DNA-mediated immunization to hepatitis B surface antigen: effects of a plasmid coexpressing hepatitis B surface antigen and interleukin 18 / 中华传染病杂志

ABSTRACT

Objective To observe the specific humoral and cellular immune response in BALB/c mice injected with pS and p18S. Methods pS and p18S were constructed separately by inserting HBsAg gene fragment and the fusion gene fragment of HBsAg and mouse interleukin 18(IL 18) into the reading frame of pcDNA3.1+. Mice were injected with either plasmid intramuscularly in a total dose of 300 ?g per mouse. Every serum sample was detected for anti HBs using enzyme linked immunosorbent assay(ELISA). Furthermore, HBsAg specific cytotoxic T lymphocytes activity was measured. Results The expression of HBsAg was demonstrated by ELISA in p815 cells transfected with pS and p18S. pS can stimulate a positive antibody response. The average level was 135 mIU/ml, with the highest level of 530 mIU/ml. p18S could elicit relatively lower antibody response which was 20 mIU/ml. HBsAg specific CTL activities were 37.1% and 34% separately in pS and p18S immunized mice. It was only 13.2% when detected in pcDNA3.1+ immunization. Conclusion pS is effective to stimulate a humoral and cellular response in H 2d mice. IL 18 gene can not enhance the immune response when fused with HBsAg gene. Conversely, it seems to inhibit an immune response.