Hepatitis C virus-like particles combined with novel adjuvant systems enhance virus-specific immune responses

We have previously described the generation of hepatitis C virus-like particles (HCV-LPs) in insect cells and shown that immunization with HCV-LPs elicited both humoral and cellular immune responses in mice. To further characterize the HCV-LPs as a vaccine candidate, we evaluated the effects of adjuvant AS01B (monophosphoryl lipid A [MPL] and QS21), CpG 10105, and the combination of the 2 adjuvants on the immunogenicity of HCV-LPs in AAD mice (transgenic for HLA-A2.1). All HCV-LP-immunized mice (with or without adjuvant) developed high titers of anti-HCV E1/E2 antibodies after 4 injections intramuscularly. However, antibody titers in mice immunized with HCV-LP plus AS01B, plus CpG 10105, or plus the combination of AS01B and CpG 10105 were 4, 3, and 10 times higher, respectively, than that of HCV-LP alone. Isotype analysis of the induced anti-envelope antibodies showed that HCV-LP alone induced a predominant immunoglobulin (Ig) G1 response. In contrast, when the 2 adjuvants AS01B and CpG 10105 were combined, the response became predominantly IgG2a whereas HCV-LP plus AS01B or CpG 10105 gave a mixed IgG1 and IgG2a response, indicating that AS01B and CpG 10105 promote a more T-helper type 1 (Th1) response and that combining the 2 adjuvants results in an additive or synergistic interaction. These observations were further confirmed by the results of CD4(+) enzyme-linked immunospot assay for interferon (IFN)-gamma and interleukin (IL)-4 and intracellular cytokine staining of IFN-gamma producing CD8(+) cells. In conclusion, HCV-LP is a promising vaccine candidate against HCV infection and the adjuvants used are potent immune enhancers for this approach.     

Vaccine-induced cross-genotype reactive neutralizing antibodies against hepatitis C virus

We detected cross-reactive neutralizing antibodies (NtAb) against hepatitis C virus (HCV) in chimpanzees vaccinated with HCV-1 (genotype 1a) recombinant E1/E2 envelope glycoproteins. Five vaccinated chimpanzees, protected following HCV-1 challenge, were initially studied using the heterologous H77 (genotype 1a) HCVpp assay. All animals had developed NtAb after the second vaccination; 4 animals had reciprocal titers of ≥200 at the time of challenge. Using genotypes 1a-6a HCV pseudoparticles (HCVpp) and cell culture-derived HCV (HCVcc) assays, cross-reactive NtAb were detected against 1a, 4a, 5a, and 6a, with limited reactivity against 2a and 3a. Our study provides encouragement for the development of a recombinant envelope-based vaccine against hepatitis C.     

DNA immunization with fusion genes encoding different regions of hepatitis C virus E2 fused to the gene for hepatitis B surface antigen elicits immune responses to both HCV and HBV

AIM：Both Hepatitis B virus(HBV)and Hepatitis C virus (HCV) are major causative agents of transfusion-associated and community-acquired hepatitis wordwide.Development of a HCV vaccine as well as more effective HBV vaccines is and urgent task.DNA immunization provides a promising approach to elicit protective humoral and cellular immune responses against viral infection.The aim of this study is to achieve immune responses against both HCV and HBV by DNA immunization with fusion constructs comprising various HCV E2 gene fragments fused to HBsAg gene of HBV.METHODS:C57BL/6 mice were immunized with plasmid DNA expressing five fragmets of HCV E2 fused to the gene for HBaAg respectively.After one primary and one boosting immunizatios,antibodies against HCV E2 and HBsAg weretested and subtyped in ELISA.Splenic cytokine expression of IFN-γ and IL-10 was analyzed using an RT-PCR assay Post-immune mouse antisera also were tested for their ability to capture HCV viruses in the serum of a hepatitis C patient in vitro.RESULTS:After immunization,antibodies against both HBsAg and HCV E2 were detected in mouse sera,with Ig2a being the dominant immunoglobulin sub-class.Highlevel expression of INF-γwas detected in cultured splenic cells Mouse antisera against three of the five nfusion constructs were able to capture HCV viruses in an in vitro assay.CONCLUSION:The results indicate that these fusion constructs could efficiently elicit humoral and Th1 dominant cellular immune responses against both HBV S and HCV E2 antigens in DNA-immunized mice.They thus could serve as candidates for a bivalent vaccine against HBV and HCV infection.In addition,the capacity of mouse antisera against three of the five fusion constructs to capture HCV viruses in vitro suggested that neutralizing epitopes may be present in other regions of E2 besides the hypervariable region1.     

