CHARACTERIZATION OF THE EPSTEIN-BARR-VIRUS PROTEINASE AND COMPARISON WITH THE HUMAN CYTOMEGALOVIRUS PROTEINASE

The BVRF2 gene of Epstein-Barr virus (EBV) shows homology to the UL26 and UL80 genes of herpes simplex virus type 1 (HSV-1) and cytomegalovi rus (CMV), respectively. These genes are believed to provide a scaffol d protein for the assembly of capsids leading to the formation of infe ctious viral particles. We have cloned the BVRF2 gene from the B95.8 s train of EBV and shown that the BVRF2 gene product is a polyprotein ca pable of autoproteolytic cleavage. Two Ala-Ser-containing recognition sequences wee identified in the BVRF2, polyprotein at amino acid posit ions 568/569 and 570/571 where this cleavage was expected to occur. He re, we show that EBV proteinase is capable of cleaving at the first Al a-Ser bond but not the second. Comparison of the processing of the EBV and human CMV assembly domains in vitro by either EBV or human CMV pr oteinase revealed that, while both proteinases could cleave their nati ve assembly domain, only EBV proteinase was able to cleave the assembl y domain of the other virus.