Immunity to tapeworms: intraspecific cross-protective interactions betweenHymenolepis citelli, H. diminutaandH. microstomain mice

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Abstract
SUMMARY: Interactions between tapeworm species in a single host offer intriguing opportunities for immunological studies that attempt to identify the mechanism(s) underlying protection against cestode infections. Mice that are immunized againstHymenolepis citelliinfections were shown to be refractory to subsequentH. diminutachallenge infections. The reciprocity of the response was also demonstrated, although the protection recorded forH. diminutawhen mice are sensitized withH. citelliis weaker than that observed when mice are primed withH. diminutaagainstH. citellichallenge.H. citelliwas also shown to be expelled simultaneously during the rejection phase ofH. diminutain concurrent infections, indicating the susceptibility of the former tapeworm to the rejection mechanism initiated by the latter.H. microstomaimmunized mice were shown to be strongly protected against heterologousH. citellichallenge. However, mice primed againstH. citelliwere not as strongly protected againstH. microstomachallenge infections: a statistically significant protection was obtained only after a 12-cysticercoidH. citelliprimary infection, although a 6-cyst infection did stunt the growth ofH. microstomachallenge worms. It is presently suggested that the cross-protective responses observed in the study betweenH. citelli, H. diminutaandH. microstomamay have emanated from a specific immunological cross-reactivity due to the sharing of similar immunogens.