Enhancing immune responses to inactivated foot-and-mouth virus vaccine by a polysaccharide adjuvant of aqueous extracts from Artemisia rupestris L.

BACKGROUND: New-generation adjuvants for foot-and-mouth disease virus (FMDV) vaccines can improve the efficacy of existing vaccines. Chinese medicinal herb polysaccharide possesses better promoting effects. OBJECTIVES: In this study, the aqueous extract from Artemisia rupestris L. (AEAR), an immunoregulatory crude polysaccharide, was utilized as the adjuvant of inactivated FMDV vaccine to explore their immune regulation roles. METHODS: The mice in each group were subcutaneously injected with different vaccine formulations containing inactivated FMDV antigen adjuvanted with three doses (low, medium, and high) of AEAR or AEAR with ISA-206 adjuvant for 2 times respectively in 1 and 14 days. The variations of antibody level, lymphocyte count, and cytokine secretion in 14 to 42 days after first vaccination were monitored. Then cytotoxic T lymphocyte (CTL) response and antibody duration were measured after the second vaccination. RESULTS: AEAR significantly induced FMDV-specific antibody titers and lymphocyte activation. AEAR at a medium dose stimulated Th1/Th2-type response through interleukin-4 and interferon-γ secreted by CD4⁺ T cells. Effective T lymphocyte counts were significantly elevated by AEAR. Importantly, the efficient CTL response was remarkably provoked by AEAR. Furthermore, AEAR at a low dose and ISA-206 adjuvant also synergistically promoted immune responses more significantly in immunized mice than those injected with only ISA-206 adjuvant and the stable antibody duration without body weight loss was 6 months. CONCLUSIONS: These findings suggested that AEAR had potential utility as a polysaccharide adjuvant for FMDV vaccines.

Cationic Poly(Amino Acid) Vaccine Adjuvant for Promoting Both Cell-Mediated and Humoral Immunity Against Influenza Virus.

Powerful adjuvants to augment vaccine efficacy with a less immunogenic vaccine system are in great demand. In this study, a novel squalene-based cationic poly(amino acid) adjuvant (CASq) that elicits both cellular (Th1) and humoral (Th2) immune responses is developed. CASq is demonstrated to promote cellular uptake of viral antigen and stimulate macrophages, leading to active production of interleukin-12. Furthermore, co-administration of inactivated pdm H1N1 vaccine with CASq significantly increases the generation of antigen-specific antibodies and T cell immune responses in mice, as well as resulting in complete prevention of disease symptoms and protection against lethal infection.

The Taishan Robinia pseudoacacia polysaccharides enhance immune effects of rabbit haemorrhagic disease virus inactivated vaccines.

Robinia pseudoacacia flower, a common component in traditional Chinese medicine, has long been well-known for its high pharmaceutical value. This study aimed to assess the immunopotentiating effects of Taishan Robinia Pseudoacacia polysaccharides (TRPPS) in rabbits inoculated with a rabbit haemorrhagic disease virus (RHDV) inactivated vaccine. The rabbits were administered with the RHDV vaccine in conjunction with varying concentrations of TRPPS, and their blood samples were collected at different time points to analyze the ratio and number of blood lymphocytes. In addition, sera were prepared and analyzed to determine the overall antibody titer and the level of IL-2, a cytokine commonly used as an indicator of immune activity. The various TRPPS-supplemented vaccines were shown to be more effective in enhancing the immune functions of the inoculated rabbits compared to their polysaccharide-free counterpart, with 200 mg/mL of TRPPS exhibiting the most pronounced benefits that were comparable to those of propolis. In addition, the TRPPS-supplemented RHDV inactivated vaccines could significantly improve the survival rates of the immunized rabbits against RHDV infection. Our studies offered convincing experimental evidence for the development of TRPPS as a new type of plant-derived immunopotentiator.

Progress on the research and development of human enterovirus 71 (EV71) vaccines.

Enterovirus 71 (EV71) infections, which can cause severe complications, have become one of the serious public health issues in the Western Pacific region and China. To date, a number of pharmaceutical companies and institutes have initiated the research and development of EV71 vaccines as a countermeasure. As is the case with innovative vaccine development, there are several critical bottlenecks in EV71 vaccine development that must be overcome before the clinical trials, including the selection of vaccine strain, standardization of the procedure for quantifying neutralizing antibody (NTAb) and antigen, establishment and application of a reference standard and biological standards, development of animal models for the evaluation of protective efficacy, and identification of the target patient population. To tackle these technical obstacles, researchers in Mainland of China have conducted a series of studies concerning the screening of vaccine strains and the establishment of criteria, biological standards and detection methods, thereby advancing EV71 vaccine development. This review summarizes recent worldwide progress on the quality control and evaluation of EV71 vaccines.

Adjuvant regulation of cytokine profile and antibody isotype of immune responses to Mycoplasma agalactiae in mice.

