鸡传染性支气管炎病毒CK/CH/LSD/05I的分离鉴定及弱毒疫苗对其保护研究

本研究从2005到2006年中国部分地区鸡场疑似鸡传染性支气管炎病毒感染鸡分离到12株鸡传染性支气管炎病毒，并对其部分生物学特性及基因型进行了研究。发现其中11株病毒分属于LX4和CK/CH/LSC/99I型。通过S1 基因比较、进化树分析、BLAST搜寻以及动物试验等方面研究发现CK/CH/LSD/05I是一株新型变异毒株。动物感染试验表明CK/CH/LSD/05I感染鸡的肾脏病变不明显，仅有20%的感染鸡肾脏病毒分离呈阳性，但100%感染鸡呼吸道病毒分离阳性，表明该病毒不是中国普遍流行的“肾型”毒株，而其对呼吸道具有强的嗜性。同时，试验应用弱毒疫苗H120和本实验室致弱的3株异种毒株进行了动物保护试验，结果显示用CK/CH/LSD/05I攻毒后，这4株异种传染性支气管炎病毒的免疫对气管的保护率很低。初步提示该毒株可能属新的血清型病毒。

Isolation of an Avian Infectious Bronchitis Virus CK/CH/LSD/05I in China and the protection conferred by attenuated vaccines

Twelve infectious bronchitis virus isolates obtained from commercial suspect chicken flocks in China between 2005 and 2006 were characterized by genotyping and investigation of biological characteristics. Evidence suggested that eleven of the twelve infectious bronchitis virus belonged to the LX4-type and CK/CH/LSC/99I-type. CK/CH/LSD/05I—an IBV variant, which was identified by the phylogenic analysis, BLAST searches of the entire S1 gene and the vaccination-challenge test. Virulence studies indicated that there are not obviously kidney pathological changes on chickens, and the rate of recovery of the virus in the kidney and trachea is 20﹪ and 100﹪, respectively, post-inoculation. Thus CK/CH/LSD/05I was unlike the nephropathogenic IBV isolates found in China, however, it exhibited an affinity for the respiratory tract. Additionally, sufficient respiratory protection was not provided by the commercial vaccine H120 and three heterologous strains against CK/CH/LSD/05I challenge. It was showed that CK/CH/LSD/05I may be a variant of IBV.