Characterization of recent H5 subtype avian influenza viruses from US poultry.
In the US, the isolation of H5 subtype avian influenza (AI) viruses has been uncommon in commercial chickens and turkeys, although sporadic isolations have been made from the live bird markets or its supply chain since 1986. In 2002, two different outbreaks of H5 AI occurred in commercial chicken or turkey operations. The first occurred in Texas and was identified as a H5N3 subtype AI virus. The second outbreak was caused by a H5N2 virus isolated from a turkey farm in California. In this study we analyzed recent H5 subtype AI viruses from different avian species and different sources in the US. Most recent H5 subtype isolates shared a high sequence identity and phylogenetically assorted into a separate clade from the Pennsylvania/83 lineage isolates. However, no established lineage was found within this clade and the recent H5 subtype isolates seemed to be the result of separate introductions from the wild bird reservoir. The Texas H5N3 isolate shared the lowest homology with the other recent isolates in the haemagglutinin gene and had a unique haemagglutinin cleavage site sequence of REKR/G (other recent isolates have the typical avirulent motif, RETR/G). Furthermore, this isolate had a 28 amino acid deletion in the stalk region of the neuraminidase protein, a common characteristic of chicken adapted influenza viruses, and may indicate that this virus had actually been circulating in poultry for an extended period of time before it was isolated. In agreement with genetic evidence, the Texas H5N3 isolate replicated better than other H5 isolates in experimentally infected chickens. The outbreak in Texas with a more chicken-adapted H5N3 virus underscores the importance of ongoing surveillance and control efforts regarding the H5 subtype AI virus in the US.
Lee
Chang-Won
CW
Southeast Poultry Research Laboratory, USDA-ARS, 934 College Station Road, Athens, GA 30605, USA.
Senne
Dennis A
DA
Linares
Jose A
JA
Woolcock
Peter R
PR
Stallknecht
David E
DE
Spackman
Erica
E
Swayne
David E
DE
Suarez
David L
DL
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens / Q000821:virology*; D004196:Disease Outbreaks / Q000662:veterinary*; D005843:Geography; D006388:Hemagglutinins / Q000235:genetics; D009980:Influenza A virus / Q000235:genetics* / Q000472:pathogenicity; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013045:Species Specificity; D014422:Turkeys / Q000821:virology*; D014481:United States / Q000453:epidemiology
D006388:Hemagglutinins