Methods to identify prime and boost immunogens for use in a B cell lineage-based vaccination protocol

Abstract

The present invention relates, in general, to an HIV-1 vaccine and, in particular, to a B cell lineage-based vaccination protocol.

Claims

1. A method to identify prime and boost immunogens for use in a B cell lineage-based vaccination protocol comprising: i) identifying pairs of variable heavy (V.sub.H) and variable light (V.sub.L) chain sequences expressed as B-cell receptors by a single cell of clonally related B cells from a subject producing broad neutralizing antibodies (bnAbs), including a pair of V.sub.H and V.sub.L chain sequences of a mature bnAb, ii) inferring from the sequences of step (i), a pair of V.sub.H and V.sub.L chains of an unmutated ancestor antibody (UA) of the mature bnAb, and one or more pairs of V.sub.H and V.sub.L chains of likely intermediate antibodies (IAs) of the mature bnAb, iii) expressing the pair of V.sub.H and V.sub.L chains of the UA inferred in step (ii) to produce the UA, and expressing the one or more pairs of V.sub.H and V.sub.L chains of the one or more likely IAs inferred in step (ii) to produce the one or more likely IAs, iv) performing one or more UA binding assays, wherein the binding affinity of the expressed UA of step (iii) for one or more immunogens is determined, v) identifying a first immunogen with a binding affinity for the UA determined in step (iv), wherein the first immunogen is identified as a prime immunogen, vi) performing one or more IA binding assays, wherein the binding affinity of the one or more expressed likely IAs of step (iii) for one or more immunogens is determined, wherein the one or more immunogens comprises the first immunogen identified as the prime immunogen in step (v), and vii) identifying one or more second immunogens with enhanced binding affinity for the one or more likely IAs relative to the first immunogen of step (v), wherein the one or more second immunogens is identified as one or more boost immunogens, wherein the first immunogen identified as a prime immunogen has an antigenic structure different than each of the one or more immunogens identified as one or more boost immunogens.

2. The method of claim 1, further comprising: viii) performing one or more additional binding assays, wherein the binding affinity of the mature bnAb for one or more immunogens is determined, wherein the one or more immunogens comprises the one or more second immunogens identified as the one or more boost immunogens in step (vii), and ix) identifying one or more additional immunogens with enhanced binding affinity for the mature bnAb relative to the one or more second immunogens of step (vii), wherein the one or more additional immunogens with enhanced binding affinity for the mature bnAb is identified as one or more boost immunogens.

3. The method of claim 1, using computational methods to infer the sequence of the V.sub.H and V.sub.L chains of the UA of step (ii).

4. The method of claim 1, wherein the IAs are inferred at each branch point of the clonal lineage of the clonally related B cells.

5. The method of claim 1, wherein the first immunogen identified in step (v) is a different protein than each of the one or more second immunogens identified in step (vii).

6. The method of claim 2, wherein the first immunogen identified in step (v) is a different protein than each of the one or more additional immunogens identified in step (ix), or each of the one or more second immunogens identified in step (vii) is a different protein than each of the one or more additional immunogens identified in step (ix).

7. The method of claim 6, wherein the first immunogen identified in step (v) is a different protein than each of the one or more second immunogens identified in step (vii), wherein the first immunogen identified in step (v) is a different protein than each of the one or more additional immunogens identified in step (ix), and wherein each of the one or more second immunogens identified in step (vii) is a different protein than each of the one or more additional immunogens identified in step (ix).

8. The method of claim 1, wherein the broad neutralizing antibodies of step i) are broad neutralizing antibodies to HIV-1 and wherein the one or more immunogens of step iv) and step vi) is an HIV-1 envelope polypeptide immunogen.

9. The method of claim 8, further comprising: viii) performing one or more additional binding assays, wherein the binding affinity of the mature bnAb for one or more HIV-1 envelope polypeptide immunogens is determined, wherein the one or more HIV-1 envelope polypeptide immunogens comprises the one or more second immunogens identified as the one or more boost immunogens in step (vii), and ix) identifying one or more additional immunogens with enhanced binding affinity for the mature bnAb relative to the one or more second immunogens of step (vii), wherein the one or more additional immunogens with enhanced binding affinity for the mature bnAb is identified as one or more boost immunogens.

