
suppression of rous sarcoma virus growth in tissue
cultures by mycoplasma orale
an agent
which produced cell destruction in human diploid and chick-embryo fibroblasts
was isolated from wi-26 strain of human diploid fibroblasts and shown to be a
mycoplasma.  the multiplication of rous sarcoma virus (rsv) and rous associated
virus (rav) was inhibited in wi-26, wi-38, and chick-embryo fibroblasts
infected with this mycoplasma.  the mycoplasma isolate, designated strain 941,
reacted strongly in the complement-fixation test with antiserum to mycoplasma
orale ch19299, an isolate obtained from the human oral cavity.  the cytopathic
effect of mycoplasma strain 941 could be eliminated by growing the mycoplasma
on an artificial agar medium before inoculation into chick-embryo fibroblasts.
serial passage in chick-embryo fibroblasts restored the cytopathogenicity of
the agar-grown mycoplasma.  however, growth of rsv and rav was inhibited by
both the tissue culture-grown and the agar-grown 941 strain, and also by the
ch19299 strain which did not produce any cytopathic effect.
