Use of the agar-gel precipitin test to evaluate broiler breeder and commercial layer flocks for Mycoplasma gallisepticum infection [Chickens]

In the absence of Mycoplasma gallisepticum (MG) isolation, the importance of agar-gel precipitin (AGP) tests along with micro-hemagglutination-inhibition (mHI) and serum plate agglutination (SPA) tests for the evaluation of poultry flocks for MG infection was demonstrated. A good correlation between AGP, mHI, and SPA tests for the early confirmation of MG in a flock was observed, except for the breeder flocks from which WVU 907 was isolated. The serums of such breeder flocks were positive for SPA and AGP test but negative for the mHI test. Isolation of MG for confirmation of the status of the flock was unsatisfactory in the later stages of infection or when nonpathogenic organisms were present in appreciable numbers. In the absence of MG or M. synoviae (MS) isolation, demonstration of agglutinin, precipitin, and/or mHI antibodies in the serums of such flocks were confirmatory for MG or MS infection. The new isolate WVU 907 gave positive reactions on the SPA and AGP tests with MG antiserum. The isolate hemagglutinated chicken red blood cells (RBC) and induced low HI antibody levels (≤1:20) when inoculated into chickens. Like MG, WVU 907 precipitin antigen was partially denatured by urea, Triton x-100, and sodium dodecyl sulfate treatment.