Induction of immune responses in mice by hepatitis B virus large envelope DNA vaccine delivered by attenuated Salmonella typhimurium

The enhanced green fluorescent protein (EGFP) expression plasmid was transformed into an attenuated AroA- autotrophic mutant of Salmonella typhimurium SL7207, the resultant bacteria was administered orally to BALB/c mice. EGFP expressed in spleen cells was detected by flow cytometry. A DNA vaccine encoding HBV large envelope protein was immunized BALB/c mice by oral delivery through SL7207 or by direct intramuscular injection. The serum antibodies, T lymphocyte proliferative response and cytotoxic T lymphocyte response of mice were detected. The results showed that both DNA immunization methods could induce cellular and humoral immune responses, whereas oral vaccination elicited stronger immune responses than intramuscular vaccination did. Therefor, oral administration with HBV DNA vaccine using attenuated Salmonella may be a simple and effective method for the therapy of hepatitis B.