Polycation-decorated PLA microspheres induce robust immune responses via commonly used parenteral administration routes

Recombinant viral subunit-based vaccines have gained increasing attention due to their enhanced safety over the classic live-attenuated or inactivated vaccines. The low immunogenicity of the subunit antigen alone, however, requires the addition of an adjuvant to induce immunity. Particulate-based delivery systems have great potential for developing new vaccine adjuvants, compared to traditional aluminum-based saline adjuvants. The physicochemical properties of particulate vaccines have been extensively investigated; however, few studies have focused on how the administration route of various adjuvant–antigen combinations impacts the efficacy of the immune response. Here, for the first time, the viral Hepatitis B surface antigen (HBsAg) was combined with aluminum-based or cationic-microsphere (MP) based adjuvants to investigate the characteristics of immune responses elicited after immunization via the subcutaneous, intramuscular, or intraperitoneal routes respectively. In vitro, the MP-based vaccine significantly increased dendritic cell (DC) activation with up-regulated CD40 and CD80 expression and IL-12 production compared to alum-based vaccine. After immunization, both MP and alum-based vaccines produced increased IgG titers in mice. The administration route of these vaccines did influenced immune responses. The MP-based vaccine delivered via the intramuscular route yielded the highest levels of the IgG2a isotype. The alum-based vaccine, delivered via the same route, produced an IgG1-dominated humoral immune response. Moreover, subcutaneous and intramuscular immunizations with MP-based vaccine augmented Granzyme B, Th1-type cytokines (IL-2, IL-12, and IFN-γ), and Th2 cytokine IL-4 secretions. These results demonstrate that MP-based vaccines have the capacity to induce higher cellular and humoral immune response especially via an intramuscular administration route than an alum-based vaccine.     

Posintro™-HBsAg, a modified ISCOM including HBsAg, induces strong cellular and humoral responses

To improve the hepatitis B vaccines on the market new adjuvant systems have to substitute aluminium. In this study the hepatitis B surface antigen (HBsAg) was incorporated into a novel adjuvant system, the Posintro?, a modification of the traditional immune stimulatory complexes (ISCOMs). This new HBsAg vaccine formulation, Posintro?-HBsAg, was compared to two commercial hepatitis B vaccines including aluminium or monophosphoryl lipid A (MPL) and the two adjuvant systems MF59 and QS21 in their efficiency to prime both cellular and humoral immune responses. The Posintro?-HBsAg induced the strongest humoral response with high titers of HBsAg specific antibody, high number of antigen specific B-cells and a strong T helper 1 (Th1) antibody profile when compared to the other adjuvant formulations. The Posintro?-HBsAg was also a strong inducer of cellular immune responses with induction of delayed type hypersensitivity (DTH) reaction and CD4(+) T-cell proliferation. In addition, Posintro?-HBsAg was the only vaccine tested that also induced a strong cytotoxic T lymphocyte (CTL) response, with high levels of antigen specific CD8 T-cells secreting IFN-gamma mediating cytolytic activity. The results demonstrate that this novel experimental vaccine formulation, the Posintro?-HBsAg, is strongly immunogenic and can induce both class I and class II responses in experimental animals. This shows promise both for the protection against hepatitis B virus infection and as a potential therapeutic vaccine.     

The potential adjuvanticity of quaternized chitosan hydrogel based microparticles for porcine reproductive and respiratory syndrome virus inactivated vaccine

Infectious diseases possess a big threat to the livestock industry worldwide. Currently, inactivated veterinary vaccines have attracted much attention to prevent infection due to their safer profile compared to live attenuated vaccine. However, its intrinsic poor immunogenicity demands the incorporation of an adjuvant. Mineral oil based adjuvant (Montanide™ ISA206) was usually used to potentiate the efficacy of veterinary vaccines. However, ISA206 could not induce robust cellular immune responses, which was very important in controlling virus replication and clearing the infected cells. Moreover, mineral oil would result in severe side effects. To improve both the humoral and cellular immune responses of porcine reproductive and respiratory syndrome virus (PRRSV) inactivated vaccine, we developed pH-sensitive and size-controllable quaternized chitosan hydrogel microparticles (Gel MPs) without using chemical cross linking agent. Gel MPs, ionic cross-linked with glycerophosphate (GP), were biocompatible and could efficiently adsorb the inactivated PRRSV vaccine with a loading capacity of 579.05 μg/mg. After intramuscular immunization in mice, results suggested that Gel MPs elicited significantly higher cell-mediated immune responses and comparable humoral immune responses compared to ISA 206. Regarding the biocompatibility, safety and effectiveness, Gel MPs would be a promising candidate to enhance the efficacy of veterinary vaccine.     

