Pathogenicity characteristics of an Iranian variant-2 (IS-1494) like infectious bronchitis virus in experimentally infected SPF chickens

Abstract

Summary. -Avian infectious bronchitis (IB) is a major cause of economic loss to the poultry industry. IB virus primarily affects respiratory tract, but strains differ in their tropism for such other target organs as kidneys and alimentary tract. The objective of this study was to estimate the pathogenicity of an Iranian IB virus (IBV) variant (variant-2) which is one of the most prevalent isolates circulating in Iranian poultry farms. SPF chickens were intranasally inoculated with 10 4 EID 50 /0.1 ml of the virus. Sera, fecal swabs, and different tissue samples were collected on different days post infection. Clinical signs, gross pathology, and histological changes were recorded. The amount of virus genome was quantified in different tissues and feces using quantitative real-time PCR assay. The highest viral loads were detected in the feces and cecal tonsils. Real-time PCR results demonstrated variant-2 tropism for respiratory tract, digestive system and renal tissue that is due to its epitheliotropic nature. This is the first pathogenicity study of Iranian variant-2 virus. Based on histology observations and clinical signs this isolate was classified as a nephropathogenic IBV. Further knowledge of IBV pathogenesis permits to perform more effective prevention practice.

Including 793/B type avian infectious bronchitis vaccine in 1-day-old chicken increased the protection against QX genotype

“…Before use, the plasmid concentration was determined by spectrophotometry at 260 nm and calculated as genomeequivalents (copies) per milliliter as the ELISA titer, ciliostasis score, tracheal viral load, and kidney viral load are shown in all groups a,b,c,d There was a non-significant difference (P ≤0.05) between the non-vaccinated-challenged group with vaccinated groups molecular weight of the plasmid was known. Serial dilutions were performed togive a final concentration between 102 and 105 (for 5′-UTR) and 102 and 105 (for 28s rRNA) copies for generating the standard curves (Najafi et al 2016a).…”

Coronavirus: proteomics analysis of chicken kidney tissue infected with variant 2 (IS-1494)-like avian infectious bronchitis virus

“…Each group consisted of 10 SPF chickens that were kept in a separate positive-pressure SPF chicken isolator for 22 days. Group A was the control group, and the chickens in group B were inoculated with 0.1 ml of 10 4.5 EID 50 of the isolate IBV/chicken/Iran/UTIVO-C/2014 (KR869776) via the oculonasal route at the age of 14 days [14]. Group A (control) received 0.1 ml of PBS via the same route.…”

“…Up to now, published research has been carried out on IBV strains such as H120 and IBV CK/CH/LDL/97I, but no studies have investigated proteome changes following infection with a variant 2 genotype [10,13]. The nephropathogenicity of the variant 2 genotype isolate IS/1494/06 has been demonstrated [14].…”

Complete genome analysis of Iranian IS-1494 like avian infectious bronchitis virus

“…The IS-1494 like IBVs is the main genotype in the Middle East, and African countries such as Iran, Jordan, Egypt, Turkey and recently reported from Europe [ 9 ]. The IS-1494 like IBV is known to be nephropathogenic, and it also affects the respiratory system [ 15 ]. Till now, seven genotypes of IBV (Massachusetts (Mass), 793/B, IS-1494, IS-720, QX, IR-1, and IR-2) are reported in Iran [ 16 ].…”

“…In the study done by Najafi et al (2015), IS-1494 like IBV with the total prevalence of 34% in Iranian chicken flocks. Regarding the pathogenicity of Iranian IS-1494 like a virus, Najdfi et al [ 14 ] demonstrated variant-2 has high tropism to the respiratory tract, digestive system, and renal tissue that is due to its epitheliotropic nature. The Mahed genome organization was: (5′-1a-1b-S-3a-3b-E-M-4b-4c-5a-5b-N-6b-3′).…”