THE TRANSCRIPTIONAL REGULATORY PROTEINS ENCODED BY VARICELLA-ZOSTER VIRUS OPEN READING FRAMES (ORFS) 4 AND 63, BUT NOT ORF-61, ARE ASSOCIATED WITH PURIFIED VIRUS-PARTICLES

Of the five varicella-zoster virus (VZV) open reading frames (ORFs) kn own to encode proteins which influence viral transcriptional events, t wo (ORFs 10 and 62) encode proteins associated with the tegument of vi rus particles, where they may function during the immediate-early even ts of infection. In this study, antibodies which recognize the product s of the three additional VZV ORFs, ORFs 4, 61, and 63, were made and used to characterize their association with virus particles. ORF 4 enc oded a 52-kDa polypeptide, and antibodies to ORF 63 reacted with polyp eptides of 47 and 28 kDa. Antibodies to ORF 61 recognized heterogeneou s polypeptides of 62 to 66 kDa in cells infected with a vaccinia virus recombinant expressing ORF 61 and in VZV-infected melanoma cells but reacted very weakly with polypeptides of VZV-infected human foreskin f ibroblasts, suggesting that cell-specific factors were involved in ORF 61 protein accumulation. Analysis of virus particles purified from me lanoma cells indicated that a 52-kDa polypeptide from ORF 4 and the 47 -kDa polypeptide from ORF 63, but not any from ORF 61, were associated with virus particles. The virion proteins were likely components of t he tegument, as they were not solubilized by treatment of virus with m ild detergents and were completely resistant to trypsin digestion unle ss prior envelope solubilization was performed. The products of ORFs 4 and 63 were not found in purified VZV nucleocapsids. These results su ggest that forms of the ORF 4- and ORF 63-encoded transcriptional regu latory proteins are also structural and may also have roles in the imm ediate-early events of infection.