis, or effects of malignant and non-malignant tumors; and providing prophylactic protection from a disease or the effects of a disease.
(64) Where the suppression of an immunological response is desired, for example, in the treatment of autoimmune disease or allergy, an effective amount also encompasses that amount sufficient to effect a measurable or observable decrease in a response associated with the condition or pathology to be treated.
(65) The amount of an antigen-containing composition to be administered and the frequency of administration can be determined empirically and will take into consideration the age and size of the patient being treated, and the condition or disease to be addressed. An appropriate dose is within the range of 0.01 g to 100 g per inoculum, but higher and lower amounts may also be indicated. Secondary booster immunizations can be given at intervals ranging from one week to many months later.
(66) The following examples demonstrate certain embodiments of the invention. One of ordinary skill in the art will recognize the numerous modifications and variations that may be performed without altering the spirit or scope of the present invention. Such modifications and variations are believed to be encompassed within the scope of the invention. The examples do not in any way limit the invention.
EXAMPLES
(67) The following experimental techniques and reagents were used to demonstrate certain nonlimiting embodiments of the invention.
(68) Transgenic Mice
(69) The HLA-DR1-transgenic H-2 class II-KO (IA .sup.b) mice were obtained at the Institut Pasteur of Lille by crossing HLA-DR1-transgenic mice (Altmann, D. M. et al., J Exp Med 181, 867-875 (1995)) with H-2 class II-KO (IA .sup.b) mice (Rohrlich, P. S. et al., Int Immunol 15, 765-772 (2003)). The HLA-A2.1-transgenic mice, expressing a chimeric monochain (HHD molecule: 1-2 domains of HLA-A2.1, 3 to cytoplasmic domains of H-2 D.sup.b, linked at its N-terminus to the C terminus of human 2m by a 15 amino-acid peptide linker) were created (Pascolo, S. et al., J Exp Med 185, 2043-2051 (1997)). HLA-A2.1 (HHD)-transgenic H-2 class I-KO and HLA-DR1-transgenic H-2 class II-KO (IA .sup.b) mice were intercrossed and progenies screened until HLA-A2.1.sup.+//HLA-DR1.sup.+/ double transgenic H-2-class I (2m.sup.0)-/class II (IA.sup.0)-KO animals were obtained and used for the experiments described herein. HLA-A2.1.sup.+/ single transgenic H-2-class I (2m.sup.0)-/class II (IA.sup.0)-KO mice were used as controls in the protection assays. Mice were bred in the animal facilities at the Institut Pasteur, Paris; all protocols were reviewed by the Institut Pasteur competent authority for compliance with the French and European regulations on Animal Welfare and with Public Health Service recommendations.
(70) Genotyping
(71) The HLA-DRB1*0101, HLA-DRA*0101 and HLA-A*0201 transgenes were detected by PCR. Tail-DNA was extracted after overnight incubation at 56 C. in 100 mM NaCl, 50 mM Tris-HCl pH 7.2, 100 mM EDTA, 1% SDS and 0.5 mg/ml proteinase K, followed by the addition of 250 l of saturated NaCl solution and isopropanol precipitation. The samples were washed (3) in 70% ethanol and resuspended in 150 l of 10 mM Tris-HCl, 1 mM EDTA pH 8. PCR conditions were: 1.5 mM MgCl.sub.2, 1.25 U of Taq Polymerase, buffer supplied by the manufacturer (InVitrogen, Carlsbad, Calif.), 1 cycle (7 min, 94 C.), 40 cycles (30 sec, 94 C.; 30 sec, 60 C.; 1 min, 72 C.), 1 cycle (4 min, 72 C.), using as forward and reverse primers, for HHD: 5CAT TGA GAC AGA GCG CTT GGC ACA GAA GCA G 3 and 5GGA TGA CGT GAG TAA ACC TGA ATC TTT GGA GTA CGC 3, for HLA-DRB1*0101: 5 TTC TTC AAC GGG ACG GAG CGG GTG 3 and 5 CTG CAC TGT GAA GCT CTC ACC AAC 3, and for HLA-DRA*0101: 5 CTC CAA GCC CTC TCC CAG AG 3 and 5 ATG TGC CTT ACA GAG GCC CC 3.
