College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701, Korea.
Poult Sci. 2012 Jan;91(1):89-94. doi: 10.3382/ps.2011-01739.
Infectious bronchitis virus (IBV) infections cause great economic losses to the poultry industry worldwide, and the emergence of new variant strains complicates disease control. The present study investigated the genetic and protectotypic features of newly emerged Korean IBV strains. A phylogenetic analysis showed that several recent isolates formed 2 different clusters (new cluster 1 and 2), which were distinct from other preexisting clusters. New cluster 1 IBV strains represented recombinants between Korean nephropathogenic strain KM91 and the QXIBV strain. New cluster 2 IBV strains showed low amino acid homology (<58.7%) compared with previous isolates. We evaluated the protective efficacy of commercial IBV vaccines (H120 and K2 strain) against these new isolates. In cross-protection studies, the H120 strain did not provide sufficient protection against these variants. However, highly attenuated nephropathogenic IBV vaccine, K2 strain, provided significantly higher levels of protection against variants compared with chickens vaccinated with H120 (P < 0.05 or better). These results indicate that the K2 vaccine could be helpful for the reduction of economic losses caused by newly evolving IBV recombinants (new cluster 1) and variants (new cluster 2).
传染性支气管炎病毒 (IBV) 感染给全球家禽业造成了巨大的经济损失,新变异株的出现使疾病控制变得更加复杂。本研究调查了新出现的韩国 IBV 株的遗传和保护型特征。系统进化分析表明,最近的几个分离株形成了 2 个不同的簇(新簇 1 和 2),与其他现有的簇明显不同。新簇 1 IBV 株代表了韩国肾病株 KM91 与 QXIBV 株之间的重组。与以前的分离株相比,新簇 2 IBV 株的氨基酸同源性较低(<58.7%)。我们评估了商业 IBV 疫苗(H120 和 K2 株)对这些新分离株的保护效果。在交叉保护研究中,H120 株不能为这些变异株提供充分的保护。然而,高度减毒的肾病性 IBV 疫苗 K2 株对变异株的保护水平明显高于用 H120 接种的鸡(P<0.05 或更好)。这些结果表明,K2 疫苗可能有助于减少由新进化的 IBV 重组体(新簇 1)和变异体(新簇 2)引起的经济损失。