Antigenic properties of Schistosoma mansoni aminopeptidases: evolution during the development in mammalian hosts

The involvement in the immunity to schistosomiasis of an aminopeptidase activity of schistosomula, 20-day-old and adult worms of Schistosoma mansoni has been studied. This activity, hydrolysing leucine-p-nitroanilide and alanine-p-nitroanilide at pH 7.4 was immunoprecipitated by various infected rat and human sera. These antigenic enzymes were expressed at day 28 after infection in the rat and seemed to be specific for the Schistosoma species. Several aminopeptidase activities were found after analysis by isoelectric focusing of the adult extract but only the pI 8.3 peak was antigenic. Three antigenic peaks were demonstrated after AcA 34 Ultrogel filtration. The biological relevance of these antigenic enzymes in schistosomiasis is discussed.