An isotopic antiglobulin assay was developed to measure
antibodies in "normal" cats to
FOCMA, a
cell surface antigen associated with immunity to FeLV-induced
tumors. The assay was shown to be specific for detecting
FOCMA antibody by several criteria including a correlation with cell membrane immunofluorescence and absorption tests. Antibody to
FOCMA developed following FeLV
infection and was expressed in heterologous species. In combination with an assay for antibody to FeLV p30, the major virion structural
protein, 200 cats sera from three different geographic areas were examined for evidences of FeLV-type-C-
virus infection. Approximately 17% of all sera examined contained antibody to
FOCMA.
Antibodies directed to the FeLV p30 were detected in 8 of the sera and only in cats with
FOCMA antibody. The correlation in cat sera between antibody to
FOCMA and FeLV p30
antigen suggests that both are associated with the same process,
infection with FeLV type-C-virus. The relationship of the observed pattern of antibody response is discussed in relation to other horizontally transmitted
RNA-containing viruses.