10. The method of claim 8, using computational methods to infer the sequence of the V.sub.H and V.sub.L chains of the UA of step (ii).

11. The method of claim 8, wherein the IAs are inferred at each branch point of the clonal lineage of the clonally related B cells.

12. The method of claim 8, wherein the first immunogen identified in step (v) is a different HIV-1 envelope polypeptide than each of the one or more second immunogens identified in step (vii).

13. The method of claim 9, wherein the first immunogen identified in step (v) is a different HIV-1 envelope polypeptide than each of the one or more additional immunogens identified in step (ix), or each of the one or more second immunogens identified in step (vii) is a different HIV-1 envelope polypeptide than each of the one or more additional immunogens identified in step (ix).

14. The method of claim 13, wherein the first immunogen identified in step (v) is a different HIV-1 envelope polypeptide than each of the one or more second immunogens identified in step (vii), wherein the first immunogen identified in step (v) is a different HIV-1 envelope polypeptide than each of the one or more additional immunogens identified in step (ix), and wherein each of the one or more second immunogens identified in step (vii) is a different HIV-1 envelope polypeptide than each of the one or more additional immunogens identified in step (ix).

15. The method of claim 1, wherein the broad neutralizing antibodies of step i) are broad neutralizing antibodies to influenza and wherein the one or more immunogens of step iv) and step vi) is an influenza hemagglutinin polypeptide immunogen.

16. The method of claim 15, further comprising: viii) performing one or more additional binding assays, wherein the binding affinity of the mature bnAb for one or more influenza hemagglutinin polypeptide immunogens is determined, wherein the one or more influenza hemagglutinin polypeptide immunogens comprises the one or more second immunogens identified as the one or more boost immunogens in step (vii), and ix) identifying one or more additional immunogens with enhanced binding affinity for the mature bnAb relative to the one or more second immunogens of step (vii), wherein the one or more additional immunogens with enhanced binding affinity for the mature bnAb is identified as one or more boost immunogens.

17. The method of claim 15, using computational methods to infer the sequence of the V.sub.H and V.sub.L chains of the UA of step (ii).

18. The method of claim 15, wherein the IAs are inferred at each branch point of the clonal lineage of the clonally related B cells.

19. The method of claim 15, wherein the first immunogen identified in step (v) is a different influenza hemagglutinin polypeptide than each of the one or more second immunogens identified in step (vii).

20. The method of claim 16, wherein the first immunogen identified in step (v) is a different influenza hemagglutinin polypeptide than each of the one or more additional immunogens identified in step (ix), or each of the one or more second immunogens identified in step (vii) is a different influenza hemagglutinin polypeptide than each of the one or more additional immunogens identified in step (ix).

21. The method of claim 20, wherein the first immunogen identified in step (v) is a different influenza hemagglutinin polypeptide than each of the one or more second immunogens identified in step (vii), wherein the first immunogen identified in step (v) is a different influenza hemagglutinin polypeptide than each of the one or more additional immunogens identified in step (ix), and wherein each of the one or more second immunogens identified in step (vii) is a different protein than each of the one or more additional immunogens identified in step (ix).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

(2) FIG. 1. Human B cells arise from committed progenitor cells that proliferate following expression of functional immunoglobulin heavy- (H-) chain polypeptides that associate with surrogate light chains (SLC). In pre-B I cells. H-chain and SLC pairs associate with Ig/Ig heterodimers to form pre-B cell receptors (pre-BCR) and initiate cell proliferation. When these proliferating cells exit the cell cycle as pre-B II cells, increased RAG1/2 expression drives light-(L-) chain rearrangements and the assembly of mature BCR capable of binding antigen. Most newly generated immature B cells are autoreactive and consequently lost or inactivated at the first tolerance checkpoint; the remainder mature as transitional 1 (T1) and T2 B cells characterized by changes in membrane IgM (mIgM) density, increased mIgD expression, and the loss/diminution of CD10 and CD38. Newly formed T2 B cells are subject to a second round to immune tolerization before entering the mature B cell pools. Mature B cells activated by antigens and TFH characteristically down-regulate mIgD and increase CD38 expression as they enter the germline center (GC) reaction, GC are sites on intense B-cell proliferation, AICDA dependent Ig hypermutation and class-switch recombination, and affinity maturation.

