Effect of immunization with metabolic antigens on experimental infection of rats with Angiostrongylus cantonensis.

Immunization of rats with excretions and secretions from an in vitro culture fluid (ES antigens) of adult female Angiostrongylus cantonensis markedly enhanced their resistance to infection by third-stage larvae. Mortality rate, survival period, worm development and worm recovery, determined after a lethal challenge with infective larvae, were compared in immunized and unimmunized animals. With regard to these criteria, the results obtained with animals that had been immunized with ES antigens from adult males were found to be indistinguishable from those of the unimmunized controls. On the contrary, those immunized with ES antigens from adult females had lower mortality rate, increased survival period, and lower worm burden. Both male and female worms recovered from brain and mature adults recovered from pulmonary arteries of rats that had been immunized with female ES antigens were also found to be stunted.