P-29. Enhancement of humoral immune response by combination vaccine against Hepatitis B surface antigen “HBsAg“ and Hepatitis E partial capsid protein “NE“

To assess the humoral response in combination vaccine of HBV+HEV with liposome co-encapsulating DNA and its corresponding protein. Mice were immunized subcutaneously with three doses on 0, 4 and 8 week, of liposome formulations containing a) 1μg HBV DNA and 1μg HBsAg protein (lipo-B) b) 1μg NE DNA and 1μg NE protein (lipo-E), c) 1μg HBV DNA and 1μg HBsAg protein + 1μg NE DNA and 1μg NE protein (lipo-COMBO), d) 1μg HBV DNA (lipo-HBV DNA), e) 1μg NE DNA (lipo-NE DNA), f) 1μg HBV Protein (lipo-HBsAg), h) 1μg NE Protein (lipo-rNEp), Mice were bled at 2 week interval and sera were tested for anti-HBs and/or anti-HEV IgG by ELISA. Anti-HBs titres in mice immunized with lipo-B and lipo-HBsAg were similar. However, the dominant subtype of IgG was IgG2a in mice receiving lipo-B as compared to IgG1 with lipo-HBsAg. No sero-conversion was found with lipo-HBV DNA immunized mice. Anti-HEV titres in mice immunized with lipo-E were significantly higher (p= 0.007) than mice immunized with lipo-rNEp. The pre-dominant isotope was IgG1 irrespective of the type of immunogen. Similarly, no antibody production was observed with Lipo-NE DNA immunized mice. Anti-HBs titres in mice immunized with lipo-COMBO formulation were comparable with lipo-B-induced titres, IgG2a being the dominant isotope of IgG. Similarly, anti-HEV titres receiving lipo-COMBO or lipo-E were comparable with the predominance of IgG1. Encapsulation of HBsAg, corresponding DNA and NE DNA and protein of HEV results in a candidate combination vaccine for hepatitis B and E.