融合基因S2S/IFNα对小鼠免疫反应的影响

目的探讨S2S/IFNα融合基因疫苗诱导HBV preS2S特异性体液免疫及细胞免疫应答的作用。方法pcDNA3.1S2S/IFNα作为实验组,设立pcDNA3.1S2S＋pcDNA3 IFNα组、pcDNA3.1S2S组及空载体对照组作为对照组,免疫BALB/c小鼠。采用0、2、4周的方案接种,检测各次接种后抗体水平。初次免疫后7周,测定免疫脾细胞的杀伤活性、增殖活性、细胞因子的分泌水平及免疫脾细胞CD25的表达量。结果pcDNA3.1S2S/IFNα组小鼠抗体滴度、免疫脾细胞的杀伤活性和增殖活性、Th1型细胞因子的分泌水平及CD25表达量均比对照组明显增强。结论S2S/IFNα融合基因能诱导更强的特异性体液免疫及细胞免疫应答。     

重组质粒pcDNA3．1S2S／Fc在小鼠诱导免疫反应的观察

目的探讨S2S／Fc融合基因疫苗诱导小鼠HBV preS2S特异性体液和细胞免疫应答情况。方法取pcDNA3．1S2S/Fc、pcDNA3．1S2S＋pCMVsFc、pcDNA3．1S2S和空载体对照免疫BALB／c小鼠。在免疫动物2,4和6周后检测血清抗-HBs水平;在初次免疫7周后,测定免疫脾细胞的杀伤活性、增殖活性及细胞因子的分泌水平。结果经pcDNA3．1S2S／Fc免疫小鼠6周抗体滴度升至最高,免疫脾细胞的杀伤活性在效靶比为20：1时最高,免疫脾细胞的增殖活性以及IL-2和IFN-γ的分泌水平均比对照组明显增高。结论S2S／Fc融合基因在小鼠能诱导很强的特异性体液和细胞免疫应答。     

Immunization of Mice by BCG Formulated HCV Core Protein Elicited Higher Th1-Oriented Responses Compared to Pluronic-F127 Copolymer

Background

A supreme vaccine for Hepatitis C virus (HCV) infection should elicit strong Th1-oriented cellular responses. In the absence of a Th1-specific adjuvant, immunizations by protein antigens generally induce Th2-type and weak cellular responses.

Objectives

To evaluate the adjuvant effect of BCG in comparison with nonionic copolymer-Pluronic F127 (F127) as a classic adjuvant in the formulation of HCV core protein (HCVcp) as a candidate vaccine for induction of Th1 immune responses.

Materials and Methods

Expression of N-terminally His-Tagged HCVcp (1-122) by pIVEX2.4a-core vector harboring the corresponding gene under the control of arabinose-inducible (araBAD) promoter was achieved in BL21-AI strain of E.coli and purified through application of nitrilotriacetic acid (Ni-NTA) chromatography. Mice were immunized subcutaneously (s.c.) in base of the tail with 100 μl of immunogen (F127+HCVcp or BCG+HCVcp; 5 μgHCVcp/mouse/dose) or control formulations (PBS, BCG, F127) at weeks 0, 3, 6. Total and subtypes of IgG, as well as cellular immune responses (Proliferation, In vivo CTL and IFN-γ/IL-4 ELISpot assays against a strong and dominant H2-d restricted, CD8+-epitopic peptide, core 39-48; RRGPRLGVRA of HCVcp) were compared in each group of immunized animals.

Results

Expression and purification of core protein around the expected size (21 kDa) was confirmed by Western blotting. The HCVcp + BCG vaccinated mice showed significantly higher lymphocyte proliferation and IFN-γ production but lower levels of cell lysis (45% versus 62% in CTL assay) than the HCVcp+F127 immunized animals. “Besides, total anti-core IgG and IgG1 levels were significantly higher in HCVcp + F127 immunized mice as compared to HCVcp + BCG vaccinated animals, indicating relatively higher efficacy of F127 for the stimulation of humoral and Th2-oriented immune responses”.

