Protective efficacy of hepatitis E virus DNA vaccine administered by gene gun in the cynomolgus macaque model of infection.

The protective efficacy of a DNA vaccine against hepatitis E virus (HEV) infection was tested in cynomolgus macaques (cynos) vaccinated with a plasmid containing a full-length HEV open-reading frame 2 (ORF2) sequence (Burmese strain) and subsequently challenged with a heterologous strain of HEV (Mexican strain). Cynos administered vaccine by gene gun developed antibodies to HEV (anti-HEV), whereas cynos administered vaccine by intradermal injections and cynos administered a mock DNA construct did not develop anti-HEV. Anti-HEV-positive cynos were protected from HEV infection after challenge with an inoculum that produced infection in the anti-HEV-negative cynos. These results indicate that DNA vaccine with HEV ORF2 administered by gene gun is protective against a heterologous viral challenge.