(72) FACS Analysis
(73) Cytofluorimetry studies were performed on red-blood cell-depleted, Lympholyte M-purified (Tebu-bio, Le Perray en Yvelines, France) splenocytes using FITC-conjugated W6/32 (anti-HLA-ABC, Sigma, St Louis, Mo.) and biotinilated anti-28-8-6S (anti-H-2 K.sup.b/D.sup.b, BD Biosciences, San Diego, Calif.) m.Ab. CD4.sup.+ and CD8.sup.+ T lymphocytes were stained using PE-labeled CT-CD4 anti-mouse CD4 (CALTAG, South San Francisco, Calif.) and FITC-labeled 53-6.7 anti-mouse CD8 m.Ab (BD Biosciences). Analysis of MHC class II molecule expression was performed on B220.sup.+ B lymphocytes positively selected on MS columns (Miltenyi Biotec, Bergisch Gladbach, Germany). Following saturation of Fc receptors with 2.4G2 m.Ab, expression of HLA-DR1 and H-2 IA.sup.b was analyzed using FITC-labeled L243 (anti-HLA-DR) and PE-labeled AF6-120.1 (anti-H-2 IA.sup.b) m.Ab (BD Biosciences). Paraformaldehyde fixed cells were analyzed with a FACSCalibur (Becton Dickinson, Bedford, Mass.).
(74) Immunoscope Analyses
(75) CD4.sup.+ and CD8.sup.+ T cells from naive mice were positively selected on Auto-Macs (Miltenyi Biotec), RNA prepared using RNA Easy Kit (Qiagen, Hilden, Germany) and used for cDNA synthesis. The cDNA was PCR-amplified using forward primers specific for each BV segment family and a reverse primer shared by the two BC segments. PCR-products were subjected to a run-off-elongation with internal BC FAM-tagged primer. The run-off products were loaded on a 6% acrylamide/8 M urea gel for separation (7 h, 35 W) with a 373A DNA sequencer (Perkin Elmer Applied Biosystem, Foster City, Calif.). Data were analyzed using immunoscope software (Pannetier, C. et al., Proc Natl Acad Sci USA 90, 4319-4323 (1993)).
(76) Peptides
(77) The HLA-A2 binding peptides HBsAg.sub.348-357 GLSPTVWLSV and HBsAg.sub.335-343 WLSLLVPFV, the H-2 K.sup.b binding peptide HBsAg.sub.371-378 ILSPFLPL, the HLA-DR1 binding peptide HBsAg.sub.180-195 QAGFFLLTRILTIPQS, the H-2 IA.sup.b binding peptide HBsAg.sub.126-138 RGLYFPAGGSSSG and the preS2 peptide HBsAg.sub.109-134 MQWNSTTFHQTLQDPRVRGLYFPAGG were synthesized by Neosystem (Strasbourg, France) and dissolved in PBS-10% DMSO at a concentration of 1 mg/ml. The numbering of the amino acid sequence of peptides starts from the first methionine of the HBV ayw subtype preS1 domain.
(78) Immunization with DNA Encoding the S2-S Proteins of HBV
(79) The pCMV-S2.S plasmid vector (Michel, M. L. et al., Proc Natl Acad Sci USA 92, 5307-5311 (1995)) coding for the preS2 and the S HBV surface antigens expressed under the control of the human CMV immediate early gene promotor was purified on Plasmid Giga Kit columns under endotoxin free conditions (Qiagen). Anesthesized mice were injected (50 g each side) into regenerating tibialis anterior muscles, as previously described (Davis, H. L., Michel, M. L. & Whalen, R. G., Hum Mol Genet 2, 1847-1851 (1993)).
(80) T Cell Proliferation Assay
(81) Twelve days after the last immunization, red-blood cell-depleted, Ficoll-purified splenocytes (5.Math.10.sup.6 cells/25 cm.sup.2 culture flask (Techno Plastic Products (TPP), Trasadingen, Switzerland)) were co-cultured with peptide-pulsed (20 g/ml), -irradiated (180 Gy) LPS-blasts (5.Math.10.sup.6 cells/culture flask) in RPMI medium supplemented with 10% FCS, 10 mM HEPES, 1 mM sodium pyruvate, 510.sup.5 M 2-mercaptoethanol, 100 I.U/ml penicillin and 100 g streptomycin, as described (Loirat, D., Lemonnier, F. A. & Michel, M. L., J Immunol 165, 4748-4755 (2000)). On day 7, for proliferation assays, cells were plated (510.sup.5 cells/well of flat bottomed 96 well microplates, (TPP)) with peptide-pulsed irradiated LPS-Blasts (210.sup.5 cells/well) for 72 h in complete RPMI medium supplemented with 3% FCS. Cells were pulsed for the final 16 h with 1 Ci of (.sup.3H)-thymidine per well before being harvested on filtermates with a TOMTEC collector (Perkin Elmer Applied Biosystem), and incorporated radioactivity was measured on a micro- counter (Perkin Elmer Applied Biosystem). Results are given as stimulation index (SI)=cpm with specific peptide/cpm with irrelevant peptide.