Conclusions

Results showed that HCVcp + BCG induced a moderate CTL and mixed Th1/Th2 immune responses with higher levels of cell proliferation and IFN-γ secretion, indicating that BCG may have a better outcome when formulated in HCVcp-based subunit vaccines.     

丙型肝炎病毒结构区抗原联合基因重组体DNA免疫的实验研究

目的 试图通过ＤＮＡ免疫的方法进行改进达到增强免疫效率及改变免疫的答类型。方法：应用丙型肝炎病毒（ＨＣＶ）结构区基因重组体（ｐＣ和ｐＣＥ１Ｅ２）与白细胞介素（ＩＬ－２）ｐ３５和ｐ４０编码基因重组体（ｐＩＬ－１２），转染真核细胞并对其表达产物进行检测，并且将ｐＣ、ｐＣＥ１Ｅ２和ｐＩＬ－１２联合免疫ＢＡＬＢ／Ｃ鼠，对其体液免疫和体内、体外细胞免疫应答进行检测。结果 所构建的重组体均可在真核细胞内瞬时或     

CD4 T lymphocyte proliferative responses to hepatitis C virus (HCV) antigens in patients coinfected with HCV and human immunodeficiency virus who responded to anti-HCV treatment

CD4 T lymphocyte proliferative responses to hepatitis C virus (HCV) antigens were evaluated before and during an anti-HCV regimen (interferon-alpha2a and ribavirin) in 36 patients coinfected with HCV and human immunodeficiency virus (HIV), to determine whether immune responses against HCV antigens are present in such patients, whether these responses are modified by anti-HCV treatment, and whether they are correlated with treatment efficacy. The CD4 responses against HCV antigens (primarily core antigens) detected at study entry in one-half of the patients did not correlate with anti-HCV treatment efficacy. Of 36 patients, 8 had patterns of persistent immune response to infection by genotypes 3 or 4 that were significantly correlated with sustained virologic response. Persistent immunologic reactivity and sustained virologic response coexisted only in patients infected with genotype 3. These findings suggest that HCV genotype may influence specific immune response, which, in turn, is implicated in virologic control.     

CpG DNA functions as an effective adjuvant for the induction of immune responses in aged mice.

The present studies demonstrate that the immunization of aged mice with Diphtheria toxoid in formulations containing unmethylated immunostimulatory CpG motifs, promotes the successful development of immune responses that are qualitatively and quantitatively comparable to those induced in young animals vaccinated in a similar manner. Aged mice given vaccines containing CpG oligodeoxynucleotides (ODNs) expressed primary and secondary systemic humoral immune responses having isotype profiles consistent with an enhancement in Th-1 type immunity. The ability to generate common mucosal immunity was also restored in aged animals given CpG ODN-containing vaccines. Dendritic cells (DCs) were determined to represent one of the cellular targets of CpG ODN activities in aged mice since restoration of immune function was observed when DCs from aged donors were pulsed with antigen and CpG ODNs, prior to injection into syngeneic young adult or aged recipients. Interestingly, antigen-pulsed DCs from young donors were fully capable of stimulating immune responses following their injection into syngeneic young adult or aged hosts, without a need for exposure to CpG ODNs. Although the mechanism(s) by which CpG DNA exerts its beneficial adjuvant effects on the aged immune system remains unclear, our findings suggest that the incorporation of CpG ODNs into vaccine formulations provided to the aged could prove useful in the development of more effective vaccines for the elderly.     

Clearance of genotype 1b hepatitis C virus in chimpanzees in the presence of vaccine-induced E1-neutralizing antibodies

Accumulating evidence indicates that neutralizing antibodies play an important role in protection from chronic hepatitis C virus (HCV) infection. Efforts to elicit such responses by immunization with intact heterodimeric E1E2 envelope proteins have met with limited success. To determine whether antigenic sites, which are not exposed by the combined E1E2 heterodimer structure, are capable of eliciting neutralizing antibody responses, we expressed and purified each as separate recombinant proteins E1 and E2, from which the immunodominant hypervariable region (HVR-1) was deleted. Immunization of chimpanzees with either E1 or E2 alone induced antigen-specific T-helper cytokines of similar magnitude. Unexpectedly, the capacity to neutralize HCV was observed in E1 but not in animals immunized with E2 devoid of HVR-1. Furthermore, in vivo only E1-vaccinated animals exposed to the heterologous HCV-1b inoculum cleared HCV infection.     

