Preclinical evaluation of cellular immune responses elicited by a polyvalent DNA prime/protein boost HIV-1 vaccine

While DNA vaccines have been shown to prime cellular immune responses, levels are often low in nonhuman primates or humans. Hence, efforts have been directed toward boosting responses by combining DNA with different vaccination modalities. To this end, a polyvalent DNA prime/protein boost vaccine, consisting of codon optimized HIV-1 env (A, B, C, E) and gag (C) and homologous gp120 proteins in QS-21, was evaluated in rhesus macaques and BALB/c mice. Humoral and cellular responses, detected following DNA immunization, were increased following protein boost in macaques and mice. In dissecting cellular immune responses in mice, protein-enhanced responses were found to be mediated by CD4+ and CD8+ T cells with a Th1 cytokine bias. Our study reveals that, in addition to augmenting humoral responses, protein boosting of DNA-primed animals augments cellular immune responses mediated by CD8+ CTL, CD4+ T-helper cells and Th1 cytokines; thus, offering much promise in controlling HIV-1 in vaccinees.     

Robust immune response elicited by a novel and unique Mycobacterium tuberculosis protein using an optimized DNA/protein heterologous prime/boost protocol

An efficacious tuberculosis (TB) vaccine will probably need to induce both CD4 and CD8 T‐cell responses specific to a protective Mycobacterium tuberculosis antigen(s). To achieve this broad cellular immune response we tested a heterologous DNA/protein combination vaccine strategy. We used a purified recombinant protein preparation of a unique M. tuberculosis antigen (rMT1721) found in the urine of TB patients, an optimized plasmid DNA expressing this protein (DNA‐MT1721), and a Toll‐like receptor 4 agonist adjuvant. We found that priming mice with DNA‐MT1721 and subsequently boosting with rMT1721 elicited high titres of specific IgG1 and IgG2a antibodies as well as high magnitude and polyfunctional CD4⁺ T‐cell responses. However, no detectable CD8⁺ T‐cell response was observed using this regimen of immunization. In contrast, both CD4⁺ and CD8⁺ T‐cell responses were detected after a prime/boost vaccination regimen using rMT1721 as the priming antigen and DNA‐MT1721 as the boosting immunogen. These findings support the exploration of heterologous DNA/protein immunization strategies in vaccine development against TB and possibly other infectious diseases.     

A bicistronic DNA vaccine containing apical membrane antigen 1 and merozoite surface protein 4/5 can prime humoral and cellular immune responses and partially protect mice against virulent Plasmodium chabaudi adami DS malaria

The ultimate malaria vaccine will require the delivery of multiple antigens from different stages of the complex malaria life cycle. In order to efficiently deliver multiple antigens with use of DNA vaccine technology, new antigen delivery systems must be assessed. This study utilized a bicistronic vector construct, containing an internal ribosome entry site, expressing a combination of malarial candidate antigens: merozoite surface protein 4/5 (MSP4/5) (fused to a monocyte chemotactic protein 3 chemoattractant sequence) and apical membrane antigen 1 (AMA-1) (fused to a tissue plasminogen activator secretion signal). Transfection of COS 7 cells with bicistronic plasmids resulted in production and secretion of both AMA-1 and MSP4/5 in vitro. Vaccination of BALB/c mice via intraepidermal gene gun and intramuscular routes against AMA-1 and MSP4/5 resulted in antibody production and significant in vitro proliferation of splenocytes stimulated by both AMA-1 and MSP4/5. Survival of BALB/c mice vaccinated with bicistronic constructs after lethal Plasmodium chabaudi adami DS erythrocytic-stage challenge was variable, although significant increases in survival and reductions in peak parasitemia were observed in several challenge trials when the vaccine was delivered by the intramuscular route. This study using a murine model demonstrates that the delivery of malarial antigens via bicistronic vectors is feasible. Further experimentation with bicistronic delivery systems is required for the optimization and refinement of DNA vaccines to effectively prime protective immune responses against malaria.     

