Genetic characteristics of the virus detected in the first Mpox imported case in Tokyo, Japan

抄録

Mpox, caused by the mpox virus (MPXV), produces symptoms similar to those of smallpox when transmitted to humans. Since 1970, this disease had been endemic mainly in Africa. However, since May 2022, the number of patients without a history of traveling to endemic areas has been globally and rapidly increasing. Under these circumstances, in July 2022, two different real-time PCR methods were used on specimens brought to the Tokyo Metropolitan Institute of Public Health, MPXV was detected in the skin samples, and it was inferred that the MPXV was of the West African strain. Furthermore, a more detailed analysis of the genetic characteristics of the detected MPXV using next-generation sequencing revealed that the MPXV detected in Tokyo this time was strain B.1, corresponding to the same strain as that prevalent in Europe and the USA. This suggests that the mpox reported for the first time in Japan was imported and related to outbreaks in Europe and the USA. It is thus necessary to continue monitoring the outbreak in Japan in conjunction with the global epidemic situation.