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Mohamed E. El Zowalaty, Martha Abin, Subhatra Raju1 Yogesh Chander, Patrick T Redig, Hemmat K. Abd El Latif, Mona A. El Sayed and Sagar M. Goyal
Scientific Tracks Abstracts: JAA
Avian infl uenza virus (AIV) is one of the most important zoonotic pathogens because of its potential risk to cause severe disease outbreaks in avian and human hosts. Virus isolation in embryonated chicken eggs (ECEs) remains a gold standard technique for AIV detection. However, some laboratories prefer molecular methods such as qRT-PCR for initial sample screening because of their high throughput sample processing and rapid results. Samples found positive on qRT-PCR are then inoculated in ECEs for virus isolation and characterization. Th is approach is based on the premise that qRT-PCR will detect all AIV-positive samples. Th e current study aimed to determine if AIV can be isolated from cloacal samples of waterfowl that were initially found to be negative by qRT-PCR screening. Quantitative RT-PCR?negative cloacal samples (n=1,369) were inoculated for virus isolation in commercial non?specifi c pathogenfree ECE. Aft er 4 days of incubation, the allantoic fl uids were harvested and inoculated in fresh ECE for a second passage. Allantoic fl uids from 147 samples were positive for hemagglutination (HA) with chicken erythrocytes. Of the 147 HA-positive allantoic fl uids, 82 were AIV positive when confi rmed with qRT-PCR. Ten isolates were subtyped as H7N2 (n = 7), H7N1, H1N2, and H2N2. In addition, N subtype could be determined for isolates from an additional 25 samples. Th ese results highlight the fact that screening by qRT-PCR may result in some false-negative cloacal samples for AIV. Results of the current study indicate that it may not be necessary to use costly SPF eggs unless an AIV vaccine is used in the commercial fl ocks.
Dr. Sagar M. Goyal is a professor of virology at the Veterianry Diagnostic Laboratory and the department of Veterinary Population Medicine, University of Minnesota. M. El Zowalaty is a Ph D student waiting for graduation at Veterianry Diagnostic Laboratory on a scholarship to pursue doctoral research and an assitant lecturer at department of microbiology, Zagazig University, Egypt.