Differential effects of antiseptic mouth rinses on SARS-CoV-2 infectivity in vitro

SARS-CoV-2 is detectable in saliva from asymptomatic individuals, suggesting the potential necessity for the use of mouth rinses to suppress viral load to reduce virus spread. Published studies on anti-SARS-CoV-2 activities of antiseptics determined by virus-induced cytotoxic effects cannot exclude antiseptic-associated cytotoxicity. Here, we determined the effect of commercially available mouth rinses and antiseptic povidone-iodine on the infectivity of pseudotyped SARS-CoV-2 virus. We first determined the effect of mouth rinses on cell viability to ensure that antiviral activity was not a consequence of mouth rinse-induced cytotoxicity. Colgate Peroxyl (hydrogen peroxide) exhibited the most cytotoxicity, followed by povidone-iodine-10% solution, chlorhexidine gluconate-0.12% (CHG), and Listerine (essential oils and alcohol). Analysis of the anti-viral activity of mouth rinses at non-cytotoxic concentrations showed that 1.5% (v/v) diluted CHG was a potent inhibitor when present in cells during infection, but the potency was reduced when CHG was removed after viral attachment, suggesting that the prolonged effect of mouth rinses on cells impacts the anti-viral activity. To minimalize mouth rinse-associated cytotoxicity, we pelleted treated-viruses to remove most of the mouth rinse prior to infection of cells. Colgate Peroxyl or povidone-iodine at 5% (v/v) completely blocked the viral infectivity. Listerine or CHG at 5% (v/v) had a moderate suppressive effect on the virus, and 50% (v/v) Listerine or CHG blocked the viral infectivity completely. Prolonged incubation of virus with mouth rinses was not required to block viral infectivity. Our results indicate that mouth rinses can significantly reduce virus infectivity, suggesting their potential use to reduce SARS-CoV-2 spread.