| Research Abstract |
EBV encodes seven viral genes that are essential for the oriLyt-dependent DNA replication. The BZLF1 protein is an oriLyt-binding protein and acts also the lytic transactivator. The BALF5 gene encodes the DNA Pol catalytic subunit and the BMRF1 gene encodes the DNA Pol accessory subunit. A single-stranded DNA-binding protein is encoded by the BALF2 gene . The functions of the remaining three proteins encoded by the genes BBLF4 , BSLFI, and BBLF2/3 are not demonstrated but predicted to be helicase, primase, and helicase-primase associated proteins, respectively. We have constructed recombinant baculoviruses which express the products of each of these three genes in infected insect cells. Insect cells infected with the recombinant baculovirus, AcBBLF4, AcBSLF1, or AcBBLF2/3, produced each protein of 90, 89, or 76 k, respectively. These products were identified as BBLF4, BSLF1, and BBLF2/3 gene products in Western blots using anti- each of the protein-specific antibodies. The anti-BSLF1 protein-specific antibody could immunoprecipitate the BSLF1 protein, but did not react directly with BBLF4 or BBLF2/3 protein. The antibody precipitated the BSLF1, BBLF4, and BBLF2/3 proteins from the extracts of the insect cells triply infected with these recombinant baculoviruses. In addition, experiments performed by using the extracts from doubly infected cells indicated that the BSLF1 protein interacts separately with each of the BBLF4 and BBLF2/3 proteins. Furthermore, both of the BBLF4 and BSLF1 proteins were purified via the histidine-tagged BBLF2/3 protein through the column of metal affinity resine. These results indicate that the EBV BBLF4, BSLF1, and BBLF2/3 proteins form a tripartite complex at least via BSLF1 protein.
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