Influenza viruses, which are responsible for annual outbreaks, can exist in any of 198 possible influenza subtypes resulting from the combinations of 18 hemagglutinin and 11 neuraminidase types. However, the number of subtypes capable of infecting humans has never been predicted or investigated. Influenza virus outbreaks that occur every year can be categorized as follows: a pandemic with high ...

Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 20, No. 11, November 2014 1955 virus infections in Hangzhou (online Technical Appendix Figure). Prompt control of A(H7N9) infection outbreaks and vaccination against seasonal influenza viruses could reduce the potential for co-infections with A(H7N9) virus and seasonal viruses. Taken together with the previous finding of human co-infection w...

Sixteen avian influenza (AI) H9N2 viruses were isolated from disease outbreaks in different parts of Iranduring (1998–2001). These AI isolates were used for pathogenicity, haemagglutinin (HA) gene variation andphylogenetic analysis. Results in both pathogenicity tests and HA gene cleavage site sequence detectionrepresented a non-highly pathogenic feature for all Iranian AI isolates studied. The...

Background and Aims: The caspases are unique proteases that mediate the host cell apoptosis during viral infection. In this study, we identified the caspase cleavage motifs of H5N1 and H9N2 influenza viruses isolated during 1998-2012. Materials and Methods: Amino acid sequences of the eleven proteins encoded by the viruses as the caspase substrates downloaded from NCBI. The caspase cleavage mot...

Introduction of influenza viruses with gene segments of avian origin into the human population may result in the emergence of new pathogenic human influenza viruses. The recent infection of a 3-year-old boy with an influenza A (H5N1) virus of avian origin can be considered as an example of such an event. However, this virus, influenza A/Hong Kong/156/97 (H5N1) and the 17 additional H5N1 viruses...

UNLABELLED Zoonotic avian influenza virus infections may lead to epidemics or pandemics. The 1918 pandemic influenza virus has an avian influenza virus-like genome, and its H1 hemagglutinin was identified as a key mammalian virulence factor. A chimeric 1918 virus expressing a contemporary avian H1 hemagglutinin, however, displayed murine pathogenicity indistinguishable from that of the 1918 vir...

Continuous circulation of influenza A(H5N1) virus among poultry in Egypt has created an epicenter in which the viruses evolve into newer subclades and continue to cause disease in humans. To detect influenza viruses in Egypt, since 2009 we have actively surveyed various regions and poultry production sectors. From August 2010 through January 2013, >11,000 swab samples were collected; 10% were p...

Some avian influenza viruses may be transmissible to mammals by ingestion. Cats and dogs have been infected by H5N1 avian influenza viruses when they ate raw poultry, and two human H5N1 infections were linked to the ingestion of uncooked duck blood. The possibility of zoonotic influenza from exposure to raw poultry products raises concerns about flocks with unrecognized infections. The present ...

Two novel influenza A-like viral genome sequences have recently been identified in Central and South American fruit bats and provisionally designated "HL17NL10" and "HL18NL11." All efforts to isolate infectious virus from bats or to generate these viruses by reverse genetics have failed to date. Recombinant vesicular stomatitis virus (VSV) encoding the hemagglutinin-like envelope glycoproteins ...

Past pandemics arose from low pathogenic avian influenza (LPAI) viruses. In more recent times, highly pathogenic avian influenza (HPAI) H5N1, LPAI H9N2 and both HPAI and LPAI H7 viruses have repeatedly caused zoonotic disease in humans. Such infections did not lead to sustained human-to-human transmission. Experimental infection of human volunteers and seroepidemiological studies suggest that a...