GUANGZHOU -- Chinese researchers have unveiled a crucial mutation in the Ebola virus that significantly enhanced its infectivity during a major outbreak, providing new insights for epidemic surveillance and drug development.

The research effort, published in the journal Cell, was conducted by a team led by Professor Qian Jun from Sun Yat-sen University, in collaboration with researchers from Guangzhou Eighth People's Hospital of Guangzhou Medical University, both located in South China, the First Hospital of Jilin University in Northeast China, and other Sun Yat-sen University teams, the research team told Xinhua on Monday.

"The research tells us that during major emerging infectious disease outbreaks, real-time genomic surveillance and evolutionary analysis of the pathogen are crucial," said Qian.

"This is not only able to warn of changes in transmission risk but also to prospectively assess the effectiveness of existing drugs and vaccines, guiding us to preemptively adjust control strategies."

The study focused on the Ebola virus disease (EVD) outbreak in the Democratic Republic of the Congo (DRC) from 2018 to 2020, the second-largest in history, which caused over 3,000 infections and more than 2,000 deaths. A key question drove the research, namely beyond the impact of local healthcare challenges, did viral evolution itself contribute to this outbreak's prolonged duration?

"We have long been aware that key viral mutations often act as invisible drivers accelerating transmission during major outbreaks. Having worked on Ebola for over a decade, we had to investigate whether similar patterns of mutation existed for this virus," said Qian, explaining the team's motivation.

In 2022, the team analyzed 480 complete Ebola virus genomes and discovered that a variant carrying a specific mutation in the viral glycoprotein, named GP-V75A, had emerged early in the DRC epidemic. This variant rapidly replaced the original strain, and its rising prevalence closely mirrored the surge in case numbers, suggesting it might confer a transmission advantage, according to the research team.

Subsequent experiments using various models confirmed the mutation's biological impact. It showed that GP-V75A had significantly enhanced the virus's ability to infect multiple types of host cells and mice.

Furthermore, this study revealed a potential clinical concern, notably that the GP-V75A mutation had diminished the antiviral effectiveness of some existing therapeutic antibodies and small-molecule entry inhibitors, indicating a possible risk of drug resistance.

These findings underscore the importance of continuous viral genome monitoring during outbreaks to anticipate evolutionary threats and inform the development of broad-spectrum countermeasures, the research team said.

The paper titled "Molecular characterization of Ebola virus glycoprotein V75A substitution in the 2018-2020 epidemic," is available online.