(3) FIG. 2. Schematic diagram of trimeric HIV-1 Env with sites of epitopes for broadly neutralizing antibodies. The four general specificities for BnAbs so far detected are: the CD4 binding site; the V2,V3 variable loops; certain exposed glycans; and the MPER. Red ovals: gp120 core; dark-red ovals, V1-V2 loops; magenta ovals: V3 loop; blue oval, gp41; bright red stripe: MPER of gp41; light brown, curved stripe: viral membrane bilayer. The PGT glycan antibodies depend on the N-linked glycan at position 332 in gp120; like the V2,V3 conformational antibodies, they also depend on the glycan at position 160.

(4) FIG. 3. Clonal lineage of V2,V3 conformational antibodies, CH01-CH04, their inferred intermediate antibodies (IAs, labeled 1, 2, and 3), and the inferred unmutated ancestor antibody (UA). Design of immunogens to drive such a pathway might involve producing the UA and IAs and using structure-based alterations in the antigen (i.e., changes in gp120 or gp140 predicted to enhance binding to UA or IA) or deriving altered antigens by a suitably designed selection strategy. Vaccine administration might prime with the antigen that binds UA most tightly, followed by sequential boosts with antigens optimized for binding to each IA. For this clonal lineage, an Env known to bind the UA (AE.A244 gp120: ref 21) could be a starting point for further immunogen design.

(5) FIG. 4. Monkey study 62.1.

(6) FIG. 5. Monkey study 34.1.

(7) FIG. 6. Levels of binding antibodies to A244 gp120D11 induced by A244gp120D11 alone (NHP #34.1) and sequential Env immunization (NHP #62.1).

(8) FIG. 7. HIV neutralization: comparisons of isolate means (in log.sub.10).

(9) FIG. 8. Sequences of A244 11gp120 (SEQ ID NO: 2), AE. 42729911gp120 (SEQ ID NO: 3), and B.9021 gp140C (SEQ ID NO: 4).

(10) FIG. 9. Sequence of 9021 All gp120 (SEQ ID NO: 1).

DETAILED DESCRIPTION OF THE INVENTION

(11) Definitions of Terms

(12) Autologous neutralizing antibodies: Antibodies that are produced first after transmission of HIV-1 and that selectively neutralize the transmitted/founder virus.

(13) B-cell anergy: A type of B cell tolerance that renders potentially responding B cells unresponsive to antigen.

(14) B-cell tolerance: The activity of the immune system to suppress B cells that are dangerously host reactive. These cells are either deleted from the B cell repertoire or rendered unresponsive or anergic. A third tolerance mechanism is swapping of either light chains (light chain editing) or heavy chains (heavy chain editing) to prevent self-reactivity of antibodies.

(15) Broadly neutralizing antibodies (BnAbs): Antibodies produced by B cells that neutralize diverse strains of a particular infectious agent.

(16) CD4-binding-site gp120 broadly neutralizing antibodies: The T-lymphocyte surface antigen, CD4, is the cellular receptor of HIV-1. It binds at a defined, conserved site on gp120. Although many antibodies recognize the region on the surface gp120 that includes the CD4 binding site, their footprint also covers adjacent parts of the surface, where mutation can lead to escape from neutralization by those antibodies. A few, broadly neutralizing antibodies (the VRC01-VRC03 clonal lineage, PG04, the CH30-CH34 clonal lineage) bind gp120 in a way that closely resembles the contact made by CD4: the heavy-chain VH region of these antibodies (nearly all are V.sub.H 12) mimics the N-terminal, Ig-like domain of CD4, with relatively few interactions outside the conserved, CD4-binding pocket.

(17) Germinal center: Location in immune tissues at which dendritic and other cells present B cell contact antigen, helper T cells make contact with B cells, and immunoglobulin class switching and somatic hypermutation take place.

