Spread of SARS-CoV-2 variants that escape the immune system in Japan

As of February 12, 2021, more than 100 people were infected with the SARS-CoV-2 variants in Japan. In February 2021, a large-scale cluster (infected population) of SARS-CoV-2 variants-infected persons occurred in Saitama Prefecture in Japan. Infection with SARS-CoV-2 variants is gradually spreading in Japan. The World Health Organization (WHO) reports that "the infectivity of SARS-CoV-2 variants is 1.4 to 1.7 times higher than that of conventional SARS-CoV-2" (1). Infectious disease experts in Japan are becoming more cautious about the spread of infection by SARS-CoV-2 variants.

As of February 12, 2021, in Japan, 93 people were infected with the SARS-CoV-2 variant derived from the United Kingdom (UK), 11 people were infected with the SARS-CoV-2 variant derived from South Africa, and 4 people are infected with the SARS-CoV-2 variant derived of Brazil (2). As of February 8, 2021, WHO reports that cases of SARS-CoV-2 variants derived from the UK have been identified in 86 countries around the world.

In 2020 of October, in the Manaus city in Brazil, 76% of residents of Manaus city, had acquired the anti-SARS-CoV-2 antibody (Photo). However, since the detection of the SARS-CoV-2 variant derived from Brazil in mid-December 2020, the number of people infected with the SARS-CoV-2 variant derived from Brazil has increased significantly (Photo). In other words, the immunological antiviral effect of the neutralizing antibody against SARS-CoV-2 has not been observed for the SARS-CoV-2 variant derived from Brazil.

Recent studies have revealed the following matters (3).
The N501Y mutation does not affect the three-dimensional structure of conventional SARS-CoV-2 spike glycoproteins. From this research result, it was clarified that the binding property of the spike glycoprotein N501Y mutant to human ACE2 was stronger than that of the conventional SARS-CoV-2 spike glycoprotein.

From this study, it was revealed that the affinity between the spike glycoprotein N501Y mutant and 24 of the 27 neutralizing antibodies examined was clearly weak compared to the conventional SARS-CoV-2 spike glycoprotein.

With the advent of the variants of the SARS-CoV-2, there is a possibility that the vaccine effect is inhibited. Therefore, the development of antiviral drugs against SARS-CoV-2 is even more important.

Ethics statement
This study was reviewed and approved by the Central Ethics Review Board of the National Hospital Organization of Japan. The approved number for this study is 50-201504. In order to carry out this research, the authors attended a research ethics education course (e-APRIN) conducted by Association for the Promotion of Research Integrity (APRIN; Shinjuku, Tokyo, Japan). The approved numbers of e-APRIN are AP0000151756, AP0000151757, AP0000151758, AP0000151769.

Disclosure
The authors declare no potential conflicts of interest. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Acknowledgments
We thank medical staffs for the research assistance at National Hospital Organization Kyoto Medical Center.

1. https://www.who.int/csr/don/21-december-2020-sars-cov2-variant-united-kingdom/en/
2. Experts urge caution as coronavirus variants spread in Japan. February 11, 2021 (Mainichi Japan)
3. Hayashi T. et al. bioRxiv Cold Spring Harbor https://www.biorxiv.org/content/10.1101/2020.11.27.401893v1

がん医療専門ドクター/癌ゲノム医療/新興感染症　　　　　　　　　　Science Published on February 11. 2021. by Kyoto@Takuma H