Characterization of avian H9N2 and human 2009 pandemic influenza viruses isolated in Singapore

Abstract

Influenza A virus infection imposes major public health problem. In the past, there were several influenza pandemic outbreaks that killed millions of people. One of the most notable is the 1918 "Spanish Flu", followed by "Asian Flu" in 1957 and "Hong Kong Flu" in 1968. Since then, highly pathogenic avian influenza virus H5Nl outbreaks have been highlighted for the potential of the pandemic emergence. The emergence of high pathogenic avian influenza (HP AI) strains was resulted from the mutation of low pathogenic avian influenza (LPAI) strains. Similarly, H9N2 influenza viruses also have spread around the world, from wild birds to domestic poultry, especially in Asia. There is a documented evidence of the infection of H9N2 influenza viruses in humans, thus posing them as potential pandemic risks. Recently the 2009 pandemic swine influenza virus also emerged in April 2009, which has reached pandemic level, and co-circulates with seasonal influenza virus.