(82) Measurement of CTL Activity
(83) Cytotoxicity assays were performed on the same immune splenocyte populations as the proliferation assays. Responder cells (5.Math.10.sup.6 cells/25 cm.sup.2 culture flask, TPP) and stimulating peptide-pulsed (20 g/ml), -irradiated (180 Gy) LPS-blasts (5.Math.10.sup.6 cells/culture flask) were co-cultured for 7 days in the same supplemented RPMI medium as for proliferation assays. Cytolytic activity was tested in a standard 4 h .sup.51Cr assay against RMA-S HHD target cells pulsed with 10 g/ml of the experimental or control peptides. Specific lysis, in %, was calculated in duplicates, according to: [experimentalspontaneous release]/[maximalspontaneous release]100, substracting the non-specific lysis observed with the control peptide.
(84) Measurement of In Vivo Antibody Production
(85) At various times before and after DNA injection, blood was collected from mice by retrobulbar puncture with heparinized glass pipettes, and sera recovered by centrifugation were assayed for anti-HBs and anti-preS2 by specific ELISA. Purified recombinant particles containing HBV small S protein (1 ug/ml) or preS2 (120-145) synthetic peptide (1 ug/ml) were used as the solid phase. After blocking with PBST (PBS containing 0.1% Tween 20) supplemented with 10% FCS, serial dilutions were added. After extensive washing, the bound antibodies were detected with anti mouse Ig (total IgG) labeled with horseradish peroxidase (Amersham, Little Chalfont, UK). Antibody titers were determined by the serial end-point dilution method. Mouse sera were tested individually, and titers were the mean of at least three determinations. Serum dilutions below 1/100 were considered negative.
(86) Antibody Titration
(87) Sera from immunized mice were individually assayed by ELISA (Michel, M. L. et al., Proc Natl Acad Sci USA 92, 5307-5311 (1995)) on either purified HBV middle and small proteins or preS2 synthetic HBs.sub.109-134. peptide, After blocking with PBS 1 supplemented with 0.1% Tween 20, 10% FCS and washings (3), bound antibodies were detected with horseradish peroxidase-labeled anti-mouse IgG (Amersham, Little Chalfont, UK). Antibody titers (means of at least 3 determinations) were determined by the serial end-point dilution method. Titers below 1/100 were considered negative.
(88) Vaccinia Challenge and Plaque Assay
(89) DNA-injected mice were challenged intraperitoneally 12 days post last injection with 10.sup.7 PFU of recombinant vaccinia virus (Western Reserve strain) expressing either the HbsAg (Smith, G. L., Mackett, M. & Moss, B., Nature 302, 490-495 (1983)) or the HBx protein (Schek, N., Bartenschlager, R., Kuhn, C. & Schaller, H., Oncogene 6, 1735-1744. (1991)) kindly provided, respectively, by Dr B. Moss and Dr H. Schaller. Four days later, ovaries were assayed for rVV titers by plaque assay on BHK 21 cells (Buller, R. M. & Wallace, G. D., Lab Anim Sci 35, 473-476 (1985).
Example 1: Cell Surface Expression of MHC Molecules
(90) Cell surface expression of the HLA-A2.1, H-2 K.sup.b/D.sup.b, HLA-DR1, and H-2 IA.sup.b molecules was evaluated on splenocytes by flow cytometry. As illustrated in
Example 2: Peripheral CD4+ and CD8+ T Cells
(91) CD4.sup.+ and CD8.sup.+ splenic T cell numbers were determined by immunostaining and flow cytometry analysis as illustrated in
(92) CD4.sup.+ T cells represented 13-14% of the splenocyte population in both HLA-A2.1-/HLA-DR1-transgenic, H-2 class I/class II-KO mice and HLA-DR1-transgenic, H-2 class II-KO mice. In contrast, only 2-3% of the cells were CD4.sup.+ in H-2 class II-KO mice (data not shown), in agreement with the initial report on mice lacking MHC class II molecules (Cosgrove, D. et al., Cell 66, 1051-1066 (1991)). As expected, expression of transgenic HLA-A2.1 molecules led to an increase in the size of the peripheral CD8.sup.+ T cell population, which reached 2-3% of the total splenocytes in both HLA-A2.1-/HLA-DR1-transgenic, H-2 class I/class II-KO mice and HLA-A2.1-transgenic, H-2 class I-KO mice, compared to 0.6-1% in the 2 microglobulin (2m)-KO MHC class I-deficient mice (Pascolo, S. et al., J Exp Med 185, 2043-2051 (1997)).
