Pharmaceutical composition that includes the surface and nucleocapsid antigens of the hepatitis B virus

Abstract

This invention reveals the pharmaceutical composition that includes the surface antigen (HBsAg) of the hepatitis B virus (HBV) and the antigen of the nucleocapsid (or core, HBcAg) of the same virus. The HBcAg of this composition contains messenger ribonucleic acid (mRNA) at a proportion of over 45% of the total amount of ribonucleic acid (RNA) in this antigen. Because of the changes in the constitution of the antigens forming it, the composition of the invention is useful for the prevention or treatment of chronic hepatitis B. It also covers the use of this pharmaceutical composition in the production of a drug for immuno-prophylaxis or immunotherapy against HBV infection, and its use to increase the immune response against an additional antigen that is co-administered with the mixture of these antigens.

Claims

1. A method for immunoprophylaxis or immunotherapy against infection of hepatitis B virus (HBV), said method comprising administering to an individual in need thereof an effective amount of a pharmaceutical composition comprising i) core antigen of the hepatitis B virus (HBcAg) that includes messenger ribonucleic acid (mRNA) for the HBcAg antigen at a proportion of more than 45% of total ribonucleic acid (RNA) in the HBcAg antigen, and ii) surface antigen (HBsAg) of the hepatitis B virus (HBV), wherein the HBsAg includes phosphatidylserine at a proportion of over 5% of the total amount of phospholipids in the HBsAg.

2. The method of claim 1 wherein the pharmaceutical composition is administered by the parenteral and mucosal routes.

3. The method of claim 1 wherein the individual receiving the immunotherapy is a patient with chronic hepatitis B (CHB).

4. The method of claim 3 wherein the immunotherapy of the CHB patients is used for the prevention of hepatocellular cancer derived from the HBV infection.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1. Response of IgG anti-HBcAg antibodies after administering two doses.

(2) FIG. 2. AntibodiesIgG anti-CR3.

(3) FIG. 3. Proliferative response of T cells CD8+CR3 (HIV-1)-specific.

DETAILED ACCOUNT OF THE MODES OF REALIZATION/EXAMPLES OF REALIZATION

Example 1. Obtaining the HBcAG Protein with Different Proportions of the RNA Variants

(4) The HBcAg was obtained from a strain of E. coli that was genetically transformed with a plasmid that carried the gene codifying for this antigen [Aguilar J C, et al. Immunol Cell Biol (2004) 82:539-46].

(5) On characterizing the particles of HBcAg, from the fermentative process made during different periods of time, it was observed that there was an increase in the proportion of mRNA incorporated in the preparations of HBcAg produced with longer fermentation periods. After 20 hours of fermentation, the levels of mRNA in the antigen increased more than 20%, compared to the HBcAg obtained in processes of up to 14 hours, as observed in Table 1. No significant changes were detected in the total amount of RNA in the particle, since no significant differences were found in the levels of total RNA, or in the ratio of RNA content/protein content. However, there was a significant increase in the level of mRNA when compared to other variants, specifically the ribosomal RNA (rRNA), which showed a reduction in its presence with the increase of the mRNA. No other relevant changes were found in the minor components associated to HBcAg or in specific contaminants, on carrying out trials by mass spectrometry or other chemical and physical studies.

(6) TABLE-US-00001 TABLE 1 Variation of the percentage in relation to the main types of RNA in the HBcAg according to the duration of the fermentation process tRNA rRNA mRNA Variant (%) (%) (%) 1 (10 hr) 0.1 76.3 23.6 .sup.  2 (12 hr) 0.1 60.0 39.9 .sup.  3 (14 hr) 0.09 54.9 45.0 .sup.  4 (16 hr) 0.09 40.0 59.1(*) 5 (18 hr) 0.1 34.5 65.5(*) 6 (20 hr) 0.1 32.8 67.1(*)

(7) The results represent the average values of the five determinations. In the column titled “Variant” the duration time of the fermentation is indicated in parenthesis. tRNA: transference RNA, rRNA: ribosomal RNA and mRNA: messenger RNA. (*): Significant differences (p<0.05).

