Swine flu virus may not mix with other viruses: Study

The WHO predicts a third of the world's population will eventually be infected with swine flu.


The H1N1 swine flu virus out-competes all other strains of influenza viruses by reproducing on an average,twice as much within an infected body. This, scientists say, reduces the possibility that this superior H1N1 virus would interact and mix with other flu viruses to form a more virulent superbug.In a first study to examine how the pandemic virus interacts with other flu viruses, American scientists made three different flu viruses compete against the H1N1 inside ferrets.

"The results suggest that the 2009 H1N1 influenza may out-compete seasonal flu virus strains and may be more communicable as well. H1N1 causes more severe disease in animal studies, but it shows no signs of mixing with either of the two seasonal flu viruses to form a new so-called reassortant virus," said Dr Anthony Fauci of the National Institute of Allergy and Infectious Diseases.

On June 11, WHO declared a new H1N1 influenza pandemic -- the first in the last 41 years. This pandemic strain is as transmissible as seasonal H1N1 and H3N2 influenza A viruses. Major concerns facing this pandemic have been whether the new virus will replace, co-circulate and/or reassort with seasonal H1N1 and/or H3N2 human strains.

"Using the ferret model, we investigated which of these three possibilities were most likely. Our studies showed that the current pandemic virus is more transmissible than, and has a biological advantage over, prototypical seasonal H1 or H3 strains," the scientists said.
Some of the animals who were infected with both the new virus and one of the more familiar seasonal viruses (H3N2) developed not only respiratory symptoms but intestinal illness as well.

"It is reassuring that this virus does not seem to be in search of additional genes to become more powerful," Perez said.