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Abstract 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.
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Received: 26 January 2008
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