MOLECULAR CHARACTERIZATION OF 2 SCHISTOSOMA-MANSONI PROTEINS SHARING COMMON MOTIFS WITH THE VIF PROTEIN OF HIV-1

We have previously described a rat mAb directed against a peptide deri ved from the vif protein of HIV-1 that recognized two Schistosoma mans oni (Sm) antigens with a major band at 65 kDa. Epitope mapping of this mAb using overlapping hexapeptides derived from the vif peptide revea led that the motif recognized was PLPSVT. The screening of a Sm cDNA l ibrary led to the identification of two clones, Sm70 and Sm65. The two deduced protein sequences did not share any common structural feature s apart from the epitope recognized by the mAb (see below), and did no t show significant identity to sequences present in the data bases. Ho wever, the N terminus of the deduced sequence of the Sm70 protein exhi bits a consensus sequence known to be an ATP/GTP binding site. Further more, the C terminus of the deduced Sm65 protein sequence was found to contain a conserved hexapeptide with a consensus sequence LPETGE repo rted to be an important motif of the surface proteins of gram-positive cocci. Both proteins exhibit a peptide sequence (PLRSVT for Sm70 and PVGSVT for Sm65) similar to the epitope recognized by the mAb anti-vif . Western blotting experiments showed that the mAb anti-vif reacted wi th both proteins. However, only Sm65 was recognized by sera from HIV-1 -seropositive individuals, whereas both proteins were recognized by S. mansoni-infected patients.