SCHISTOSOMA-MANSONI - VACCINATION OF MICE WITH CRYOPRESERVED IRRADIATED SCHISTOSOMULES

In our earlier experiments, NIH/Nmri (CV) mice developed protective immunity to a Schistosoma mansoni cercarial challenge when previously exposed percutaneously to highly 60Co-irradiated homologous cercariae. Experiments reported here were conducted to assess the immunogenicity of unfrozen and frozen and thawed schistosomules derived from 60Co-irradiated cercariae (irradiated schistosomules). Immunization of NIH/Nmri (CV) mice by 60Co-irradiated unfrozen schistosomules reduced worm burdens from a subsequent percutaneous challenge with normal cercariae by 41 to 72%. Immunogenicity was not narrowly dependent on irradiation dose rates between 1 and 8 kR/min, or on the total dose of irradiation given the schistosomules between 25 and 50 kR. Comparable protective immunity developed after injection of irradiated schistosomules which had been frozen to -196 C in liquid nitrogen and thawed. Cryopreservation appears to offer a solution to the problem of storage of attenuated, immunogenic S. mansoni schistosomules. © 1979.