An Epstein-Barr virus that expresses only the first 231 LMP1 amino acids efficiently initiates primary B-lymphocyte growth transformation.
An Epstein-Barr virus (EBV) recombinant (MS231) that expresses the first 231 amino acids (aa) of LMP1 and is truncated 155 aa before the carboxyl terminus transformed resting B lymphocytes into lymphoblastoid cell lines (LCLs) only when the infected cells were grown on fibroblast feeder cells (K. M. Kaye et al., J. Virol. 69:675-683, 1995). Higher-titer MS231 virus has now been compared to wild-type (WT) EBV recombinants for the ability to cause resting primary B-lymphocyte transformation. Unexpectedly, MS231 is as potent as WT EBV recombinants in causing infected B lymphocytes to proliferate in culture for up to 5 weeks. When more than one transforming event is initiated in a microwell, the MS231 recombinant supports efficient long-term LCL outgrowth and fibroblast feeder cells are not required. However, with limited virus input, MS231-infected cells differed in their growth from WT virus-infected cells as early as 6 weeks after infection. In contrast to WT virus-infected cells, most MS231-infected cells could not be grown into long-term LCLs. Thus, the LMP1 amino-terminal 231 aa are sufficient for initial growth transformation but the carboxyl-terminal 155 aa are necessary for efficient long-term outgrowth. Despite the absence of the carboxyl-terminal 155 aa, MS231- and WT-transformed LCLs are similar in latent EBV gene expression, in ICAM-1 and CD23 expression, and in NF-kappaB and c-jun N-terminal kinase activation. MS231 recombinant-infected LCLs, however, require 16- to 64-fold higher cell density than WT-infected LCLs for regrowth after limiting dilution. These data indicate that the LMP1 carboxyl-terminal 155 aa are important for growth at lower cell density and appear to reduce dependence on paracrine growth factors.
Kaye
K M
KM
Department of Medicine, Harvard Medical School, Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. kkaye@rics.bwh.harvard.edu
Izumi
K M
KM
Li
H
H
Johannsen
E
E
Davidson
D
D
Longnecker
R
R
Kieff
E
E
D001402:B-Lymphocytes / Q000821:virology*; D001665:Binding Sites; D002471:Cell Transformation, Neoplastic; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology; D015870:Gene Expression; D005814:Genes, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000502:physiology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010641:Phenotype; D011995:Recombination, Genetic; D014763:Viral Matrix Proteins / Q000235:genetics / Q000502:physiology*; D017735:Virus Latency
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D016328:NF-kappa B; D014763:Viral Matrix Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases