肾型鸡传染性支气管炎病毒DQ株S_1基因结构分析

Structural analysis of the S_1 gene of nephropathogenic isolate DQ of avian infectious bronchitis virus

选用Trizol试剂抽提肾型鸡传染性支气管炎病毒 (IBV)DQ株基因组RNA ,采用特异性引物通过RT -PCR扩增其S1基因cDNA ,克隆入pBluescript质粒载体中 ,作测序分析。结果表明 ,DQ株S1基因全长为 1731nt ,编码一条 5 76个氨基酸组成的多肽 ,其核苷酸与IBV - 4 / 91,Gray ,D4 1,Bei jing ,ZJ971,Beaudette ,H12 0 ,M4 1毒株的同源性为 78.4 %～ 82 .73% ,氨基酸同源性为 74 .4 1%～ 78.96 %。DQ株不同于其它血清型IBV的主要特征为 :在S1基因核苷酸序列上 ,第 2 78- 2 99位之间插入了一段新的序列 ,第 4 2 3- 4 31位碱基缺失 ,有许多点突变 ;二级结构上表现为第 2 - 2 2位氨基酸区域、第 92 - 98位氨基酸区域亲水性增强 ,第 74 - 76位氨基酸区域疏水性增强 ,最大亲水峰改变。S1分子进化系统分析显示 ,DQ株与其它各毒株的亲缘关系较远。

The genome RNA of nephropathogenic isolate DQ of avian infectious bronchitis virus was extracted by means of Trizol reagent ,cDNA of S 1 gene of isolate DQ was amplified by reverse transcription polymerase chain reation with special primer and was cloned into plasmid pBluescript SK.The cloned S 1 gene was sequenced and was analysed. Results showed that cDNA of S 1 gene of isolate DQ was composed of 1 731 nucleotides encoding for a polypedptide of 576 amino acids.Nucleotide homogeneity of S 1 gene between isolate DQ and other IBV isolates of different serotypes 4/91,Gray,D41,Beijing,ZJ971,Beaudette,H 120 ,M41 ranged from 78.4% to 80.73%.Amino acid homogeneity was 74.41% to 78.96%. Major specialities of isolate DQ differing from other isolates were base insertion at the site 278-299 bp and base deletion at the site 423-431 bp ,as well as much point mutation.These mutations caused conformational changes in the secondary structure of S 1 glycoprotein of isolate DQ with increased hydrophilicity at the both sites of 2-22AA and 92-98AA, and increased hydrophobicity at the site 74-76AA.Evolution analysis indicated that isolate DQ was in far relation to the other strains of IBV.