The combined effects of irradiation and herpes simplex virus type 1 infection on an immortal gingival cell line

Virol J. 2014 Jul 8:11:125. doi: 10.1186/1743-422X-11-125.

Abstract

Background: Oral mucosa is frequently exposed to Herpes simplex virus type 1 (HSV-1) infection and irradiation due to dental radiography. During radiotherapy for oral cancer, the surrounding clinically normal tissues are also irradiated. This prompted us to study the effects of HSV-1 infection and irradiation on viability and apoptosis of oral epithelial cells.

Methods: Immortal gingival keratinocyte (HMK) cells were infected with HSV-1 at a low multiplicity of infection (MOI) and irradiated with 2 Gy 24 hours post infection. The cells were then harvested at 24, 72 and 144 hours post irradiation for viability assays and qRT-PCR analyses for the apoptosis-related genes caspases 3, 8, and 9, bcl-2, NFκB1, and viral gene VP16. Mann-Whitney U-test was used for statistical calculations.

Results: Irradiation improved the cell viability at 144 hours post irradiation (P = 0.05), which was further improved by HSV-1 infection at MOI of 0.00001 (P = 0.05). Simultaneously, the combined effects of infection at MOI of 0.0001 and irradiation resulted in upregulation in NFκB1 (P = 0.05). The combined effects of irradiation and HSV infection also significantly downregulated the expression of caspases 3, 8, and 9 at 144 hours (P = 0.05) whereas caspase 3 and 8 significantly upregulated in non-irradiated, HSV-infected cells as compared to uninfected controls (P = 0.05). Infection with 0.0001 MOI downregulated bcl-2 in non-irradiated cells but was upregulated by 27% after irradiation when compared to non-irradiated infected cells (P = 0.05). Irradiation had no effect on HSV-1 shedding or HSV gene expression at 144 hours.

Conclusions: HSV-1 infection may improve the viability of immortal cells after irradiation. The effect might be related to inhibition of apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics
  • Caspases / genetics
  • Cell Line, Transformed
  • Cell Survival / radiation effects
  • Gingiva / cytology
  • Gingiva / radiation effects*
  • Gingiva / virology*
  • Herpes Simplex / virology
  • Herpes Simplex Virus Protein Vmw65 / genetics
  • Herpesvirus 1, Human / physiology*
  • Humans
  • Keratinocytes / radiation effects
  • Keratinocytes / virology
  • Mouth Mucosa / cytology
  • Mouth Mucosa / radiation effects*
  • Mouth Mucosa / virology*
  • Mouth Neoplasms / radiotherapy
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Radiography, Dental / adverse effects
  • Radiotherapy / adverse effects
  • Virus Replication
  • Virus Shedding

Substances

  • Herpes Simplex Virus Protein Vmw65
  • Proto-Oncogene Proteins c-bcl-2
  • Caspases