Early detection of the lytic LMP-1 protein in EBV-infected B-cells suggests its presence in the virion.
The Epstein-Barr virus (EBV)-positive B958 cell line expresses two related membrane proteins encoded by BNLF-1 open reading frames. One protein (LMP-1) has been shown to be essential for the growth transforming properties of EBV. The second protein (the lytic LMP-1) is an amino-terminally truncated form of LMP-1 whose expression is associated with induction of EBV's lytic cycle. We have investigated the expression of full-length and lytic forms of LMP-1 immediately after infection of the EBV-negative, B-lymphoma cell line BJAB. Only the lytic LMP-1 protein is present in BJAB cells early (within minutes following addition of virus) after infection with virus derived from either uninduced or tetradecanoyl phorbol acetate and sodium butyrate-induced B958 cells. Lytic LMP-1 protein levels begin to decline by 48 hr after infection, whereas levels of full-length LMP-1 increase between 24 and 48 hr after infection and then remain constant. The presence of the lytic LMP-1 protein in infected cells is independent of both protein synthesis and virus internalization. We also find the lytic LMP-1 protein in BJAB cells early after infection (within 3 hr of addition of virus) with the HH514 strain of EBV, and HH514 cells treated with tetradecanoyl phorbol acetate and sodium butyrate, express high levels of both the lytic LMP-1 and full-length LMP-1 proteins. The lytic LMP-1 protein is enriched in purified virion preparations, and immunoelectron microscopic analysis indicates that EBV virions can be specifically labeled with anti-LMP-1 antisera. Together, these results are consistent with a model in which the lytic LMP-1 protein is present in the EBV virion and is carried into the B-cell upon infection and suggest a role for this protein in early infection events and/or in EBV's lytic cycle.
Erickson
K D
KD
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309, USA.
Martin
J M
JM
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000821:virology*; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002144:Callithrix; D002460:Cell Line; D002461:Cell Line, Transformed; D003513:Cycloheximide / Q000494:pharmacology; D015870:Gene Expression; D004854:Herpesvirus 4, Human / Q000737:chemistry*; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics; D008934:Mitogens; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014763:Viral Matrix Proteins / Q000032:analysis* / Q000235:genetics; D014771:Virion / Q000737:chemistry
D002087:Butyrates; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D008565:Membrane Proteins; D008934:Mitogens; D011500:Protein Synthesis Inhibitors; D011993:Recombinant Fusion Proteins; D014763:Viral Matrix Proteins; D020148:Butyric Acid; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate