Using RRT-PCR analysis and virus isolation to determine the
prevalence of avian influenza virus infections in ducks at Minto Flats
State Game Refuge, Alaska during August 2005
Jonathan A. Runstadler*1 , George M. Happ 1 , Richard D. Slemons 2 , Z.-M. Sheng 3 , Nancy Gundlach 1 , Michael Petrula 4 , Dennis Senne 5 , Jacqueline Nolting 2 , David L. Evers 3 , Angela Modrell 1 , Heather Huson 1 , Sue Hills 1 , Tom Rothe 4 , Tom Marr 1 , and Jeffery K. Taubenberger 3
1 Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775-7000
2 Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio, 43210
3 Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, 20892
4 Alaska Department of Fish and Game, Division of Wildlife Conservation, 333 Raspberry Road, Anchorage, Alaska 99518
5 National Veterinary Services Laboratory, Animal Plant Health Inspection Service, United States Department of Agriculture, Ames, Iowa 50010
*Corresponding Author:
Institute of Arctic Biology
University of Alaska Fairbanks
902 North Koyukuk Drive
Fairbanks, Alaska 99775
j.runstadler@uaf.edu
Summary
This study describes surveillance for avian influenza viruses (AIV) in the Minto Flats State Game Refuge, high density waterfowl breeding grounds in Alaska. Five hundred paired cloacal samples from dabbling ducks (Northern Pintail, Mallard, Green Wing Teal, and Widgeon) were placed into ethanol and viral transport medium (VTM). Additional
ethanol preserved samples were taken. Of ethanol preserved samples, 25.6% were AIV RNA-positive by Real-time RT-PCR. The hemagglutinin (HA) and neuraminidase (NA) subtypes were determined for 38 of the first passage isolates and four first passage isolates could not be definitively subtyped. Five influenza A virus HA-NA combinations
were identified: H3N6, H3N8, H4N6, H8N4, and H12N5. Differences in the prevalence of AIV infections by sex and by age classes of Northern Pintail and Mallard ducks were detected but the significance of these differences is undefined. In the 500 paired samples, molecular screening detected positive birds at a higher rate than viral isolation (¥ö 2 8.35, p=0.0035, 1 df), however, 20 AIV isolates were recovered from PCR negative ducks. Further research is warranted to compare the two screening protocols potential for estimating true prevalence in wild birds. Our success during 2005 indicates Minto Flats will be a valuable study site for a longitudinal research project designed to gain further insight into the natural history, evolution, and ecology of AIV in wild birds.
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