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Abstract：
Avian infectious bronchitis (AIB) is a highly transmissible infection that affects the poultry industry globally. This study aims to isolate and characterize emerging strains of infectious bronchitis virus (IBV) from field samples of layer chickens in Bangladesh. A total of 108 samples (trachea, lung, and kidney) were taken from dead and sick layer chickens from 18 farms in 4 areas detecting outbreaks in Bangladesh. The samples were processed and inoculated in embryonated chicken eggs (ECEs) and finally screened by the trypsin-induced hemagglutination (THA) test. Using various techniques such as hemagglutination inhibition (HI), agar gel immuno-diffusion (AGID), virus neutralization test (VNT), reverse transcription-polymerase chain reaction (RT-PCR), and nucleotide sequencing, we were able to identify and confirm the isolated IBV viruses. The study also determined the hemagglutination (HA) pattern of isolated virus using avian and mammalian red blood cells. The pathogenicity of the isolated IBV was determined using embryonated chicken eggs and day-old chicks. The study found that 8 samples were positive for IBV using ECEs, and 4 were positive by the THA test. These isolates were confirmed using HI, AGID, and VN tests. S1 gene-based RT-PCR confirmed all four isolates as IBV, with the recent isolates belonging to the genotype-QX and being similar to IBV isolates from Thailand, Saudi Arabia, and India. The HA pattern of the recent isolates showed that the isolated IBV was virulent. The pathogenicity test also revealed that the four isolates were highly pathogenic. The study indicated that the prevalent genotype (QX) of the IBV strain is present in the layer chicken population of Bangladesh.
摘要：
禽传染性支气管炎（AIB）是一种高度传染性的感染，影响着全球的家禽业。这项研究旨在从孟加拉国蛋鸡的田间样品中分离和鉴定新出现的传染性支气管炎病毒（IBV）菌株。总共108个样本(气管，肺，和肾脏）取自孟加拉国4个地区发现疫情的18个农场的死病层鸡。将样品处理并接种在含胚鸡蛋(ECE)中,最后通过胰蛋白酶诱导的血凝(THA)试验进行筛选。使用各种技术，如血凝抑制（HI），琼脂糖免疫扩散（AGID），病毒中和试验（VNT），逆转录-聚合酶链反应(RT-PCR),和核苷酸测序，我们能够鉴定和确认分离的IBV病毒。该研究还确定了使用禽类和哺乳动物红细胞的分离病毒的血凝（HA）模式。使用含胚鸡蛋和日龄雏鸡确定分离的IBV的致病性。研究发现，使用ECE的8个样本对IBV呈阳性，和4通过THA测试为阳性。这些分离株使用HI进行了确认，AGID,和VN测试。基于S1基因的RT-PCR证实所有四个分离株为IBV，最近的分离株属于基因型QX，与泰国的IBV分离株相似，沙特阿拉伯,和印度。最近分离株的HA图谱表明，分离的IBV具有毒力。致病性测试还显示，这四个分离株具有高致病性。研究表明，IBV菌株的流行基因型（QX）存在于孟加拉国的蛋鸡种群中。