Influenza vaccine and adjuvant

Adjuvant is originated from the Latin word "adjuvare" which means "help" in English to enhance the immunological responses when given together with antigens. The beginning of adjuvant was mineral oil which enhanced the immune response when it was given with inactivated Salmonella typhimurium. Aluminium salt was used to precipitate diphtheria toxoid and increased level of antibody response was demonstrated when administered with alum-precipitated antigens. Since 1930, aluminium salt has been used as DTaP (diphtheria-tetanus-acellular pertussis vaccine) adjuvant. Many candidates were tested for adjuvant activity but only aluminum salt is allowed to use for human vaccines. New adjuvant MF59, oil-in-water emulsion type, was developed for influenza vaccine for elderly (Fluad) and series of AS adjuvant are used for hepatitis B, pandemic flue, and human papiloma virus vaccines. Oil-adjuvanted influenza pandemic vaccines induced higher antibody response than alum-adjuvanted vaccine with higher incidence of adverse events, especially for local reactions. Alum-adjuvanted whole virion inactivated H5N1 vaccine was developed in Japan, and it induced relatively well immune responses in adults. When it applied for children, febrile reaction was noted in approximately 60% of the subjects, with higher antibodies. Recent investigation on innate immunity demonstrates that adjuvant activity is initiated from the stimulation on innate immunity and/or inflammasome, resulting in cytokine induction and antigen uptake by monocytes and macrophages. The probable reason for high incidence of febrile reaction should be investigated to develop a safe and effective influenza vaccine.     

重组病毒载体疫苗的研究进展

重组病毒载体疫苗的原理是将外源基因插入病毒基因组以构建重组病毒,免疫机体后在体内表达相应蛋白并诱导特异性免疫应答。该类疫苗具有载体种类多、插入片段长、能同时诱导体液免疫和细胞免疫等优势,能克服灭活疫苗的效力维持时间短和减毒活疫苗回复突变的弊端。此文综述了重组病毒载体疫苗的最新研究进展,为将来的研究提供参考。     

Evaluation of an ompA-based phage-mediated DNA vaccine against Chlamydia abortus in piglets

Chlamydia abortus (C. abortus) is an obligate intracellular pathogen that causes abortion in pigs and poses a zoonotic risk in pregnant women. Although attenuated and inactivated vaccines are available, they do not provide complete protection in animals underlining the need to develop new vaccines. In this study, we tested the hypothesis that intramuscular immunization with an ompA-based phage-mediated DNA chlamydial vaccine candidate will induce significant antigen-specific cellular and humoral immune responses. Thus, groups of piglets (five per group) were immunized intramuscularly with the phage-MOMP vaccine (λ-MOMP) or a commercial live-attenuated vaccine (1B vaccine) or a GFP-expressing phage (λ-GFP) or phosphate buffered saline (PBS) (control) and antigen-specific cell-mediated and humoral immune responses were evaluated. By day 63 post-immunization, the λ-MOMP vaccine elicited significantly higher (P < 0.05) levels of antigen-specific serum IgG antibody responses than the 1B vaccine or control did. Also, piglets immunized with λ-MOMP vaccine had significantly higher (P < 0.05) MOMP-specific lymphocyte proliferative responses compared to those immunized with the 1B vaccine or control. Furthermore, the total T-cell numbers (CD3 +) and the proportion of CD4 + and CD8 + T-cell subsets as well as the ratio of CD4 +/CD8 + T cells elicited following immunization were comparable between the λ-MOMP- and 1B-vaccinated animals on both days 63 and 70. Interestingly, although the proportion of CD3+CD4−CD8− double negative T cells on day 63 was significantly higher (P < 0.05) in the 1B vaccine group compared to the λ-MOMP-immunized group, there was a significant decrease in the proportion of this T-cell population on day 70 in the 1B compared to the λ-MOMP vaccinated group. These results indicate that the λ-MOMP DNA vaccine is capable of inducing antigen-specific cellular and humoral immune responses that may provide protective immunity against a live challenge infection with C. abortus.     