(8) Evaluation in Balb/c Mice of the Immunogenicity of the Variants of HBcAg with Different Percentages of mRNA Incorporated

(9) After obtaining the different variants of HBcAg with different percentages of the mRNA incorporated inside the particle (Table 1), the immunological evaluations of these preparations was carried out in Balb/c mice. For this study we used female mice of between 8 and 12 weeks of age, receiving two immunizations on days 0 and 15, through the SC route, with a dose of 1 μg of HBcAg in phosphate buffered saline (PBS), administrating a final volume of 100 μL. The detailed description of the schedule is shown in Table 2.

(10) TABLE-US-00002 TABLE 2 Design of the immunization schedule to evaluate the influence of the percentage of mRNA incorporated in the particle of HBcAg in the immunogenicity of this antigen. Group Treatment No. of animals 1 1 ug HBcAg (23% mRNA) 10 2 1 ug HBcAg (39% mRNA) 10 3 1 ug HBcAg (45% mRNA) 10 4 1 ug HBcAg (60% mRNA) 10 5 1 ug HBcAg (65% mRNA) 10 6 1 ug HBcAg (67% mRNA) 10 7 PBS 1X 10

(11) Blood extractions for the evaluation of the specific antibody response generated by immunization were performed 10 days after the second dose. The measurement of antibody anti-HBcAg response was carried out using the ELISA technique.

(12) As observed in FIG. 1, showing the IgG antibody titers anti-HBcAg obtained in each study group, the IgG anti-HBcAg response generated was significantly higher for the groups receiving the HBcAg with mRNA incorporated at above 45% (groups from 3 to 6 of Table 2). Among groups 3, 4, 5 and 6, no significant differences were detected, although there is a slight trend towards an increase of the IgG response associated to the increase in the percentage of mRNA incorporated. The results indicate that the increase in the proportion of mRNA incorporated inside the HBcAg particle at levels above 45% with respect to the total RNA incorporated confers a greater humoral immunogenicity to this protein. The preliminary analyses of the pattern of IgG subclases, suggest a similar performance at the level of the cellular type immune response.

Example 2. Obtaining the Virus Like Particles (VLP) of HBsAg with Different Proportions of Phosphatidylserine

(13) The recombinant HBsAg was obtained from a strain of genetically transformed P. pastoris using the gene that codifies this antigen [European Patent No. EP 480525]. It is known that the HBsAg expressed in this yeast species contains phosphatidylserine within its structural lipids [Lobaina Y, et al. Biotecnología Aplicada (2008), 25:325-331]. However, up until this invention, the influence of the presence of this lipid in the immunogenicity of this antigen had not been studied.

(14) In order to study how the proportion of phosphatidylserine affects the immunogenicity of the HBsAg, we obtained the preparations of this VLP under different fermentation conditions. During the culture in recombinant yeast fermenters, we increased the concentration of Mg.sup.(2+) in the culture medium, to percentages of between 1.0 and 2.0%, which led to the increase of this phospholipid associated to the VLP of HBsAg. This was detected by using thin layer chromatography during the characterization of the HBsAg obtained under the different growth conditions.

(15) The phosphatidylserine is associated to the VLP of the HBsAg, of known lipid nature. The results shown in Table 3 represent the average values of the five different repetitions. The purification was similar for all preparations of HBsAg produced under different experimental conditions. As observed in the table, there was no detection of phosphatidylserine in the samples obtained when the fermentation was carried out with a culture medium that contained a concentration of Mg.sup.(2+) at less than 1.2%. The levels of phosphatidylserine found in the preparation obtained with culture media containing 2.0% Mg.sup.(2+) were significantly higher than those found in the preparation obtained with the culture medium containing 1.4% Mg.sup.(2+) (Variant C).

