Avian Disease Laboratory, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Vaccine. 2010 Apr 1;28(16):2887-94. doi: 10.1016/j.vaccine.2010.01.062. Epub 2010 Feb 11.
A nephropathogenic K2/01 strain of infectious bronchitis virus (IBV) was attenuated by 170 serial passages in embryonated chicken eggs for possible use as a future IBV vaccine strain. High-growth properties and narrow tissue tropisms (limited replication in respiratory tracts) were achieved by the adaptation process. Unlike the parent strain, the attenuated strain (K2p170) was safe in day-old specific-pathogen-free chicks since replication of the virus did not induce mortality and nephritis, and rarely induced histological changes in the trachea and kidney after intraocular administration. In day-old broilers, even though coarse spray administration of K2p170 induced clinical signs, ciliostasis, and histopathological lesions in the trachea and the kidney, they were all comparable to birds vaccinated with commercial H120 vaccine. Despite restriction of viral replication in the respiratory tract, K2p170 elicited the production of antiserum with a neutralization index of 4.5. K2p170 provided almost complete protection against both two distinct subgroups of Korean nephropathogenic strain (KM91-like and QX-like subgroup). Furthermore, K2p170 provided significantly greater cross-protection against two heterologous strains (Massachusetts and Korean respiratory strain) than those conferred by the commercial H120 vaccine. K2p170 also had no virulence reversion after five back passages in chickens. In conclusion, K2p170 exhibits a fine balance between attenuation and immunogenicity, possesses cross-protective efficacy, and merits further investigation as a potential live vaccine as an alternative means of protection against the recently emergent nephropathogenic IBV infection in many Eurasian countries.
一株肾病变型传染性支气管炎病毒（IBV）K2/01 株通过在鸡胚中连续传代 170 代而被弱毒化，可能被用作未来的 IBV 疫苗株。通过适应过程，实现了高生长特性和狭窄的组织嗜性（在呼吸道中的有限复制）。与亲代株不同，减毒株（K2p170）在 1 日龄无特定病原体雏鸡中是安全的，因为病毒复制不会引起死亡率和肾炎，并且在眼内给药后很少引起气管和肾脏的组织学变化。在 1 日龄肉鸡中，即使粗喷雾给予 K2p170 也会引起临床症状、纤毛停滞和气管和肾脏的组织病理学病变，但与接种商业 H120 疫苗的鸟类相当。尽管病毒在呼吸道中的复制受到限制，但 K2p170 诱导产生了中和指数为 4.5 的抗血清。K2p170 对两种不同的韩国肾病变型分离株（KM91 样和 QX 样亚群）几乎提供了完全的保护。此外，K2p170 对两种异源株（马萨诸塞州株和韩国呼吸株）的交叉保护作用明显大于商业 H120 疫苗。K2p170 在鸡中连续传代 5 次后也没有毒力返祖。总之，K2p170 在弱化和免疫原性之间表现出精细的平衡，具有交叉保护效力，值得进一步研究，作为一种潜在的活疫苗，作为保护许多欧亚国家最近出现的肾病变型 IBV 感染的替代手段。