Immunization with hepatitis C virus-like particles results in control of hepatitis C virus infection in chimpanzees

Recombinant hepatitis C virus (HCV)-like particles (HCV-LPs) containing HCV structural proteins (core, E1, and E2) produced in insect cells resemble the putative HCV virions and are capable of inducing strong and broad humoral and cellular immune responses in mice and baboons. Here, we present evidence on the immunogenicity and induction of protective immunity by HCV-LPs in chimpanzees. Chimpanzees (two in each group), were immunized with HCV-LPs or HCV-LPs plus AS01B adjuvant. After immunizations, all animals developed an HCV-specific immune response including IFN-gamma(+), IL-2(+), CD4(+), and CD8(+) T cell and proliferative lymphocyte responses against core, E1, and E2. Upon challenge with an infectious HCV inoculum, one chimpanzee developed transient viremia with low HCV RNA titers (10(3) to 10(4) copies per ml) in the third and fourth weeks after the challenge. The three other chimpanzees became infected with higher levels of viremia (10(4) to 10(5) copies per ml), but their viral levels became unquantifiable (<10(3) copies per ml) 10 weeks after the challenge. After the HCV challenge, all four chimpanzees demonstrated a significant increase in peripheral and intrahepatic T cell and proliferative responses against the HCV structural proteins. These T cell responses coincided with the fall in HCV RNA levels. Four na?ve chimpanzees were infected with the same HCV inoculum, and three developed persistent infection with higher viremia in the range of 10(5) to 10(6) copies per ml. Our study suggests that HCV-LP immunization induces HCV-specific cellular immune responses that can control HCV challenge in the chimpanzee model.     

细胞因子佐剂白介素23和佐剂CpG2216对呼吸道合胞病毒重组疫苗免疫原性的影响

目的 研究细胞因子佐剂白介素23(IL-23)和佐剂CpG2216对呼吸道合胞病毒(RSV)重组疫苗G1F/M2免疫原性的影响.方法 将编码IL-23的质粒(简称IL-23)单独作为佐剂以及将IL-23和CpG2216联合作为佐剂与G1F/M2共免疫BABL/c小鼠三次,在每次免疫后10 d取血,分离血清,用间接ELI...     

结核复合抗原疫苗不同抗原组合对小鼠免疫功能的影响

目的 探讨在辅以卡介苗非甲基化的胞嘧啶鸟嘌呤二核苷酸重复序列(CpG)佐剂和铝佐剂的情况下,结核病复合抗原疫苗中抗原85b(Ag85b)、融合蛋白早期滤液蛋白10(CFP-10)和相对分子质量为6000的早期分泌抗原靶蛋白(ESAT-6)及热休克蛋白X(HspX)不同组合对小鼠免疫功能的影响.方法 将48只BALB/c小鼠按抗原组合分为8组:(1)A组:Ag85b+CFP-10/ESAT-6+HspX+佐剂,(2)B组:CFP-10/ESAT-6+HspX+佐剂,(3)C组:Ag85b+HspX+佐剂,(4)D组:Ag85b+CFP-10/ESAT-6+佐剂,(5)E组:Ag85b+佐剂,(6)F组:CFP-10/ESAT-6+佐剂,(7)G组:HspX+佐剂,(8)对照组:生理盐水.每组6只,皮下免疫,共免疫3次,间隔2周,末次免疫后1周处死小鼠.酶联免疫斑点实验和淋巴细胞增殖实验检测小鼠脾淋巴细胞分泌γ-干扰素和白细胞介素-4及抗原特异性淋巴细胞增殖情况.酶联免疫吸附实验检测小鼠血清中IgG、IgG1和IgG2a抗体滴度.结果 E组γ-干扰素的斑点数[中位数(四分位间距),122.8个(78.4～184.4个)]明显高于C组和对照组[14.3个(6.5～14.6个)和0.5个(0.5～1.3个)],差异均有统计学意义(u值均为0.0,均P＜0.01);D组白细胞介素-4的斑点数[173.5个(7 8.8～233.4个)和132.8个(50.3～159.4个)]明显多于对照组[0.5个(0.5～1.3个)和5.3个(2.9～6.5个)],差异有统计学意义(u值均为0.0,均P＜0.01);A、C、D和E组的刺激指数(2.42±0.50、2.18±0.37、2.86±0.51和2.70±0.15)明显高于对照组(1.11±0.13),差异有统计学意义(F值为20.96,均P＜0.01);HspX激发的抗原特异性IgG、IgG1和IgG2a抗体稀释倍数对数值(3.90～5.21)均明显高于Ag85b(3.30～4.51)和CFP-10/ESAT-6蛋白(3.10～4.05),差异均有统计学意义(F值为43.8～70.4,均P＜0.01).结论 在辅以佐剂的情况下,不同抗原组合对小鼠免疫功能的影响有差别,3种抗原同时免疫并未获得最好的免疫效果,提示抗原间的相互作用可能对免疫效果产生影响.

