Table 2.

Selected pro-oncogenic properties of HCMV, HSV and HHV-6

	HCMV	HHV-6	HSV-1 and -2
Detection in the tumors	Brain tumors, breast cancer, colon cancer, cervix cancer, prostate carcinoma, EBV-negative Hodgkin’s lymphoma	Brain tumors, lymphomas and leukemias, cervical cancer	Malignant and benign thyroid tumors
Cellular entry receptor	PDGFR alpha	CD46	Nectin-1 and-2, HSV entry mediator A
Distribution of cellular entry receptors	Various cell types including astrocytes and neural stem/progenitor cells,	Various cell types including astrocytes and neural stem/progenitor cells	Various cell types including neurons, ependymal cells, oligodendrocytes, astrocytes. Neural stem/progenitor cells (?)
Expression of the cellular entry receptors in gliomas	Yes	Yes	Yesa
Influence on cell cycle progression	Differs between the transformed and primary cells, probably depends on P53 status	(?)	(?)
Pro- and anti-apoptotic activity	Anti-apoptotic effect. Pro-apoptotic effect related to blocking cell cycle progression (?)	(?)	Differs between the cancer cells and normal cells. Pro- apoptotic in the lytic, and anti-apoptotic in the latent phase
Cellular senescence	Upregulation of telomerase	Integration into telomeres. Elongation of telomeres (?)	Upregulation of telomerase
Cellular differentiation	Inhibition of cell differentiation, reactivation in differentiated cells (?)	(?)	(?)
Transactivation in the absence of wild type p53	Yes	(?)	Yes
DNA-damage	Yes	(?)	(?)
Mutagenesis of cellular genomic DNA	Yes (?)	(?)	(?)
Dependence on histone deacetilase inhibition	Yes	Yes	Yes
Immunomodulation	Yes	Yes	Yes
Cell migration, invasion, angiogenesis	Enhancement	(?)	(?)

^aAuthor’s data (unpublished)