(93) The results presented in Examples 1 and 2 show that: (1) In the HLA-A2.sup.+HLA-DR1.sup.+ 2mIA mouse, the expression of HLA-A2 molecules, the absence of expression of H2-K.sup.b molecules, the number of CD8.sup.+ peripheral T-lymphocytes, and the diversity of the CD8.sup.+ T repertoire are generally comparable to the HLA-A2.sup.+ 2m mouse; (2) In the HLA-A2.sup.+HLA-DR1.sup.+ 2mIA mouse, the expression of HLA-DR1 molecules, the absence of expression of H2-IA.sup.b molecules, the number of CD4.sup.+ T-lymphocytes, and the diversity of the CD4.sup.+ repertoire are generally comparable to the HLA-DR1.sup.+IA mouse; and (3) The HLA-A2.sup.+HLA-DR1.sup.+ 2mIA mouse has all the characteristic advantages found in HLA-A2.sup.+2m mice, and the HLA-DR1.sup.+IA mice.
Example 3: TCR BV Segment Usage
(94) As the presence of a single MHC class I and single MHC class II molecule could diminish the size and diversity of the TCR repertoire, the expression of the various BV families and the CDR3 length diversity was studied as previously described (Cochet, M. et al., Eur J Immunol 22, 2639-2647 (1992)) by the RT-PCR-based immunoscope technique, on purified splenic CD4.sup.+ or CD8.sup.+ T cells. Peaks of significant magnitude with a Gaussian-like distribution were observed for most BV families (15 out of the 20 analyzed) in both CD8.sup.+ (
(95) Absence of expansion (or profoundly altered profile) as observed for BV 5.3 and 17 were expected since these two BV segments are pseudogenes in C57BL/6 mice (Wade, T., Bill, J., Marrack, P. C., Palmer, E. & Kappler, J. W., J Immunol 141, 2165-2167 (1988)); Chou, H. S. et al., Proc Natl Acad Sci USA 84, 1992-1996 (1987). However, the altered profiles observed for BV 5.1, 5.2 and 11 segments were due to a small subpopulation of corresponding BV-expressing T cells (they represent lower than 5% in C57BL/6 mice, and around 2% in HLA-DR1-transgenic H-2 class II-KO mice) (data not shown). Other than these instances, both CD4.sup.+ and CD8.sup.+ T cells in HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice display, respectively, a pattern of TCR BV chain usage and CDR3 diversity, which is similar to that of non-transgenic C57BL/6 mice.
Example 4: Functional Characterization
(96) HLA-A2.sup.+HLA-DR1.sup.+ 2mIA mice immunized with Ag HBs (hepatitis B envelope protein) were analyzed.
(97) These results show that the HLA-A2.sup.+HLA-DR1.sup.+ 2mIA mouse allows for simultaneous analysis of the specific humoral response, of the Ag-specific HLA-DR1-restricted response of CD4.sup.+ T helper cells, and of the cytolitic response of Ag-specific HLA-A2-restricted CD8.sup.+ T cells in an immunized individual.
(98) Additional data obtained from these mice is provided in the following Tables 1-3.
