Successful nucleic acid based immunization of newborn chimpanzees against hepatitis B virus.

To determine whether DNA based immunization could protect newborn chimpanzees against a challenge infection with hepatitis B virus, two chimpanzees were immunized on the day of birth with a plasmid coding for hepatitis B surface antigen, and boosted at 6 and 24 weeks. Both animals produced transient antibody to the hepatitis B surface antigen. Following challenge with hepatitis B virus at 33 weeks the two immunized animals developed anamnestic antibody responses, however, neither developed detectable hepatitis B surface antigen or antibody to the core protein, the conventional markers of hepatitis B infection. Both of these markers appeared in an unimmunized control animal. We conclude that DNA based immunization can induce protective immunity in newborn chimpanzees.