Protective immunity against Angiostrongylus cantonensis in rats following sensitizing infections.

Three strains (ACI, August and Wistar) of rats previously sensitized by oral infection with intact third-stage larvae of Angiostrongylus cantonensis developed significant protective immunity to challenge infections 6 weeks later. The degree of the immunity was highest in the August strain of rats, followed by Wistar and ACI rats. Protective immunity appears to affect both third-stage larvae and fourth- and/or fifth-stage worms. ACI rats showed poor antibody responses, especially in the IgE fraction. When 24-day-old young adult worms were transferred from the brain of donor rats into the peritoneal cavity of sensitized rodents, peritoneal eosinophils predominantly adhered to the worm surfaces in vivo.