基于杆状病毒表达系统的流感病毒样颗粒疫苗研究进展

流感疫苗是目前应对流感最有效的措施,传统疫苗包括全病毒灭活疫苗、裂解疫苗和减毒活疫苗,近年来逐渐成为研发趋势的有重组亚单位疫苗、核酸疫苗、活病毒载体疫苗等。病毒样颗粒(virus-like particle,VLP)疫苗作为特殊形式的亚单位疫苗,具有生产迅速、安全性高、免疫原性较高等优势。VLP可以高效地诱发体液免疫与细胞免疫,且可经多种途径接种。目前已有多种表达系统用于制备VLP,其中应用最为广泛的是杆状病毒表达系统。此文综述了流感病毒VLP的类型、组装、抗原选择、免疫途径以及流感病毒VLP疫苗在杆状病毒表达系统中的研究进展。     

Coimmunization with RANTES plasmid polarized Th1 immune response against hepatitis B virus envelope via recruitment of dendritic cells

Induction of T help cell type 1 (Th1) response seems to be a prerequisite of HBV clearance. DNA vaccines have shown its potential to elicit Th1-biased immune response. However, its immunogenicity needs to be improved. Regulated upon activation normal T cell expressed and secreted (RANTES) is an inflammatory chemokine that promotes the accumulation and activation of CD4+, CD8+ T cells, and dendritic cells (DCs), which would favor antiviral immunity. In this study, the efficacy of a DNA vaccine encoding hepatitis B virus (HBV) preS2 plus S protein was enhanced through co-injection of a plasmid encoding RANTES in a BALB/c model. Co-injection of RANTES gene resulted in a moderate increase in the HBV specific humoral and cellular immune responses and a significant increase following an HBsAg booster vaccination compared to DNA encoding HBsAg alone. This enhancement was due to an enrichment of DCs in the draining lymph node and an up-regulation of DCs maturation by RANTES. More importantly, RANTES polarized the specific immunity towards a dominant Th1 profile and even converted an established Th2 response to a Th1 phenotype. Our study suggested the feasibility of using a plasmid-encoded RANTES as a modulatory Th1 adjuvant in genetic vaccination.     

MDCK细胞基质与鸡胚基质单价流感疫苗在小鼠中诱导的免疫反应的比较研究

目的:比较鸡胚基质和细胞基质的H1N1单价流感疫苗在小鼠体内诱导的免疫反应的差异.方法:分别采用鸡胚基质和MDCK细胞基质H1N1流感疫苗注射C57BL/6小鼠,通过体外中和实验,胞内细胞因子染色及多细胞因子检测比较2种基质生产的单价流感疫苗诱导的体液及细胞免疫反应的差异.结果:体液免疫方面,细胞基质疫苗组血清滴度与鸡...     

DNA-based vaccination against hepatitis B virus using dissolving microneedle arrays adjuvanted by cationic liposomes and CpG ODN

DNA vaccines are simple to produce and can generate strong cellular and humoral immune response, making them attractive vaccine candidates. However, a major shortcoming of DNA vaccines is their poor immunogenicity when administered intramuscularly. Transcutaneous immunization (TCI) via microneedles is a promising alternative delivery route to enhance the vaccination efficacy. A novel dissolving microneedle array (DMA)-based TCI system loaded with cationic liposomes encapsulated with hepatitis B DNA vaccine and adjuvant CpG ODN was developed and characterized. The pGFP expression in mouse skin using DMA was imaged over time. In vivo immunity tests in mice were performed to observe the capability of DMA to induce immune response after delivery of DNA. The results showed that pGFP could be delivered into skin by DMA and expressed in skin. Further, the amount of expressed GFP was likely to peak at day 4. The immunity tests showed that the DMA-based DNA vaccination could induce effective immune response. CpG ODN significantly improved the immune response and achieved the shift of immune type from predominate Th2 type to a balance Th1/Th2 type. The cationic liposomes could further improve the immunogenicity of DNA vaccine. In conclusion, the novel DMA-based TCI system can effectively deliver hepatitis B DNA vaccine into skin, inducing effective immune response and change the immune type by adjuvant CpG ODN.     

