ABSTRACT
Developing a safe and effective H7N9 influenza vaccine was initiated in early spring 2013, following human infections with a novel avian influenza A (H7N9) virus. In this study, a candidate H7N9 vaccine seed strain is produced using reverse genetics, with HA and NA derived from a human H7N9 virus and the remaining genes from the PR8 backbone virus which grows well in eggs. We verified that the virulence and transmissibility of the recombinant H7N9 vaccine seed strain were decreased as compared to wild-type H7N9 virus, to levels comparable with PR8. Using the seed virus, we produced a monovalent split influenza A (H7N9) MF59-adjuvanted vaccine that was immunogenic in mice. Our H7N9 vaccine is selected for clinical investigation and potential human use. To assess the safety of our H7N9 vaccine, we performed acute toxicity, repeated dose toxicity and active systemic anaphylaxis tests. Our results showed that, under the conditions used in this study, the NOEAL (no obvious adverse effect level) was 30 µg/0.5 mL.
Subject(s)
Adjuvants, Immunologic/pharmacology , Immunogenicity, Vaccine , Influenza A Virus, H7N9 Subtype/drug effects , Influenza Vaccines/pharmacology , Orthomyxoviridae Infections/prevention & control , Polysorbates/pharmacology , Squalene/pharmacology , Adjuvants, Immunologic/toxicity , Animals , Castration , Disease Models, Animal , Dogs , Female , Ferrets , Guinea Pigs , Influenza A Virus, H7N9 Subtype/genetics , Influenza A Virus, H7N9 Subtype/immunology , Influenza A Virus, H7N9 Subtype/pathogenicity , Influenza Vaccines/genetics , Influenza Vaccines/immunology , Influenza Vaccines/toxicity , Madin Darby Canine Kidney Cells , Male , Mice, Inbred C57BL , No-Observed-Adverse-Effect Level , Orthomyxoviridae Infections/blood , Orthomyxoviridae Infections/immunology , Orthomyxoviridae Infections/virology , Polysorbates/toxicity , Rats, Sprague-Dawley , Risk Assessment , Squalene/immunology , Squalene/toxicity , Time Factors , Vaccines, Attenuated/pharmacology , Vaccines, Synthetic/pharmacology , VirulenceABSTRACT
The H7N9 influenza virus caused significant mortality and morbidity in humans during an outbreak in China in 2013. A recombinant H7N9 influenza seed with hemagglutinin (HA) and neuraminidase (NA) gene segments from A/Zhejiang/DTID-ZJU01/2013(H7N9) and six internal protein gene segments from A/Puerto Rico/8/34(H1N1; PR8) were generated using reverse genetics. We sought to determine the immunogenic, protective properties, and mechanisms of a split avian influenza A/H7N9 vaccine mixed with MF59 adjuvant in comparison to vaccines that included other adjuvant. BALB/c mice were vaccinated with two doses of different amounts and combinations of this novel A/ZJU01/PR8/2013 split vaccine with adjuvant. Mice were subsequently challenged with A/Zhejiang/DTID-ZJU01/2013(H7N9) by intranasal inoculation. We verified that MF59 enhanced the HI, MN, and IgG antibody titers to influenza antigens. Compared with alum, MF59 could more potentially induce humoral immune responses and Th2 cytokine production after virus infection, while both MF59 and alum can slightly increase NK cell activity. This split H7N9 influenza vaccine with MF59 adjuvant could effectively induce antibody production and protect mice from H7N9 virus challenge. We have selected this vaccine for manufacture and future clinical studies to protect humans from H7N9 virus infection.
