Hypochlorous acid solution is a potent antiviral agent against SARS-CoV-2

Abstract

Aim: A novel coronavirus, termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suddenly appeared in Wuhan, China, and has caused pandemic. In this study, we evaluated antiviral activity of purified hypochlorous acid (HClO) against coronaviruses such as SARS-CoV-2 and transmissible gastroenteritis virus (TGEV) responsible for pig diseases.

Materials and results: In a suspension test, 28.1 ppm HClO solution inactivated SARS-CoV-2 in phosphate-buffered saline with the reduction of 10⁴ of 50% tissue culture infectious dose per ml (TCID₅₀ per ml) within 10 s. When its concentration increased to 59.4 ppm, the virus titre decreased to below the detection limit (reduction of 5 logs TCID₅₀ ) within 10 s even in the presence of 0.1% foetal bovine serum. In a carrier test, incubation with 125 ppm HClO solution for 10 min or 250 ppm for 5 min inactivated SARS-CoV-2 by more than 4 logs TCID₅₀ per ml or below the detection limit. Because the titre of TGEV was 10-fold higher, TGEV was used for SARS-CoV-2 in a suspension test. As expected, 56.3 ppm HClO solution inactivated TGEV by 6 logs TCID₅₀ within 30 s.

Conclusions: In a carrier test, 125 ppm HClO solution for 10 min incubation is adequate to inactivate 4 logs TCID₅₀ per ml of SARS-CoV-2 or more while in a suspension test 56.3 ppm HClO is adequate to inactivate 5 logs TCID₅₀ per ml of SARS-CoV-2 when incubated for only 10 s regardless of presence or absence of organic matter.

Significance and impact of the study: Effectiveness of HClO solution against SARS-CoV-2 was demonstrated by both suspension and carrier tests. HClO solution inactivated SARS-CoV-2 by 5 logs TCID₅₀ within 10 s. HClO solution has several advantages such as none toxicity, none irritation to skin and none flammable. Thus, HClO solution can be used as a disinfectant for SARS-CoV-2.

Keywords: COVID-19; SARS-CoV-2; TGEV; antiviral activity; hypochlorous acid.

FIGURE 1

Antiviral activity of hypochlorous acid (HClO) against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). Concentrated SARS‐CoV‐2 by polyethylene glycol was treated with (a) 56.3, 113 or 225 ppm of HClO for 0.5 (), 1 (), 3 () or 5 () min, and (b) 11.3 (), 28.1 (), 56.3 () or 113 () ppm of HClO for 10 s followed by determination of virus titer with 50% tissue culture infective dose. All data represent the mean + SD from three independent experiments. Dot line indicates detection limit for experiment. * indicates that values are significantly different between phosphate‐buffered saline (PBS) and each experimental condition

FIGURE 2

Antiviral activity of various concentrations of hypochlorous acid (HClO) against transmissible gastroenteritis virus (TGEV). Concentrated TGEV by polyethylene glycol was treated with 56.3, 113 or 225 ppm of HClO for 0.5 (), 1 (), 3 () or 5 () min followed by determination of virus titer with 50% tissue culture infective dose. All data represent the means + SD from three independent experiments. Dot line indicates detection limit for experiment. * indicates that values are significantly different between phosphate‐buffered saline (PBS) and each experimental condition

FIGURE 3

Antiviral activity of various concentrations of hypochlorous acid (HClO) against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in the presence of 0.1% FBS. SARS‐CoV‐2 cultured in DMEM supplemented with 2% FBS was treated with 29.7, 59.4, 119 or 238 ppm of HClO for 10 (), 30 () s, 1 () or 3 () min followed by determination of virus titer with 50% tissue culture infective dose. All data represent the means + SD from three independent experiments. Dot line indicates detection limit for experiment. * indicates that values are significantly different between phosphate‐buffered saline (PBS) and each experimental condition

FIGURE 4

Antiviral activity of various concentrations of hypochlorous acid (HClO) against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in carrier test. 10 µl of concentrated SARS‐CoV‐2 was spotted on slide glass and dried. Then, 50 µl of 62.5, 125 or 250 ppm HClO was dropped on the slide glass and kept for 30 (), 60 () s, 5 () or 10 () min followed by determination of virus titer with 50% tissue culture infective dose. All data represent the means + SD from three independent experiments. Dot line indicates detection limit for experiment. * indicates that values are significantly different between phosphate‐buffered saline (PBS) and each experimental condition