A non-living nasal influenza vaccine can induce major humoral and cellular immune responses in humans without the need for adjuvants

Twenty-eight healthy adult volunteers were immunized intranasally with an inactivated whole-virus influenza vaccine based on the strain A/New Caledonia/20/99 (H1N1), either in saline or mixed with formaldehyde-inactivated Bordetella pertussis as a mucosal adjuvant, or in a thixotropic vehicle with mucoadhesive properties. After four doses, all groups of vaccinees developed significant IgG- and IgA-antibody responses, measured by ELISA, in respectively serum and nasal secretions. None of the volunteers had demonstrable hemagglutination inhibition (HAI) antibodies in serum before being immunized, whereas more than 80% of them reached HAI titers>or=40, considered protective, after immunizations. In addition, cellular immune responses, measured as significant increases in CD4+ T-cell proliferation and granzyme B-producing cytotoxic T-cells, were detected against the vaccine strain as well as against heterologous virus strains (H3N2). However, no additive effect on these responses could be demonstrated with use of B. pertussis or the thixotropic substance in the present vaccines. It appeared, actually, that the mucoadhesive vehicle containing the thixotropic substance was less efficient than were the two other formulations. An influenza vaccine made as a simple particulate formulation of inactivated virus, and given repeatedly onto the nasal mucosa, may thus be an attractive alternative to currently available vaccines.     

Cell and antibody mediated immunity induced by vaccination with novel Candida dubliniensis mannan immunogenic conjugate

Antigen-specific humoral response, as well as the induction of cellular immunity generated by Candida dubliniensis mannan-human serum albumin (HSA) conjugate, a novel proposed immunogenic structure for subcellular vaccine, were evaluated in rabbits. Mannan-HSA conjugate-induced specific IgG and IgA increased significantly after boosters (IgG: P<0.001 and IgA: P<0.01). Mannan-HSA conjugate up-regulation of cell-surface expression of B-lymphocyte and granulocyte activation antigens CD25 and CD11b indicated the effective activation. Immunogenic effect of conjugate on T lymphocytes was demonstrated via inductive increase of CD4+ T lymphocyte subset and CD4+/CD8+ ratio and via induction of T(H)1 cytokines. Immunogenic effectiveness of mannan-HSA conjugate at a dose of 0.25 mg of mannan antigenic moiety overcame that of the mannan alone and of yeast whole cells, thus promising further application in Candida vaccine development.     

Nanotechnology in vaccine delivery

With very few adjuvants currently being used in marketed human vaccines, a critical need exists for novel immunopotentiators and delivery vehicles capable of eliciting humoral, cellular and mucosal immunity. Such crucial vaccine components could facilitate the development of novel vaccines for viral and parasitic infections, such as hepatitis, HIV, malaria, cancer, etc. In this review, we discuss clinical trial results for various vaccine adjuvants and delivery vehicles being developed that are approximately nanoscale (< 1000 nm) in size. Humoral immune responses have been observed for most adjuvants and delivery platforms while only viral vectors, ISCOMs and Montanide™ ISA 51 and 720 have shown cytotoxic T cell responses in the clinic. MF59 and MPL® have elicited Th1 responses, and virus-like particles, non-degradable nanoparticles and liposomes have also generated cellular immunity. Such vaccine components have also been evaluated for alternative routes of administration with clinical successes reported for intranasal delivery of viral vectors and proteosomes and oral delivery of a VLP vaccine.     

