Molecular and Serological Detection of Avian Influenza H9N2 Virus in Asymptomatic Commercial Layers in Faisalabad District, Punjab

The present study aimed at measuring the antibody titres against H9N2 influenza viruses and its molecular detections in asymptomatic commercial layers from Faisalabad district of Punjab, Pakistan. Overall 120 blood samples, 24 tissue samples from each organ (trachea, lung and intestine) were collected from the 12 commercial layer flocks selected randomly at the age of 35-50 weeks without any direct clinical manifestation of avian influenza. Serum collected from 120 birds was tested for antibodies against H9N2 by using Haemagglutination Inhibition assay. Calculated geometric mean titers of 5.37 revealed the infectivity of the flock with H9N2 Influenza virus. To investigate the presence of virus in the study population, trachea, lung and intestine tissue samples were processed for RNA isolation and subjected to molecular detection of H9 gene of H9N2 subtypes using one step Reverse Transcriptase Polymerase Chain Reaction (RT-PCR).Out of 24 samples taken from each organ, 22, 21, and 18 samples from trachea, lungs, and intestine showed viral RNA, respectively. Taken together, results showed that the H9N2 is endemic and widely distributed in asymptotic layers. Furthermore results indicated that H9N2 subtype may survive in layers without showing any symptoms.