Transplantation of peripheral blood lymphocytes (PBLs) from healthy humans with latent Epstein-Barr virus (
EBV) infection into
severe combined immunodeficiency (SCID) mice results in development of EBV-associated human
B-cell lymphoma. However, the expression of EBV genes in relation to
lymphoma development has not been reported. We investigated latent
membrane protein (LMP) and
EBV nuclear antigen (EBNA) gene expression in PBLs from EBV-positive blood donors and induced-
lymphoma cells from SCID mice to elucidate the functions and effects of the EBV genome in the occurrence and development of
lymphoma. PBLs were isolated from 9 healthy blood donors and transplanted into SCID mice. Gene expression levels of LMP-1, LMP-2A, and LMP-2B and
EBNA-1, EBNA-2, EBNA-3A, EBNA-3B, EBNA-3C and EBNA-LP were monitored by real-time quantitative-polymerase chain reaction (qRT-PCR) in cells from nine EBV-induced
lymphomas and in matched lymphocytes from healthy subjects. LMP-1,
EBNA-1 and EBNA-2
protein levels were detected by western blotting. As a result, LMP-1, LMP-2A and LMP-2B
mRNA levels were upregulated 256-, 38- and 331-fold, respectively, in the EBV-induced
lymphoma cells compared with the controls, while
EBNA-1 and EBNA-3A
mRNA levels were upregulated 1157- and 1154-fold, respectively. EBNA-2, EBNA-3B, EBNA-3C and EBNA-LP mRNAs were detected in
lymphoma cells, but not in lymphocytes from EBV-positive blood donors. LMP-1 and EBNA-2
proteins were not expressed in lymphocytes from EBV-positive blood donors, according to western blotting. Weak
EBNA-1 expression was observed in lymphocytes from blood donors with latent
EBV infection, while LMP-1,
EBNA-1 and EBNA-2
protein levels were significantly upregulated in EBV-induced
lymphoma cells, consistent with
mRNA expression levels detected by qRT-PCR. In conclusion, LMP-1, LMP-2A, LMP-2B,
EBNA-1 and EBNA-3A were upregulated in EBV-induced
lymphoma cells, while EBNA-2, EBNA-3B, EBNA-3C and EBNA-LP were absent in lymphocytes from humans with latent
EBV infection, but were positively expressed in EBV-induced
lymphoma cells.