(18) Heavy chain third complementary determining region (HCDR3): Three loops from each of the two immunoglobulin polypeptide chains contribute to its antigen-binding surface. The third of these complementarity determining regions (CDRs) on the heavy chain is particularly variable and often makes a particularly important contribution to antigen recognition.

(19) Hemagglutinin broadly neutralizing determinants: The influenza virus hemagglutinin (HA), one of the two principal surface proteins on influenza A and B, has, like HIV-1 Env, both strain-specific and conserved determinants for neutralizing antibodies. Like HIV-1 Env neutralizing antibodies, most hemagglutinin neutralizing antibodies are strain specific and not broadly neutralizing. The conserved targets of broadly neutralizing influenza antibodies are the binding pocket for the receptor, sialic acid, and the stalk of the rod-like HA trimer.

(20) Immunoglobulin class switching: The process in germinal centersby which antigen drives switching of immunoglobulin made by a developing memory B cell from IgM to IgG, IgA or IgE. This process, which requires activation of the recombination activating genes I and II (RAGI, RAGII), is independent of somatic hypermutation. Not all memory B cells undergo class switching, however, and some memory B cells retain surface IgM.

(21) Intermediate antibodies (IAs): Antibodies made by intermediates in the clonal lineage generated by affinity maturation of a nave B cell in a germinal center.

(22) Membrane-proximal-external-region (MPER) gp41 broadly neutralizing antibodies: The MPER is a site on HIV-1 Env gp41 near the viral membrane at which a number of neutralizing antibodies bind. Isolated natural antibodies that bind this region (2F5, 4E10, CAP206-CH12) are polyreactive; the tip of their HCDR3 associates with the viral lipid membrane while awaiting exposure of the gp41 intermediate neutralizing determinant.

(23) Polyreactivity: the common characteristic of those virus-specific antibodies that also bind either host self antigens or other non-viral antigens.

(24) V2, V3 conformational (quaternary) HIV-1 envelope gp120 broadly neutralizing antibodies: A group of HIV-1 broadly neutralizing antibodies recognizing an epitope on gp120 that is properly configured only (or primarily) when gp120 is part of the complete Env trimer. Mutational analysis of regions of gp120 that bind quaternary antibodies show that most of them recognize the second variable (V2) and third variable (V3) loops of HIV-1 Env. Examples include PG9, PG16 and the CH01-04 clonal lineage of human mAbs.

(25) Somatic hypermutation: The process in germinal centers, mediated by the enzyme activation-induced cytidine deaminase (AID), that leads to affinity maturation of the antibody-antigen contact.

(26) Third variable loop neutralizing antibodies: The third variable loop of HIV-1 envelope (V3) is part of the binding site for the CCR5 and CXCR4 Env co-receptors; it is a frequent target of neutralizing antibodies. Examples of V3 neutralizing antibodies isolated from chronically infected subject are 447, 19b and CH19. The V3 loops is masked on the envelopes of most transmitted/founder viruses, and thus V3 loop antibodies by themselves are likely to be of limited value as a vaccine response. V3 loop antibodies are easily elicited, however, and they could be useful in combination with an antibody that induced V3 loop exposure (e.g., a CD4-binding-site antibody).

(27) Unmutated ancestor antibodies (UAs): Antibodies that represent the B cell receptors (BCRs) on nave B cells. UAs can be isolated from nave or transitional B cell populations or inferred from memory B-cell mutated clonal lineages.

(28) VH restriction: occurrence of the same VH in the antibody responses of many different individuals to the same epitope.

(29) B Cell Lineage Vaccine Design

(30) FIG. 3 shows a general outline for B-cell lineage vaccine design. There are several points that distinguish this approach from previous vaccination strategies. First, existing vaccines generally use the same immunogens for prime as for boosts. In the scheme outlined in FIG. 3, different antigens can be used for multiple steps. Design of the priming antigen can utilize the B cell receptor from the inferred unmutated ancestor (UA, see below) or from an actual, isolated nave B cell as a template, while design of boosting antigens can use the B-cell receptor from inferred (or isolated) maturation intermediates as templates (see immunogen design section below).sup.68. Second, the B cell lineage notion targets, for the priming immunogen, the earliest stages of B cell clonal development, following the basic understanding of B cell antigen drive reviewed above (FIG. 1). Third, for boosting immunogens, the scheme in FIG. 3 anticipates choosing components that might have the highest affinity for early stages of B cell maturation.