Induction of protective and therapeutic anti-cancer immunity by using bispecific anti-idiotype antibody G22-I50 for nasopharyngeal carcinoma

Increasing evidence has suggested that bispecific and multivalent antibodies which have more antigen binding sites will improve their immunogenicity. The bispecific anti-idiotype antibody vaccine G22-I50 was obtained through genetic engineering to enhance the immunogenicity of anti-idiotype antibody vaccines G22 and I50. G22-I50 vaccination could induce anti-tumor immunity in the Balb/c mouse model. The protective and therapeutic efficacy of G22-I50 was also evaluated using the hu-PBL–SCID mouse model injected three times with G22-I50, G22, or I50 mixed with Freund's adjuvant. Results demonstrated that the protective anti-tumor effect of G22-I50 could be relevant with the production of Ab3 antibody and activation of CD8⁺ cytotoxic T-lymphocytes. In preventive and therapeutic experiments, G22-I50 could reduce tumor size and prolong the survival time of HNE2-bearing mice (p < 0.05). Human CD8⁺ T lymphocytes infiltrated the tumor sites, and high levels of human IFN-γ, TNF-α, and caspase-3 were also detected in the tumors from G22-I50-vaccinated and -treated mice. Therefore, the bispecific anti-idiotype antibody vaccine G22-I50 can induce strong humoral and cell-mediated immune responses. This vaccine can be potentially applied to prevent and treat nasopharyngeal carcinoma.     

Immunogenicity of a scalable inactivated rotavirus vaccine in mice

Inactivated rotavirus vaccine is a safe and effective potential vaccine for the prevention of rotavirus infection among children, but no approved licensed vaccine is available now. In this study, a scalable inactivated rotavirus vaccine, prepared in Vero cells cultured by microcarrier fermentation, inactivated by formalin and absorbed by Al(OH)(3) adjuvant, was vaccinated into the six weeks-old female Balb/c mice by intramuscular injection. After twice immunization at interval of three weeks, both humoral and cell-mediated immune responses were assessed by ELISA, microneutralization assay and EISPOT assay. The results indicated that the scalable inactivated rotavirus vaccines induced not only high serum IgG antibody and neutralizing antibody responses, but Th1 and Th2 cytokine-secreting cell responses in mice immunized by the inactivated rotavirus vaccines. These results suggest that the scalable inactivated rotavirus vaccine has good immunogenicity, which provided the base for the scaled development of inactivated rotavirus vaccine in the future.     

Evaluation of CD4+/CD8+ T-cell expression and IFN-γ, perforin secretion for B-T constructs of F1 and V antigens of Yersinia pestis

Yersinia pestis is a facultative bacterium that can survive and proliferate inside host macrophages and cause bubonic, pneumonic and systemic infection. Understanding the immune response generated by epitopes recognized by CD4+ and CD8+ T cells is important for the development of safe and effective vaccines designed to promote protective cellular immunity. Apart from humoral response, CD4+ T cells have shown to have a major role in combating the pneumonic form of the disease. In the present study, the secretion of IFN-γ and IL-4 by splenocytes, stimulated by different constructs of B and T cell epitopes of F1 and V antigens, was measured by ELISpot assay. We also measured perforin and IFN-γ expression as a function of cell mediated immunity by flow cytometry. Three B-T constructs of F1 and seven B-T constructs of V antigens produced a high number of IFN-γ secreting cells as compared to native antigen and a low number of IL-4 secreting cells. B-T conjugates of F1 and V antigens showed significantly high (p<0.001) percentage of CD4+ IFN-γ(+) cells as compared to CD8+ IFN-γ(+) cells. Thus, the study highlights the importance of Th1 cytokine and existence of high proportion of CD4+ T cells probably contributing protection in the host. This study proposes a new perspective for the development of vaccination strategies for Y. pestis that trigger T cell immune response.     

In vitro effects of an immunostimulating bacterial lysate on human lymphocyte function

MLBL is an oral immunostimulating vaccine consisting of bacterial standardized lysates obtained by mechanical lysis of different strains of Gram-positive and Gram-negative bacteria that can cause acute and chronic infections of the respiratory tract. Previous studies suggested a stimulating effect of MLBL both on humoral and cellular immune responses. In the present study, the in vitro effects of MLBL on human lymphocyte effector functions and its mechanisms of action were evaluated. The results show that the most remarkable effects of MLBL on the immune system are: i) activation of the IL-2 receptor (IL-2Ralpha) on different lymphocyte subsets (B, CD4+ T and CD8+ T cells) involved both in humoral and cellular immune responses; ii) induction of cytokine synthesis (IL-2, IL-10, IL-12, IFNgamma) in the immune competent cells that induce and regulate immune responses; iii) generation of CD4+ and CD8+ effector T cells. Overall, these results suggest that the therapeutic effect of MLBL on acute and recurrent infections of the respiratory tract is related to its ability to activate the responses of different subsets of immune competent cells both for humoral and cellular immunity. Moreover, these effects can be induced either by direct immune cell activation or through the generation and activation of immune effector cells.     

