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Long-lasting protective immunity against H7N9 infection is induced by intramuscular or CpG-adjuvanted intranasal immunization with the split H7N9 vaccine

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  • Long-lasting protective immunity against H7N9 infection is induced by intramuscular or CpG-adjuvanted intranasal immunization with the split H7N9 vaccine


    Int Immunopharmacol. 2019 Dec 2:106013. doi: 10.1016/j.intimp.2019.106013. [Epub ahead of print] Long-lasting protective immunity against H7N9 infection is induced by intramuscular or CpG-adjuvanted intranasal immunization with the split H7N9 vaccine.

    Zhou Y1, Li S2, Bi S3, Li N3, Bi Y3, Liu W3, Wang B4.
    Author information

    1 CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China. 2 China National Vaccine and Serum Institute, Beijing, China. 3 CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China. 4 CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China. Electronic address: wangbn@im.ac.cn.

    Abstract

    There is an urgent need for efficient vaccines against the highly pathogenic avian influenza A viral strain H7N9. The duration and intensity of the immune response to H7N9 critically impacts the epidemiology of influenza viral infection at the population level. However, the insufficient immunogenicity of H7N9 raises concerns about vaccine efficacy. In this study, we evaluated the impact of immunization routes and the adjuvant CpG on the immune response to a split H7N9 vaccine in mice. Determination of humoral and cellular responses to the vaccine revealed that after four vaccine doses, high titers of H7N9-specific serum IgG, determined by the influenza hemagglutination inhibition (HI) assay, were induced through the intramuscular (i.m.) route and lasted for at least 40 weeks. CpG-adjuvanted immunization increased the levels of long-lived IFN-γ+ T cells and raised the Th1-biased IgG2a/IgG1 response ratio. In addition, aside from mucosal IgA, CpG-adjuvanted intranasal (i.n.) immunization elicited serum IgG and cellular responses of a similar duration and intensity to CpG-adjuvanted i.m. immunization. Mouse challenge assays demonstrated that 24 weeks following i.m. immunization without CpG or CpG-adjuvanted immunization through the i.m. or i.n. routes, both offered a high level of protection against H7N9 infection. These results indicate that efficient long-term protection against H7N9 can be achieved via the optimization of vaccination strategies, such as immunization doses, routes, and adjuvants.
    Copyright ? 2019 Elsevier B.V. All rights reserved.


    KEYWORDS:

    Ab-secreting cells; CpG; H7N9; Influenza vaccine; Mucosal immunization; NALT

    PMID: 31806571 DOI: 10.1016/j.intimp.2019.106013


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