Some effects of growth medium composition on the antigenicity of a T-strain mycoplasma.

T-strain 960 was passaged through 24 serial 10-fold dilutions in media without added urea and with porcine serum albumin fraction V as the only protein enrichment. The organism, either grown in this manner or passaged an additional three times in medium containing horse serum and 0.1 per cent urea, was inoculated into rabbits. Resultant antisera were tested for activity against T-960 growing in these different media by: (i) growth curve analysis in the presence of antiserum, (ii) metabolic inhibition in the presence or absence of complement (fresh guinea pig serum), (iii) complement-dependent killing curves, (iv) double diffusion in gel (Ouchterlong), and (v) a new visual method for the detection of antigen-antibody reactions on glass slides coated with a thin film of indium metal. Our results indicate that the reactivity of the antisera, as assayed by the above methods, is significantly affected by the composition of the growth medium used for preparation of the antigen. In addition, it was possible to determine that the guinea pig serum-dependent killing of T960 was not affected by the presence of ammonium ion.