(16) TABLE-US-00003 TABLE 3 Obtaining the variants of the HBsAg with growing amounts of phosphatidylserine Variant Mg.sup.(2+) Concentration (%) FS (%) A 1.0 ND B 1.2 ND C 1.4 2.5 ± 0.3  .sup.  D 1.6 5.0 ± 0.4 (*) E 1.8 6.1 ± 0.4 (*) F 2.0  7.7 ± 0.5 (**) ND: Not detected. Mg.sup.(2+) (%): concentration of the Mg ion (in percentage) found in the saline additives of the culture medium. FS (%): percentage of phosphatidylserine within the total phospholipids, determined after the extraction of the purified HBsAg. (*): Significant differences (p < 0.05), (**) Highly significant differences (p < 0.01).

(17) The preparations of the HBsAg represented in Table 3 were identical in their protein composition, according to the characterization made to study their primary, secondary and tertiary structure, comparable to the original variant. It is important to point out that the lipid concentration/protein concentration ratio did not change for any of the variants in the study. The same finding was obtained with the proportion of total phospholipids vs. the total protein content. No other significant changes took place during the analyses of impurities of the HBsAg or of other minor compounds, as a result of the analysis of their composition using mass spectrometry.

Example 3. Immunological Evaluation of the HBsAg Preparations Showing Different Percentages of Phosphatidylserine

(18) With the aim of evaluating if the presence of the phosphatidylserine affects the immune response against HBsAg, we carried out an immunogenicity study in transgenic mice that expressed the HBsAg in the serum [Castro F O, et al. Interferón y Biotecnología (1989) 6:251-257; Pérez A, et al. Acta Biotechnol (1993) 13: 373-383]. Seven groups of six mice each were used. These were female mice of 8-12 weeks of age that were immunized by the intranasal route (IN). The first six groups of the study received 5 μg each of the different variants of the HBsAg described in Table 3 with the Freund adjuvant. The seventh group was used as the control group and received PBS 1×. All treatment groups received 10 doses of the immunogen, which was administered every 14 days. The blood extractions were carried out before the initial immunization and 10 days after each dose, as of the third dose. In Table 4 the levels of HBsAg in the blood of transgenic mice are shown, as well as the levels of cytokines (IFN gamma (IFN-γ), tumoral necrosis factor (TNF-α), and IL-2 induced in supernatants of splenocyte cultures, isolated after administrating the 10 dosages. The evaluations were made using the ELISA technique.

(19) After the administration of 5 μg of HBsAg, by the IN route in 10 successive immunizations, the concentration of HBsAg in the blood of transgenic mice for HBsAg was significantly reduced, when the level of the phosphatidylserine in this HBsAg was of 5% or more (variants D, E and F in Table 3, Example 2). In the same way, the variants of HBsAg of 5% or more phosphatidylserine induced significantly superior levels of IFN-γ, TNF-α and IL-2, compared to variants with low levels (variant C) or those where phosphatidylserine was undetectable, suggesting a dose-dependent effect. This is observed in Table 4.

(20) When compared to the HBsAg that does not contain any phosphatidylserine, there was a significant increase of the Th1 cytokines and a higher elimination capacity of the circulating HBsAg was found after the immunization of transgenic HBsAg mice with variants of HBsAg containing levels of more than 5% phosphatidylserine (Table 4, variants D to F). The cytokine levels that are found for variants D-F were significantly higher than those of conditions A-C. The D-F variants induced the strongest reductions in the concentration of HBsAg, as well as the most potent secretions of cytokines after the in vitro stimulation of spleen cells in immunized transgenic animals.

