北京地区急性呼吸道感染儿童RSV F蛋白抗原位点变异分析

Antigenic sites variation of fusion protein of respiratory syncytial virus isolated from children with acute respiratory tract infection in Beijing area

目的 为了解我国北京地区呼吸道合胞病毒（Respiratory Syncytial Virus RSV）融合蛋白F基因特征及抗原位点变异情况,本研究对61株RSV分离毒株F蛋白主要抗原位点区进行了基因序列分析.方法 应用RT-PCR方法分段扩增获得F蛋白主要抗原位点区基因,并对产物进行序列测定及拼接.序列比对分析,构建系统发育树,进行亲缘关系分析.结果 61株RSV分离株中,A亚型为43株,B亚型为18株.A、B亚型内核苷酸（氨基酸）同源性较高,分别为95.9％ - 100％（98.3％ - 100％）及97.5％ - 100％ （98.7％ - 100％）,亚型间为83.2％ -84.9％（93.1％ -95.1％）.基于F蛋白主要抗原位点区基因亲缘进化分析,所有分离株可分为两个主要亚群,分别对应A/B亚型;两个亚群又可分别分成6个及3个不同的进化分支.两个亚群中分别存在7个及4个氨基酸位点突变,其中抗原位点（Φ）存在209位从Q到K及211位从S到N的变异,帕利珠单抗作用的抗原位点Ⅱ存在276位从N到S的位点突变,其余突变均位于非抗原位点决定区.结论 北京地区RSV流行株与原型株相比,F蛋白存在一定的变异,但仍具有较高的核苷酸及氨基酸同源性;各抗原位点区氨基酸保守,为疫苗及相关药物研究的重要候选蛋白.

Objective Respiratory Syncytial Virus （RSV） fusion protein is an important transmembrane glycoprotein associated with virus infection and immunity.To clarify the genetic characteristics and antigenic sites variation in F protein,comprehensive analysis was performed with 61 RSV stains isolated in Beijing area.Methods The antigenic sites area of F protein gene of RSV was amplified by RT-PCR and sequenced.The Phylogenetic trees were constructed with MEGA program.The identity matrices and genetic sites variation were determined with Bioedit software.Results Pairwise nucleotide （amino acid） sequences identities were 95.9%-100% （98.3%-100%） among 43 subtype A,97.5% -100% （98.7%-100%） among 18 subtype B,and 83.2%-84.9% （93.1%-95.1%） between groups A and B,respectively.Phylogenetic analyses revealed that all the strains could be divided into two groups.Further,group A could be divided into 6 clusters,and group B could be divided into 3 clusters.There were 7 and 4 amino acid changes at group A and group B,respectively.Variations at antigenic site （Φ） were observed in amino residues 209 and 211.No more mutation was found on the antigenic sites area except the 276 （N→S） on palivizumab binding site.Conclusions The nucleotide and amino acid have high identity in F protein of Beijing RSV isolates except a few mutations.The F protein remains the potential candidate of RSV vaccine and molecular drugs.