ISOLATES OF TRICHURIS-MURIS VARY IN THEIR ABILITY TO ELICIT PROTECTIVE IMMUNE-RESPONSES TO INFECTION IN MICE

Much of what is currently known of the host-parasite interaction betwe en mice and the parasitic nematode Trichuris muris has come from exper iments using a single parasite isolate (E/N). This isolate has been co mpared with 2 others which, on morphological criteria, belong to the s ame species. In 3 inbred strains of mouse that show distinct, genetica lly determined response phenotypes, there was a consistent pattern in terms of parasite survival time regardless of host strain, E/K worms b eing expelled early, E/N expelled later and S worms very late or not a t all. High-responder CBA mice expelled E/K and E/N worms earlier than low-responder C57 B1/10 mice. B10.BR mice were permissive to S isolat e infection, mounted a very late response to E/N worms but expelled E/ K worms effectively by day 25. The differential response of mice to th ese isolates provides an experimental system for identifying the basis of variation in this host-parasite relationship.