Expression of MHV-68 genes in tumor S11E cell line under hypoxic conditions

Introduction

S11E cell line was derived from lymphoma of BALB/c mouse infected with oncogenic murine gammaherpesvirus 68 (MHV-68) for > 1 year. MHV-68 behaved similarly as human gammaherpesviruses (KSHV and EBV) during a latent infection when host B lymphocytes contain its genome in both linear and episomal form and release infectious virus. Changes in physiological factors have been shown to affect expression of viral genes. For many viruses, differences in oxygen tension between hypoxia and normoxia alter viral genes expression or their function. We used S11E cell line shown to be latently infected with MHV-68 to study viral genes expression during virus reactivation induced by hypoxia.

Materials/methods

To examine whether hypoxia influences the expression of MHV-68 genes, S11E cells were cultured under hypoxic or normoxic conditions for 3-48 hours. mRNA levels of selected viral genes were measured by qRT-PCR. Samples of cell suspensions were taken at six time intervals to determine growth activity, viability and titer of MHV-68.

Results and conclusions

We demonstrated that the exposure of S11E cells to hypoxia changed the expression of three MHV-68 genes playing an important role during latency (ORF73, M3), reactivation (ORF50), but also elevate expression of gene encoding small capsid protein (ORF65). We confirmed that the hypoxia enhanced/induced the expression of some genes but also virus replication and the amount of virus released from tumor cells. Data suggest that S11E cell line might represent a suitable animal model to study mechanisms of oncogenesis related gammaherpesviruses.

Acknowledgment

This research was supported by the Slovak Research and Development Agency (#APVV- 0621-12) and by the joint grant agency of the Slovak Ministry of Education and the Slovak Academy of Sciences VEGA (#2/0091/13). We thank Prof. J.P. Stewart PhD. for S11 cells.