DNA immunization by intramuscular injection or gene gun induces specific IgG antibodies against a Schistosoma japonicum 22 kDa antigen, Sj22, when fused to the murine Ig K-chain secretory leader sequence

The 22 kDa tegumental surface membrane-associated antigen of Schistosoma ja ponica, Sj22, is of recognized interest in schistosomiasis vaccine research . However, previous attempts to induce antibody responses against Sj22 by D NA immunization have been unsuccessful. In this report we demonstrate that fusing the Sj22 cDNA to the murine immunoglobulin Ig kappa-chain secretory leader sequence results in the generation of antigen-specific IgG antibodie s following DNA immunization. Mice were immunized into the skin with DNA-co ated gold microspheres rising a gene-gun, or into the quadriceps muscle by intramuscular injection, Both methods of delivery generated antigen-specifi c IgG antibodies against the 22 kDa schistosome antigen. The use of a secre tory leader sequence, such as the murine Ig-kappa chain used in this study, may facilitate the induction of host antibody responses following DNA immu nization with other parasite cDNAs.