SUMMARY

Four hybridoma cell lines producing monoclonal antibodies (MAbs) to bovine papillomavirus type 1 (BPV-1) L2 open reading frame (ORF) gene products have been established from mice immunized with a BPV-1 L2-fl-galactosidase fusion protein. Hybridomas were selected and cloned (from over 700 hybridomas) on the basis of specific reactivity of supernatant fluids with BPV-1 L2 epitopes on disrupted BPV-1 particles and L2-fl-galactosidase fusion proteins by ELISA and Western blotting, and with acetone-fixed frozen sections of BPV-l-induced fibropapillomas by immuno-fluorescence. These MAbs were not reactive with intact BPV-1 particles or BPV-1 L 1-p-galactosidase fusion proteins by ELISA or with fl-galactosidase by ELISA and Western blotting. The four MAbs detected viral structural proteins of Mr 76K, 68K and possibly 55K in purified BPV-1 preparations by Western blotting. Two of the four MAbs were cross-reactive with BPV-2-induced fibropapillomas. These findings suggest that (i) the BPV-1 L20RF encodes the minor capsid protein(s), (ii) the gene products of the BPV-1 L20RF have Mr values of 76K, 68K and possibly 55K, (iii) minor capsid epitopes are internal to the BPV-1 particle, and (iv) MAbs reactive with genetically engineered truncated BPV-1 L20RF gene products can distinguish between BPV-1 and BPV-2 productive infections