Integration and expression of murine retrovirus-related sequences in schistosomes

Antibodies against the retrovirus envelope glycoprotein (gp70) of mouse xenotropic retrovirus, BALB virus 2 (Bv2) reacted with the adult worms of Schistosoma japonicum and S. mansoni. This reaction was completely inhibited after adsorption of the antibodies with virions of retrovirus. The reactive schistosome antigen was located in the subtegumental layer of the adult male fluke and in the vitelline gland of the adult female of S. japonicum and S. mansoni. Proteins extracted from both parasites were examined by immunoblot analysis. Anti-Bv2 gp70 antiserum reacted with those proteins from both schistosomes and the band patterns were different among sexes and species. Southern hybridization of the DNA extracted from adults of S. japonicum and S. mansoni demonstrated the presence of sequences homologous to the env gene of mouse ecotropic and xenotropic retroviruses. DNA sequences homologous to the gag and pol regions of the ecotropic murine leukaemia virus were also detected in the DNAs of schistosomes.