Further investigations on the porcine lymphoma C-type particle (PLCP) and the possible biological significance of the virus in pigs.

The possible biological significance of the procine lymphoma C-type particle (PLCP) was investigated serologically. The screening of 1 200 field sera of apparently normal breeder pigs, performed with an immunodiffusion test, revealed negative results. The same results were obtained with sera from a herd with hereditary lymphosarcoma and with sera from experimentally infected piglets. In cases of doubtful precipitation lines additional tests with a more sensitive indirect immunofluorescence assay were performed. In no case a specific cytoplasmic fluorescence could be observed. The same sera of the 1 200 pigs were tested with BLV antigen as well as 350 bovine sera from BLV-positive cattle were tested with PLCP antigen. A possible antigenic relationship between BLV and PLCP could not be detected by the assays mentioned above. Purified PLCP was compared in SDS-PAGE with MuLV, FeLV, and BLV. The electrophoretical pattern presents suggestive evidence for a typical oncornavirus polypeptide composition. Apart from the presumable major internal protein with a molecular weight of 28 000 d, three low molecular weight proteins appeared at 12 000 d, 11 000 d, and 10 000 d. High molecular weight proteins could not be detected yet. The antigenic specificity of these bands has still to be confirmed.