(31) Three general steps are contemplated for any lineage-based approach to vaccine design. First, identify a set of clonally related memory B cells, using single cell technology to obtain the native variable heavy (V.sub.H) and variable light (V.sub.L) chain pairs. Second, infer with the computational methods described below, the unmutated ancestral B-cell receptor (i.e., the presumptive receptor of the nave B cell to be targeted), along with likely intermediate antibodies (IAs) at each clonal lineage branch point (FIG. 3, circular nodes 1-3). Finally, design immunogens with enhanced affinity for UA and IAs, using the UA and IAs as structural templates (FIG. 3). Thus, in contrast to the usual vaccine immunogens that prime and boost with the same immunogen, a B cell lineage-based vaccination protocol can prime with one immunogen and boost with another, and potentially boost with a sequence of several different immunogens.sup.12-14,20-23 (FIG. 3). In recent work, a gp140 Env antigen that did not bind the UA of a BnAb was modified by native deglycosylation; unlike the untreated native Env antigen, the deglycosylated gp140 Env bound the BnAb UA with reasonable efficiency. Immunization of rhesus macaques showed that the Env that bound well to the UA was the superior immunogen .sup.19.

(32) It is important to note that variability of the antibody repertoire among individuals poses a potential problem for this strategy: a clonal lineage isolated from one subject may not be relevant for inducing a similar antibody in another subject. Recent observations of limited VH usage summarized above suggest that for some viral neutralizing epitopes the relevant immunoglobulin repertoire is restricted to a very small number of VH families and that the maturation pathways may be similar among individuals or require the same immunogens to drive similar pathways of affinity maturation. One example of convergent evolution of human antibodies in different individuals comes from work on B cell chronic lymphocytic leukemia (B cell CLL), in which similar B CLL VH HCDR3 sequences can be found in different people.sup.95,96. A second comes analysis of influenza and HIV-1 VH1-69 antibodies, in which similar VH1-69 neutralizing antibodies can be isolated from different subjects.sup.97-101. A third example comes from structures of V2,V3 conformational (quaternary) antibodies in which the antibodies have very similar HCDR3 structures but arise from different VH families.sup.22,101,102. Recently, use of 454 deep sequencing technology has shown convergent evolution of VH1-2 and VH1-46 CD4 in maturation of broadly neutralizing antibodies, but determining how distinct the affinity maturation pathways are for each specificity of HIV-1 broadly neutralizing antibodies requires experimental testing. Nonetheless, for major classes of such antibodies, the data summarized suggest commonalities among affinity maturation pathways in different individuals.

(33) Inferring UAs and Intermediates of BnAb Clonal Lineages

(34) B cell lineage immunogen design requires that it be possible to infer from the sequences of the mature mutated antibodies in a lineage those of the intermediate and unmutated ancestors, as in the reconstructed clonal lineage in FIG. 3. Antibody genes are assembled from a fixed set of gene segments; that there are relatively small numbers (i.e., non-astronomical) of possible genes ancestral to any given set of clonally-related antibody genes allows one to infer the ancestor antibodies.sup.20-23.

(35) The starting point for any likelihood-based phylogenetic analysis is a model for the introduction of changes along the branches. For the inference of unmutated ancestor antibodies of a clonal lineage (See UA, FIG. 3), a model is needed for somatic mutation describing the probability that a given nucleotide (for example, the one at position 21 in the V region gene) that initially has state n.sub.1 will, after the passage oft units of evolutionary time, have state n.sub.2. This substitution model makes it possible to compute the probability of the observed data given any hypothesized ancestor. From there, the application of Bayes' rule provides the posterior probability for any hypothesized ancestor. The posterior probability at each position in the unmutated ancestor can now be computed from the posteriors over the gene segments and over other parameters of the rearrangement. The complete probability function provides a measure of the certainty of the inference at each position in addition to the most-likely nucleotide state itself. This additional information may be crucial to ensuring the relevance of subsequent assays performed on the synthesized unmutated ancestor. Some of the intermediate forms of the antibody genes through which a given member of the clone passed can be similarly inferred, though not all of them (antibodies at nodes 1-3, FIG. 3). The more members of the antibody clone that it is possible to isolate, the higher the resolution with which the clonal intermediates can be reconstructed.sup.20. 454 deep sequencing has recently proved useful for expanding the breadth and depth of clonal lineages.sup.20,23.

