Inactivated and adjuvanted whole-virion clade 2.3.4 H5N1 pre-pandemic influenza vaccine possesses broad protective efficacy against infection by heterologous clades of highly pathogenic H5N1 avian influenza virus in mice.

In this study, we evaluated the immunogenicity and protective efficacy of a candidate attenuated H5N1 pre-pandemic influenza vaccine of clade 2.3.4, rgAnhui, which was reverse genetically generated from highly virulent A/Anhui/01/2005 (H5N1) wild-type virus. When a low-dose antigen (0.3µg HA) vaccine was combined with aluminum hydroxide adjuvant, virus neutralization and anti-HA IgG antibodies induced in the sera of vaccinated mice showed similar levels as those in mice vaccinated with non-adjuvanted high-dose antigen (3µg HA) vaccine. Serum antibodies had broad reactivity against highly pathogenic H5N1 viruses of both homologous and heterologous clades. All mice vaccinated with adjuvanted and non-adjuvanted rgAnhui vaccines at low and high antigen doses survived, without any significant weight loss, lethal challenge infection with homologous clade 2.3.4 viruses, including antigenic variant virus and heterologous clade 2.1.3. Mice vaccinated with low-dose antigen without adjuvant, however, exhibited 20% and 60% survival rates against clade 1 and clade 2.2 viruses, respectively; but, addition of adjuvant improved these rates to 80% and 100%, respectively. The data strongly suggest that aluminum hydroxide-adjuvanted rgAnhui vaccine can elicit broad cross-reactive and protective immunities against homologous and heterologous clades, and that the rgAnhui vaccine is a useful pre-pandemic H5N1 vaccine.

Characterization of a whole, inactivated influenza (H5N1) vaccine.

OBJECTIVES: Effective vaccines against the highly pathogenic influenza A/H5N1 virus are being developed worldwide. In Japan, two adjuvanted, inactivated, whole-virion influenza vaccines were recently developed and licensed as mock-up, pre-pandemic vaccine formulations by the Ministry of Health and Labor Welfare of Japan. During the vaccine design and development process, various obstacles were overcome and, in this report, we introduce the non clinical production, immunogenicity data in human and development process that was associated with egg-derived adjuvanted, inactivated, whole-virion influenza A (H5N1) vaccine. DESIGN: Pilot lots of H5N1 vaccine were produced using the avirulent H5N1 reference strain A/Vietnam/1194/2004 (H5N1) NIBRG-14 and administered following adsorption with aluminum hydroxide as an adjuvant. Quality control and formulation stability tests were performed before clinical trials were initiated (phase I-III). The research foundation for microbial diseases of Osaka University (BIKEN) carried out vaccine production, quality control, stability testing and the phase I clinical trial in addition to overseeing the licensing of this vaccine. Mitsubishi Chemical Safety Institute Ltd. carried out the non clinical pharmacological toxicity and safety studies and the Japanese medical association carried out the phase II/III trials. Phase I-III trials took place in 2006. RESULTS: The production processes were well controlled by established tests and validations. Vaccine quality was confirmed by quality control, stability and pre-clinical tests, and the vaccine was approved as a mock-up, pre-pandemic vaccine by the Ministry of Health and Labor Welfare of Japan. CONCLUSIONS: Numerous safety and efficacy procedures were carried out prior to the approval of the described vaccine formulation. Some of these procedures were of particular importance e.g., vaccine development, validation, and quality control tests that included strict monitoring of the hemagglutinin (HA) content of the vaccine formulations. Improving vaccine productivity, shortening the production period and improving antigen yield of the avirulent vaccine strains were also considered important vaccine development criteria.