Induction of protective immunity to schistosomiasis with immunologically cross-reactive Lumbricus molecules

Immunologically cross-reactive molecules of Schistosoma japonicum and Lumbricus terrestris were identified by antibodies derived from human and rodent sera. Pooled IgG from schistosomiasis patients but not uninfected individuals bound multiple antigens of identical molecular weight in both soluble S. japonicum worm antigen preparations (SWAP) and soluble earthworm preparations (SEWP). These antigens had molecular weights corresponding to 18, 40, 62, 64, 74, 97, and > 110 kDa. Three of these antigens of 74, 97 and > 110 kDa were immuno-affinity purified using antibodies derived from schistosomiasis patients' sera. Vaccination of mice with SEWP produced murine antibodies which bound parasite molecules of 40, 74, 97, and > 110 kDa and induced 36% protection from S. japonicum infection (P < 0.05). Antibody production to S. japonicum paramyosin, a molecule previously shown to induce protection from schistosome infection, was prominently expressed in the protected murine immune sera. The study shows that Lumbricus sp. represent a potential source for paramyosin and other candidate vaccine molecules for schistosomiasis.