结核分枝杆菌联合DNA疫苗初免-BCG加强的免疫效果观察

目的:研究并比较结核分枝杆菌免疫保护性抗原DNA(Ag85A和ESAT-6)疫苗联合免疫,BCG免疫以及联合DNA疫苗初免-BCG加强免疫等不同的免疫策略,诱导免疫应答效果观察.方法:健康雌性BALB/c小鼠24只,随机分成PBS 阴性对照组,DNA初免-BCG异源加强组,DNA(Ag85A和ESAT-6)初免DNA同源加强组和BCG阳性对照组,共进行3次免疫,初免2次,最后1次加强,间隔2周1次.PBS组3次均注射PBS 溶液;DNA/BCG组以质粒DNA免疫2次,最后1次以BCG加强免疫;DNA/DNA组3次均以质粒DNA进行免疫;BCG组则注射PBS溶液2次后以BCG免疫.末次免疫后4、6、8周分别分离血清测定总IgG水平,同时分离小鼠脾细胞,体外经TB-PPD刺激后进行淋巴细胞增殖实验(XTT法)并测定脾细胞培养上清中IFN-γ和IL-4水平.结果:DNA/BCG、DNA/DNA、BCG组体外经TB-PPD刺激后均检测到特异性IgG抗体产生,3组平均效价为1:120、1:160、1:80,DNA/DNA组的抗体效价高于另外2组;小鼠脾细胞体外经TB-PPD刺激后,均能产生特异性淋巴细胞增殖并诱生较强的IFN-γ反应,其中DNA/BCG组IFN-γ的分泌水平高于DNA/DNA组和BCG组(P<0.05).结论:联合DNA疫苗初免-BCG加强的免疫策略能在小鼠体内诱导较强的特异性细胞免疫反应,产生高水平的IFN-γ.     

HIV-1 CN54 Gag蛋白与DNA疫苗联合免疫策略研究

目的:通过蛋白疫苗与DNA疫苗联合免疫效果的分析,探讨这种免疫方案的优势。方法:用DNA质粒PVRC2000-syngag,在0,2,4周初始免疫BALB/c小鼠,在第6周用HIV-1CN54Gag蛋白加强免疫,每间隔两周采小鼠尾血作结合抗体滴度变化的检测,在第10周处死小鼠,检测小鼠的体液和细胞免疫水平。结果:小鼠在第1次免疫后两周就产生了特异性的结合抗体,抗体在4周开始快速增长,在Gag蛋白加强后两周达到最高峰,之后开始缓慢下降。这种联合免疫组诱导出了细胞免疫和体液免疫,抗体亚型检测倾向于Th2型体液免疫。结论:本实验为提高亚单位疫苗免疫原性提供了新的免疫方法。为免疫策略的深入研究奠定了一定的基础,提供了一定的数据支持和启示。     

An update on vaccines for tuberculosis – there is more to it than just waning of BCG efficacy with time

Introduction: Apart from better diagnostics and new anti-microbial drugs, an effective vaccine for tuberculosis is urgently needed to halt this poverty-related disease, afflicting millions of people worldwide.

Areas covered: After a general introduction on the global threat of tuberculosis, the pros and cons of the existing M. bovis BCG vaccine are discussed. As the correlates of protection against tuberculosis remain largely unknown, new findings in biomarker research are described. Next, an update on the ongoing Phase I and Phase II clinical trials is given. Finally, some of the most promising novel pre-clinical developments using live attenuated vaccines, sub-unit vaccines, prime-boost strategies, and new vaccination routes are discussed. The field has made considerable progress and 12 vaccine candidates have now actually entered Phase I or Phase IIa and IIb clinical trials.

Expert opinion: It is argued that the variable protection conferred by the existing BCG vaccine against reactivation of latent TB is caused not only by waning of its efficacy with time but also by its weak induction of MHC class I restricted responses. Prime-boost strategies based on the actual BCG vaccine may not be sufficient to overcome this hurdle. The use of plasmid DNA vaccination might offer a solution.     