Characterization of humoral and cellular immune responses elicited by meningococcal carriage

In order to study the immune response elicited by asymptomatic carriage of Neisseria meningitidis, samples of serum, peripheral blood mononuclear cells (PBMCs), and saliva were collected from a cohort of more than 200 undergraduate students in Nottingham, United Kingdom, who were subject to high rates of acquisition and carriage of meningococci. Serum immunoglobulin G levels were elevated following increases in the rate of carriage, and these responses were specific for the colonizing strains. In order to investigate T-cell responses, PBMCs from 15 individuals were stimulated with a whole-cell lysate of the H44/76 meningococcal strain (B:15:P1.7,16), stained to detect cell surface markers and intracellular cytokines, and examined by flow cytometry. The cells were analyzed for expression of CD69 (to indicate activation), gamma interferon (IFN-gamma) (a representative T-helper 1 subset [Th1]-associated cytokine), and interleukin-5 (IL-5) (a Th2-associated cytokine). Following a brief meningococcal stimulation, the numbers of CD69(+) IFN-gamma(+) CD56/16(+) NK cells were much higher than cytokine-positive CD4(+) events. Both IFN-gamma(+) and IL-5(+) events were detected among the CD69(+) CD4(+) population, leading to the conclusion that an unbiased T-helper subset response was elicited by meningococcal carriage.     

Long-term humoral and cellular immunity induced by a single immunization with replication-defective adenovirus recombinant vector

This study examines the suitability of replication-defective adenovirus vectors for engineering recombinant vaccines. The immunological abilities and limitations of E1-deleted adenoviruses containing the lac Z gene (Ad-β-gal) were investigated by examining the humoral and cellular immune responses to the β-galactosidase protein. BALB/c mice (H-2^d) were given in a single injection of recombinant adenovirus. The cytotoxic T lymphocyte (CTL) response of spleen cells was evaluated. Recognized target cells were H-2^d-derived tumor cells transfected by the lac Z gene, or incubated with the 876–884 β-galactosidase peptide known to be restricted by the L^d molecule of the major histocompatibility complex. A long-lasting β-galactosidase-specific cytotoxic T cell response was obtained. By contrast, CTL from mice immunized with the L^d-restricted peptide were less specific for the endogenous epitope presented by the transfectants expressing β-galactosidase. Ad-β-gal-immunized mice were also protected against an intra-cerebral challenge with a recombinant vaccinia virus expressing the lac-Z gene. These results suggest that Ad-β-gal-induced CTL have protective abilities in vivo. The induction of β-galactosidase-specific T helper lymphocytes and humoral IgG responses were also examined. A proliferative response occurred only late after immunization and the primed T lymphocytes produced interleukin-2, but no interleukin-4. A humoral IgG response to the β-galactosidase protein was detected 15–30 days after a single immunization and remained stable for 6 months without boosting. Lastly, we followed the evolution of the immune response over the course of successive immunizations. The magnitude and kinetics of the cellular and humoral responses were similar to those obtained after a single immunization. Consistent with these observations, an adenovirus-specific neutralizing antibody response was detected as early as the second immunization. Thus, a single immunization with a replication-defective adenovirus recombinant vector induces long-lasting humoral and cellular immune responses specific to the transgene product.     

Hepatitis C virus-specific cellular and humoral immune responses following immunization with a multi-epitope fusion protein

Hepatitis C virus (HCV) is an important causative agent of acute and chronic hepatitis worldwide. We prepared a fusion protein in the vector of pET-11d that included three conserved broadly neutralizing B-cell epitopes and a series of T-cell epitopes located in the HCV NS3 region. In vivo administration of this fusion construct resulted in specific CD8+ cytotoxic lymphocytes in both PBMCs and splenocytes that could recognize specific antigen sites that could be detected by FACS. An HCVcc system was established and applied to detect HCV-specific neutralizing antibodies. These results suggest that the multi-epitope fusion protein is immunogenic and can elicit both humoral and cellular immune responses. In particular, this fusion protein is able to elicit HCV-specific neutralizing antibodies, which are critical for viral clearance. This construct may be significant for vaccine development and could be a potential candidate to be included in the design of a prophylactic and therapeutic vaccine against HCV.     

Single oral immunization with replication deficient recombinant adenovirus elicits long-lived transgene-specific cellular and humoral immune responses