Traditionally, adjuvants have been administered with antigens to enhance immunity. We studied the effect of several adjuvants such as Freund's complete adjuvant (FCA), Freund's incomplete adjuvant (FIA), lipopolysaccharide (LPS), homopolymers of polyinosinic-polycytidylic acid (poly I:C) and polyadenylic-polyuridylic acid (poly A:U), lithium chloride (LiCl), saponin Quil A and calcium phosphate gel (CaHPO(4)) on the immune response of mice to formalin-inactivated Mycoplasma agalactiae. The specific antibody or cytokine producing splenocytes were detected by ELISAspot and immunocytochemistry, respectively. Depending on the adjuvant given, the number of M. agalactiae-specific antibody producing cells was increased 2.5-6-fold. IgG was the major class of M. agalactiae-specific antibodies followed by IgM, IgA and IgE. Among IgG isotypes, FCA, FIA, Quil A and CaHPO(4) induced an IgG1 response with substantial increase of the IgG2a, IgG2b and IgG3 isotypes while poly I:C shifted the response toward an IgG2a/IgG3 production. Finally, poly A:U induced an IgG2b response while LPS and LiCl augmented the IgG3/IgG1/IgG2a secretion. FCA augmented IL-4, IL-5 and IL-10 production suggesting a strong Th2 response, while IFN-gamma and IL-12 remained low; poly I:C enhanced IFN-gamma, IL-12 and TNF-alpha eliciting a Th1 response; poly A:U resulted in a IL-10, IL-5, IL-6 and IL-12 secretion; and LPS enhanced the IL-10, IL-6 and TNF-alpha production. Our data show that adjuvants augment M. agalactiae-specific antibody production and lead to B cell isotype-switching via the appropriate cytokine milieu. Certain adjuvants, such as poly I:C, therefore, appear as promising immune enhancers for vaccination against M. agalactiae infections.

Staphylococcus aureus capsular polysaccharide type 5 conjugate and whole cell vaccines stimulate antibody responses in cattle.

Dairy heifers were immunized subcutaneously with one of four different vaccines which contained preparations of Staphylococcus aureus capsular polysaccharide type 5 (CP5) and a mineral oil adjuvant, or received a placebo containing saline and adjuvant. The vaccine containing a CP5-human serum albumin conjugate (CP5-HSA) and the vaccine with formaldehyde inactivated whole cells expressing CP5, both elicited strong anti-CP5 antibody responses. After two injections three weeks apart and a third injection 10 months later, the mean level and duration of the anti-CP5 antibody response was significantly higher in the whole cell group. No differences were found between the two groups with regard to the relative proportion of IgG subclasses, and the antibody responses to the polysaccharide were composed of both the IgG1 and IgG2. Vaccines containing only free CP5 or CP5 mixed with HSA produced weak and transient humoral immune responses. Only animals vaccinated with the whole cell vaccine or the conjugate vaccine showed responses to CP5 in a lymphocyte proliferation assay conducted one year after the third vaccination. This study indicates that CP5 expressed on the surface of formaldehyde inactivated whole cells, emulsified in an oil adjuvant, gives a strong and long lasting immune response in cattle. The use of conjugation technology, although effective, might not be necessary in order to achieve an immune response against S. aureus CP5 in cattle.

Involvement of gag- and env-specific cytotoxic T lymphocytes in protective immunity to feline immunodeficiency virus.

Definition of the immunological mechanisms involved in protective immunity against lentiviral infections is crucial to the development of an effective vaccine. The induction of gag- and env-specific cell-mediated immune responses was studied in cats following vaccination with whole inactivated feline immunodeficiency virus (FIV). Cats were immunized by inoculation with three doses of paraformaldehyde-inactivated FIV, derived from the feline lymphoid cell line, FL-4, which is persistently infected with the Petaluma isolate of FIV. Autologous or allogeneic skin fibroblasts either infected with recombinant FIV gag- or env-vaccinia virus or pulsed with FIV env peptides were used as targets in chromium-51 release assays. Effector cells were fresh peripheral blood mononuclear cells. Following the third immunization, all vaccinated cats, but none of the control cats immunized with adjuvant alone, had detectable FIV env-specific lymphocytotoxicity in their peripheral blood. Two cats also exhibited gag-specific activity. There was no recognition of either allogeneic skin fibroblasts infected with recombinant vaccinia virus or autologous target cells infected with wild-type vaccinia virus, indicating the specificity and MHC-restricted nature of the response. Vaccinated cats, but not control cats, were protected from challenge with the homologous Petaluma isolate of FIV. Partial epitope mapping of the env-specific cytotoxic response was performed using overlapping 10-amino acid peptides from the env V3 domain of FIV. This response appeared to be directed at env peptide 1 (RAISSWKQRN) and env peptide 3 (QRNRWEWRPD), which lie adjacent to a beta-turn within the V3 domain.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation and immunogenicity of an inactivated hepatitis A vaccine.

A hepatitis A vaccine was prepared by formaldehyde inactivation of purified hepatitis A virus (HAV) LSH/S strain grown on human diploid MRC-5 cells. The vaccine was devoid of residual infectivity in vitro and failed to induce in marmoset monkeys any pathological features or variations of haematological and clinical chemistry values. Infectious HAV particles were not detected in faeces and sera of the vaccinated primates by ELISA or after passages in MRC-5 cells. The immunogenicity of the vaccine was evaluated by injecting guinea-pigs with 0.8, 0.2 or 0.05 micrograms of HAV antigen adsorbed onto 0.5 and 1 mg of Al (OH)3 or 0.3 mg of AlPO4. The antibody response, measured by a competitive radioimmunoassay, was dose- and adjuvant-dependent. One injection of 0.2 micrograms of AlPO4-adsorbed HAV antigen induced seroconversion in 100% of animals and high levels of specific and neutralizing serum antibodies. A further increase of antibody titres was observed after the second and third inoculations. These results show that this vaccine formulation is safe and immunogenic in animal models, and suggest that it should be evaluated further by human clinical studies.