[Expression and immunity of multi-HIV B'/C subype genes in replicating DNA vaccines]

To understand the effect of various gene structures of HIV B'/C subtype on the gene expression and immunity in DNA vaccine, replicating DNA vector pSCK2 was used to construct seven DNA vaccines carrying one or more of HIV B'/C subtype genes: gagpol, gp160 and rtn (rev, tat and nef fusion gene). Immunofluorescence staining indicated that Gag, Gp160, Rev, Tat and Nef could be expressed from the seven DNA vaccines. Stronger expression was observed with the gene in single-gene expression plasmid or with the gene located at upper-IRES in double- or multi-gene expression plasmid. ELISA test showed that Gag induced higher antibody response, but the antibody titers stimulated by Gp160, Pol, or RTN were very low. Both Gag single-gene expression plasmid and Gag-RTN double-gene expression plasmid separately inoculating induced stronger antibody response against Gag than Gag-Gp160 double-gene expression plasmid and Gagpol-Gp160-RTN multi-gene expression plasmid or combined inoculation of Gag and Gp160 single-gene expression plasmids did. ELISPOT detection showed that all the seven DNA vaccines could stimulate cellular immune response against Gag, Pol, Gp160, Tat, and Nef, respectively. Gagpol or Gp160 single-gene expression plasmid separately inoculating stimulated the strongest cellular immune response. Tat and Nef expressed in all the plasmids induced similar immune response. These results indicated that HIV B'/C subtype genes gagpol, gp160 and rtn could be efficiently expressed in the replicating DNA vaccine vector, single-gene expression plasmid had the higher gene expression level and induced stronger immune response; combined immunization of Gagpol and Gp160 had dramatically lower immunity than Gagpol or Gp160 separated immunization did. Immunity of RTN had no difference between combined and separated immunizations. Therefore, in case of immunization with DNA vaccines containing different HIV genes, it is necessary to optimize the combined immunization procedure, especially for the combination of Gag and Gp160-containing vaccines.