(99) TABLE-US-00001 TABLE1 ProliferativeresponsesofTCD4+ againstHBVvirusenvelope HLA-DR1epitopesfromHLA-A2+DR1+H-2CI-CII-transgenicmice injectedwithpcmvS2-S Responder/ Stimulation position AminoAcidsequence testedmice index 109-134 MQWNSTTFHQTLQDPRVRGLYFPAGG (12/12) 3-4 200-214 TSLNFLGGTTVCLGQ (6/12) 3-4 16/31 QAGFFLLTRILTIPQS (12/12) 3-6 337/357 SLLVPFVQWFVGLSPTVWLSV (5/12) 4-5
(100) TABLE-US-00002 TABLE2 CytolyticresponsetoHLA-A2+DR1+H-2CI-CII- transgenicmiceinjectedwithpcmvS2-S AminoAcid Responder/ position sequence testedmice Maximallysis 348-357 GLSPTVWLS (12/12) 20-70% 335-343 WLSLLVPVF (4/12) 30%
(101) TABLE-US-00003 TABLE3 Anti-PreS2Antibodyresponseantiof HLA-A2+DR1+H-2CI-CIItransgenicmiceinjected withpcmvS2-S Responder/ position AminoAcidsequence testedmice preS2 MQWNSTTFHQTLQDPRVRGLYFPAGG (9/12)
Example 5: Immune Response to HBsAg-DNA-Vaccine
(102) To evaluate the immunological potential of HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice, and to compare their humoral, CD4.sup.+ and CD8.sup.+ T cell responses to those of humans, mice were immunized with an HBsAg-DNA plasmid. This plasmid encodes two hepatitis B virus envelope proteins (preS2/S middle and S/small) that self-assemble in particles carrying hepatitis B surface antigen. The currently used vaccine against hepatitis B comprises these two proteins.
(103) As illustrated in
(104) The CD8.sup.+ CTL response to HBsAg was examined to determine whether the CD8.sup.+ T cells in the periphery of the HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mouse were functionally restricted by the transgenic human class I molecules. In HBV-infected HLA-A2.1.sup.+ humans, the immunodominant HLA-A2.1-restricted HBsAg-specific CTL response is directed at the HBsAg.sub.348-357 (Maini, M. K. et al., Gastroenterology 117, 1386-1396 (1999)) and at the HBsAg.sub.335-343 (Nayersina, R. et al., J Immunol 150, 4659-4671 (1993)) peptide (i.e., a multi-epitopic response is observed). In C57BL/6 mice, the H-2 K.sup.b-restricted HBsAg-specific CTL response is directed at the HBsAg.sub.371-378 peptide (Schirmbeck, R., Wild, J. & Reimann, J., Eur J Immunol 28, 4149-4161 (1998)). To evaluate whether the humanized mouse may respond as humans, splenic T cells were restimulated for 7 days, as described herein, with either relevant (HBsAg.sub.348-357, HLA-A2.1-restricted), or control (HBsAg.sub.371-378, H-2 K.sup.b-restricted; MAGE-3.sub.271-279, HLA-A2.1-restricted) peptide.
(105) To determine whether the CD4.sup.+ T cells in the periphery of this HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mouse may be functionally restricted by the transgenic human class II molecules, the CD4.sup.+ T cell response to the HBsAg protein was examined. In HBsAg-vaccinated or HBV-infected HLA-DR1.sup.+ humans, an immunodominant HLA-DR1-restricted HBsAg-specific CD4.sup.+ T cell response is directed at the HBsAg.sub.180-195 peptide (Mm, W. P. et al., Hum Immunol 46, 93-99 (1996)). In C57BL/6 mice, the H-2 IA.sup.b-restricted HBsAg-specific CD4.sup.+ T cell response is directed at the HBsAg.sub.126-138 peptide (Milich, D. R., Semin Liver Dis 11, 93-112 (1991)). To compare the humanized mouse with humans and wild-type mice, splenic T cells were restimulated in vitro with either relevant (HBsAg.sub.180-195, HLA-DR1-restricted) or control (HBsAg.sub.126-138, H-2 IA.sup.b-restricted; HIV 1 Gag.sub.263-278, HLA-DR1-restricted) peptides.
(106) Having documented in a first HBsAg-DNA-immunized HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-KO mouse the development and the specificity of the HBsAg-specific antibody, proliferative and cytolytic T cell responses, 6 additional HBsAg-DNA-immunized and 6 naive control HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-KO mice were also tested individually for the same three responses. As illustrated in
Example 6: Protection Assays
(107) The above examples document the induction of HBsAg-specific humoral, CD4.sup.+ and CD8.sup.+ T cell responses in HLA-A2.1-/HLA-DR1-transgenic, H-2 class I-/class II-KO mice, and show that they are directed at the same immunodominant epitopes as those of naturally-infected or HBsAg-vaccinated humans. This example tested whether these responses conferred protection to vaccinated animals. Since mice are not permissive to HBV, a HBsAg-recombinant vaccinia virus (rVV-HBsAg) was used for these experiments. Mice were immunized twice intramuscularly with 100 g of HBsAg-DNA. Twelve days after the last immunization, mice were challenged intraperitoneally with 10.sup.7 PFU of rVV-HBsAg. Four days later, virus titers were determined according to published methods and recorded as rVV PFU/ovary (Buller, R. M. & Wallace, G. D., Lab Anim Sci 35, 473-476 (1985)).
