Six
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 combination with several groups of cattle sera, for the evaluation of electrophoretic immunoblotting as a serological test method. Sera (89) from cattle naturally-infected with
bovine leukosis virus, a panel of reference sera from infected and uninfected cattle (18), and serial bleedings from experimentally-infected cows (4) were used. Major differences between the six
antigen preparations were observed in their reactivity with the various sera. The immunological variabilities of these
antigens were confirmed further by their reactions with a gp51-specific
monoclonal antibody. The known immunodominant gp51 failed as a reliable
indicator 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 lack of staining of gp51
antigen by many sera, probably due to the labile nature of the gp51 molecule. On the other hand, non-specific staining in the gp51 region appeared with high frequency in some
antigens. Antibody staining of the internal
viral protein p24 correlated well with the results of the three reference tests. Other bands stained infrequently and were of no diagnostic value.