Recombinant Schistosoma mansoni elastase was expressed in Escherichia
coli and an antiserum raised against the recombinant protein was used
to investigate stage-specific control of elastase in the parasite, and
to determine whether the enzyme could form the basis of a strategy to
prevent larval invasion of the host. Results showed that the expressi
on of elastase is developmentally regulated, even if the basal promote
r activity does not seem to be stage specific. The analysis of mRNA ex
pression showed the presence of elastase transcript in adult worms alt
hough we could not detect the protein at this stage, suggesting that S
. mansoni employs a form of translational control. The measurement of
elastase levels in supernatants of culture schistosomula combined with
the localization of elastase in cercariae invading mouse skin showed
that the enzyme is heavily released during penetration. Finally, we st
udied the cytotoxic activity of rat anti-elastase sera, and the analys
is of the isotypic profile suggested that IgG2a anti-elastase may be r
esponsible for the cytotoxic effect.