Oral inoculation with Gymnorhynchus gigas induces anti-parasite anapyhylactic antibody production in both mice and rats and adverse reactions in challenge mice

This study was performed to mimic human consumption of fish flesh infected with larvae of the fish cestode Gymnorhynchus gigas and examine possible side effects thereof. Both a rat and a mouse G. gigas oral inoculation model were used. The rat model was evaluated according to propensity to induce stress responses in three tissues and anaphylactic antibody production. The mouse model measured anti-G. gigas IgG, M and A (H+L) levels in intestinal fluids, fecal suspensions and serum and specific serum IgE levels by enzyme-linked immunosorbent assay. Additionally, biological activity of anaphylactic antibodies in test mice and rats were evaluated utilizing challenge reinoculation(s) and intradermal skin testing, respectively. With the rat inoculation model, we noted both occurrence of a shock response, viz. increased expression of heat shock proteins in intestine and spleen, and of immediate-type skin reactions. No positive wheals were seen on skin sites treated with PBS or soluble Trichinella spiralis extract. With the mouse model, our results showed that all body fluids tested had significantly more anti-G. gigas IgG, M and A (H+L) than their counterparts from either PBS-treated or T. spiralis-infected controls. In addition, the mouse G. gigas model had significantly higher specific serum IgE. When challenged by oral route all test mice (n=5) manifested immediate-type signs of distress. Repeated exposure to the “allergen”, produced clinical signs appearing more rapidly and persisting longer. These findings suggest that feeding on fish infected with G. gigas plerocercoids triggers the production of anaphylactic-type antibodies in both rats and mice and, by implication, possibly also in humans.