(36) Using UAs and IAs as Templates for Immunogen Design

(37) The goal of the immunogen-design strategy described herein is to derive proteins (or peptides) with enhanced affinity for the unmutated common ancestor of a lineage or for one or more of the inferred intermediate antibodies. The method of choice for finding such proteins will clearly depend on the extent of structural information available. In the most favorable circumstances, one might have crystal structures for the complex of the mature antibody (Fab) with antigen, structures of the UA and of one or more IAs, and perhaps a structure of an IA:antigen complex. It is likely that the native antigen will not bind tightly enough to the UA to enable structure determination for that complex. In the absence of any direct structural information, consideration can also be given to cases in which the antibody footprint has been mapped by one or more indirect methods (e.g., mass spectrometry).

(38) Computational methods for ligand design are becoming more robust, and for certain immunogen-design applications, they are likely to be valuable.sup.103. It is anticipated that for the epitopes presented by HIV Env, however, the available structural information may be too restricted to allow one to rely primarily on a computational approach. The area of the interface between an antibody and a tightly-bound antigen is generally between 750 and 1000 .sup.2, and on the surface of gp120, for example, such an interface might include several loops from different segments of the polypeptide chain. Even if both the structure of the mature-antibody:Env complex and that of the UA were known, computational design of a modified Env with enhanced affinity for the UA would be challenging. Selection approaches should, in the near term at least, be more satisfactory and more reliable.

(39) For continuous epitopes, phage display is a well-developed selection method for finding high-affinity peptides.sup.104. The best-studied continuous epitopes on HIV Env are those for the antibodies, 2F5 and 4E10, directed against the membrane proximal external region (MPER) of gp41. Efforts to obtain neutralizing antibodies by immunization with peptides bearing the sequence of these epitopes have been generally unsuccessful, presumably in part because the peptide, even if cyclized, adopts only rarely the conformation required for recognition in the context of gp41. In a computational effort to design suitable immunogens, the 2F5 epitope was grafted onto computationally selected protein scaffolds that present the peptide epitope in the conformation seen in its complex with the 2F5 antibody. These immunogens indeed elicited guinea-pig antibodies that recognize the epitope in its presented conformation.sup.105. The MPER epitopes are exposed only on the fusion intermediate conformation of gp41, however, not on the prefusion trimer.sup.106 and to have neutralizing activity, these antibodies must have a membrane-targeting segment at the tip of their heavy-chain CDR3 in addition to a high-affinity site for the peptide epitope.sup.107. Thus, more complex immunogens (e.g., coupled to some sort of membrane surface) may be necessary to elicit antibodies that have both properties.

(40) Differences between antibody 2F5 and its probable unmutated ancestor have been mapped onto the 2F5 Fab:peptide-epitope complex. The side chains on the peptide that contact the antibody are all within a ten-residue stretch, and several of these (a DKW sequence in particular) must clearly be an anchor segment even for a complex with the UA. Randomization of no more than 5 positions in the peptide would cover contacts with all the residues in the UA that are different from their counterparts in the mature antibody. Phage display libraries can accommodate this extent of sequence variation (i.e., about 310.sup.6 members), so a direct lineage-based, experimental approach to finding potential immunogens is possible, by selecting from such libraries peptides that bind the UCA of a lineage or one of the inferred intermediates.

