April 5, 2013

expert reaction to emergence of new strain of bird flu in China

Further cases of infection with the H7N9 bird flu virus have been reported.

Dr Holly Shelton, Avian Influenza Research Fellow at The Pirbright Institute, said:

“This H7N9 Influenza virus is unique in several ways; firstly, it is the first time that low pathogenicity avian influenza has been associated with human fatalities, secondly, according to the phylogenic data this virus has resulted from a novel reassortment between H7N9 viruses circulating in birds in Europe and Asian lineage H9N2 viruses, and thirdly, no animal reservoir for the virus has yet been identified.

“There are several sequence motifs identified in this H7N9 virus that suggest that the virus has gone some way towards adaptation to mammalian hosts, for example in the receptor binding pocket of the H7 protein which is important for attachment of the virus and the polymerase gene PB2 responsible for replication of the viral genetic material.

“However we can also see that the virus is probably susceptible to the anti-viral treatments of Tamiflu and Relenza and so far there does not appear to be any person to person spread of the virus which limits the ability of this virus to disseminate quickly through a population.

“The fact that people have died from this infection is naturally worrisome but what we don’t know is whether the people who have caught this infection have any underlying medical issues or predispositions to infections and in particular Influenza infections. We saw with the recent 2009 pandemic H1N1 strain that certain conditions including obesity and asthma resulted in a more severe outcome from a virus that for the majority of the population was a mild. The Chinese government and scientists with help from the international community now have a lot of work to do in understanding the source of this virus, its transmission route to human and in sampling the local populations to understand if infection without severe symptomology is occurring.

“Here at the Pirbright Institute we are investigating what characteristics make an avian Influenza virus likely to jump species including to humans and other economically important livestock such as pigs. This virus is another example that can be investigated in order to understand this more thoroughly.”