A survey on presence of new strains of infectious bronchitis virus in some chicken farms of Egyptian Delta provinces during 2014

Abstract

for drawing the epidemiological chart of distribution of IBV through the forementioned localities.The cardinal signs of the disease in layers were drop in egg production, with watery albumen, inferior (pale-misshape shell) eggs, while in broilers were respiratory distress, renal urate deposition and mortality. Identification of IBV was by reverse transcriptase -polymerase chain reaction (RT-PCR) of RNA extracted from trachea and kidney tissues from freshly dead birds. There were 7/16 (about 43.7%) of selected suspected farms were positive for IBV with RT-PCR. A 600bp hypervariable spike glycoprotein (S1) gene was amplified and sequenced to study genetic diversity between viruses. Sequence analysis was successfully performed with six isolates and failed with one isolate. The phylogenetic analysis revealed that four isolates related to variant Israelin strains , three of them related to (IS/1494/06 ) and other one related to( IB isolate-variant -2 S1).Other two isolates ,one of them related to classical vaccinal strain (H120) and other related to variant vaccinal strain (D274). Using two IBV isolates related to IS/1494/06 as challenging viruses one of them respiratory form and other nepherotropic form , 6 different vaccination programs of different commercial available IB vaccines. The results indicated that priming with M48 vaccine at 7 day old followed by IB Primer one week later gave the highest protection as assessed by clinical signs , weight loss , antibody titer and histopathological lesion of trachea and kidneys.

Investigation of Cross Neutralization of Egyptian Variant 2 among both Classic and Variant Vaccinal Infectious Bronchitis Viruses

“…Infectious Bronchitis Virus is a positivesense, single stranded RNA virus. Different genotypes of IBV have been identified allover the world [1,2]. Although the routine and continuous vaccination of chicken with IBV, outbreaks still frequently occur in the field due to the emergence of different variant serotypes beside the classical subtypes.…”

“…In this respect, different researchers concluded that HI test is an IBV serotype specific test, and NT is the gold standard test for the detection of IBV serotype specific antibodies in sera of chickens after single vaccination [1,2,11,[21][22][23]. The specificity of the HI test is considered to be lower than that of the NT.…”

“…In Egypt, Infectious Bronchitis (IB) is an important contagious viral disease which threatens continuously the growing chicks coinfected with other respiratory pathogens such as low pathogenic avian influenza virus, subtype H9N2, Newcastle disease virus, pathogenic Escherichia coli, and mycoplasma species [1,2]. The causative avian coronavirus is an enveloped single stranded positive sense RNA virus.…”

“…The vaccination regime using the vaccine(s) of suitable protectotype strain(s) that are compatible at least with the predominant circulating virus is one of the effective tools that could control IB-infection in chickens. In Egypt, vaccines of classic IBV Mass strains, and European variant strains are registered and used, while variant-2 of IB virus have been isolated routinely from broiler chick flocks suffering from respiratory manifestations and high mortalities [1,2]. The full length S1 gene nucleotide sequence and its deduced amino acids homology percentages of the Egyptian variants of 2012 against the widely used vaccinal strains, H120, Ma5, CR88, D274 and 4/91 showed low correlation from77 % to 85 % [13].…”

Evaluation Of Bivalent Inactivated Infectious Bronchitis Viral Vaccine Prepared From Local Isolates

“…IBV strains were previously isolated from different localities by Reda et al (2015), (Chicken / Egypt KP279995 / VACSERA / 2014) (classical ) and (Chicken / Egypt KP279998 / VACSERA / 2014) (variant) The two strains were propagated in SPF-ECE and tittered with infectivity titer 10 8.5 EID 50 / dose as viral seed for preparation of bivalent inactivated IB vaccine and challenge dose was adjusted to be 10 4.5 EID 50 /ml, the titration was calculated according to Reed and muench, (1938).…”