Hong Kong study uncovers immune system key to Mers high death rate
Virus, which is four times more deadly than Sars, destroys crucial cells in hours
University of Hong Kong researchers have found Middle East respiratory syndrome (Mers) is capable of disarming a person's immune defence system in a matter of hours.
HKU microbiologist Professor Yuen Kwok-yung, who led the study, told the the research offered a new explanation as to why Mers was almost four times more fatal than severe acute respiratory syndrome (Sars).
The results add to earlier studies which found that even though Mers spread less easily than Sars, it was more deadly.
The latest findings were announced as the Hong Kong government was set to lift its travel alert against South Korea as the country will have been Mers-free for 28 days today.
"We have found a major difference between Mers and Sars in the study," said Jasper Chan Fuk-woo, clinical assistant professor in microbiology at HKU, who is part of Yuen's team.
"After learning of the mechanism, we hope we can find ways to prevent the Mers virus from infecting immune cells in the future."
Yuen said his research on what are known as human blood lymphocytes had found that Mers was able to infect and kill the most important cell in the immune system in just six hours.
He said such an ability was rarely seen in other types of coronaviruses, including Sars.
The virus triggered a process called apoptosis, or programmed cell death, in which the cells can no longer function normally and die very rapidly.
Chan said patients who survived Mers usually had a better immune response than those who died.
"We only knew before that Mers had a very high killing rate, but we did not know exactly why it was so deadly. Now we know what it does to immune cells," Chan said.
The results of the two-year study were published in the this month.
As of June 26 this year, 1,356 laboratory-confirmed Mers cases had been reported to the World Health Organisation, including at least 484 related deaths. By contrast, there were more than 8,000 Sars cases in 2002 and 2003, and 774 deaths.
In South Korea, Mers infected 186 people, 36 of whom died.
A spokeswoman for the Food and Health Bureau said the government would today consider lifting the red travel alert imposed on South Korea on June 9.
