The gel diffusion test was carried out using
Mycoplasma gallisepticum (
MG) antigen extracted by sonication from the organisms grown in PPLO broth (Eiken) with addition of horse serum (contained at 20%), and anti-
MG rabbit serum which had been prepared from growth in Hofstad's medium containing 20% chicken serum. The results obtained are as follows.
1) Repeated tests by gel diffusion did not always give similar results with the same lot of antigen and its antiserum. An increase or decrease in the number of precipitation lines was observed, though it aws limited to one line.
2) The protein concentration of antigen and time for bleeding from immunized rabbits greatly affected the number of precipitation lines in the gel diffusion test. Under suitable conditions, however, 5 lines were obtained in this test.
3) With antisera S6 and KP-13, the number of precipitation lines varied from 2 to 5 depending on 27 strains used. At least 2 antigen components were common to these strains. Three strains, S6, KP-13, and PG-31, were employed for the cross tests by gel diffusion under more suitable conditions. At least 3 common antigen components were observed among the three strains. One more common precipitation line was seen between the strains S6 and KP-13, or S6 and PG-31. The additional lines were not serologically related. This indicates that a part of MG antigen was not serologically uniform among the strains.
4) Of 54 serum samples from
MG-infected chickens, seventeen produced one or three precipitation lines against the antigens of
MG (a total of 26 strains). However, there seemed to be some differences in antigenicity among the strains.
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