Field detection of avian influenza virus in wild birds: evaluation of a portable rRT-PCR system and freeze-dried reagents.
Wild birds have been implicated in the spread of highly pathogenic avian influenza (HPAIV) of the H5N1 subtype, prompting surveillance along migratory flyways. Sampling of wild birds is often conducted in remote regions, but results are often delayed because of limited local analytical capabilities, difficulties with sample transportation and permitting, or problems keeping samples cold in the field. In response to these challenges, the performance of a portable real-time, reverse transcriptase-polymerase chain reaction (rRT-PCR) unit (RAPID((R)), Idaho Technologies, Salt Lake City, UT) that employed lyophilized reagents (Influenza A Target 1 Taqman; ASAY-ASY-0109, Idaho Technologies) was compared to virus isolation combined with real-time RT-PCR conducted in a laboratory. This study included both field- and experimental-based sampling. Field samples were collected from migratory shorebirds captured in northern California, while experimental samples were prepared by spiking fecal material with an H6N2 AIV isolate. Results indicated that the portable rRT-PCR unit had equivalent specificity to virus isolation with no false positives, but sensitivity was compromised at low viral titers. Use of portable rRT-PCR with lyophilized reagents may expedite surveillance results, paving the way to a better understanding of wild bird involvement in HPAIV H5N1 transmission.
Takekawa
John Y
JY
U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 505 Azuar Drive, Vallejo, CA 94592, USA. john takekawa@usgs.gov
Iverson
Samuel A
SA
Schultz
Annie K
AK
Hill
Nichola J
NJ
Cardona
Carol J
CJ
Boyce
Walter M
WM
Dudley
Joseph P
JP
D000818:Animals; D001715:Bird Diseases / Q000175:diagnosis* / Q000821:virology*; D001717:Birds; D002140:California; D005189:False Positive Reactions; D005612:Freeze Drying / Q000379:methods; D053124:Influenza A Virus, H5N1 Subtype / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000175:diagnosis* / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*