Feline oncornavirus-associated cell membrane antigen. II. Antibody titers in healthy cats from household and laboratory colony environments.

Antibody titers to the feline oncornavirusassociated cell membrane antigen (FOCMA) were determined for 447 healthy cats from laboratory colony and household environments. Only 2.7 percent of 221 cats from colony environments were antibody positive as compared to 50.4 percent of 256 cats from household environments. Incidence of FOCMA antibody and geometric mean antibody titer for pet cats from New York City representing single cat apartment habitats were substantially lower than values for unscreened cats from the Boston, Glasgow, and Detroit suburban environments. Geometric mean antibody titer for young adults in the Boston population was significantly higher than titers for kittens or aged cats. This may be due to greater mobility resulting in increased exposure to other cats. In contrast to the high frequency of FOCMA antibody positivity in pet-cat populations, less than 2 percent of the same groups were positive for virus group-specific antigen in peripheral blood leukocytes and platelets. This was interpreted as an indication that many more cats became infected with feline leukemia virus under natural conditions that the number developing persistent virus infection and/or clinical leukemia.