Gene discovery by HKU team of researchers could lead to hand, foot and mouth treatment breakthrough
But researchers say drug for common disease could still be about 10 years away
A study led by the University of Hong Kong has discovered a gene key to viral infections that could lead to hand, foot and mouth disease (HFMD), shedding light on the development of a specific treatment for the illness.
But researchers said it could take about another 10 years to develop the drug.
Led by the university’s top microbiologist, Professor Yuen Kwok-yung, the study identified that a gene named hWARS – found in every human cell – was the receptor for enterovirus-A71 (EV-A71) to enter a cell and thus inflict damage. In general, without a specific receptor, a virus cannot enter a cell.
Yuen said in the past hWARS was merely seen as an ordinary gene. “We didn’t think that it was linked to viral infection,” he added.
When there is a viral infection, a specific type of protein is naturally produced by the human body. The researchers also found that this protein production creates a more favourable condition for the virus to enter cells.
“Now we’re starting to understand why some patients had such a severe condition,” Yuen said. “In the past we didn’t know why, but now we finally understand.”
The study findings are being published in the Journal of Clinical Investigation on Tuesday (Hong Kong time).
In the past, scientists did not understand in detail why EV-A71 could lead to severe complications in some patients.
EV-A71 is one of the viruses that can lead to HFMD, a common disease among children. Those who are afflicted display symptoms such as fever and small red spots with blisters on their tongue, gums and insides of their cheeks.
In Hong Kong, an average of about 2,000 to 5,000 HFMD cases were recorded every year between 2010 and 2017. Yuen estimated about 5 to 10 per cent of those cases were caused by EV-A71 infection, which is more likely than other causes of HFMD to lead to severe complications such as inflammation of the brain and even death. The number of people who died in the city from HFMD ranged between zero and three every year, he added.
According to the Centre for Health Protection, the usual peak season for HFMD locally is from early summer to autumn. A smaller surge may also occur in winter.
In the latest study, researchers found that in attempts to infect cells with EV-A71, those whose hWARS gene was stopped from being formed through a process called knockdown had a viral load level of almost zero. However, those for whom hWARS was not reduced in potency showed a high level of the virus.
Aside from EV-A71, infections caused by eight other types of enterovirus were also significantly prevented when hWARS’ potency was reduced, the scientists also noted.
In addition, they found that when the human body produced a protein named interferon gamma during a viral infection, it could lead to an increased production of hWARS, thus helping EV-A71 enter cells.
“The body produces [interferon gamma] in the hope of regulating those viruses,” Yuen explained. “But the virus is smarter and makes use of this condition. The receptor that is needed by the virus will also be produced in a greater supply, resulting in easier entry into the cells.”
The study further provided more evidence supporting the current use of a treatment named intravenous immunoglobulin, which some doctors administer for severe HFMD cases.
While there is no specific drug treatment targeting HFMD or EV-A71 infection, researchers are hoping to develop medication that can block hWARS to prevent enterovirus from entering into cells.