Oral-gastric delivery of vaccines is a preferred route of immunization and is particularly relevant to the development of vaccine-vector systems. We have investigated the ability of a replication deficient (E1-deleted) adenovirus construct (RAd68), which efficiently expresses the measles virus nucleocapsid (N) protein under the control of the strong HCMV IE promoter, to elicit antibody and cytotoxic T cell (CTL) responses in mice following intragastric administration. Measles virus N protein-specific CTL memory and serum antibody responses were analyzed in a total of 140 mice at time points 2-51 weeks after immunization either with a single dose of 10(8) pfu RAd68 or with a fivefold higher dose. Of the 20 animals analyzed in the first 4-week period following low-dose immunization, 6 mounted low-level splenic CTL responses while 13 animals had CTL in the mesenteric lymph nodes. Splenic CTL responses were largely undetectable at later times. Only 23% of low-dose-immunized mice made serum antibody responses and these were generally of low magnitude and frequently of short duration. In contrast, the majority of animals immunized orally with 5 x 10(8) pfu RAd68 mounted splenic CTL responses (70%) and/or antibody responses (89%). Notably, these responses were stronger and of greater duration than those seen following immunization at the lower dose. Gut mucosal immunization with replication deficient adenoviruses is a promising approach, not only for the development of complementary measles vaccine strategies which may be required for measles virus eradication, but also generally for vaccination against other infections.     

Strong cellular and humoral anti-HIV Env immune responses induced by a heterologous rhabdoviral prime-boost approach

Recombinant rhabdovirus vectors expressing human immunodeficiency virus (HIV) and/or simian immunodeficiency virus (SIV) proteins have been shown to induce strong immune responses in mice and rhesus macaques. However, the finding that such responses protect rhesus macaques from AIDS-like disease but not from infection indicates that further improvements for these vectors are needed. Here, we designed a prime-boost schedule consisting of a rabies virus (RV) vaccine strain and a recombinant vesicular stomatitis virus (VSV) both expressing HIV Envelope (Env). Mice were primed and boosted with the two vaccine vehicles by different routes and in different combinations. Mucosal and systemic humoral responses were assessed using enzyme linked immunosorbent assay (ELISA) while the cellular immune response was determined by an IFN-gamma ELISPOT assay. We found that an immunization combination of RV and VSV elicited the highest titers of anti-Env antibodies and the greatest amount of Env-specific IFN-gamma secreting cells pre- and post-challenge with a recombinant vaccinia virus expressing HIV(89.6) Env. Furthermore, intramuscular immunization did not induce antigen-specific mucosal antibodies while intranasal inoculation stimulated vector-specific IgA antibodies in vaginal washings and serum. Our results show that it is feasible to elicit robust cellular and humoral anti-HIV responses using two different live attenuated Rhabdovirus vectors to sequentially prime and boost.     

Protective immune responses to apical membrane antigen 1 of Plasmodium chabaudi involve recognition of strain-specific epitopes.

Apical membrane antigen 1 (AMA-1), an asexual blood-stage antigen of Plasmodium falciparum, is an important candidate for testing as a component of a malaria vaccine. This study investigates the nature of diversity in the Plasmodium chabaudi adami homolog of AMA-1 and the impact of that diversity on the efficacy of the recombinant antigen as a vaccine against challenge with a heterologous strain of P. chabaudi. The nucleotide sequence of the AMA-1 gene from strain DS differs from the published 556KA sequence at 79 sites. The large number of mutations, the nonrandom distribution of both synonymous and nonsynonymous mutations, and the nature of both the codon changes and the resulting amino acid substitutions suggest that positive selection operates on the AMA-1 gene in regions coding for antigenic sites. Protective immune responses induced by AMA-1 were strain specific. Immunization of mice with the refolded ectodomain of DS AMA-1 provided partial protection against challenge with virulent DS (homologous) parasites but failed to protect against challenge with avirulent 556KA (heterologous) parasites. Passive immunization of mice with rabbit antibodies raised against the same antigen had little effect on heterologous challenge but provided significant protection against the homologous DS parasites.     

Augmented humoral and cellular immune responses induced by canine adenovirus type 1 DNA vaccine in BALB/c mice

Infectious canine hepatitis (ICH) is caused by canine adenovirus type 1 (CAV-1), which severely harms infected animals. Vaccination provides an effective approach to preventing canine infectious diseases. With the objective of exploring a new vaccination strategy that may prevent or cure ICH, we constructed a DNA vaccine, pVAX1-CpG-Loop, and evaluated its immune efficacy. We found that vaccination of BALB/c mice with the DNA vaccine alone, or priming with DNA vaccine and boosting with the Loop protein, resulted in the following: (1) High-level specific antibody (IgG) against CAV-1 was induced; (2) T cell activation was elicited; and (3) neutralizing antibodies were detectable in immunized mice. Collectively, these data indicate that the availability of a DNA vaccine could prevent hepatitis contagiosa canis.     

