Specific antibody patterns of Wistar rats inoculated with third stage larvae of Anisakis simplex.

Levels of excretory-secretory (ES)-specific antibody were measured in Wistar rats inoculated with 1, 5, or 20 third stage larvae (L3) of Anisakis simplex. Primary inoculation induced ES-specific IgM and IgG titers, paralleling inoculum size. Secondary inoculations resulted in an IgM and IgG titer augmentation in 1 or 5 larvae-inoculated animals to levels comparable to those of animals inoculated with 20 larvae, but titers in high inoculum animals did not increase upon secondary inoculation. Primary inoculation induced low ES-specific IgE antibody titers. However, secondary inoculation produced a different pattern than with IgM or IgG titers. Instead of titers equivalent to animals receiving more larvae, rats receiving 1 larva developed higher IgE titers than rats receiving larger inoculums. IgE titers of single larvae-inoculated rats peaked at 3-5 days after secondary inoculation but disappeared by day 14. The time course of IgE production is therefore consistent with duration of the infection. As the natural infection typically involves few larvae, monitoring ES-specific IgE may be a useful diagnostic tool for human intestinal anisakiasis.