Epstein-Barr Virus Latent Gene Expression during the Initiation of B Cell Immortalization

• Published in: Journal of general virology Vol. 70; no. 7; pp. 1755 - 1764
• Main Authors: Allday, M. J, Crawford, D. H, Griffin, B. E
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.07.1989; Society for General Microbiology
• Subjects: Animals; Antigens, Viral - analysis; B-Lymphocytes - analysis; B-Lymphocytes - microbiology; B-Lymphocytes - pathology; Biological and medical sciences; Cell Line, Transformed; Cell Transformation, Viral; Epstein-Barr Virus Nuclear Antigens; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genes, Viral; Herpesvirus 4, Human - analysis; Herpesvirus 4, Human - genetics; Herpesvirus 4, Human - immunology; Humans; Leukemia, Prolymphocytic - metabolism; Leukemia, Prolymphocytic - microbiology; Leukemia, Prolymphocytic - pathology; Mice; Microbiology; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Viral Matrix Proteins; Virology; Gammaherpesvirinae; Herpesviridae; Virus replication cycle; B-Lymphocyte; Epstein Barr virus; Indirect immunofluorescence; Gene expression; Latency; Strain; Virus; Gene; Temporal study; Immunoblotting assay; Infected cell
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-70-7-1755

Department of Virology, Royal Postgraduate Medical School, Du Cane Road, London W12 0NN, U.K. Epstein-Barr virus (EBV) has the capacity to immortalize a subpopulation of resting B lymphocytes. Lymphoblastoid cell lines (LCL) established in this way carry the latent EBV genome as multiple copies of an extrachromasomal episome. Viral gene expression in LCLs is highly restricted; products identified correspond to a membrane protein (latent membrane protein; LMP), a nuclear antigen complex (Epstein-Barr nuclear antigens; EBNAs 1 to 6), two small RNA species (EBERs 1 and 2) and RNA species thought to encode a second membrane-associated polypeptide designated terminal protein (TP). Here we have investigated the temporal sequence of expression of the characterized ‘latent’ proteins during the initiation of immortalization when resting B cells are stimulated to enter and traverse the cell cycle. The analysis has been carried out on prolymphocytic leukaemia cells infected in vitro with either the immortalizing B95-8 strain of virus or the non-immortalizing P3HR1 strain. The results reveal that following B95-8 infection, a sequence of EBV expression is initiated within approximately 8 h with the synthesis of detectable levels of EBNA 2 shortly followed by EBNAs 1, 3, 4, 5 and 6. There is then a delay of approximately 40 h until the expression of LMP completes the latent pattern of proteins found in LCLs. P3HR1 infection, however, produces only transient expression of some EBNA species in a small percentage of cells after approximately 48 h. These observations suggest the failure of P3HR1 virus to immortalize may not be due solely to the absence of EBNA 2 expression and that cellular and/or virus-mediated events occur after EBNA synthesis which then facilitate efficient LMP expression and immortalization. Keywords: EBV, latent gene expression, immortalization Received 11 November 1988; accepted 3 March 1989.