Abdullah Alkhalaf

Introduction Avian pneumovirus (APV) is the causative agent of turkey rhinotracheitis (TRT) and swollen head syndrome (SHS) in turkeys and chickens, respectively (Buys et al., 1989). The APV belongs to the family paramyxoviridae which has two subfamilies, the paramyxovirinae and pneumovirinae (Regenmortel et al., 2000). The first isolate of APV was obtained in South Africa in 1979 (Buys et al., 1 ...