(21) TABLE-US-00004 TABLE 4 Evaluation of the circulating HBsAg and the levels of cytokines after the immunization of transgenic mice with variants of HBsAg with different percentages of phosphatidylserine. % Reduction of Secretion of Secretion of Secretion of Variant of the HBsAg the IFN-γ TNF-α IL-2 HBsAg Concentration (pg/mL) (pg/mL) (pg/mL) A 20 ± 3 50 ± 7  .sup.  37 ± 6  .sup.  14 ± 6 B 23 ± 4 65 ± 12  45 ± 18  22 ± 4 C 26 ± 5 149 ± 15  .sup.  200 ± 26  .sup.  36 ± 7 D   .sup. 66 ± 5 (*) 250 ± 20 (*) 570 ± 30 (*)   .sup. 50 ± 5 (*) E   .sup. 70 ± 6 (*) 300 ± 27 (*) 660 ± 27 (*)   .sup. 77 ± 8 (*) F  .sup.  90 ± 5 (**)  359 ± 31 (**)  750 ± 37 (**)    .sup. 90 ± 10 (**) A-F: Variants of HBsAg produced with growing levels of phosphatidylserine in their composition, shown in Table 3. (*): Significant differences (p < 0.05), (**) Highly significant differences (p < 0.01).

(22) As observed, there was a significant increase of Th1 cytokines and a greater elimination capacity of the circulating HBsAg, by the immunization of the mice that were transgenic to HBsAg with the variants of HBsAg having a higher content of phosphatidylserine, thereby demonstrating an increase of the immunogenicity of the antigen with the increase in the proportion of this lipid component within the lipids associated to the VLP formed by this antigen.

(23) The insertion of the phosphatidylserine in the particles of HBsAg had been previously reported in the state of the art. However, the way that the proportion of this component affects the immunogenicity of these particles had not been studied. Although in 2008 Lobaina et al. had speculated on the role of the phosphatidylserine in the higher HBsAg produced in P. pastoris [Lobaina Y, et al. Biotecnología Aplicada (2008), 25:325-331], in this same report it was demonstrated that two vaccines based on HBsAg produced in the same host differed in terms of immunogenicity, although the levels of the phosphatidylserine were presumably the same, because of the yeast species producing it.

Example 4. Demonstration of the Increase of Immunogenicity in Patients with CHB of Variants of HBcAg Having a Higher Proportion of Encapsulated mRNA

(24) In Example 1 it was proven in mice that there was an increase in the immunogenicity of the HBcAg with the increase in the proportion of the mRNA within the total amount of encapsulated RNA. Taking these results into account, the immunological behavior and the antiviral in vivo response of the formulations including both HBcAg and HBsAg, with modifications in their mRNA and phosphatidylserine, respectively, were characterized.

(25) For this, a phase II randomized and double blind clinical trial was carried out in chronic hepatitis B patients. The patients selected had high viral loads of above 10 000 copies/mL and the HBeAg was positive at the start of the study. The patients were distributed in 6 groups, of 15 patients each, to which the treatments described in Table 5 were administered. A total of 10 dosages were given, which were divided into two cycles of 5 doses each, with an interval of one month between them. The first 5 doses were administered by the IN route alone, and the other 5 were administered IN/SC at the same time. In both administration cycles the doses were given at 14 day intervals.

(26) TABLE-US-00005 TABLE 5 Treatment groups in the phase II clinical trial where the evaluation of the HBcAg and HBsAg antigens with modifications in the content of the mRNA and the phosphatidylserine, respectively, were carried out Groups Treatment 1 50 μg mHBsAg + 50 μg mHBcAg 2 100 μg mHBsAg + 100 μg mHBcAg 3 1000 μg mHBsAg + 1000 μg mHBcAg 4 50 μg HBsAg + 50 μg HBcAg 5 100 μg HBsAg + 100 μg HBcAg 6 1000 μg HBsAg + 1000 μg HBcAg mHBcAg: HBcAg containing mRNA at a proportion of 50% of the total RNA of this antigen; mHBsAg: HBsAg containing 7% phosphatidylserine within the lipid components of the VLP.

(27) Surprisingly, significantly higher levels of seroconversion to HBeAg and HBsAg were found in the group of patients treated with the formulation containing both modified antigens (that is, the formulation that contained HBsAg with levels of phosphatidylserine of over 5%, and HBcAg with mRNA above 45%), when compared to the groups of patients treated with formulations without these characteristics (see Table 6). This shows the relevance of these modifications in the increase of the quality of the anti-viral response generated in the patients.

