Induction of Oxidative DNA Damage in Bovine Herpesvirus 1 Infected Bovine Kidney Cells (MDBK Cells) and Human Tumor Cells (A549 Cells and U2OS Cells).

Liqian Zhu,Xiaotian Fu,Gaiping Zhang,Xinyi Jiang,Chen Yuan

doi:10.3390/v10080393

Abstract

Bovine herpesvirus 1 (BoHV-1) is an important pathogen of cattle that causes lesions in mucosal surfaces, genital tracts and nervous systems. As a novel oncolytic virus, BoHV-1 infects and kills numerous human tumor cells. However, the mechanisms underlying the virus-induced cell damages are not fully understood. In this study, we demonstrated that virus infection of MDBK cells induced high levels of DNA damage, because the percentage of comet tail DNA (tailDNA%) determined by comet assay, a direct indicator of DNA damage, and the levels of 8-hydroxyguanine (8-oxoG) production, an oxidative DNA damage marker, consistently increased following the virus infection. The expression of 8-oxoguanine DNA glycosylase (OGG-1), an enzyme responsible for the excision of 8-oxoG, was significantly decreased due to the virus infection, which corroborated with the finding that BoHV-1 infection stimulated 8-oxoG production. Furthermore, the virus replication in human tumor cells such as in A549 cells and U2OS cells also induced DNA damage. Chemical inhibition of reactive oxidative species (ROS) production by either ROS scavenger N-Acetyl-l-cysteine or NOX inhibitor diphenylene iodonium (DPI) significantly decreased the levels of tailDNA%, suggesting the involvement of ROS in the virus induced DNA lesions. Collectively, these results indicated that BoHV-1 infection of these cells elicits oxidative DNA damages, providing a perspective in understanding the mechanisms by which the virus induces cell death in both native host cells and human tumor cells.

Highlights

Bovine herpesvirus-1 (BoHV-1) is a large enveloped double stranded DNA virus
Initial studies examined the effects of BoHV-1 productive infection on DNA damage in MDBK cells using comet assay
Trypan-blue exclusion test indicated that neither diphenylene iodonium (DPI) (5 μM) nor NAC (20 mM) had obvious cytotoxicity to MDBK cells (Figure 2G), and they could efficiently rescue the virus infection-induced cell death, with cell viability increasing by approximately 15% (Figure 2H), which corroborated with our previous results that either DPI or NAC could significantly reduce virus productive infection [35]

Summary

Introduction

Bovine herpesvirus-1 (BoHV-1) is a large enveloped double stranded DNA virus. Together with herpes simplex 1 and 2 (HSV-1, HSV-2) and varicella zoster virus (VZV), BoHV-1 belongs to the family Herpesviridae and the subfamily Alphaherpesvirinae [1,2]. BoHV-1 is a widespread cattle pathogen causing severe respiratory infection, conjunctivitis, vaginitis, balanoposthitis, abortion, and encephalitis [2,3]. Acute virus infection causes lesions on mucosal surfaces, corpus luteum, and the nervous system followed by the establishment of life-long latency primarily in trigeminal ganglia [3,4]. Due to immune suppression and mucosal lesions by the virus infection, secondary infection by diverse bacteria tends to occur, and causes bovine respiratory disease complex (BRDC), the costliest disease for cattle [1,5]. In view of the fact that the virus induced lesions in the respiratory tract, productive tract and nerve system are associated with diseases outcome, a better understanding of the molecular basis of virus-induced cell damage would be helpful to learn its pathogenesis

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Conclusion