Genotyping and pathotyping of diversified strains of infectious bronchitis viruses circulating in Egypt

• 作者: Abdel-Satar Arafa Ali Zanaty Magdy El-Kady Naglaa Hagag
• 来源期刊: 世界病毒学杂志
• 学科: 医学
• 关键词: INFECTIOUS BRONCHITIS VIRUS PHYLOGENETIC analysis Variant INFECTIOUS BRONCHITIS VIRUS S1 gene HVR-3 Sequencing EGYPT
• 年，卷（期）: 2016,（3）
• 页码范围: 125-134
• 页数: 10页
• 分类号: R

摘要

AIM:To characterize the circulating infectious bronchitis virus(IBV)strains in Egypt depending on the sequence of the spike-1(S1)gene[hypervariable region-3(HVR-3)]and to study the pathotypic features of these strains.METHODS:In this work,twenty flocks were sampled for IBV detection using RRT-PCR and isolation of IBV in specific pathogen free(SPF)chicks during the period from 2010 to 2015.Partial sequencing and phylogenetic analysis of 400 bp representing the HVR-3 of the S1 gene was conducted.Pathotypic characterization of one selected virus from each group(Egy/Var-Ⅰ,Egy/Var-Ⅱand classic)was evaluated in one day old SPF chicks.The chicks were divided into 4 groups 10 birds each including the negative control group.Birds were inoculated at one day by intranasal instillation of 105EID50/100μL of IBV viruses[IBV-EG/1212B-2012(Egy/Var-Ⅱ),IBV/EG/IBV1-2011(Egy/Var-Ⅰ)and IBV-EG/11539F-2011(classic)],while the remaining negative control group was kept uninfected.The birds were observed for clinical signs,gross lesions and virus pathogenicity.The real-time rRTPCR test was performed for virus detection in the tissues.Histopathological examinations were evaluated in both trachea and kidneys.RESULTS:The results revealed that these viruses were separated into two distinct groups;variant(GI-23)and classic(GI-1),where 16 viruses belonged to a variant group,including 2 subdivisions[Egy/Var-Ⅰ(6 isolates)and Egy/Var-Ⅱ(10 isolates)]and 4 viruses clustered to the classic group(Mass-like).IBV isolates in the variant group were grouped with other IBV strains from the Middle East.The variant subgroup(Egy/Var-Ⅰ)was likely resembling the original Egyptian variant strain(Egypt/Beni-Suif/01)and the Israeli strain(IS/1494/2006).The second subgroup(Egy/Var-Ⅱ)included the viruses circulating in the Middle East(Ck/EG/BSU-2 and Ck/EG/BSU-3/2011)and the Israeli strain(IS/885/00).The two variant subgroups(Egy/Var-Ⅰand Egy/Var-Ⅱ)found to be highly pathogenic to SPF chicks with mortalities up to 50%than those of the classic gr