초록
IBV는 전세계적으로 양계산업에 문제시되고 있는 호흡기성 질병으로 육계 및 산란계의 생산성에 큰 영향을 미치고 있다. 본 연구는 2018년도에 분리된 3개의 IBV의 병원성을 확인하였다. 동물실험을 통해서 염증정도, 섬모소실도 그리고 폐사율의 결과를 바탕으로 2018년도 분리주인 QX-like IBV형은 병아리에게서 충분한 병원성을 지닌 것을 확인하였다.
Infectious bronchitis virus (IBV) is an acute respiratory disease, causing economic losses in poultry production. IBV commonly manifests respiratory disease symptoms and poor egg quality in poultry, affecting overall performance of both broilers and layers. IBV infection further predisposes poultry to secondary opportunistic bacterial infections. IBV undergoes rapid genetic evolution resulting in various new strains. There is no cross protection among IBV serotypes which makes full protection against wild-type IBV virtually impossible. In this study, recently isolated IBVs (K24/18, K29/18, K183/18) from Korean broiler farms were genetically analyzed based on S1 gene. According to the results, IBV isolates showed highest homology with QX-IBV. However, phylogenetic tree analysis revealed that isolates were divided into distinct sub-clusters within QX-IBV. To determine pathogenicity of IBV, day-old chicks were challenged with IBV through ocular route. After challenging the chicks, we executed microscopic examination, virus detection in their organs, and observation of clinical signs and mortality. We found that the K24/18, K29/18, K183/18 challenge groups showed 28%, 57%, and 42% mortality, respectively, with high microscopic trachea lesion scores, indicating that these QX-IBV-like strains are pathogenic to chicks and can therefore be a threat to poultry production.
