In correspondence published this week in the journals Science and Nature, the researchers announced that they will conduct what is called “gain of function” testing to see what happens when characteristics that could make avian influenza A H7N9 more easily transmissible or more lethal are added under carefully controlled laboratory conditions.
The new strain, which normally circulates just among birds, emerged in people in March but so far has been contained to China and Taiwan, according to the World Health Organization. There have been 133 people infected, and 43 have died, according to WHO.
This avian virus so far hasn’t been nearly as deadly as the avian influenza A H5N1 virus, which has infected 633 people and killed 377 and spread to 15 countries, although it has not shown the ability to spread easily from person to person.
Because the newer strain has not shown the same lethality it does not fall into a category where work on it would have certain restrictions and guidelines but the researchers still took the extra step of publishing their intent to conduct the new work on it, Dr. S. Mark Tompkins said. Tompkins is an associate professor of infectious diseases at the University of Georgia and a project leader in the Influenza Pathogenesis & Immunology Research Center, a center of excellence in influenza between UGA and Emory University.
“However, and this is why we want to do the work, it is a public health concern,” he said. “And some of the work that is proposed to do and is important to do can potentially modify the virus to meet some of these types of studies that fall under” the higher concern categories.
The researchers, in labs in Georgia, across the U.S. and internationally, would – under carefully controlled circumstances – add characteristics that could make the virus more lethal, more easily transmissible through aerosol droplets or more resistant to treatment. The strains would be handled under the same high-level biosafety measures as the more lethal viruses, and no more than one adaptation would be added to a strain at a time, according to the guidelines.
“To be able to assess pandemic potential of viruses in nature we need to evaluate the viruses that we now have in the laboratory to understand how readily they can adapt and what features need to be changed to enable adaptation,” Tompkins said.
Often, influenza viruses will meet up with and exchange genetic information with other influenza viruses inside a host, a process called reassortment.
“That’s one of the key questions is how readily could the H7N9 viruses reassort with other viruses that are circulating, either in other animals or in humans, to generate a new potentially pandemic virus or a virus that has drug-resistance or could be more virulent,” Tompkins said.
Drug resistance could be a concern because some of the H7N9 viruses gathered from patients showed “acquired resistance to the primary medical countermeasure” according to the correspondence, which would be antivirals such as oseltamivir or Tamiflu.
Testing might start in the lab but move to animal models to see how the virus strains behave in a host, Tompkins said.
“If we need to and if the evidence warrants, we could move those into animals to see, well, does this drug resistance affect the ability of the virus to infect, to replicate, to transmit,” he said. “Because often when you see drug resistance changes you see other changes in the virus as well. It may take a hit in terms of the viral fitness.”
The new avian strain appears to have gone dormant for now, but as China moves into its flu season that could change soon, Tompkins said.
“It could be occurring any time,” he said.