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目的利用生物信息学方法分析Sao蛋白结构并预测B细胞抗原表位,筛选可用于疫苗设计的序列。方法以Sao蛋白的氨基酸序列为基础,利用Protparam工具分析蛋白基本理化性质,TMHMM预测跨膜区,PredictProtein在线分析蛋白二级结构,SWISS-MODEL软件模拟三级空间构象,DNASTAR分析亲(疏)水性、可塑性和表面可及性,综合使用在线ABCPred和BepiPred工具预测B细胞抗原表位,筛选能用于构建基因工程疫苗的蛋白序列。结果 Sao蛋白羧基端存在7个高度一致的重复序列以及1个LPVTG保守膜锚定基序,二级结构组分中无规卷曲比例高达74.21%,三级空间构象模拟结果与二级结构预测一致。蛋白的亲水区域、可塑性区域、表面可及性区域比例分别为76.21%、64.06%和75.04%。Sao存在多个线性抗原表位,经筛选得到两个可用于疫苗设计的蛋白序列,BLAST显示这两个序列为猪链球菌所特有,存在于2型猪链球菌9种不同的分离菌株中,同时也存在于猪链球菌致病性血清型1、2、1/2、3、7、9、14型中。结论 Sao蛋白为不稳定蛋白,亲水性强,筛选得到的两个蛋白序列抗原性强且高度保守,为猪链球菌特有序列,能够用于基因工程疫苗的构建。
Objective To analyze the structure of Sao protein and predict the B cell epitopes by bioinformatics method and screen the sequences which can be used in vaccine design. Methods Based on the amino acid sequence of Sao protein, Protparam tool was used to analyze the basic physical and chemical properties of protein. TMHMM was used to predict the transmembrane region. PredictProtein was used to analyze the protein secondary structure. SWISS-MODEL software was used to simulate tertiary spatial conformation. DNASTAR was used to analyze the hydrophobicity , Plasticity and surface accessibility using online ABCPred and BepiPred tools to predict B cell epitopes and to screen for protein sequences that can be used to construct genetically engineered vaccines. Results There were seven highly identical repeats and one LPVTG conserved membrane anchoring motif at the carboxy-terminal of Sao protein. The percentage of random coil in the secondary structure was as high as 74.21%. The results of the three-space conformation simulation were consistent with those of the secondary structure. The hydrophilic region, plasticity region and surface accessibility region of the protein were 76.21%, 64.06% and 75.04% respectively. Sao has a number of linear epitopes. Two protein sequences were screened for vaccine design. BLAST showed that these two sequences were unique to S. suis and existed in 9 different isolates of Streptococcus suis type 2, Also present in Streptococcus suis pathogenic serotypes 1,2,1 / 2,3,7,9,14 type. Conclusions Sao protein is an unstable protein with strong hydrophilicity. The two selected protein sequences are highly antigenic and highly conserved, which are unique to Streptococcus suis and can be used to construct genetic engineering vaccines.