Molecular Characterization of Infectious Bursal Disease Virus Isolated from Naturally Infected Broiler Chickens in Erbil, Iraq

Abstract

The infectious bursal disease (IBD) is a highly contagious and immunosuppressive disease of broiler chickens and the development of a new genetic variant of the virus is responsible for major economic losses in the poultry industry. For this purpose, it was essential to isolate the molecular characterization of the virus from vaccinated broiler in Erbil, Iraq. Clinically, the infectious bursal disease is characterized by high mortality (10-15%) with hemorrhagic lesions on the breast and thigh muscles, hemorrhagic and edematous bursa of diseased chickens. In this study, the Bursa of Fabricus (BF) samples were collected between June 2018 and January 2019. Histopathological changes of the bursal sections showed existence of the cystic vacuolation of the lymphoid follicles with leukocytes infiltration as pathognomic features for IBD virus infection; and homogenates samples inoculated in chorioallantoic-membrane showed mortality in the second passage with varying degrees of hemorrhages. Agar gel precipitation test (AGPT) was positive with specific antisera. Reverse transcription polymerase chain reaction (RT-PCR) and nucleotide sequence analysis of five fragments in the hypervariable region of VP2 gene revealed transition and transversion changes. Among the five recent IBD virus isolates, the rate of identity was approximately 99% as compared with the very virulent IBD virus from Iran (ID: DQ785171.1). Phylogenetic analysis revealed that the five isolates were closely related to the Asian group with a different percentage ranged from 98-99% while it was 97% in the European group. The local isolate of the virus was registered in the Genebank under the accession number MN48052.1. In conclusion, the isolated IBDVs belong to a very virulent group. In addition, this study demonstrates the spread of this virulent virus to poultry industries in Erbil, Iraq. Further widespread surveys could help in delivering more information on the virus variability and might assist in designing novel vaccines for this pathogen

Characterization of the dominant strain (G-VII) of Newcastle disease viruses isolated from commercial chickens in Bangladesh during recent outbreaks

“…HI and AGID tests utilizing NDV-specific hyperimmune serum revealed that all 60 isolates tested positive for NDV. The HI test results of the current study support the findings of Ahmed and Odisho [ 31 ], El-Bagoury et al [ 32 ], and Seal et al [ 33 ], who confirmed NDV by the HI test. Hasan et al [ 25 ] and Mohammed et al [ 34 ] detected the NDV virus in field samples utilizing hyper-immune serum of NDV by AGID test.…”

“…The ICPI, IVPI, and MDT assays confirmed that the isolates were velogenic strains of NDV, which is similar to the findings of Rashi et al [ 41 ], Ahmed and Odisho [ 31 ], and Kommers et al [ 42 ]. The MDT in chicken embryos and the ICPI in day-old chicks were two of the pathogenicity tests carried out by Nooruzzaman et al [ 7 ].…”

“…Similarly, the rapid detection method was employed for the preliminary screening of all 420 and was found positive in 87 samples. Bordoloi et al [ 29 ], Duad et al [ 30 ], and Ahmed and Odisho [ 31 ] utilized 9–10 days of seronegative chicken eggs for the propagation and isolation of the NDV virus from clinical field samples. Again, among the 87 screening-positive samples, 60 were successfully grown.…”

Molecular identification of the common viral respiratory viruses in backyard chickens in Basrah, Southern Iraq

“…The study also showed that the prevalence of infection was significantly higher in backyard chickens than in commercial chickens [20]. Similarly, a separate study conducted in the Kurdistan region of (northern Iraq) showed a lower infection rate than the present study [21]. Numerous factors, such as the geographical region and the specific breed of birds, might influence the distribution of NDVs.…”