Sequencing and Sequence Analysis of Sl Spike Protein Gene from Avian Infectious Bronchitis Virus Proventriculus Strain Isolated in Qingdao(SD／97／02)

A pair of primers were designed and synthesized according to the reported S1 spike protein gene sequence of IBV.The viral RNA of SD/97/02 strain was amplified by reverse transcription polymerase chain reaction(RT PCR).The amplified product was analyzed by agarose gel electrophoresis,all appeared a fragment of 1657 bp as expected.The RT PCR product was cloned into pMD18 T vector,and then the recombinant plasmid was sequenced.The result suggested that it was the S1 spike gene of IBV.The recombinant plasmid was designated pMDQXS1.The sequence has been published in the Genbank,and the accession number is AF193423.Sequence analysis showed that the S1 gene has low G+C content at about 37.0%.There existed several RE cleavage sites such as Hin d III, Bam H I, Bgl III, Sac I and Sal I,but have no Eco R I site,which is different from that of other strains.Its homology compared with other IBV strains was between 87.02% and 94.21%.In the site between 154 and 429 of this S1 gene is a highly variation r