(28) In human beings, the antigens were evaluated in the range of concentrations from 50 μg per antigen per dose, up to 1 000 μg per antigen per dose, with evidence of anti-viral response, in terms of seroconversion to HBsAg and HBeAg, virological control and sustained virological response of under 10 000 copies of DNA of the HBV per mL, at more than 1 year after the end of the treatment.

(29) TABLE-US-00006 TABLE 6 Frequency of patients with seroconversion to HBeAg and to HBsAg at one year after the end of the treatment in the phase II clinical trial with HBcAg and HBsAg having modifications in their mRNA and phosphatidylserine content respectively. Treatment Seroconversion Seroconversion Groups to HBeAg to HBsAg 1 6/15 2/15 2 7/15 3/15 3 12/15  6/15 4 3/15 0/15 5 3/15 0/15 6 4/15 0/15

(30) Similar results were also found in the model of mice that were transgenic to HBsAg, where a trial was carried out to evaluate treatment groups that are similar to those described in Table 5, and a greater decrease of the circulating HBsAg was obtained, as well as higher anti-HBsAg antibody titers, and with an earlier appearance, for the groups receiving the formulations that contained the antigens with the modifications described above.

(31) Interestingly, the formulations containing the variants of modified HBcAg and HBsAg developed more potent Th1 immunogenicity in mice transgenic to HBV and in patients, compared to the response obtained with the formulations containing the unmodified antigens, or the formulations that contained only one of these modified antigens.

Example 5. Adjuvant Effect of the HBcAg and HBsAg Antigens Having Modifications in their mRNA and Phosphatidylserine Content Respectively in Multivalent Formulations

(32) Adjuvant capacity was compared in this study, i.e., the increase of the immune response toward antigens that are co-administered, within a mixture of recombinant HBcAg and HBcAg proteins with modifications in their mRNA and phosphatidylserine content, respectively, with the mixture of unmodified HBcAg and HBsAg, through the parenteral and mucosal routes. For this purpose, the recombinant chimeric protein CR3 was selected; this is the multiepitopic antigen of HIV-1 [Iglesias E et al. J Biochem Mol Biol & Biophys (2001) 1:109-122]. Eight groups of eight female Balb/c (H-2.sup.d) mice of 6-8 weeks of age were inoculated with: 1) PBS (Placebo) through SC immunization (which will hitherto be referred to as Placebo (SC); 2) Sodium acetate buffer (NaAc), pH=5.2, through IN immunization (Placebo (IN)); 3) the mixture of HBcAg (C) and HBsAg (S) through the SC route (C+S (SC)); 4) the mixture of HBcAg that contains mRNA in a proportion of 50% of the total RNA of this antigen (mC) and HBsAg that contains 7% of phosphatidylserine within its lipid components (mS) through the SC route (mC+mS (SC)); 5) C+S through the IN route (C+S (IN)); 6) mC+mS through the IN route (mC+mS (IN)); 7) mixture of CR3 with HBcAg (C) and HBsAg (S) through the SC route (CR3+C+S (SC)); 8) CR3+mC+mS (SC); 9) CR3+C+S (IN) and 10) CR3+mC+mS (IN). The dose used was of 5 μg of each antigen by each route; and the immunogens were administered on days 0, 7 and 21 of the immunization schedule. For the SC immunizations, the proteins were dissolved in PBS and adsorbed in 1.4 mg/mL of aluminum hydroxide (Superfos Biosector A/S, Vedbaek, Denmark). For the IN route, the proteins were dissolved in NaAc, pH=5.2. The animals were anaesthetized by the intra-peritoneal (IP) administration of 30 μL of ketamine (10 mg/mL), located in a supine position, and the immunogens were slowly dispensed in 50 μL (25 μL/per nostril) with a pipette tip. Ten days after the immunizations, the sera of all animals were collected and five animals were sacrificed (in a random manner) at the end of the study, to obtain their spleen for the studies of cellular immune response.

