Researchers in Hong Kong have discovered a new way to stop influenza viruses from replicating. Doctors hope it will keep them one step ahead of mutating viruses that kill thousands every year.

When H1N1, or swine flu, hit Thailand last year, the government at first restricted the use of antiviral drugs, worried that indiscriminate use would help the virus build drug resistance.

Dr. Wasun Chantratita studied hundreds of Thailand’s 2009 influenza cases. He worries about resistance in H1N1 influenza, because it was deadlier than the 2008 seasonal flu.

“[The number of] people who passed away after infection of 2009 is higher than seasonal flu [because of] the way that the infection goes deeper into the lungs,” he said.

Most flu drugs target the neuraminidase, a protein at the surface of an infected cell that helps the virus spread to other cells.

At the University of Hong Kong, researchers found a way to hit deeper into an infected cell, where the virus reproduces.

Dr. Richard Kao is part of the team that discovered a chemical compound called nucleozin. It clumps together nucleoproteins from the flu virus, so they cannot get into a healthy cell’s core, or nucleus.

“If the nucleoprotein cannot get into the nucleus, then the virus cannot replicate itself,” he said.

The finding is a payoff from years of research into Severe Acute Respiratory Syndrome (SARS) which killed more than 200 people in Hong Kong in 2003.

Because viruses often outsmart treatments over time and emerge in new variations, Dr. Kao says the team also found a way to rapidly identify more targets deep inside the cell using a method picked up from SARS research.

“Then we can find more new drugs, targeting different proteins… And also, if you look at resistance, if you can find a target that is very difficult for the virus to mutate, or the bacteria to mutate, then you’ve got a higher chance to find a drug that can be used for a longer time,” added Dr. Kao.

Dr. Wasun says with more drugs in the arsenal, more lives can be saved.

“The more drug[s we have at our disposal, the better] for us because these are the anti-virus, [and] no matter what, if you keep using that drug, sooner or later [a virus] will [be able] resist to that drug, for sure,” noted Dr. Wasun.

Influenza kills hundreds of thousands worldwide every year. Last year, the World Health Organization issued a pandemic alert after H1N1 flu, an entirely new virus, appeared in Mexico and rapidly spread around the world.