A research group led by Professor Kawaoka of the University of Tokyo isolated a virus resistant to baloxavir marboxil (trade name: Zofluza) from influenza patients and clarified its basic properties.
Zofluza was used in earnest for the first time after marketing approval in the 2018/2019 influenza pandemic season, and the convenience of completing treatment with a single oral administration was supported, and its market share occupied 4%.On the other hand, mutant viruses showing resistance to zofluza were detected at a high rate, and their basic properties such as the degree of pathogenicity and ability to transmit infection were unknown.
The research group obtained samples collected from influenza A patients who visited medical institutions in Japan during the above-mentioned influenza pandemic season, and analyzed the viral genes.As a result, zofluza-resistant virus frequently appeared in influenza A patients under the age of 12 who took zofluza.In addition, resistant virus was detected in pediatric patients with influenza A who had not been treated with the drug.This indicates that it is highly possible that the resistant virus was transmitted from the infected person to the surrounding people.
In addition, this research group analyzed the properties of resistant virus isolated from patients using influenza model animals and compared it with zofluza-susceptible virus.As a result, it was found that the zofluza-resistant virus has the same proliferation and pathogenicity in mammals as the susceptible virus, and also efficiently propagates between mammals by air.This suggests that the zofluza-resistant virus may spread from person to person in the future.
The results of this research will be useful in selecting appropriate anti-influenza drugs in the medical field, and will be important information for the formulation and implementation of future influenza control plans by government agencies such as risk assessment of resistant viruses.
