Molecular Identification of Some Respiratory Pathogens from Broiler Chickens in Sharkia Governorate, Egypt

In this study, we investigated the prevelance of avian influenza virus (AIV) (subtypes H5 and H9), infectious bronchitis virus (IBV), Newcastle disease virus (ND) and Mycoplasma gallisepticum (MG) incriminated in respiratory troubles among chicken broilers at different localities in Sharkia Governorate during 2013-2017 outbreaks. Out of  53  broiler flocks, 225 chickens showing respiratory manifestations were examined. Viral isolation from respiratory tissues, serological and molecular identification were done. Based on hemagglutination inhibition (HI) test, for 42 positive haemagglutinating allantoic fluids, the prevalence of NDV and AIV (H9 and H5 subtypes) was 64.3%, 45.3%and 2,4% respectively.  Two diagnostic polymerase chain reaction (PCR) assays were used. Based on TaqMan probe base real-time PCR, 17/19, 10/42 and 1/42 flocks were confirmed to be infected with IBV, AIV subtype H9 and H5 respectively. Moreover, conventional PCR amplification for detection of Mycoplasma gallisepticum in 25 flocks was performed and revealed 56% (14/25) positive flocks. Subsequently, amplified products of three M. gallisepticum representative isolates were sequenced and phylogenitically analyzed with other strains on GenBank. The results revealed that the three examined isolates were wild type (field isolates).We could conclude that there were continuous circulation of different respiratory agents (viral (NDV, AIVH9 & H5, and IBV) and bacterial (MG) in broiler flocks in Sharkia Governorate either as single or mixed infection although wide using of different vaccination regimes and antibiotics so early diagnosis of these pathogens is considered the most effective tool in prevention and control of diseases.