Deletion of the A35 gene from Modified Vaccinia Virus Ankara increases immunogenicity and isotype switching.

We show here that the immunogenicity of the Modified Vaccinia Ankara MVA vaccine strain can be improved by deletion of the A35 gene, without diminishing the ability of the virus to replicate. Deletion of the A35 gene resulted in increased virus-specific immunoglobulin production, class switching to IgG isotypes, and virus-specific IFNγ-secreting splenocytes. The MVA35 deletion virus provided excellent protective efficacy against virulent virus challenge. These results suggest that A35 deletion mutant strains will have superior vaccine performance for poxvirus vaccines as well as platform vaccines for other infectious diseases and cancer.