Abstract：

Objective To study the immune function of mice immunized by different combinations of antigen 85b ( Ag85b), fusion protein culture filtered protein 10 ( CFP-10), early secreted antigenic target 6 kDa protein (ESAT-6) and heat shock protein X (Hsp X) with combined adjuvants of Bacille CalmetteGuerin (BCG) CpG and aluminum.Methods According to antigen combinations, 48 BALB/c mice were divided into 8 groups: ( 1 ) group A: Ag85b + CFP-10/ESAT-6 + HspX + adjuvant; (2) group B: CFP-10/ESAT-6 + HspX + adjuvant; ( 3 ) group C: Ag85b + HspX + adjuvant; (4) group D: Ag85b + CFP-10/ESAT-6 + adjuvant; (5) group E: Ag85b + adjuvant; (6) group F: CFP-10/ESAT-6 +adjuvant; (7)group G: HspX + adjuvants; (8) control group: saline (6 mice per group).The mice were subcutaneously immunized 3 times.One week after the third subcutaneous immunization, spleens were collected for enzymelinked immunospot (ELISPOT) assay to detect IFN-γ and IL-4 secretion, and for the lymphocyte proliferation assay to observe antigen-specific lymphocyte proliferation.Serum samples were separated for enzyme-linked immunosorbent assay (ELISA) to detect the titers of antigen-specific IgG, IgG1 and IgG2a antibodies.Results The amount of IFN-γ spots in Group E [median ( quartile), 122.8 (78.4 - 184.4 )]was significantly more than that in group C [14.3 (6.5 - 14.6)] and the control group [0.5 (0.5 - 1.3)](u =0.0, P ＜ 0.01 ).The amount of IL-4 spots in Group D stimulated with Ag85b and CFP-10/ESAT-6 [173.5 (78.8 -233.4), 132.8 ( 50.3 - 159.4)] were significantly more than those in the control group [0.5 (0.5 - 1.3 ), 5.3 ( 2.9 - 6.5 )] ( u = 0.0, P ＜ 0.01 ).The level of stimulation index of lymphocyte proliferation in Group A, C, D, E(2.42 ±0.50, 2.18 ±0.37, 2.86 ±0.51, 2.70 ±0.15) was significantly higher than that of the control group ( 1.11 ± 0.13 ) ( F= 20.96, P ＜ 0.01 ).The level of antigen-specific IgG, IgG1 , IgG2a antibody titers induced by Hsp X [lg( antibody dilution degree), 3.90 -5.21] was significantly higher than those induced by Ag85b (3.30-4.51 ) and CFP-10/ESAT-6 (3.10 -4.05) ( F = 63.8 - 70.4, P ＜ 0.01 ) .Conclusions With the use of adjuvants, different antigen combinations showed different influences on the immune function in mice.A combination of 3 antigens did not elicit the best immune effect, suggesting that the interaction among antigens may affect their immunity.     

丙型肝炎病毒不同功能区抗体与病毒核糖核酸的相关性

目的 探讨慢性丙型肝炎患者体内不同功能区抗体的免疫应答及与HCV RNA浓度的关系。方法 克隆表达丙型肝炎病毒不同功能区优势表位抗原蛋白(HCV—C、NS3、NS4、NS5和HVR1)，建立单片段ELISA法检测抗HCV抗体，并以定量HCV RT—PCR法检测患者血清中HCV RNA浓度。结果 慢性丙型肝炎患者体内HCV不同功能区抗体检出有较大的差异，HCV—C、HVR1检出最高，其次为NS3、NS4和NS5。结论 HCV—C、NS3、NS4、和HVR1抗体滴度与HCV RNA浓度均有较好的相关性。     

In vitro assay for neutralizing antibody to hepatitis C virus: evidence for broadly conserved neutralization epitopes