(108) The results are illustrated in
(109) The specificity of the protection conferred by HBsAg-DNA-vaccination was documented by challenging HBsAg-DNA-immunized mice with another HBx-recombinant VV (encoding hepatitis Bprotein). No reduction of rVV-HBx replication was observed in HBsAg-DNA-immunized mice compared to unimmunized controls.
Example 7: HLA-DR1-Restricted CD4+ T Cells are Critical for Antibody and CTL Responses and Protection Against Viral Infection
(110) To evaluate whether HLA-DR1-restricted T helper lymphocytes contribute to antibody and CTL responses in the humanized mice, the immune response and the efficiency of viral infection were compared in single (HLA-A2.1) and double (HLA-A2.1/HLA-DR1) transgenic, H-2 class I-/class II-KO mice. As shown in Table 4, a potent HBsAg.sub.348-357-specific CTL response was observed in HLA-A2.1-/HLA-DR1-double transgenic, H-2 class I-/class II-KO mice, but not in HLA-A2.1-single transgenic H-2 class I-/class II-KO mice. Furthermore, anti-HBs antibodies could not be detected in HBsAg-DNA-vaccinated HLA-A2.1-single transgenic H-2 class I-/class II-KO mice. As a consequence, HBsAg-DNA-immunized HLA-A2.1-single transgenic H-2 class I-/class II-KO mice were not protected against rVV-HBsAg infection.
(111) TABLE-US-00004 TABLE 4 Antibody, cytolytic, and proliferative responses of HBsAg-DNA- immunized mice, and protection against rVV-HBsAg-challenge Specific Lysis Proliferation rVV-HBsAg (%) (SI) Antibody PFU/ovary Mice 348-357 335-343 179-194 Titer (log10) A 1 0 0 1 0 2.5 .Math. 10.sup.8 2 0 0 1 0 2.5 .Math. 10.sup.8 3 0 0 1 0 10.sup.8 4 0 0 1 0 2.5 .Math. 10.sup.8 5 0 0 1 0 10.sup.8 6 0 0 1 0 1.5 .Math. 10.sup.8 B 1 30 15 4.7 2000 10.sup.4 2 14 0 3.9 3000 3 .Math. 10.sup.3 3 30 11 4 7500 4 .Math. 10.sup.3 4 5 0 2.5 6500 7.5 .Math. 10.sup.3 5 50 30 6.3 13000 7.5 .Math. 10.sup.2 6 40 18 4 16000 5 .Math. 10.sup.2 7 6 7 2.9 1500 2 .Math. 10.sup.4 8 5 5 3 2500 1.5 .Math. 10.sup.4 9 24 36 4.5 3000 <10.sup.2 10 23 14 5 15000 5 .Math. 10.sup.3 C 1 0 0 1 0 10.sup.8 2 0 0 1 0 2 .Math. 10.sup.8 3 0 0 1 0 1.5 .Math. 10.sup.8 4 0 0 1 0 10.sup.8 5 0 0 1 0 2.5 .Math. 10.sup.8 6 0 0 1 0 10.sup.8 Naive HLA-A2.1-/HLA-DR1-double transgenic H-2 class I-/class II-KO mice (A 1-6), HBsAg-DNA-immunized HLA-A2.1-/HLA-DR1-double transgenic H-2 class I-/class II-KO mice (B 1-10) and HBsAg-DNA-immunized HLA-A2.1-single transgenic H-2 class I-/class II-KO mice (C 1-6) were challenged intraperitoneally with 10.sup.7 PFU of rVV-HBsAg. Four days later, PFU per ovary, cytolytic and proliferative splenic T cell responses and serum antibody titers were assessed individually using either HBsAg.sub.348-357, (immunodominant) or HBsAg.sub.335-343 (subdominant), HLA-A2.1-restricted peptides-loaded RMAS-HHD target cells (E/T ratio 30/1) for cytolytic assays, HBsAg.sub.179-194 HLA-DR1-restricted peptide for proliferation assays and preS2.sub.109-134 peptide for the determination of antibody (IgG) titers.
(112) The entire contents of all references, patents and published patent applications cited throughout this application are herein incorporated by reference in their entirety.