Detection of circulating antigens in serum samples of mice experimentally infected with Trichinella spiralis by a sandwich ELISA based on IgY

In the present study, a sandwich ELISA based on IgY (egg yolk immunoglobulin) was developed for detection of circulating antigens (CAg) in sere of mice experimentally infected with Trichinella spiralis. The IgY-sandwich ELISA assay involved the use of chicken antibody IgY against excretory-secretory (ES) antigens of Trichinella spiralis muscle larvae as a capture antibody and mouse polyclonal antibody IgG to ES antigens as a detecting antibody. This method was able to detect as little as 3 ng/ml of ES antigens added to normal mouse serum. A group of sixteen mice was orally inoculated with 500 T. spiralis muscle larvae per animal. The serum samples from the infected mice were taken during 1–35 days post-infection (dpi). The CAg was detectable as early as 8 dpi in the sera of infected mice. The level of CAg increased dramatically during 13–15 dpi and reached a peak at 22 dpi and remained a plateau for 3 days, then declined gradually. Another peak of CAg occurred at 31 dpi. The anti-Trichinella antibodies was first detected in 14.3 % of the infected mice at 2 weeks post-infection (wpi), and reached a peak positive rate of 100 % at 5 wpi. Moreover, the infected mice were treated with abendazole at 5 wpi and the serum CAg levels increased significantly during 2–6 days posttreatment (dpt) and then declined rapidly during 8–14 dpt. By 42 dpt, the CAg levels decreased to the undetected level, but the detection rate of antibodies was still 100 %. The IgY-sandwich ELISA appears to be a sensitive for detection of antigenemia of T. spiralis and valuable to judge the efficacy of chemotherapy in trichinellosis.