Country for PR: Japan
Contributor: Kyodo News JBN
Friday, June 11 2021 - 16:00
Long-lasting Chlorine Dioxide (ClO2) Aqueous Solution Presented by Taiko Pharmaceutical and Kitasato University Inactivates over 99.99% of SARS-CoV-2 (COVID-19 Virus)
OSAKA, Japan, June 11, 2021 /Kyodo JBN-AsiaNet/---

- Solution Also Effective against Alpha and Gamma Variants of SARS-CoV-2 -

Taiko Pharmaceutical Co., Ltd. based in Osaka, Japan, hereby announced that 
long-lasting chlorine dioxide (ClO2) aqueous solution (*1) inactivated over 
99.99% of SARS-CoV-2 (COVID-19 Virus), including its Alpha and Gamma variants 
(*2), in a test conducted in collaboration with Kitasato Institute/Kitasato 
University in Tokyo, Japan.

SARS-CoV-2 strains were mixed with Taiko Pharmaceutical's long-lasting ClO2 
aqueous solution (*1) at the ratio of 1:19 (154 ppm (*3) in aqueous solution 
remained active for three years' storage) and the infectivity titer was 
determined by the plaque assay (*5) at 10 sec and 60 sec using 
TMPRSS2-expressing Vero E6 cells (*4). The results revealed that the ClO2 
aqueous solution inactivated over 99.99% of SARS-CoV-2, including the two 
variant strains.

The Alpha and Gamma variants of SARS-CoV-2 contain N501Y (*6) and E484K (*6) 
mutation, respectively, and these were suggested to affect, respectively, the 
infection/transmission potency, and antigenic drift. Currently, worldwide 
dissemination of the N501Y variant (*7, 8) has been confirmed.

A study reported that ClO2 denatures the spike protein on the surface of 
SARS-CoV-2 and inhibits its binding to the human ACE2 receptor (*9). The 
current study adds invaluable information for the effectiveness of long-lasting 
ClO2 aqueous solution in disinfecting the coronaviruses.

The pandemic dissemination of the novel coronavirus infectious disease 
(COVID-19) has seriously damaged the human society, threatening millions of 
human lives. Strategies to combat COVID-19 may be to develop vaccines to 
establish the herd immunity, effective drugs and disinfectants to inactivate 
the viruses.

Table 1: Number of Viral Particles on Day 3 of Culture

Fig. 1: Plaque Assay


(*1) Used Taiko Pharmaceutical's patented long-lasting ClO2 aqueous solution 
(Patent No. 5757975, 3 years after production). "Cleverin Spray" commonly 
marketed in Japan was used in this experiment.

(*2) Subject microorganisms: SARS-CoV-2 (3 strains above) provided by the 
National Institute of Infectious Diseases. hCoV-19/Japan/TY-WK-521 
(conventional strain), hCoV-19/Japan/QHN001/2021 (Alpha variant), 
hCoV-19/Japan/TY7-501/2021 (Gamma variant).

(*3) Unit of ppm: ppm (parts per million) represents the ratio of 1 part per 
million. The weight ratio (mg / L = ppm, 1 L water is approximately equal to 1 
kg) is used for liquids, and the volume ratio is used for gas. The ppm of this 
test applies the weight ratio in aqueous solution.

(*4) Subject cells: TMPRSS2-expressing VeroE6 cells: A cell line that is able 
to proliferate and isolate the SARS-CoV-2 developed by the National Institute 
of Infectious Diseases. In this study, the one purchased from the JCRB Cell 
Bank, the National Institutes of Biomedical Innovation, Health and Nutrition, 
was used.

(*5) Plaque Assay: One of the standard methods for measuring virus infectivity 
titer in a test sample, which is determined by the number of changes in the 
shape (plaque or white spot) of virus-infected cells.

(*6) N501Y variant: 501st amino acid of S protein is replaced from aspartic 
acid (N) to tyrosine (Y). It is suggested to be more infectious than 
conventional strains. E484K variant: 484th amino acid of S protein is replaced 
from glutamic acid (E) to lysine (K). Compared to the conventional strains, 
this variant may work as a stronger suppressor of the immune system and 
vaccination efficiency.

(*7) National Institute of Infectious Diseases New variant of SARS-CoV-2 
suggested to have more infection/transmission capability and changes in 
antigenicity (8th report).

(*8) Ministry of Health, Labour and Welfare (the measures against COVID-19 
(with SARS-CoV-2 of variant strains))

(*9) Inhibition of the Binding of Spike Protein of SARS-CoV-2 Coronavirus to 
Human Angiotensin-Converting Enzyme 2 by Chloride Dioxide, Annals of 
Pharmacology and Pharmaceutics, Volume 5, Issue 5, Article1195 (2020)

Source: Taiko Pharmaceutical Co., Ltd.