(41) For discontinuous epitopes on gp120 that are antigenic on cell-surface expressed, trimeric Env, a selection scheme for variant Envs can be devised based on the same kind of single-cell sorting and subsequent sequencing used to derive the antibodies. Cells can be transfected with a library of Env-encoding vectors selectively randomized at a few positions, and the tag used for sorting can be, for example, be a fluorescently labeled version of the UA antibody. An appropriate procedure can be used to select only those cells expressing an Env variant with high affinity for the antibody. In cases for which a comparison has been made of the inferred UA sequence with the structure of an antigen-Fab complex, partial randomization of residue identities at 3-5 positions, as in the linear-epitope example, can be expected to generate the compensatory changes one is seeking.

(42) Recognition of HIV-1 envelope by several classes of broadly neutralizing antibodies includes glycans presented by conformational protein epitopes. Such antibodies account for 25% of the broadly neutralizing activity in the plasma of subjects selected for broad activity.sup.108,109. By analogy with selection from phage-displayed libraries, synthetic libraries of glycans or peptide-glycan complexes can be screened to select potential immunogens with high affinity for UAs and IAs of clonal lineages.sup.110. Large-scale synthesis of chosen glycoconjugates can then yield the bulk material for immunization trials.sup.111,112.

(43) The various approaches described herein are equally applicable to influenza-virus vaccine design. On the influenza-virus hemagglutinin (HA), two conserved epitopes have received recent attentionone, a patch that covers the fusion peptide on the stem of the elongated HA trimer.sup.97,98,113, the other, the pocket for binding sialic acid, the influenza-virus receptor.sup.114. Screens of three phage-displayed libraries of human antibodies, each from a quite different source, yielded similar antibodies directed against the stem epitope, and additional human mAbs of this kind have been identified subsequently by B-cell sorting. Conservation of the stem epitope may be partly a consequence of low exposure, due to tight packing of HA on the virion surface, and hence low immunogenicity on intact virus particles. An antibody from a vaccinated subject that binds the sialic-acid binding pocket and that mimics most of the sialic-acid contacts has been characterized.sup.114. It neutralizes a very broad range of H1 seasonal strains.

(44) In summary, HIV-1 is a paradigm for a number of viruses that acquire resistance to immune detection by rapid mutation of exposed epitopes. These viruses do have conserved sites on their envelope proteins but a variety of mechanisms prevent efficient induction by vaccines of antibodies to these conserved epitopes. Some of these mechanisms, at least in the case of HIV-1, appear to be properties of tolerance control in the immune system. It is, therefore, clear that conventional immunization strategies will not succeed. Only rarely does the B-cell response follow the affinity maturation pathways that give rise to HIV-1 or influenza broadly neutralizing antibodies, and until recently there were no technologies available to define the maturation pathways of a particular antibody type or specificity. With recombinant antibody technology, clonal memory B-cell cultures, and 454 deep sequencing, clonal lineages of broadly neutralizing antibodies can now be detected and analyzed. Immunogens can be optimized for high affinity binding to antibodies (B-cell receptors of clonal lineage B-cells) at multiple stages of clonal lineage development, by combining analysis of these lineages with structural analysis of the antibodies and their ligands. This combination provides a viable strategy for inducing B-cell maturation along pathways that would not be taken in response to conventional, single-immunogen vaccines.

(45) Certain aspects of the present invention are described in greater detail in the non-limiting Example that follows.

