2型猪链球菌表面蛋白Sao的生物信息学分析及基因工程疫苗的设计

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。

Bioinformatics analysis of Sao protein and design of a vaccine against Streptococcus suis type 2

Objective To use bioinformatics to analyze the structure and predict the B-cell-epitopes of the protein Sao in order to screen sequences to design a vaccine against Streptococcus suis type 2. Methods Based on the sequence of the Sao protein, the basic physical and chemical properties, transmembrane domains, secondary structures, tertiary structure, hydrophilicity, flexibility, surface accessibility, and antigen epitopes of the protein Sao were predicted using bioinformatics software. Results Results indicated that the carboxy-terminal of the protein Sao had seven highly conserved repeats and one LPVTG membrane anchor motif. The random coil accounted for 74.21% of the protein, and simulation of the three-dimensional conformation was consistent with the predicted secondary structure. The hydrophilic region accounted for 76.21% of the protein, the flexible region accounted for 64.06%, and the region with an accessible surface accounted for 75. 04%. Sao had multiple linear epitopes and two protein sequences had potential for design of a vaccine. BLAST results showed that these two sequences only existed in S. suis and were highly conserved in the pathogenic S. suis serotypes 1, 2, 1/2, 3, 7, 9, and 14. Conclusion Sao is an unstable protein with strong hydrophilicity. The two screened protein sequence were highly conserved and had strong antigenicity and could be used to genetically engineer a vaccine.