IMMUNE-RESPONSE TO SCHISTOSOMA-MANSONI PHOSPHOGLYCERATE KINASE DURINGNATURAL AND EXPERIMENTAL-INFECTION - IDENTIFICATION OF A SCHISTOSOME-SPECIFIC B-CELL EPITOPE

A cDNA clone encoding Schistosoma mansoni phosphoglycerate kinase (SmP GK) was previously identified by affinity-purified antibodies which ar e specific for 3-h-old schistosomula tegumental antigens. Antibodies t o the recombinant SmPGK which has enzymatic activity were localized to various tissues including the tegument of the 3-h-old schistosomula a nd 42-day-old adult worms. In this study, we show that SmPGK is an imm unogenic molecule in both natural infection in humans and experimental vaccination in animals. To understand the role that a highly conserve d molecule like SmPGK played during schistosome infection, we affinity purified antibodies to SmPGK from patients with chronic schistosomias is and demonstrated that they did not crossreact with human PGK. Howev er, affinity-purified rabbit anti-SmPGK antibodies did show immunoreac tivity to both human PGK and rabbit PGK. Thus, during natural infectio n antibodies that cross-react with human PGK are not produced; however , as a result of active immunization with an intact conserved molecule , such cross-reacting antibodies are produced, Immunological analysis of cyanogen bromide digests of SmPGK with monoclonal antibodies that r ecognize SmPGK but not human PGK identifies a B-cell epitope on a 12.2 -kDa fragment represented by amino acids 61 to 174.