Pathogenesis of Epstein-Barr virus (EBV)-carrying lymphomas.

The EBV carrier state is almost general in men. The virus induces B lymphocyte proliferation in vitro, but this is counteracted in vivo by the immune response. Therefore, EBV-induced malignancies occur only when the immune response is impaired, e.g. in transplant recipients. The versatility of the viral gene expression strategy secures the consistent maintainance of the virus in healthy individuals. The viral proteins required for transformation render the cell immunogenic. Expression of the transforming genes leads to rejection, but these genes are not required for the maintenance of the viral genome. EBV is an important contributor for malignant transformation, even when it does not directly induce cell proliferation. Several mechanisms have been unravelled in EBV-associated tumors whereby the virus may modify the cellular phenotype and may influence the interaction of tumor cells with their microenvironment. The virus carrier state can lead to the evasion of apoptosis and can intensify the response to growth promoting signals, too.