Measurement of naturally acquired humoral immune responses against the C-terminal region of the Plasmodium vivax MSP1 protein using protein arrays

Protein arrays are powerful tools for antibody profiling and vaccine development against infectious agents. In the previous report, we successfully applied an antibody-based protein array for immunoprofiling of Plasmodium vivax infection. Herein, we developed a Ni-NTA surface based protein array to detect immune responses against the recombinant C-terminal region (19 and 42 kDa) of the P. vivax merozoite surface protein 1 (PvMSP1-19 and -42) from sera of vivax malaria patients. The PvMSP1-19 arrays detected P. vivax in 112 of 130 (86.2%; 95% CI, 83.2–89.2%) microscopically positive samples and 2 false positives were obtained among 100 sera samples from healthy subjects (2.0%; 95% CI, 0.6–3.4%). These results were in concordance with results of enzyme-linked immunosorbent assays (ELISA). Kappa values represented excellent agreement for the recombinant PvMSP1-19 protein against sera samples as measured by protein arrays and ELISA (Kappa = 0.904, 95% CI: 0.849–0.960). The PvMSP1-42 protein arrays detected antibody response in 100 of 130 microscopically positive samples (76.9%; 95% CI, 72.4–86.8%) and 8 false positives were obtained in 100 healthy subjects (8.0%; 95% CI, 2.7–13.3%). There is no significant difference between the fluorescent intensity of antibody response to PvMSP1-19 and PvMSP1-42 in the positive sera samples (P > 0.05). The novel protein array platform may be used for profiling naturally acquired humoral immune responses to P. vivax infection.     

Natural human antibody responses to Plasmodium vivax apical membrane antigen 1 under low transmission and unstable malaria conditions in Sri Lanka

Plasmodium vivax apical membrane antigen 1, an important malaria vaccine candidate, was immunogenic during natural malaria infections in Sri Lanka, where low transmission and unstable malaria conditions prevail. Antibody prevalence increased with exposure in areas where malaria was or was not endemic. A marked isotype switch to cytophilic (immunoglobulin G1 [IgG1]/IgG3) antibodies was evident with increasing exposure exclusively in residents from areas of endemicity.     

posttranslational modification of recombinant Plasmodium falciparum apical membrane antigen 1: impact on functional immune responses to a malaria vaccine candidate

Recombinant apical membrane antigen 1 (AMA1) is a leading vaccine candidate for Plasmodium falciparum malaria, as antibodies against recombinant P. falciparum AMA1 (PfAMA1) interrupt merozoite invasion into erythrocytes. In order to investigate the role of posttranslational modification in modulating the functional immune response to recombinant AMA1, two separate alleles of PfAMA1 (FVO and 3D7), in which native N-glycosylation sites have been mutated, were produced using Escherichia coli and a Pichia pastoris expression system. Recombinant Pichia pastoris AMA1-FVO (PpAMA1-FVO) and PpAMA1-3D7 are O-linked glycosylated, and 45% of PpAMA1-3D7 is nicked, though all four recombinant molecules react with conformation-specific monoclonal antibodies. To address the immunological effect of O-linked glycosylation, we compared the immunogenicity of E. coli AMA1-FVO (EcAMA1-FVO) and PpAMA1-FVO antigens, since both molecules are intact. The effect of antigen nicking was then investigated by comparing the immunogenicity of EcAMA1-3D7 and PpAMA1-3D7. Our data demonstrate that there is no significant difference in the rabbit antibody titer elicited towards EcAMA1-FVO and PpAMA1-FVO or to EcAMA1-3D7 and PpAMA1-3D7. Furthermore, we have demonstrated that recombinant AMA1 (FVO or 3D7), whether expressed and refolded from E. coli or produced from the Pichia expression system, is equivalent and mimics the functionality of the native protein in in vitro growth inhibition assay experiments. We conclude that in the case of recombinant AMA1, the E. coli- and P. pastoris-derived antigens are immunologically and functionally equivalent and are unaffected by the posttranslational modification resulting from expression in these two systems.     

Enhanced cell immune responses to hepatitis c virus core by novel heterologous DNA prime/lambda nanoparticles boost in mice

Hepatitis C virus (HCV) is a worldwide problem which does not have an effective vaccine and more than 170 million people worldwide are chronically infected by HCV. T cell responses are associated with spontaneous clearance of HCV infection. We report here the development of recombinant Lambda bacteriophage nanoparticles encoding HCV Core antigen. The aim of this study was to investigate the antigen-specific immune responses triggered in mice by different prime–boost combinations of DNA and Lambda phage nanoparticles encoding the HCV Core. The homologous prime/boost with recombinant Lambda nanoparticles induced higher levels of cellular and humoral immune response than the DNA vaccines. However, a heterologous prime/boost of HCV Core protein, using DNA vaccine priming followed by Lambda boost, induced highest level of lymphocyte proliferation, CD8 lymphocytes with cytotoxic function, and shifting the immune response toward a T helper (Th1) pattern and in overall improved immunity. Our study provides a new, safe, and effective vaccine for the prime–boost regimen which augments robust immunity and highlights novel promising strategies in HCV vaccine development.     

