RESUMO
Objective To investigate the effect of Iscom matrix on the immunogenicity of recombinant hepatitis B surface antigen containing PreS epitopes(SS1S2). Methods SS1S2+ Al(OH)3 and SS1S2+Iscom vaccines were made by combining purified SS1S2 antigen with Al( OH)3 adjuvant or Iscom matrix.Groups of BALB/c mice were injected i. m or s. c by either of the two vaccines at day 0 and day 14. Half of the mice were sacrificed and sera were taken and spleen cells separated from the mice 14 days after each injection. Anti-S, anti-PreS1, and anti-PreS2 antibody titers were measured, and total IgG1 and IgG2a titers were further detected for each serum sample. IFN-γ ELISPOT assay was performed to detect IFN-γsecreting cells from the pooled spleen cells for each vaccine group. Results The seroconversion rates and geometric mean titers(GMTs) and the numbers of IFN-γ secreting cells were approximately at the same level for the differently formulated vaccines after the first injection except that the ratio of IgG2a to IgG1 in the Iscom group was higher than the Al(OH)3 group. After boost injection, the GMTs of total IgG rise slightly in the Al(OH)3 group but significantly in the Iscom group. The IgG2a to IgG1 ratio in the Iscom group kept balanced while dropped further in the Al(OH)3 group. The number of specific IFN-γsecreting cells triggered by the Iscom vaccine exceeded significantly the number of Al( OH)3 vaccine, showinga stronger cellular response. Conclusion The results in this study shows that Iscom matrix is more potent in enhancing the immunogenicity of recombinant hepatitis B virus surface antigen containing PreS epitopes than Al( OH)3 adjuvant.