The orchestration of cellular and humoral responses is facilitated by divergent intracellular antigen trafficking in nanoparticle-based therapeutic vaccine

Therapeutic vaccination for the treatment of chronic hepatitis B is promising but has so far shown limited clinical efficacy. Herein, we employ polylactide nanoparticles (NPs) as the vaccine adjuvant and systematically explore their effect on activation of specific immunity and the underlying theoretical mechanisms. In vitro studies show that hepatitis B surface antigen (HBsAg) accumulates in antigen-presenting cells (APCs) to a larger content (270%) with the assistant of NP in comparison with the pure-antigen group. Besides the elevated costimulators (CD80/86) and increased major histocompatibility complex (MHC) II molecules, the MHC I molecules are also found upregulated. This result is mostly owing to the divergent antigen trafficking ways of NP-antigen in APCs, especially for the escape of exogenous HBsAg from the lysosomes to the cytosol. Interestingly, the MHC I level is downregulated in alum-antigen group, indicating a possible reason for its inefficiency in priming cellular response. Further in vivo experiments establish that NP-antigen group indeed enhances the CD8(+) CTL cytotoxicity and IFN-γ cytokine secretion. Meanwhile, specific antibody titer is also upregulated, and even surpasses that of the commercialized alum-antigen. All these results strongly support that NP-based antigen promotes an orchestration of cellular and humoral immune response, exhibiting favorable intrinsic properties to be applied in therapeutic vaccines.     

Just-in-time vaccines: Biomineralized calcium phosphate core-immunogen shell nanoparticles induce long-lasting CD8+ T cell responses in mice

Distributed and on-demand vaccine production could be game-changing for infectious disease treatment in the developing world by providing new therapeutic opportunities and breaking the refrigeration “cold chain”. Here, we show that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize a biocompatible adjuvant in a single step. The resulting 50 nm calcium phosphate core-immunogen shell particles are comparable to soluble protein in inducing ovalbumin-specific antibody response and class switch recombination in mice. However, single dose vaccination with nanoparticles leads to higher expansion of ovalbumin-specific CD8⁺ T cells upon challenge with an influenza virus bearing the ovalbumin-derived SIINFEKL peptide, and these cells produce high levels of IFN-γ. Furthermore, mice exhibit a robust antigen-specific CD8⁺ T cell recall response when challenged with virus 8 months post-immunization. These results underscore the promise of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines.From the Clinical EditorThis paper reports that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize into a biocompatible adjuvant in a single step, enabling distributed and on-demand vaccine production and eliminating the need for refrigeration of vaccines. The findings highlight the possibility of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines.     

早产儿疫苗免疫接种研究进展

目的：疫苗的免疫程序和疫苗使用指导原则是保证疫苗免疫效果的重要环节,也是《疫苗管理法》的重要内容之一。早产儿免疫系统发育不成熟,对于各种疫苗免疫反应低于足月儿。本综述为制定早产儿免疫程序提供参考。方法：本文对在早产儿中使用灭活脊髓灰质炎疫苗、百日咳-白喉-破伤风疫苗、乙型肝炎疫苗、肺炎链球菌疫苗、脑膜炎球菌结合疫苗和流感嗜血杆菌疫苗、轮状病毒疫苗、麻疹、腮腺炎、风疹和水痘疫苗等疫苗的免疫效果、安全性及耐受性研究进展进行了归纳整理。结果：本文对早产儿在接种不同疫苗、采取不同免疫策略时体液免疫和细胞免疫效果的研究进行了归纳总结,结果表明虽然早产儿的免疫功能相对较弱,但参照足月新生儿免疫方案接种疫苗后,大部分早产儿可以具有足够的免疫保护力。结论：本文为疫苗免疫程序的制定提供更全面的理解,为制定疫苗使用指导原则提供参考。