奶牛乳房炎主要病原菌EF-Tu蛋白同源性及T、B细胞抗原表位分析  

Homology of EF-Tu Protein and Antigen Epitopes of T and B Cells in Main Pathogenic Bacteria of Cow Mastitis

作　　者：范钊玮 陈晶[1] 杨思宇 刘慧婷 王蓝悦 王然 马骏 王欣 冯振月[1] 于永忠[1] 崔玉东[1] Fan Zhaowei;Chen Jing;Yang Siyu;Liu Huiting;Wang Lanyue;Wang Ran;Ma Jun;Wang Xin;Feng Zhenyue;Yu Yongzhong;Cui Yudong(College of Life Science and Technology,Heilongjiang Bayi Agricultural University,Daqing 163319)

机构地区：[1]黑龙江八一农垦大学生命科学技术学院,大庆163319

出　　处：《黑龙江八一农垦大学学报》2022年第3期55-61,共7页journal of heilongjiang bayi agricultural university

基　　金：黑龙江省科学基金重点项目(ZD2016004)。

摘　　要：奶牛乳腺炎是由病原菌感染引起的急性或慢性乳腺疾病,严重危害奶牛健康和影响奶业发展。随着病原菌耐药性不断增强,抗生素治疗奶牛乳腺炎的效果越来越不佳。因此,研究和使用疫苗预防奶牛乳腺炎越来越受到重视。引起奶牛乳腺炎的病原菌主要为无乳链球菌、停乳链球菌、乳房链球菌、金黄色葡萄球菌和埃希氏大肠杆菌等。能否从这些病原菌中寻找高度保守的共同蛋白质分子作为疫苗候选抗原是值得研究的课题。延伸因子-Tu(Elongation factor Tu,EF-Tu)是存在于真核细胞和细菌细胞内参与RNA翻译的常见功能蛋白。研究表明,多种病原菌的EF-Tu作为抗原均能够诱导良好免疫保护作用。因此,研究对分离得到的无乳链球菌、停乳链球菌、乳房链球菌、金黄色葡萄球菌和埃希氏大肠杆菌EF-Tu基因进行了Sanger法测序,然后对其编码蛋白的理化性质、结构、同源性、T细胞和B细胞表位等进行分析比较。结果显示,无乳链球菌、停乳链球菌、乳房链球菌EF-Tu由398个氨基酸组成;金黄色葡萄球菌、埃希氏大肠杆菌EF-Tu分别由394、409个氨基酸组成,相对分子质量均为44 kda左右,且无规则卷曲占比较高;EF-Tu蛋白是一种无信号肽、无跨膜结构域的亲水性分泌蛋白,对其核苷酸和氨基酸序列进行同源性分析显示,三种链球菌EF-Tu氨基酸序列同源性高于91%,与金黄色葡萄球菌、埃希氏大肠杆菌的同源性超过68%;对EF-Tu的T细胞表位和B细胞表位进行预测,得到11个IC50值小于50 nM的共同T细胞表位和7个阈值大于0.5的B细胞表位,说明具有交叉免疫原性,为进一步开展EF-Tu叉免疫原性研究提供参考。Cow mastitis was an acute or chronic mammary disease caused by pathogenic bacteria infection,which seriously harmed the health of dairy cows and affected the development of dairy industry.With the increasing drug resistance of pathogenic bacteria,the effect of antibiotics in the treatment of cow mastitis was becoming worse.Therefore,research and use of vaccine to prevent from cow mastitis had been paid more and more attention.The main pathogens that caused cows mastitis were mainly Streptococcus agalactiae,Streptococcus dysgalactiae,Streptococcus uberis,Staphylococcus aureus and Escherichia coli.Whether highly conserved common protein molecules were found from these pathogens as vaccine candidate antigens was useful.Elongation factor Tu(EF-Tu)was a common functional protein involving in RNA translation in eukaryotes and bacteria.Studies had shown that EF-Tu from a variety of pathogens could induce good immune protection as an antigen.Therefore,the isolated Streptococcus agalactiae,Streptococcus dysgalactiae,Streptococcus uberis,Staphylococcus aureus and Escherichia coli EF-Tu genes were sequenced by Sanger method in this study.And their physical and chemical properties,structure,homology,T cell and B cell epitopes were analyzed with bioinformatics methods.The results showed that EF-Tu proteins from Streptococcus agalactiae,Streptococcus dysgalactiae and Streptococcus uberis are composed of 398 amino acids,and Staphylococcus aureus and Escherichia coli were respectively composed of 394 and 409 amino acids.Their relative molecular weight was about 44 kDa.EF-Tu protein was a secreted hydrophilic protein without signal peptide and transmembrane domain.Homology of EF-Tu nucleotide and amino acid sequences from the three streptococcus species was higher than 91%,and the homology with Staphylococcus aureus and Escherichia coli was more than 68%.EF-Tu protein had 11 common T cell epitopes with high affinity and 7 B cell epitopes with threshold value greater than 0.5,indicating that EF-Tu protein had cross immunogenicity.

关 键 词：奶牛乳腺炎 无乳链球菌 停乳链球菌 乳房链球菌 金黄色葡萄球菌 埃希氏大肠杆菌 延伸因子-Tu 生物信息学分析 

分 类 号：S855.1[农业科学—临床兽医学]