Abstract: Dwarfing embryonated chicken eggs, HA and reverse transcription polymerase chain reaction (RT-PCR) methods were used in this test. And an infectious bronchitis virus (IBV) strain named SX01 was identified from a suspected farm in North China. The result showed that the isolate could cause a typical clinical symptom of chicken embryos. And there were no direct hemagglutination activity, but it could agglutinate chicken red blood cells after treatment with 1% trypisn. The sequencing analysis of M gene detected by RT-PCR showed that the homology of the nucleotide sequence of M genes between SX01 and GX-GL isolates was 99.4%, and with the 99.1% homology to SDZB0808 strain of QX genotype, but with lower homology in BJ/00/02 strain and H120 vaccine strain which were 90.6% and 90.0%, respectively. Analysis of the phylogenetic tree based on M gene showed that the isolate had the closed relationship with GX-GL, SDZB0808, CK/CH/LJL/110302, DY07 and IBVSX7, and were clustered into one group; but with the distant relatives from vaccine strain H120. The results suggested that SX01 was a kidney type IBV strain.

Key words: infectious bronchitis virus; virus isolation; sequence analysis