Diagnosis of trichinellosis in swine by enzyme immunoassay, using a synthetic glycan antigen

Abstract

Objective - To assess performance of a synthetic carbohydrate antigen for use in an enzyme immunoassay for diagnosis of trichinellosis in swine. Animals and Sample Population - 47 York × Duroc pigs and field sera from 265 farm pigs raised under various management systems. Procedures - Each of 47 pigs was inoculated with 25 to 500 Trichinella spiralis larvae, and blood samples were obtained weekly. At postinoculation week 12, pigs were euthanatized, and tissues recovered from the tongue and diaphragm were digested to determine worm burden. Serum samples from experimentally infected pigs and sera obtained from pigs on a farm were tested by enzyme immunoassay, using standard excretory-secretory and synthetic glycan antigens. Results - Of the 47 pigs, 46 (97.8%), with worm burden ranging from 0.02 to 248.8 larvae/g of tissue in the tongue and diaphragm, tested seropositive using both antigens. Time of seroconversion varied among pigs and was negatively correlated with intensity of infection. Minor differences were observed in time of seroconversion between the 2 antigens in 11 of 46 pigs, suggesting some differences in the antibody response. One pig with a worm burden of 0.01 larva/g was not detected by enzyme immunoassay using either antigen. Background values obtained using the 2 antigens did not differ among confinement-raised pigs, but background values for pigs raised outdoors on dirt lots were significantly lower using the glycan antigen. Low-level, naturally acquired T spiralis infections in pigs were detected in most instances by use of both antigens, although there were some differences in antibody responses of infected pigs. Conclusion - The synthetic glycan antigen has potential for replacing excretory-secretory antigens as a standardized reagent for diagnosis of trichinellosis in pigs.