(33) The response of IgG in the serum was evaluated through an indirect ELISA where the plates were coated with the CR3 protein. The methodology for the quantification of the secretion of IFN-γ in the supernatants of the cultures stimulated with CR3 have been previously informed [Garcia Diaz D et al. Immunol Lett (2013) 149:77-84].

(34) The Gaussian distribution was evaluated for the statistical analysis of the data with the Kolmogorov-Smirnov test and the equality of variances with the Bartlett test. The samples with normal distribution (or those in which the Gaussian distribution is inferred) and with equal variance were compared with parametric tests; otherwise, the alternative non-parametric test was used. All titers of IgG were transformed to log 10, in order to achieve a normal distribution of the values. The sera of the animals that did not reach seroconversion were assigned an arbitrary titer of 1:10, for statistical processing. A value of p<0.05 was considered statistically significant.

(35) The results of the IgG anti-CR3 antibody determination (HIV-1), observed in FIG. 2, showed a higher response (p<0.05) after administrations through the SC and IN routes in the groups of animals immunized with the mixture of CR3+mC+mS (groups 8 and 10) vs CR3+C+S (groups 7 and 9), respectively. Consistent with the previous results, a greater secretion of IFN-γ was also observed in the supernatants of the cultures from mice of the same groups, as observed in Table 7. For this analysis, ten days after the last immunization (day 31), splenocytes from five mice per group were cultivated. Splenocyte suspensions of individual animals were prepared for the placebo group. They were stimulated ex vivo with 2.5 μg/mL of the CR3 protein for five days. In the supernatant liquids, the CR3-specific IFN-γ was quantified with a sandwich type ELISA. The detection limit was 0.80 ng/mL.

(36) TABLE-US-00007 TABLE 7 Secretion of IFN-γ measured in the supernatant liquids of the cultures. Group Inoculum Replicate (mouse) IFN-γ (ng/mL) 1 Placebo (SC) Pool <0.80 2 Placebo (IN) Pool <0.80 3 C + S (SC) 1 <0.80 2 <0.80 3 <0.80 4 <0.80 5 <0.80 4 mC + mS (SC) 1 <0.80 2 <0.80 3 <0.80 4 <0.80 5 <0.80 5 C + S (IN) 1 <0.80 2 <0.80 3 <0.80 4 <0.80 5 <0.80 6 mC + mS (IN) 1 <0.80 2 <0.80 3 <0.80 4 <0.80 5 <0.80 7 CR3 + C + S(SC) 1 6.35 2 7.86 3 3.32 4 4.45 5 3.54 8 CR3 + mC + mS (SC) 1 10.35 2 9.86 3 8.62 4 9.05 5 11.24 9 CR3 + C + S(IN) 1 <0.80 2 2.03 3 1.68 4 0.97 5 2.25 10 CR3 + mC + mS (IN) 1 4.55 2 5.36 3 3.87 4 2.54 5 3.98

(37) Finally, the frequency of the CD8+ cells that are specific for CR3 (HIV-1) were compared after the ex vivo stimulation in the groups immunized by the SC route. A higher frequency of CD8+ cells were obtained in the stimulated group in CR3+mC+mS (SC) vs CR3+C+S (SC) (p<0.05), which is observed in FIG. 3.

(38) These results, as a whole, show that the mixture of HBcAg having mRNA above 45% (mC) and of HBsAg with levels of phosphatidylserine above 5% (mS) have a higher Th1 adjuvant effect, by the parenteral and mucosal routes. Particularly, for the vaccination against HIV, this result is of great importance, because the antiviral Th1 response has been related to the protection against the infection and progression to AIDS.

