Acta Vet. Brno 2007, 76: 405-413

Detection of Avian Influenza Virus of H9 Subtype in the Faeces of Experimentally and Naturally Infected Chickens by Reverse Transcription-Polymerase Chain Reaction

H. Noroozian1, M. Vasfi Marandi1, M. Razazian2

1Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran-Iran
2Private Practitioner

Received January 8, 2007
Accepted July 9, 2007

Avian Influenza (AI) is a viral, highly contagious disease of domestic and wild birds. In an avian diagnostic laboratory, it is essential to have methods for rapid detection of respiratory viruses. In the present study, cloacal swabs collected from chickens experimentally and naturally infected with mild pathogenicity AI virus subtype H9, used in a reverse transcription-polymerase chain reaction (RTPCR) assay for detection of AI. On cloacal swabs collected from experimentally infected chickens, AI virus was detected most frequently between days 3 and 7 post infection (p.i.) and the relative sensitivity, specificity, correlation rate, positive predictive value and negative predictive value of the RT-PCR compared to virus isolation (VI) assay were 84%, 80%, 82%, 83% and 81%, respectively. On pooled cloacal swabs collected from flocks suspected of AI, these results were 96%, 100%, 97%, 83% and 100%, respectively. The results proved that the RT-PCR assay could be a reliable and rapid alternative to VI assay for detection of AI virus subtype H9 in faecal specimens.


AI, RT-PCR, H9, cloacal swabs.