Differential Effects of Antiseptic Mouth Rinses on SARS-CoV-2 Infectivity In Vitro

Abstract

Severe acute respiratory syndrome-related coronavirus (SARS-CoV-2) is detectable in saliva from asymptomatic individuals, suggesting a potential benefit from the use of mouth rinses to suppress viral load and reduce virus spread. Published studies on the reduction of SARS-CoV-2-induced cytotoxic effects by mouth rinses do not exclude antiseptic mouth rinse-associated cytotoxicity. Here, we determined the effect of commercially available mouth rinses and antiseptic povidone-iodine on the infectivity of replication-competent SARS-CoV-2 viruses and of pseudotyped SARS-CoV-2 viruses. 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, chlorhexidine gluconate (CHG), and Listerine (essential oils and alcohol). The potent antiviral activities of Colgate Peroxyl mouth rinse and povidone-iodine were the consequence of rinse-mediated cellular damage when the products were present during infection. The potency of CHG was greater when the product was not washed off after virus attachment, suggesting that the prolonged effect of mouth rinses on cells impacts the antiviral outcome. To minimalize mouth rinse-associated cytotoxicity, mouth rinse was largely removed from treated viruses by centrifugation prior to infection of cells. A 5% (v/v) dilution of Colgate Peroxyl or povidone-iodine completely blocked viral infectivity. A similar 5% (v/v) dilution of Listerine or CHG had a moderate suppressive effect on the virus, but a 50% (v/v) dilution of Listerine or CHG blocked viral infectivity completely. Mouth rinses inactivated the virus without prolonged incubation. The new infectivity assay, with limited impacts of mouth rinse-associated cytotoxicity, showed the differential effects of mouth rinses on SARS-CoV-2 infection. Our results indicate that mouth rinses can significantly reduce virus infectivity, suggesting a potential benefit for reducing SARS-CoV-2 spread.

Human Defensins Inhibit SARS-CoV-2 Infection by Blocking Viral Entry

“…Experiments were performed in a biosafety level 3 laboratory with personal protection equipment including powered air-purifying respirators (Breathe Easy, 3M), Tyvek suits, aprons, sleeves, booties and double gloves. Virus titers were determined by plaque assays in Vero E6 cells as described previously [ 32 ]. For the infection assay, Vero E6 cells at 1.5 × 10 4 cells/well in a black 96-well glass plate (Greiner, Monroe, NC, USA) were incubated overnight.…”

Virucidal efficacy of chlorhexidine: a systematic review

“…All in vitro studies presented an unclear risk of bias for randomization, allocation concealment, and blinding of the evaluators (Fig. 2 ) [ 23 – 38 , 40 , 44 – 47 ]. Based on RoB 2 assessment, overall low risk of bias was detected in two studies [ 41 , 42 ].…”

“…Eleven included studies verified the antiviral efficacy of CHX on SARS-CoV-2 strains, of which seven were in vitro studies [ 37 , 38 , 40 , 44 – 47 ], and four were RCT [ 39 – 42 ]. One study [ 37 ] verified the viral infectivity of SARS-CoV-2 after contact with two different products based on 0.02% CHX (Chlorhexamed Forte ® and Dynexidine Forte ® ).…”

Human Immunodeficiency Viruses Pseudotyped with SARS-CoV-2 Spike Proteins Infect a Broad Spectrum of Human Cell Lines through Multiple Entry Mechanisms

“…All experiments were performed in a biosafety level 3 laboratory with personal protection equipment, including powered air purifying respirators (Breathe Easy, 3M), Tyvek suits, aprons, sleeves, booties, and double gloves. Virus titers were determined by plaque assays in Vero E6 cells as described previously [ 19 ]. For the infection assay, Vero E6 cells at 1 × 10 4 cells per well were incubated overnight in a black 96-well glass plate (Greiner).…”