EVALUATION OF ELECTROPHORETIC IMMUNOBLOTTING FOR THE DETECTION OF ANTIBODIES AGAINST THE BOVINE LEUKOSIS VIRUS IN CATTLE

Sur antigen preparations of bovine leukemia virus, including affinity- purified glycoprotein gp51, gradient-purified fetal Lamb kidney-bovine leukemia virus antigen, and four crude antigens, were used in combina tion with several groups of cattle sera, for the evaluation of electro phoretic immunoblotting as a serological test method. Sera (89) from c attle naturally-infected with bovine leukosis virus, a panel of refere nce sera from infected and uninfected cattle (18), and serial bleeding s from experimentally-infected cows (4) were used. Major differences b etween the six antigen preparations were observed in their reactivity with the various sera. The immunological variabilities of these antige ns were confirmed further by their reactions with a gp51-specific mono clonal antibody. The known immunodominant gp51 failed as a reliable in dicator for the serological status of the sera in blots when compared to the results on the same sera, two gp51-specific ELISAs and the agar gel immunodiffusion test were used as reference tests. There was a la ck of staining of gp51 antigen by many sera, probably due to the labil e nature of the gp51 molecule. On the other hand, non-specific stainin g in the gp51 region appeared with high frequency in some antigens. An tibody staining of the internal viral protein p24 correlated well with the results of the three reference tests. Other bands stained infrequ ently and were of no diagnostic value.