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

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. PMID: 31806571 [PubMed - as supplied by publisher]
Source: International Immunopharmacology - Category: Allergy & Immunology Authors: Tags: Int Immunopharmacol Source Type: research