Infectious bronchitis (IB) is one of the avian diseases with the greatest impact on poultry farming worldwide. In Brazil, strain BR-I (GI-11) is the most prevalent in poultry flocks. The present study aimed to develop a seminested RT-PCR assay specific for the diagnosis of BR-I IBV in Brazilian samples, targeting subunit 1 of the S gene. The detection limit of this assay was 10 copies of the IBV genome. In this study, 62.24% of 572 organ pools from the 5 regions of Brazil tested positive in a 3'UTR screening, and 84.83% were typed as BR-I IBV. BR-I was detected in the respiratory, digestive and urogenital tracts in pooled samples from all Brazilian geographical regions and in all the breeding systems analyzed. Specificity and sensitivity tests as well as phylogenetic analysis successfully confirmed the expected clustering of the sequences detected by this assay with the BR-I (GI-11) group. The nested PCR described in this study represents a suitable and valuable tool in the diagnosis, epidemiology, monitoring and vaccination decisions of IBV.

中文翻译：

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半嵌套式RT-PCR，用于巴西BR-1传染性支气管炎病毒株（GI-11）的分子基因分型。

传染性支气管炎（IB）是一种禽类疾病，对全世界的家禽养殖影响最大。在巴西，BR-1型（GI-11）菌株在家禽群中最为流行。本研究的目的是开发一种半巢式RT-PCR分析法，该方法特异性用于诊断巴西样品中的BR-1 IBV，靶向S基因的亚基1。该测定法的检测极限是IBV基因组的10个拷贝。在这项研究中，来自巴西5个地区的572个器官库中的62.24％在3'UTR筛查中呈阳性，而84.83％被定为BR-1 IBV。在来自巴西所有地理区域的所有样本和分析的所有繁殖系统中，在呼吸道，消化道和泌尿生殖道中均检出了BR-1。特异性和敏感性测试以及系统发育分析成功证实了该检测方法与BR-1（GI-11）组的预期聚类。本研究中描述的巢式PCR代表了IBV的诊断，流行病学，监测和疫苗接种决策的合适且有价值的工具。