Allele specificity of naturally acquired antibody responses against Plasmodium falciparum apical membrane antigen 1

Antibody responses against proteins located on the surface or in the apical organelles of merozoites are presumed to be important components of naturally acquired protective immune responses against the malaria parasite Plasmodium falciparum. However, many merozoite antigens are highly polymorphic, and antibodies induced against one particular allelic form might not be effective in controlling growth of parasites expressing alternative forms. The apical membrane antigen 1 (AMA1) is a polymorphic merozoite protein that is a target of naturally acquired invasion-inhibitory antibodies and is a leading asexual-stage vaccine candidate. We characterized the antibody responses against AMA1 in 262 individuals from Papua New Guinea exposed to malaria by using different allelic forms of the full AMA1 ectodomain and some individual subdomains. The majority of individuals had very high levels of antibodies against AMA1. The prevalence and titer of these antibodies increased with age. Although antibodies against conserved regions of the molecule were predominant in the majority of individuals, most plasma samples also contained antibodies directed against polymorphic regions of the antigen. In a few individuals, predominantly from younger age groups, the majority of antibodies against AMA1 were directed against polymorphic epitopes. The D10 allelic form of AMA1 apparently contains most if not all of the epitopes present in the other allelic forms tested, which might argue for its inclusion in future AMA1-based vaccines to be tested. Some important epitopes in AMA1 involved residues located in domain II or III but depended on more than one domain.     

A diversity-covering approach to immunization with Plasmodium falciparum apical membrane antigen 1 induces broader allelic recognition and growth inhibition responses in rabbits

Plasmodium falciparum apical membrane antigen 1 (PfAMA1), a candidate malaria vaccine, is polymorphic. This polymorphism is believed to be generated predominantly under immune selection pressure and, as a result, may compromise attempts at vaccination. Alignment of 355 PfAMA1 sequences shows that around 10% of the 622 amino acid residues can vary between alleles and that linkages between polymorphic residues occur. Using this analysis, we have designed three diversity-covering (DiCo) PfAMA1 sequences that take account of these linkages and, when taken together, on average incorporate 97% of amino acid variability observed. For each of the three DiCo sequences, a synthetic gene was constructed and used to transform the methylotrophic yeast Pichia pastoris, allowing recombinant expression. All three DiCo proteins were reactive with the reduction-sensitive monoclonal antibody 4G2, suggesting the DiCo sequences had conformations similar to those of naturally occurring PfAMA1. Rabbits were immunized with FVO strain PfAMA1 or with the DiCo proteins either individually or as a mixture. Antibody titers and the ability to inhibit parasite growth in vitro were determined. Animals immunized with the DiCo mix performed similarly to animals immunized with FVO AMA1 when measured against FCR3 strain parasites but outperformed animals immunized with FVO AMA1 when assessed against other strains. The levels of growth inhibition (approximately 70%) induced by the mix of three DiCo proteins were comparable for FVO, 3D7, and HB3, suggesting that a considerable degree of diversity in AMA1 is adequately covered. This suggests that vaccines based upon the DiCo mix approach provide a broader functional immunity than immunization with a single allele.     

Characteristics of cellular and humoral immune responses after immunization with different rabies vaccines

Three rabies vaccines were compared: 1. the Fermi type vaccine, a phenol-treated suspension of brain tissue from infected sheep; 2. a virus grown in sheep brain, purified from the contaminating material to 85-90% and inactivated with beta-propiolactone; 3. and the MNIIP-74 strain cultured in Japanese quail embryo cells and inactivated with beta-propiolactone. A single immunization of mice with any of the preparations resulted in about 50% inhibition of splenocyte migration after 2 days; by day 15 the inhibition was 95-98%. By day 45 the migration index returned to the initial level. Increased ability to blast transformation in splenocytes was found by day 15, reached the maximum (160 to 212% of the control level taken for 100%) by day 30, and then began to decrease. The most marked change in blast transformation was brought about by the purified cerebral vaccine, while the less marked one by the tissue culture vaccine. The titre of virus-neutralizing antibodies reached a maximum after 15-30 days, 60 days after immunization it dropped twice. The resistance of mice to intracerebral infection with the rabies virus shortly after immunization might be due to cellular protective factors, while at later intervals it correlated with the level of virus-neutralizing antibodies.     

