Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot of nonspecific and specific viral proteins frequently detectedin different antigen preparations of bovine leukemia virus

Bovine leukemia virus (BLV) infection in cattle is seldom manifested clinic ally, and is routinely diagnosed by serologic tests such as enzyme-linked i mmunosorbent assay or Western blot (WB). Because of the difficulty in inter preting WE results, the aim of the present study was to determine which of the bands observed in WE were specifically produced by BLV and which corres ponded to nonspecific proteins, either derived from medium components or of a cellular nature. Five different BLV antigen preparations from 2 cell lin es (FLK-BLV and BLV-bat(2)) frequently used for the production of BLV antig en were compared. The protein profiles of these antigen preparations were a nalyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis and WE. Fetal calf serum, required for cellular growth and important in induct ion of viral transcription in vitro, was identified as a source of irreleva nt proteins. In this study, 15 nonspecific protein bands in the growth medi um were observed. These bands interfered with the interpretation of results . A nonspecific protein (25 kD) that was highly reactive in cell lysate pre paration from BLV-bat(2) was also detected. The unequivocal identification of protein bands, both specific and nonspecific, seen in WE is important no t for understanding the protein profile of antigen preparations but also fo r determining if an animal is BLV positive or negative.