The H1N1 virus that causes swine flu is not likely to mutate this season into a "superbug," one of some scientists' worst fears, according to research published Tuesday.

The University of Maryland study on ferrets found that the virus does not readily combine with seasonal flu strains that could help foster a more virulent mutant flu.

"The H1N1 pandemic virus has a clear biological advantage over the two main seasonal flu strains and all the makings of a virus fully adapted to humans," explained virologist Daniel Perez of the University of Maryland-based Prevention and Control of Avian Influenza Coordinated Agricultural Project.

"I'm not surprised to find that the pandemic virus is more infectious, simply because it's new, so hosts haven't had a chance to build immunity yet. Meanwhile, the older strains encounter resistance from hosts' immunity to them," Perez added.

Some animals infected with both the new virus and earlier seasonal viruses developed respiratory symptoms and intestinal illness as well.

Perez and his team, whose work appeared in the online journal PLOS Currents, urged more research to see if such co-infection and multiple symptoms may explain some of the deaths attributed to the new virus.

"Our findings underscore the need for vaccinating against the pandemic flu virus this season," Perez concludes. "The findings of this study are preliminary, but the far greater communicability of the pandemic virus serves as a clearly blinking warning light."

Copyright AFP