The humoral response to heat shock protein 70 in human and murine Schistosomiasis mansoni.
We have expressed two cDNA sequences encoding 121 and 230 amino acids of the C-terminus of the Schistosoma mansoni Hsp 70 in Escherichia coli. The products were synthesized as polypeptides fused to the RNA polymerase of bacteriophage MS2, and their reactivities were tested in ELISAs, using sera from human and murine infections. Anti-Hsp70 antibodies were detected in a significant number of individuals suffering from chronic schistosomiasis mansoni, but not in patients with known recent infections. This, together with the finding that antibodies directed at S. mansoni-specific Hsp70 determinants during the course of infection of experimental mice were not detectable until 5-6 weeks post-infection, suggests that the protein may be a useful marker for distinguishing late and early infections. The diagnostic specificity of Hsp70 was evaluated with sera from humans infected with different schistosome species and other parasitic diseases. While some subjects infected with S. haematobium produced antibodies which recognized the S. mansoni Hsp70, no such antibodies were generated in S. japonicum infected individuals. However, cross-reactive antibodies were elicited in donors with other parasitic diseases such as filariasis and malaria. The absence of antibodies in early infection and the observed cross-reactivities led us to conclude that Hsp70 will be of limited value in the diagnosis of schistosomiasis.