Immunologic evaluation of extracted intestinal proteins from Angiostrongylus cantonensis adult worms.

BACKGROUND: To determine whether intestinal Angiostrongylus cantonensis antigens can induce protective immunity in rats, gut antigens prepared from female adults (FAGP) and somatic antigens prepared from both male (MA) and female (FA) adult worms were used to immunize rats.

METHODS: Rats were immunized twice with MA, FA, or FAGP antigens and then challenged with 50 third-stage A. cantonensis larvae, and different readouts were used to monitor protective immunity. Additionally, protein profiles of MA, FA, and FAGP extracts were analyzed and characterized by immunodetection methods.

RESULTS: A 15% reduction in fifth-stage larvae from brains and a 14% reduction in adult worms from pulmonary arteries were observed in rats immunized with FAGP compared to controls. However, there was a >50% reduction in rats immunized with MA or FA. The lengths of larvae and adults recovered from FAGP-immunized rats were shorter than those recovered from other groups. The number of first-stage larvae recovered from fecal material in FAGP-immunized rats was significantly reduced. Additionally, FAGP induced the highest splenocyte proliferation. Serum IgG titers were not directly correlated with protective immunity. An 84 kDa gut membrane protein was strongly recognized by anti-FAGP antibodies.

CONCLUSION: We demonstrated that immune responses induced by FAGP reduced the growth, development, and reproduction of A. cantonensis in subsequent infections. While the possibility of using FAGP combining with MA or FA antigens as a multi-function vaccine in immune protection against A. cantonensis needs to be further elucidated, we hope that it provides a novel strategy for this parasite vaccine development.