Comparison of single,homologous prime-boost and heterologous prime-boost immunization strategies against H5N1 influenza virus in a mouse challenge model

Preparation for an H5N1 influenza pandemic in humans may involve priming the population with a vaccine produced from an existing, available H5N1 strain. We have used a mouse challenge model to compare the immunogenicity and efficacy of inactivated, Vero cell-derived, whole virus H5N1 vaccines in single immunization and homologous or heterologous prime-boost regimes. A single immunization was sufficient to protect against a lethal challenge with strains from matched and unmatched H5N1 clades. Homologous and heterologous prime-boost regimes induced cross-neutralizing antibodies and cross-protection against representative viruses of H5N1 clade 1, clade 2.1, clade 2.2 and clade 2.3. Moreover, the results indicate that heterologous prime-boost immunization regimes might broaden the specificity of the anti-H5N1 antibody response.     

Priming T-cell responses with recombinant measles vaccine vector in a heterologous prime-boost setting in non-human primates

Licensed live attenuated virus vaccines capable of expressing transgenes from other pathogens have the potential to reduce the number of childhood immunizations by eliciting robust immunity to multiple pathogens simultaneously. Recombinant attenuated measles virus (rMV) derived from the Edmonston Zagreb vaccine strain was engineered to express simian immunodeficiency virus (SIV) Gag protein for the purpose of evaluating the immunogenicity of rMV as a vaccine vector in rhesus macaques. rMV-Gag immunization alone elicited robust measles-specific humoral and cellular responses, but failed to elicit transgene (Gag)-specific immune responses, following aerosol or intratracheal/intramuscular delivery. However, when administered as a priming vaccine to a heterologous boost with recombinant adenovirus serotype 5 expressing the same transgene, rMV-Gag significantly enhanced Gag-specific T lymphocyte responses following rAd5 immunization. Gag-specific humoral responses were not enhanced, however, which may be due to either the transgene or the vector. Cellular response priming by rMV against the transgene was highly effective even when using a suboptimal dose of rAd5 for the boost. These data demonstrate feasibility of using rMV as a priming component of heterologous prime-boost vaccine regimens for pathogens requiring strong cellular responses.     

Heterologous prime-boost regimen adenovector 35-circumsporozoite protein vaccine/recombinant Bacillus Calmette-Guérin expressing the Plasmodium falciparum circumsporozoite induces enhanced long-term memory immunity in BALB/c mice

Background

Sustained antibody levels are a hallmark of immunity against many pathogens, and induction of long-term durable antibody titers is an essential feature of effective vaccines. Heterologous prime-boost approaches with vectors are optimal strategies to improve a broad and prolonged immunogenicity of malaria vaccines.

Results

In this study, we demonstrate that the heterologous prime-boost regimen Ad35-CS/BCG-CS induces stronger immune responses by enhancing type 1 cellular producing-cells with high levels of CSp-specific IFN-γ and cytophilic IgG2a antibodies as compared to a homologous BCG-CS and a heterologous BCG-CS/CSp prime-boost regimen. Moreover, the heterologous prime-boost regimen elicits the highest level of LLPC-mediated immune responses.

Conclusion

The increased IFN-γ-producing cell responses induced by the combination of Ad35-CS/BCG-CS and sustained type 1 antibody profile together with high levels of LLPCs may be essential for the development of long-term protective immunity against liver-stage parasites.     

