河南省肉鸡4株禽传染性支气管炎病毒的分离鉴定及S1基因序列分析

通过病料接种SPF鸡胚和鸡胚尿囊液的RT-PCR鉴定,于2017至2018年从河南省不同发病鸡场分离到4株鸡传染性支气管炎病毒(IBV),分别命名为HB/L1/201711、ZMD/L2/201704、SQ/L3/201803、LY/L4/201710,并对4株毒株S1基因进行克隆和序列分析。结果:HB/L1/201711、SQ/L3/201803 S1基因全长1 620 nt,编码540 aa,其裂解位点分别为HRRRR,分属于基因型V、Ⅰ分支;ZMD/L2/201704、LY/L4/201710株S1基因全长1 617 nt,编码539 aa,其裂解位点为RRSRR,属于基因型Ⅱ分支。ZMD/L2/201704与LY/L4/201710分离株核苷酸序列及其推导的氨基酸序列同源性较高,分别为97.6%、95.4%,与另外2株分离株之间核苷酸序列同源性为76.5%、76.8%。4株分离株与国内外参考毒株及疫苗株的氨基酸序列同源性在58.5%~98%之间,具有较大的差异性。其中:ZMD/L2/201704、LY/L4/201710与491型传支疫苗氨基酸同源性较高,可达95.4%、95.9%;SQ/L3/201803与CHI分支参考毒株氨基酸同源性在94.6%~98.9%之间;HB/L1/201711与TWⅠ型毒株2575/98、3468/07有较高同源性,分别为94.8%和93.5%。本研究表明河南省肉鸡鸡群鸡传染性支气管炎病毒基因型相对复杂,推测存在重组与突变。

Isolation and identification of four strains of infectious bronchitis virus from broilers in Henan Province and sequence analysis of the S1 gene of the strains

In this study, four strains of chicken infectious bronchitis virus(IBV) were isolated from diseased chickens on different farms in Henan Province from 2017 to 2018 by inoculation of SPF chicken embryos, and were confirmed by RT-PCR of the embryo allantoic fluid of the birds.The strains were named HB/L1/201711, ZMD/L2/201704, SQ/L3/201803 and LY/L4/201710, respectively.Then, the S1 genes of the four strains were cloned, sequenced and analyzed.The results were that the S1 of HB/L1/201711 and SQ/L3/201803 were 1620 nt, encoding 540 amino acids with a cleavage site sequence of HRRRR, and they belonged to genotypes V and I respectively.The S1 of ZMD/L2/201704 and LY/L4/201710 were 1617 nt, encoding 539 amino acids with a cleavage site sequence of RRSRR, and they belonged to genotype Ⅱ.The homologies of nucleotide sequence and deduced amino acid sequence were 97.6% and 95.4% with ZMD/L2/201704 and LY/L4/201710, and were 76.5% and 76.8% with the other two isolates.The four isolates were 58.5% to 98%homology with the reference strains and vaccine strains at home and abroad, implying a remarkable difference between them.Of the isolates, ZMD/L2/201704 and LY/L4/201710 were in 90.9%~97.5% homology with type 491.SQ/L3/201803 was in 94.6%~98.9% homology with the reference strain of CHI.HB/L1/201711 was in 94.8% and 93.5% homology with the TWI strains of 2575/98 and 3468/07,respectively.This study indicated that the genotype of IBVs from the broilers in Henan Province was rather complex,and they might harbor gene recombination and mutation.