Acidic thiol proteinase activity of Schistosoma mansoni cultured in vitro

Schistosoma mansoni cultured in vitro for periods from 12 days to 33 weeks were analyzed for proteinase activity using a fluorescent substrate and compared with adult S. mansoni worms from infected mice. The enzyme activity measured was that of an acidic thiol-dependent proteinase previously described. Proteinase activity appears early in development, and rises rapidly to an approximately constant proportion of the total extractable worm protein. Cultured worms have 5 to 20 times higher specific activity than in vivo-developed worms. However, cultured worms and in vivo worms have approximately equivalent activities per worm.