Legnardi Matteo, Franzo Giovanni, Tucciarone Claudia Maria, Catelli Elena, Menandro Maria Luisa, Cecchinato Mattia
Department of Animal Medicine, Production and Health (MAPS) - University of Padua.
Department of Animal Medicine, Production and Health (MAPS) - University of Padua, Italy.
Vet Ital. 2022 Nov 18;58(1):41-45. doi: 10.12834/VetIt.2084.11082.2.
Infectious bronchitis virus (IBV) is among the most impactful poultry pathogens, whose control, based on biosecurity and routine vaccination, is hampered by the existence of countless genetic variants sharing poor cross‑protection. A retrospective study was conducted on IBV positive samples collected in Italian broiler farms from 2012 to 2019. In 2015, the adopted vaccination protocol shifted from a Mass and 793B‑based vaccines to the administration of Mass and QX vaccines, allowing to study how changes in vaccination strategies may affect IBV epidemiology, control and diagnosis in the field. The most frequently detected lineages were QX (70.3%), 793B (15.8%) and Mass (11.9%). The relative frequencies of QX and 793B detections remained stable throughout the study, while Mass detections significantly increased after the vaccination change. Rather than to an actual growth of Mass population size, this finding may be attributable to different vaccine interactions, with Mass strains being more frequently concealed by 793B vaccines than by QX ones. Based on the obtained results, the two vaccination protocols appear to be similarly effective in fighting IB outbreaks, which in the last decade have been caused primarily by QX field strains in Italy. These results indicate that vaccination strategies may significantly affect IBV epidemiology and diagnosis, and should therefore be considered when choosing and interpreting diagnostic assays and planning control measures.
传染性支气管炎病毒（IBV）是对家禽影响最大的病原体之一，基于生物安全和常规疫苗接种的防控措施，因存在无数交叉保护能力差的基因变体而受到阻碍。对2012年至2019年在意大利肉鸡场采集的IBV阳性样本进行了一项回顾性研究。2015年，采用的疫苗接种方案从基于Mass和793B的疫苗转变为Mass和QX疫苗的接种，从而能够研究疫苗接种策略的变化如何影响该领域的IBV流行病学、防控和诊断。最常检测到的谱系是QX（70.3%）、793B（15.8%）和Mass（11.9%）。在整个研究过程中，QX和793B检测的相对频率保持稳定，而在疫苗接种改变后，Mass检测显著增加。这一发现可能并非归因于Mass种群规模的实际增长，而是由于不同疫苗之间的相互作用，与QX疫苗相比，793B疫苗更频繁地掩盖了Mass毒株。根据获得的结果，这两种疫苗接种方案在对抗IB疫情方面似乎同样有效，在过去十年中，意大利的IB疫情主要由QX田间毒株引起。这些结果表明，疫苗接种策略可能会显著影响IBV的流行病学和诊断，因此在选择和解释诊断检测方法以及规划防控措施时应予以考虑。