(39) Although it was not the objective of this experiment to measure the humoral response against the HBsAg and HBcAg antigens (abbreviated in this example as C and S), we observed responses of IgG anti-HBcAg and anti-HBsAg that were higher and statistically significant, in the groups of mice immunized with the mixture of the modified HBsAg and HBcAg antigens (mC+mS), when compared to the mixture of unmodified HBsAg and HBcAg (C+S, data not shown). This confirmed the above results.

Example 6. Passive Immunization Through the Adoptive Transfer of Cells from Balb/c Mice Immunized with Formulations of the HBcAg and HBsAg with Modifications in their mRNA Content and of Phosphatidylserine, Respectively, to Transgenic Balb/c Mice Expressing the HBsAg

(40) In this invention we wished to potentiate the immune response anti-HBsAg and anti-HBcAg in donors through the active immunization of individuals with a formulation containing the antigens of HBsAg and HBcAg, which include modifications in their content of phosphatidylserine and of mRNA, respectively and also, the cells to be transferred would be activated in vitro before the transfer, so that the response against these antigens would be maximum when the cells are inoculated into the receptor organism. Hence, a type of response that is inexistent in persons, would be obtained in an artificial manner, making it possible to increase the margin of donors to persons with similar haplotypes, regardless of whether they have been infected or not by HBV.

(41) In the current example we evaluated, through the adoptive transfer of cells, the effect of the immune response generated by vaccination with a formulation composed of the HBsAg and HBcAg antigens with modifications in their content of phosphatidylserine and of mRNA, respectively, which is applied by the IN/parenteral routes, in the context of a transgenic mouse that expresses the HBsAg, a model of the persistent infection of the HBV. One of the objectives of the study was the evaluation of the effect of the transferred immune response on the concentration of HBsAg (anti-genemia) in the serum of the transgenic mouse. Furthermore, we compared the effect of the response induced by the combination of IN/parenteral routes for the administration of the formulation of the HBsAg and HBcAg antigens in relation to the effect generated by the transfer of cells stimulated only with HBsAg in vivo and in vitro. Additionally, the kinetics of the antibody response anti-HBsAg transferred in the context of the transgenic mouse for this antigen, was studied. We used Balb/c mice and mice that were HBsAg (+) transgenic (with a genetic background of Balb/c, obtained at the CIGB).

(42) Generation of Immunity Anti-HBsAg in Balb/c Mice

(43) An immunization schedule was carried out in Balb/c female mice of 8 to 12 weeks of age. The mice were immunized with a vaccine preparation containing the modified antigens HBsAg (with a content of phosphatidylserine of more than 5%) and HBcAg (with a content of mRNA of more than 45%), simultaneously by the IN and parenteral routes. Within the parenteral route, we tested the IM, SC and ID routes. The dosage (in volume of 100 μL) was administered on days 0 and 14, and a booster shot was administered on day 100, before the transfer. The blood extractions were made at the retro-orbital plexus on days 2, 10 and 25. Table 8 shows the design of the immunization schedule, including the treatment received by each group.

(44) TABLE-US-00008 TABLE 8 Immunization schedule in non-transgenic Balb/c mice Group Treatment Route Number of animals 1 mHBsAg + mHBcAg + IM/IN 13 alúmina/ mHBsAg + mHBcAg 2 mHBsAg + mHBcAg + SC/IN 13 alúmina/ mHBsAg + mHBcAg 3 mHBsAg + mHBcAg + ID/IN 13 alúmina/ mHBsAg + mHBcAg 4 mHBsAg + mHBcAg/ IM/IN 13 mHBsAg + mHBcAg 5 mHBsAg + mHBcAg/ SC/IN 13 mHBsAg + mHBcAg 6 mHBsAg + mHBcAg/ ID/IN 13 mHBsAg + mHBcAg 7 alúmina/ IM/IN 9 PBS mHBcAg: HBcAg containing mRNA at a proportion of 50% of the total RNA of this antigen; mHBsAg: HBsAg containing 7% of phosphatidylserine within the lipid components of the VLP.

