Fatemeh Saadatpour - Molecular virology laboratory, School of Biology, College of Science, University of Tehran
Ehsan Arefian - Molecular virology laboratory, School of Biology, College of Science, University of Tehran
Fatemeh Mohammadipanah - Pharmaceutical Biotechnology Laboratory, School of Biology, College of Science, University of Tehran

Several investigations confirmed that chlorhexidine gluconat (CHG) has an antiviral activity against intraoral herpes simplex virus (HSV) infection (Brookes et al., ۲۰۲۰). The purpose of this work was to assess the in vitro antiviral effectiveness of CHG against type ۱ HSV infection at the less concentrations regularly used in mouth rinse formula to recommend a nontoxic concentration for higher frequent usage during the pandemic. The cytotoxic effects of CHG concentrations at ۰.۰۰۱% to ۰.۱۲% was evaluated by MTT assay using ISO ۱۰۹۹۳-۵ (Iso & STANDARD, ۲۰۰۹). In vitro antiviral activity of CHG was performed according to the DIN EN ۱۴۴۷۶(DIN, ۲۰۱۱). For this purpose, the concentrations of ۰.۰۰۲%, ۰.۰۱۶% and ۰.۱۲% was examined on Vero cells infected by HSV-۱ at the times of ۳۰sec, ۱, ۲ and ۳ min. CHG exhibits a dose-dependent toxicity effect for the cell tested and the viability of cells decreased to ۵۰ % (IC۵۰) at the concentration of ۰.۰۳۲%. The antiviral potency of CHG can be affected by both concentration and time factors. None of the CHG concentrations inhibited the HSV-۱ cytopathic effect (CPE) in less than ۳ min. But at concentration of ۰.۱۲%, CHG inhibited the CPE of HSV-۱ up to ۴ Log۱۰ reduction in viral titter in comparison with untreated infected cells with ۱۰۸ TCID۵۰/ml viral load. According to in vitro studies, mouthwashes containing ≥۰.۲% CHG may be beneficial for the control of intraoral HSV-۱ infection (Steinsapir & Woodward, ۲۰۱۷). These concentrations may causes different clinical symptoms because of high toxicity effect .It seems that reducing of the CHG concentration to ۰.۱۲% along with increasing the exposure time, in addition to preventing destructive effects, can also be effective in the viruses deactivation. Moreover, the range of nontoxic effective dose obtained in this study on HSV-۱ can be selected in evaluation of CHG effect on SARS-CoV-۲ as an enveloped virus.

Mouthwash, Cell Toxicity, HSV-۱, Antiviral Effect