RANTES和MIP-1α基因对HIV-1核酸疫苗诱导免疫应答的影响

目的　研究RANTES(活化T细胞调节的、正常T细胞表达和分泌的分子 )、MIP 1α(巨噬细胞炎症蛋白 1α)基因对HIV 1核酸疫苗诱导免疫应答的影响 ,以探求HIV 1核酸疫苗的新策略。方法　pCI neoGAG联合RANTES、MIP 1α基因或者pCI neoGAG单独免疫BALB c小鼠 ,采用ELISA检测免疫小鼠的特异性抗体和IFN γ水平 ,以MTT比色法检测免疫小鼠脾淋巴细胞的增殖 ,用乳酸脱氢酶 (LDH)试验检测小鼠特异性细胞毒性T淋巴细胞 (CTL)的应答。结果　与pCI neoGAG免疫组比较 ,pCI neoGAG联合RANTES、MIP基因免疫组小鼠血清的抗HIV 1p2 4抗体滴度升高 ,IFN γ升高 ,小鼠的脾淋巴细胞增殖实验刺激指数 (SI)以及特异性CTL活性均高 ,差异都有显著性 (P <0 .0 1)。结论　RANTES、MIP 1α基因联合HIV 1核酸疫苗免疫小鼠 ,可能增强特异性TH1细胞和CTL反应 ,RANTES、MIP 1α基因对体液免疫有加强作用。因此 ,RANTES、MIP 1α基因对于HIV 1核酸疫苗是具有较好应用前景的免疫佐剂。     

Intranasal immunization with plasmid DNA encoding spike protein of SARS-coronavirus/polyethylenimine nanoparticles elicits antigen-specific humoral and cellular immune responses

Background

The expression of metallothionein (MT) is involved in acquiring resistance to immune-mediated apoptosis; it is also a negative regulator of the immune response. Nasal polyps are typified by a resistance to immune-mediated apoptosis as well as by excessive immune cell infiltration. RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is a membrane protein capable of inducing the apoptosis of CTLs and NK cells. The aim of the present study has been to explore the expression of metallothionein with respect to immune cell presence and immune cell activity. In our study, we identified immune cells using CD4 and CD68 antigen expression and evaluated their activity using CD25 antigen expression. We then analyzed metallothionein, RCAS1, CD25, CD4, and CD68 in a sampling of 50 nasal polyps using the immunohistochemistry method. We were able to divide the nasal polyps into three main groups according to their predominant immune cell infiltration: eosinophilic nasal polyps (21 cases), lymphocytic nasal polyps (17 cases), and neutrophilic nasal polyps (12 cases).

Results

In the present study, statistically significant differences between the MT expression in the epithelium and that in the stroma of the nasal polyps along with the accompanying alterations in activation markers on immune cells were found and the number of macrophages in both the eosinophilic and the lymphocytic nasal polyps was assessed. RCAS1-expressing macrophages were found only in the eosinophilic nasal polyps.

Conclusion

MT expression seems to favor the survival of nasal polyp epithelial cells in the adjacent area of increasingly cytotoxic immune activity. RCAS1-expressing macrophages seem to participate in creating the immune suppressive microenvironment and so help to sustain local inflammation.     

Breadth of cellular and humoral immune responses elicited in rhesus monkeys by multi-valent mosaic and consensus immunogens

To create an HIV-1 vaccine that generates sufficient breadth of immune recognition to protect against the genetically diverse forms of the circulating virus, we have been exploring vaccines based on consensus and mosaic protein designs. Increasing the valency of a mosaic immunogen cocktail increases epitope coverage but with diminishing returns, as increasingly rare epitopes are incorporated into the mosaic proteins. In this study we compared the immunogenicity of 2-valent and 3-valent HIV-1 envelope mosaic immunogens in rhesus monkeys. Immunizations with the 3-valent mosaic immunogens resulted in a modest increase in the breadth of vaccine-elicited T lymphocyte responses compared to the 2-valent mosaic immunogens. However, the 3-valent mosaic immunogens elicited significantly higher neutralizing responses to Tier 1 viruses than the 2-valent mosaic immunogens. These findings underscore the potential utility of polyvalent mosaic immunogens for eliciting both cellular and humoral immune responses to HIV-1.