Human alpha and beta herpesviruses and cancer: passengers or foes?

Based on seroepidemiological studies, human herpes simplex virus types 1 and 2 (HSV-1, HSV-2) are put in relation with a number of cancer diseases; however, they do not appear to play a direct role, being only considered cofactors. Their ability to transform the cells in vitro could be demonstrated experimentally by removing their high lytic ability by a certain dose of UV radiation or by photoinactivation in the presence of photosensitizers, such as neutral red or methylene blue, or culturing under conditions suppressing their lytic activity. However, recent studies indicate that UV irradiated or photoinactivated HSV-1 and HSV-2, able to transform non-transformed cells, behave differently in transformed cells suppressing their transformed phenotype.

A Possible Role of Human Herpes Viruses Belonging to the Subfamily Alphaherpesvirinae in the Development of Some Cancers.

Seroepidemiological studies suggest that human herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) are linked with several types of cancer; however, they do not appear to play a direct role and are considered to be cofactors. The abilities of HSV-1 and -2 to transform cells in vitro can be demonstrated by suppressing their lytic ability via irradiation with a specific dose of ultraviolet light, photoinactivation in the presence of photosensitizers (e.g.

Transformation of Cells by Photoinactivated Murine Gamma-Herpesvirus 68 during Nonproductive and Quiescent Infection.

Infection of human MRC-5 cells and mouse NIH-3T3 cells with a murine gamma-herpesvirus (MuHV-4 strain 68; MHV-68) photoinactivated by visible light in the presence of methylene blue (MB) resulted in nonproductive infection and the appearance of morphologically transformed cells. Two stably transformed cell lines were derived from both of these cell types and were confirmed to contain both viral DNA and antigen. Next, a quiescent MHV-68 infection in MRC-5 and NIH-3T3 cells was established after cultivation at 41°C in the presence of phosphonoacetic acid.

Murine gammaherpesvirus (MHV-68) transforms cultured cells in vitro.

Human dermal fibroblasts and mouse NIH/3T3 cells acquired the transformed phenotype ('criss-cross' pattern of growth) after infection with ultraviolet-irradiated murine gammaherpesvirus (MuHV-4 strain 68; MHV-68). These cells with changed phenotype could be serially cultured for 5-6 passages (35-40 days), and then they entered into crisis and most of them died. In a small number of cultures, however, foci of newly transformed cells appeared from which two stable cell lines were derived.