Transformation of rodent fibroblasts by herpes simplex virus: Presence of morphological transforming region 1 (MTR 1) is not required for the maintenance of the transformed state

Abstract

Studies on the mechanisms of transformation of mammalian cells by herpes simplex virus (HSV) in vitro have been prevented so far by the extremely low transformation frequencies obtained in monolayer culture. Here we present a transformation system that relies on the direct seeding in soft agar of infected single cells, thus avoiding negative interactions between normal and transformed cells. We took advantage of HSV-I temperature-sensitive mutants at the UL9 locus, which codes for a DNA-binding protein necessary for viral DNA replication. At the non-permissive temperature, viral DNA synthesis and late gene expression are prevented. Viral gene expression is restricted to immediate early and early genes. Induction of transformation was highly efficient in our one-step transformation system. It depended on intact viral particles and viral DNA. Immediate early and/or early viral gene expression was sufficient to induce transformation. Colonies were stably transformed and did not show any rescue of viable virus after temperature downshift and co-cultivation with susceptible cells. Transformed cells maintained the transformed state in the absence of viral DNA. Our data therefore support the "hit-and-run" hypothesis for the transforming effect of HSV.

Basic research on herpes simplex viruses: are mutants still needed?

“…tsO /ts lesion in 99 kD component (UL5) of the heterotrimeric helicase-primase complex /isolated by R. Thompson, D. Dargan and J. H. Subak-Sharpe, Glasgow/ts lesion identified [ 4 ]/protein data [ 2 ]/used in research projects: Complementation analyses [ 4 ]; Requirement of HSV genes essential for viral DNA synthesis [ 20 ]; Interaction of herpesviral and polyomaviral DNA replication factors [ 21 ]; Initiation and mode of herpesviral DNA replication [ 6 , 12 ]. tsR /ts lesion in origin-binding protein (UL9) /isolated by R. Thompson, D. Dargan and J. H. Subak-Sharpe, Glasgow/ts lesion identified [ 4 , 13 ]/protein data [ 2 , 22 , 23 ]/used in research projects: Complementation analyses [ 4 ]; Requirement of HSV genes essential for viral DNA synthesis [ 20 ]; Initiation and mode of herpesviral DNA replication [ 6 , 12 , 13 , 23 ]; HSV-induced morphological transformation of host cells [ 24 ]. tsS /ts lesion in origin-binding protein (UL9) /isolated by I. Crombie, Glasgow /ts lesion identified [ 1 , 4 , 13 ]/protein data [ 2 , 22 , 23 ]/used in research projects: Complementation analyses [ 4 ]; Initiation and mode of herpesviral DNA replication [ 6 , 12 , 13 , 23 , 25 ]; HSV-induced morphological transformation of host cells [ 24 ]; HSV-induced amplification of heterologous (i.e.…”

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

“…Transformačná oblasť HSV-1 (mtr-1) sa nachádza v ľavej tretine genómu, zatiaľ čo tie isté funkcie HSV-2 sú rozdelené na mtr-2 a mtr-3 a nachádzajú sa približne v strede genómu [64][65][66][67]. Hypotézu "hit and run" by mohol potvrdzovať aj fakt, že tieto úseky nie sú potrebné na udržia-vanie transformovaného fenotypu, podieľajú sa pravdepodobne len na iniciá-cii transformácie [68,69].…”

Failure of Lamivudine to Reverse Hepatitis B Virus-Associated Changes in ERK, Akt and Cell Cycle Regulatory Proteins

“…Even after a brief exposure to chemical hepatocarcinogens, preneoplstic lesions will undergo malignant transformation into HCC even in the absence of continued oncogenic stimuli [36,[39][40][41][42]. It has also been proposed that malignant transformation induced by viruses may involve a 'hit-and-run' phenomenon, whereby exposure to viral genes and/or products are sufficient to initiate malignant transformation, but persistence of the malignant phenotype will occur despite the absence of continued expression of viral genes or viral replication [44,45]. The frequent absence of HBx protein and hepadnaviral DNA from HCC tumour and peri-tumour tissue [46,47] suggests a similar mechanism may also exist for HBV-associated hepatocarcinogenesis.…”