Immunization with infective larvae of Strongyloides ratti (Nematoda) exposed to microwave radiation

Abstract

Microwaves have not been tested previously for possible application in producing immunogenic preparations of parasites. This study examines the immunizing capacity of microwave-irradiated, infective larvae of Strongyloides ratti in rats. Rats were inoculated subcutaneously with untreated, microwaved, or microwaved and homogenized larvae, or distilled water, and challenged with untreated larvae. Data were collected on egg production and worm number/rat during primary infections and on egg production, worm number/rat, worm size, and eggs in utero/worm following challenge. Our results demonstrated that microwaved, infective larvae (intact or homogenized) of S. ratti were immunogenic for rats, even though they were incapable of reaching the intestine and maturing to adult worms. The immunity elicited by exposure to microwaved larvae was characterized on challenge by a significant reduction in the number of eggs produced/worm, by the formation of perioral plugs, and by reductions in worm numbers and size. These results suggest that microwave radiation may provide a valuable new tool for parasitic vaccine production. In addition, we have demonstrated the occurrence of a feature of the immune response of rats to S. ratti that may have been overlooked previously; i.e., a gut-level response that was elicited by larvae, but manifested against adult worms in the intestine.