Example 1

(46) FIG. 4 shows the set of immunizations in NHP study 62.1 wherein immunogens were chosen based on how well they bound to the antibody members of the CH01-CH04 broad neutralizing clonal lineage. A244 gp120 delta 11 was used as the prime and the boost was the placebo breakthrough infection in the RV144 trial, 427299.AE gp120 env delta 11, then a further boost with the 9021.B gp140Cenv (but could have been delta 11 gp120either one), another boost with A244 gp120 Env delta 11 and then another boost with a combination of A244 gp120 delta 11+427299 Env. As shown in FIG. 6, when the NHP study 34.1, in which A244 gp120 delta 11 alone was used (see FIG. 5)), was compared to NHP study 62.1, in terms of binding of antibodies to A244 gp120 delta 11, similar binding titers are observed. However, the comparison shown in FIG. 7 yields a completely different result. The blue neutralizing antibody levels are with A244 gp120 D11 Env (study 34.1) and are what was seen in the plasma of the RV144 trial (Montefiori et al, J. Inf. Dis. 206:431-41 (2012)) high titers to the tier 1 AE isolate that was in the vaccine AE92TH023, some other low level tier 1 neutralizing antibody levels, and the rest of the levels were negative (neutralizing antibody assay levels in this assay start at a plasma dilution of 1:20 such that levels on the graph of 10 are below the level of detection and are read as negative). In contrast, the titers to the tier is in the red bars from study 62.1 show 1-2 logs higher abs to the tier is but most importantly now significant neutralizing antibody levels to the two tier 2 transmitted founder breakthrough viruses from the RV144 trial (all assays in TZMBL assay, except for the two arrows indicate HIV isolates which were assayed in the A3R5 cell neutralizing antibody assay). Thus, by immunizing with sequential Envs chosen for their ability to optimally bind at UCA, IA and mature antibody member points of a broad neutralizing antibody lineage, the breadth of neutralizing antibody coverage has been increased by inducing new neutralizing antibodies to Tier 2 (difficult to neutralize) HIV strains AE.427299 and AE.703357, demonstrating proof of concept that the strategy of B cell lineage immunogen design can indeed induce improved neutralizing antibody breadth. Moreover, these data demonstrate a new discovery as a strategy for inducing greater breadth of neutralization in using the ALVAC/AIDSVAX type of vaccine (Haynes et al, NEJM 366: 1275-1286 (2012)) for future vaccine trials, and that is adding gp120 Envs to the primer and or the boost regimen made up of Env gp120s chosen from the breakthrough infections that did not match the original vaccine in RV144 to increase the potency of vaccine efficacy of a vaccine in Thailand. Rolland has shown that if the RV144 trial breakthrough viruses are compared from vaccinees and placebo recipients, those viruses that had similarity at the V2 region were controlled by 45% vaccine efficacy (Rolland M et al, Nature September 10, Epub ahead of print, doi: 10.1038/nature 11519, 2012). Thus, screening the sequences of RV144 breakthrough viruses for the most common HIV strains with Env V2 regions that did not match the vaccine should demonstrate the Env V2 motifs that should be included in additional prime or boosting Envs in the next vaccine to increase the vaccine efficacy. In addition, the adjuvant used will be important. In the trials above in NHP study 34.1 and 62.1 the adjuvant used was a squalene based adjuvant with TLR7+TLR9 agonists added to the squalene (see PCT/US2011/062055). Currently available adjuvants that are available and can be considered for use in humans is MF-59 (DellEra et al, Vaccine 30: 936-40 (2012)) or AS01B (Leroux-Roels et al, Vaccine 28: 7016-24 (2010)). Thus, a vaccine can be designed based on a polyvalent immunogen comprising a mixture of Envs administered in sequence as shown, for example, in FIG. 4 or alternatively the sequentially chosen Envs can be administered all together for each immunization as describe (Haynes et al, AIDS Res. Human Retrovirol. 11:211-21 (1995)) to overcome any type of primer-induce suppression of Env responses. Thus, the present invention relates, at least in part, to an approach to improving the RV144 vaccine by adding gp120s or gp140Cs (with or without the delta 11 (D11) deletion) (e.g., 427299 Env gp120 sequences) to the A244 gp120 immunogen to expand the coverage of the the RV144 original vaccine. (See, for example FIGS. 4 and 5.) It can be seen that this strategy of probing the breakthrough viruses of any partially successful vaccine trial can utilize this strategy to improve that vaccines coverage of infectious agent strains and in doing so, improve the vaccine efficacy of that vaccine.

(47) The present invention also relates in part to demonstrating proof of concept of the general strategy of vaccine design known as B Cell Lineage Immunogen Design wherein the prime and boost immunogens are chosen based on the strength of binding of each vaccine component to an antibody template in the antibody clonal lineage that is desired to induce.

(48) All documents and other information sources cited herein are hereby incorporated in their entirety by reference. Also incorporated by reference is U.S. Provisional Application No. 61/542,469, filed Oct. 3, 2011 and International Application No. PCT/US2011/000352, filed Feb. 25, 2011.

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