(45) The evaluation of the immune humoral response generated by these treatments was carried out by measuring the IgG response and the subclasses of IgG anti-HBsAg, after each inoculation, using the ELISA technique. In order to evaluate the cellular immune response, at 10 days after the first administration, we carried out an ELISPOT type trial to measure the secretion of specific IFN-γ against the HBsAg by the CD8+ lymphocytes from the spleen. The results of these evaluations indicate that Group 5 generates the greatest cellular response and a humoral response that does not differ from the rest of the groups studied. Based on this, we selected two animals from this group as splenocyte donors for adoptive transfer. The selection of the immunogen was carried out at a proportion of 1:1 (HBsAg:HBcAg)

(46) Obtaining Immune-Splenocytes

(47) Fifteen days after receiving the booster shot, the two mice from Group 5, and three mice from Group 7 (placebo) were sacrificed and their spleen was extracted. The spleens from Group 5 and those of Group 7, respectively, were grouped. The spleens were processed until the splenocytes were obtained. They were separated into aliquots of 30×10.sup.6 cells in 100 μL of PBS 1×, for their transfer to the receptor mice.

(48) Adoptive Transfer of Immunity

(49) Transgenic mice expressing the HBsAg that were used as receptors were of between 16-20 weeks of age and from both sexes. They were assigned to the different treatment groups as shown in Table 9. Before the transfer of splenocytes, a partial blood extraction was carried out to check the levels of HBsAg in the serum. Afterwards, we inoculated (through the IP route) 30×10.sup.6 splenocytes in a volume of 100 μL of PBS 1×. The blood extractions to evaluate the effect of the adoptive transfer of immunity were made through the retro-orbital plexus, each week for 5 weeks. On week 8 post-transfer, the animals were bled and sacrificed.

(50) TABLE-US-00009 TABLE 9 Design of the experiment of adoptive transfer of immunity Group Treatment Number of animals 1 Transfer of splenocytes* from Balb/c 3 mice with a response to HBsAg and HBcAg 2 Transfer of splenocytes from Balb/c 3 placebo mice 3 PBS 1x 3
Quantification of the HBsAg in the Serum of Mice Transgenic for HBsAg

(51) The levels of HBsAg in the serum were determined by ELISA. The plates were coated with the monoclonal antibody anti-HBsAg called Hep4 (produced by CIGB). All mice receiving cells with a previous immunity to HBsAg showed, from the evaluation on the week after the transfer, a marked decrease of the HBsAg in the serum, with significant differences between time zero and the 2.sup.nd and 3.sup.rd weeks (p<0.05). As of the fourth week (day 35) we observed that the concentrations of HBsAg in the serum started increasing, thus indicating that the control of the anti-genemia by the transferred immunity is decreasing. As of this point, and up to week 8 (day 63), there are no differences in the anti-genemia, with that reported for time zero of the trial.

(52) In the case of the mice receiving the splenocyte transfer with specific immunity against HBsAg, we detected marked decreases of the HBsAg in the serum, which were more notable between days 7 and 28. However, for the mice that received the placebo splenocyte transfer, or the PBS, although there are changes in the concentration of the HBsAg in the serum, it never reached a significant difference with time zero, and values below 5 μg/ml were never detected.

(53) These results indicate that it is possible, through the adoptive transfer of immunity, mediated by cells, to effectively decrease the levels of HBsAg circulating in the serum of these transgenic animals of this protein. The control established on the anti-genemia, by the immune response transferred in this case, was effective, and lasted about 3 weeks after a single cell transfer.

(54) IgG Anti-HBsAg Response in the Serum

(55) A specific IgG antibody response against HBsAg was detected for all mice receiving the transfer of splenocytes with prior immunity for this antigen. This agrees with the anti-genemia results obtained. In the case of the animals with an anti-HBsAg response, the titers detected were high (Titer>10.sup.4) and started to decrease as of the third week, which may be related to the increase of the anti-genemia that is observed for these animals at about the 4.sup.th week (day 35). The groups receiving the transfer of placebo cells or PBS do not show specific antibodies.