DNA vaccination against hepatitis E virus infection in cynomolgus macaques.

Background: : The feasibility of DNA vaccination against hepatitis E in non-human primates has not been evaluated. In the present study a full-length hepatitis E virus (HEV) open reading frame (ORF)2 (Burmese strain) was assembled, cloned, and used for genetic immunization of cynomolgus macaques (cynos), which were subsequently challenged with a heterologous HEV strain (Mexico).

Methods: : Four cynos were vaccinated intramuscularly with the HEV ORF2 DNA cassette and one animal was vaccinated with a mock DNA construct.

Results: : Following vaccination anti-HEV antibodies were detected in the four HEV-DNA-vaccinated cynos, but not in the control animal. When challenged, two of the four HEV-DNA-vaccinated cynos were protected against HEV infection and had no elevated alanine aminotransferase activity, viremia, or fecal shedding. The two other DNA-vaccinated animals developed HEV infection and disease.

Conclusion: : These findings demonstrate the feasibility of DNA vaccination for the protection of HEV infection and warrant further studies to explore routes other than intramuscular for induction of a stronger and efficacious immune response.