Identification and characterization of the BPV-2 L2 protein

The bovine papilloma virus type 2 (BPV-2) L2 open reading frame was cloned into a λ pL promoter expression vector. This plasmid was shown to express a fusion protein which constituted 75% of the BPV-2 L2 ORF linked to the first 13 N-terminal amino acids of the λ cll gene product. Antisera generated against this fusion protein were used to identify the L2 gene product as a 64,000-Da protein in BPV-2 virions. Western blot analysis demonstrated that the L2 viral protein was present in full capsids and in small amounts in empty capsids. Densitometer analysis indicated that the L2 protein constituted only 8% of the total l1 + L2 protein content of full capsids. Antisera was also used to demonstrate that the BPV-2 L2 protein is antigenically related to the BPV-1 L2 protein.