rAd/MDC-VP1初免pcDNA3/MDC-VP1加强策略抗CVB3的免疫效果研究

目的:应用柯萨奇病毒B3(CVB3)腺病毒载体疫苗rAd/MDC-VP1初免,核酸疫苗pcDNA3/MDC-VP1加强免疫的策略免疫小鼠,观察其免疫效果。方法:BALB/c小鼠随机分为A～D 4组,分别肌肉注射PBS、rAd/MDC-VP1、pcD-NA3/MDC-VP1、rAd/MDC-VP1+pcDNA3/MDC-VP1,用ELISA和微量中和试验法分别检测CVB3 VP1特异性IgG和中和抗体滴度,CCK-8法检测脾淋巴细胞增殖活性和特异性CTL杀伤活性;用致死量的CVB3攻击小鼠后,检测小鼠血中病毒滴度并观察动物的存活情况。结果:D组CVB3 IgG、非特异性淋巴细胞增殖活性及特异性CTL杀伤活性明显高于其他各组(P<0.05);CVB3攻击后,D组小鼠血中病毒滴度较其他各组显著降低,生存率为41.67%,明显高于其他各组(P<0.05)。结论:rAd/MDC-VP1初免pcDNA3/MDC-VP1加强的免疫策略能显著提高小鼠细胞和体液免疫水平,提高致死量病毒攻击后的保护率。     

Differences in the priming effect of various clades/subclades of inactivated H5N1 vaccine for booster injection with heterologous clades of vaccine strains

The prime-boost response induced by different combinations of four H5N1 vaccines (NIBRG-14 (clade 1), Indo05/2005(H5N1)/PR8-IBCDC-RG2 (clade 2.1), A/Bar-Headed Goose/Qinhai Lake/1A/05 SJ163222 (clade 2.2), and Anhui01/2005(H5N1)-PR8-IBCDC-RG5 (clade 2.3.4)) was evaluated in mice. Clade 1-primed BALB/c mice showed a booster response to all of the other three H5N1 vaccines. Clade 2.2 vaccine was also a good priming vaccine. However, mice primed with clade 2.1 or clade 2.3.4 vaccine did not respond to booster injection with clade 1 vaccine, suggesting that priming might actually inhibit the booster response with some combinations of vaccines belonging to different clades. Analysis of the mechanism involved showed that lymphocytes from primed mice secreted comparable amounts of cytokines with any combination of priming and booster vaccines. Therefore, impairment of B cell immunity specific to certain booster strains may have been involved.     

The successful immune response against hepatitis C nonstructural protein 5A (NS5A) requires heterologous DNA/protein immunization

The aim of this study was to evaluate the immunogenicity of NS5A protein of human hepatitis C virus (HCV) when delivered as naked DNA (NS5A DNA), or recombinant protein (rNS5A). DBA/2J mice received NS5A DNA, rNS5A, or NS5A DNA/rNS5A in different prime-boost combinations with a peptidoglycan Immunomax^®. The weakest response was induced after rNS5A prime and NS5A DNA boost; rNS5A alone induced an immune response with a strong Th2-component; and NS5A DNA alone, a relatively weak secretion of IL-2 and IFN-γ. The most efficient was co-injection of NS5A DNA and rNS5A, which induced a significant increase in CD4⁺ and CD8⁺ T-cell counts, anti-NS5A antibodies, specific T-cell proliferation, and proinflammatory cytokine production in vitro against a broad spectrum of NS5A epitopes. Administration of the mixture of adjuvanted DNA and protein immunogens can be selected as the best regimen for further preclinical HCV-vaccine trials.     

Vaccine strategies against Babesia bovis based on prime-boost immunizations in mice with modified vaccinia Ankara vector and recombinant proteins

In this study, a recombinant modified vaccinia virus Ankara vector expressing a chimeric multi-antigen was obtained and evaluated as a candidate vaccine in homologous and heterologous prime-boost immunizations with a recombinant protein cocktail. The chimeric multi-antigen comprises immunodominant B and T cell regions of three Babesia bovis proteins. Humoral and cellular immune responses were evaluated in mice to compare the immunogenicity induced by different immunization schemes. The best vaccination scheme was achieved with a prime of protein cocktail and a boost with the recombinant virus. This scheme induced high level of specific IgG antibodies and secreted IFN and a high degree of activation of IFNγ⁺ CD4⁺ and CD8⁺ specific T cells. This is the first report in which a novel vaccine candidate was constructed based on a rationally designed multi-antigen and evaluated in a prime-boost regime, optimizing the immune response necessary for protection against bovine babesiosis.