Murine Schistosoma bovis infection:: analysis of parasitic and immune parameters

Humoral and cellular responses to Schistosoma bovis antigens have been evaluated over a period of II weeks in mice exposed to S. bovis cercariae and data analysed in the context of the parasitic parameters (worm and egg loads) recorded at days 30, 60 and 80 of the ongoing infection. Results revealed a decrease of worm burden, particularly marked for female worms, between day 60 and day 80 of infection suggesting a higher susceptibility of female schistosomes to attrition mechanisms. The B-cell response, studied by measuring the production of different isotypes, was directed against different stage specific antigens, with a predominance of IgG1 antibodies associated with a significant increase of IgA and IgE antibodies after egg deposition. The T-cell response, assessed after in vitro stimulation of splenocytes, showed a predominant production of Th-2 cytokines (IL-4, IL-5 and IL-10) occurring after egg laying. Interestingly in contrast to S. mansoni infection the Th-2 polarization did not seem to be exclusively triggered by egg-associated antigens since significant amounts of IL-10 were produced after stimulation with adult worm antigen preparation (SWAP) before the beginning of egg deposition.