TY - JOUR AU - Al-Ali, Ahmed M. AU - El-Sabagh, Ibrahim M. AU - Mohamed, Mahmoud H. AU - Alluwaimi, Ahmed M. AU - Arif, Ibrahim A. PY - 2018/08/02 Y2 - 2024/03/29 TI - Molecular characterization of common respiratory viral infections in broilers in Al-Hassa, Eastern Province, Saudi Arabia JF - The Thai Journal of Veterinary Medicine JA - TJVM VL - 48 IS - 2 SE - Original Articles DO - UR - https://he01.tci-thaijo.org/index.php/tjvm/article/view/137828 SP - 235-245 AB - <p><span class="fontstyle0">Newcastle disease virus (NDV), Infectious bronchitis virus (IBV) and H9N2 avian influenza virus (AIV) are<br>the most significant respiratory pathogens. Several outbreaks have been reported frequently in Saudi Arabia despite of<br>the intensive use of vaccination programs. Ten broiler flocks suffering from complicated respiratory disease were<br>subjected to necropsy and samples were collected for molecular identification of involved viruses and pathogenic<br>bacterial infections. Seven out of the ten flocks were positive for single or combined viral infection. The seven flocks<br>were positive for HA test. All positive samples were subjected for molecular identification, three flocks were positive<br>for single NDV while one flock was positive for both NDV and IBV. Three flocks were positive for H9N2 and IBV.<br>Three flocks were negative for viral infection and subjected for pathogenic bacteria detection. The sequence analysis of<br>F gene of NDV revealed that all isolates exhibited the cleavage site (</span><span class="fontstyle0">112</span><span class="fontstyle0">RRQKRF</span><span class="fontstyle0">117</span><span class="fontstyle0">) of virulent NDVs. The<br>neuraminidase-haemagglutinin gene revealed that all AI isolates belonged to H9N2 low pathogenic avian influenza<br>virus (LPAIV) subtype. The S1 gene of IBV showed that one isolate was closely related to the Connecticut IBV strain<br>while another isolate belonged to the H120 IBV strain. In conclusion, combined pathogens causing respiratory infection<br>in broilers is very common, which leads to the increase in disease severity and economic losses. The continuous<br>detection of virulent NDV as well as IBV from broiler flocks emphasize the need to review the vaccination strategies<br>based on further epidemiological and molecular studies.</span></p> ER -