Abstract
The regular updates of molecular studies of Avian Infectious Bronchitis Virus in Egypt become imperative specially with the ongoing emergence of new strains of infectious bronchitis virus (IBV) that worsen the situation in poultry farms and causing extensive economic losses. In our study, we collect samples from twenty broiler flocks range from 18 to 36 days of age and manifested severe respiratory signs with mortality up to 30%. The collected flocks located in Qalyoubia governorate during period between January 2017 to December 2018. IBV Screening in collected samples was conducted by real time rRT-PCR targeting the nucleoprotein (N) gene. A total of 12 out of 20 examined farms were positive for IBV with percentage of (60%). Five positive IBV isolates were selected for amplification and sequencing of 400 –bp targeting the hypervariable region-3 (HVR 3) of S1 protein. Phylogenetic analysis confirmed that these viruses were closely related to each other (90-98% identity) and were clustered to variant II (GI 23) viruses within the Egy/Var-Ⅱ subgroup. The amino acids homology showed (75% to 80% identity) between our Egyptian/Qal variants and the common vaccine used for IBV infection in Egyptian poultry farms.
Highlights
Avian Infectious Bronchitis Virus (IBV) is a member of genus Gammacoronavirus, family Coronaviridae, order Nidovirales (De Groot et al, 2011 and King et al, 2011)
Samples collection In the present study, samples were collected from broiler flocks range from 18 to 36-day-old and suffering from severe respiratory signs from twenty different farms located in AL-Qalyoubia Governorate during the period from January 2017 till December 2018
Virus detection and isolation infectious bronchitis virus (IBV) was detected in examined samples in 12 out of 20 farms with percentage of (60%) using reverse transcription-polymerase chain reaction (rRT-PCR) (Fig. 1)
Summary
Avian Infectious Bronchitis Virus (IBV) is a member of genus Gammacoronavirus, family Coronaviridae, order Nidovirales (De Groot et al, 2011 and King et al, 2011). IBV strains have been reported in chickens worldwide (Jackwood, 2012). Earlier IBV genotypes related to Massachusetts, D3128, D274, D08880 and 4/91 were circulating in poultry farms with nephropathy (Abdel-Moneim et al, 2006 and Jackwood et al, 2012) and with the continuing detection of IBV strains, different variants closely related to the Israeli variant strain were identified including Egyptian variant I (Egypt/Beni-Seuf/01) in 2001 (Abdel-Moneim et al, 2002) and Egyptian variant II (CK/Eg/BSU-2,3/2011) in 2012 (AbdelMoneim et al, 2012). The continous circulation of different variants of IBV in majority of farms all over Egypt even in vaccinated ones with different strains (H120, MA5 and 4/91) was dramatically complicated the situation in poultry sector and allow to emerge new mutants with risk of IBV vaccination failure (Zanaty et al, 2016). Our study was a contribution in IBV surveillance in Qalyoubia which represent one of the provinces that characterized by the intensity of poultry production in Egypt for updating and monitoring the most important molecular changes in currently circulating IBV isolated form poultry farms through the partial sequence of S1 gene during a period between 2017-2018
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