Our understanding of the humoral immune response to hepatitis C virus (HCV) is limited because the virus can be studied only in humans and chimpanzees and because previously described neutralization assays have not been robust or simple to perform. Nevertheless, epidemiologic and laboratory studies suggested that neutralizing Ab to HCV might be important in preventing infection. We have recently described a neutralization assay based on the neutralization of pseudotyped murine retrovirus constructs bearing HCV envelope glycoproteins on their surface. We have applied the assay to well characterized clinical samples from HCV-infected patients and chimpanzees, confirmed the existence of neutralizing Ab to HCV, and validated most previously reported neutralizations of the virus. We did not find neutralizing anti-HCV in resolving infections but did find relatively high titers (>1:320) of such Ab in chronic infections. Neutralizing Ab was directed not only to epitope(s) in the hypervariable region of the E2 envelope protein but also to one or more epitopes elsewhere in the envelope of the virus. Neutralizing Ab was broadly reactive and could neutralize pseudotype particles bearing the envelope glycoproteins of two different subgenotypes (1a and 1b). The ability to assay neutralizing anti-HCV should permit an assessment of the prospects for successful Ab-mediated passive and active immunoprophylaxis against hepatitis C.     

Association of antibodies to hepatitis C virus glycoproteins 1 and 2 (anti-E1E2) with HCV disease

Summary.  Hepatitis C virus (HCV) causes acute and chronic liver diseases in humans. Its two envelope glycoproteins, E1 and E2, provide a target for host immune recognition. HCV genotypes are classified into six genetic groups. To study the role of anti-HCV E1 and E2 (anti-E1E2) in HCV disease, the correlation between antibody level and viral load, genotype, disease severity and response to treatment was investigated. The levels of antibodies to HCV glycoproteins E1 and E2 antibodies were evaluated in 230 sera of patients with chronic hepatitis C by enzyme-linked immunosorbent assay. The antigens used were recombinant HCV glycoproteins derived from genotype 1 (H77c) and genotype 3 (UKN3A1.28). Seroreactivity was greater when sera were tested against antigen derived from their homologous genotype than against heterologous antigen. Reactivity against UKN3A1.28 in sera from patients infected with genotype 3 was significantly higher than corresponding reactivity between patients infected with genotype 1 and H77c. The seroreactivity was inversely proportional to the viral load and to the degree of liver fibrosis. The pre-treatment level of anti-E1E2 was higher in sustained responders to combination therapy. These results demonstrate that seroreactivity against E1E2 depends upon the genotypic origin of the E1E2 antigens and the infecting genotype, and suggest a possible protective effect of anti-E1E2 against disease progression.     

Plasmid DNA immunization against Japanese encephalitis virus: immunogenicity of membrane-anchored and secretory envelope protein.

Plasmid DNA synthesizing membrane-anchored or secretory Japanese encephalitis virus (JEV) envelope (E) protein and premembrane protein was delivered to mice by intramuscular injection or gene gun. Intramuscular plasmid immunization induced anti-E antibody responses similar to those associated with commercial JEV vaccine. The gene gun induced less antibody response. The 2 forms of the E protein induced similar antibody titers when administered by the same delivery mode. Both plasmids generated high titers of JEV-neutralizing antibodies, although the titers were lower than those induced by the vaccine. Intramuscular DNA immunization induced T helper 1 (Th1) immune responses, and the gene gun induced Th2 responses. Compared with secretory E protein, the membrane-anchored protein heavily skewed the immune response toward either Th1 or Th2, depending on the route of immunization. In an intracerebral JEV challenge model, plasmid-immunized mice had approximately 60% protection; this was not affected by the form of the E protein or by immunization route.     

Vaccination of chimpanzees with plasmid DNA encoding the hepatitis C virus (HCV) envelope E2 protein modified the infection after challenge with homologous monoclonal HCV

Hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. Development of vaccines to prevent HCV infection, or at least prevent progression to chronicity, is a major goal. In mice and rhesus macaques, a DNA vaccine encoding cell-surface HCV-envelope 2 (E2) glycoprotein stimulated stronger immune responses than a vaccine encoding intracellular E2. Therefore, we used DNA encoding surface-expressed E2 to immunize chimpanzees 2768 and 3001. Chimpanzee 3001 developed anti-E2 after the second immunization and antibodies to hypervariable region 1 (HVR1) after the third immunization. Although chimpanzee 2768 had only low levels of anti-E2 after the third immunization, an anamnestic response occurred after HCV challenge. CTL responses to E2 were not detected before challenge, but a strong response was detected after HCV challenge in chimpanzee 2768. An E2-specific CD4+ response was detected in chimpanzee 2768 before challenge and in both chimpanzees postchallenge. Three weeks after the last immunization, animals were challenged with 100 50% chimpanzee-infectious doses (CID(50)) of homologous monoclonal HCV. As a control, a naive chimpanzee was inoculated with 3 CID(50) of the challenge virus. The vaccine did not generate sterilizing immunity because both vaccinated chimpanzees were infected. However, both vaccinated chimpanzees resolved the infection early whereas the control animal became chronically infected. Compared with the control animal, hepatitis appeared earlier in the course of the infection in both vaccinated chimpanzees. Therefore, DNA vaccine encoding cell surface-expressed E2 did not elicit sterilizing immunity in chimpanzees against challenge with a monoclonal homologous virus, but did appear to modify the infection and might have prevented progression to chronicity.     

Effect of oral administration of CpG ODN-OVA on WBB6F1-W/Wv mice.

BACKGROUND: We have already reported that antigen-specific IgG1 antibody production in WBB6F1-W/Wv (W/Wv) mice after oral administration of ovalbumin (OVA) was extremely high. Active systemic anaphylaxis (ASA) was induced in these mice after intraperitoneal (i.p.) administration of OVA, and Th2-dominant helper T-cell activation occurred. In this study, we examined the effect of CpG oligodeoxynucleotide (ODN) conjugation of OVA on oral immunization of W/Wv mice. METHODS: W/Wv mice were sensitized by administration of 0.1 mg OVA or CpG ODN-OVA by gavage every day for 4 weeks, and the serum titers of OVA-specific IgG1, IgE, and IgG2a antibody were determined. ASA was induced by i.p. injection of OVA, and the changes in body temperature were monitored. In vitro production of Th1- and Th2- type cytokines by splenocytes re-stimulated with antigen was also measured. RESULTS: The antigen-specific IgG1 antibody titer in the CpG ODN-OVA-sensitized W/Wv mice was lower than in the OVA-sensitized group, but the IgG2a titer was higher. ASA was not induced by i.p. OVA challenge. There were significant increases in the production of Th1-type cytokine (IFN-gamma) by splenocytes in the CpG ODN-OVA-sensitized mice, but the Th2-type cytokine (IL-4) level in the splenocyte culture medium was lower. CONCLUSIONS: These results indicated that oral administration of CpG ODN-OVA conjugate significantly induced antigen-specific Th1 responses and reduced Th2 responses (allergic reactions) on re-stimulation. These findings suggest that CpG ODN-antigen conjugate may be useful as an oral vaccine.     

Anti-Glycoprotein G Antibodies of Herpes Simplex Virus 2 Contribute to Complete Protection after Vaccination in Mice and Induce Antibody-Dependent Cellular Cytotoxicity and Complement-Mediated Cytolysis

We investigated the role of antibodies against the mature portion of glycoprotein G (mgG-2) of herpes simplex virus 2 (HSV-2) in protective immunity after vaccination. Mice were immunized intramuscularly with mgG-2 and oligodeoxynucleotides containing two CpG motifs plus alum as adjuvant. All C57BL/6 mice survived and presented no genital or systemic disease. High levels of immunoglobulin G subclass 1 (IgG1) and IgG2 antibodies were detected and re-stimulated splenic CD4⁺ T cells proliferated and produced IFN-γ. None of the sera from immunized mice exhibited neutralization, while all sera exerted antibody-dependent cellular cytotoxicity (ADCC) and complement-mediated cytolysis (ACMC) activity. Passive transfer of anti-mgG-2 monoclonal antibodies, or immune serum, to naive C57BL/6 mice did not limit disease progression. Immunized B‑cell KO mice presented lower survival rate and higher vaginal viral titers, as compared with vaccinated B-cell KO mice after passive transfer of immune serum and vaccinated C57BL/6 mice. Sera from mice that were vaccinated subcutaneously and intranasally with mgG-2 presented significantly lower titers of IgG antibodies and lower ADCC and ACMC activity. We conclude that anti-mgG-2 antibodies were of importance to limit genital HSV‑2 infection. ADCC and ACMC activity are potentially important mechanisms in protective immunity, and could tentatively be evaluated in future animal vaccine studies and in clinical trials.