摘要
猪链球菌2型(SS2)是一种重要的人畜共患病病原,研究表明其致病力与毒力因子的相关性各有不同。为探究SS2毒力因子与致病性间的相关性,明确毒力因子能否用于致病性的评价,本研究通过PCR方法对来自吉林省9个不同规模和经营模式的猪场临床健康猪群的32株SS2分离菌株和5个强毒参考菌株的毒力相关基因(38KD蛋白、GDH、OFS、SLY、HYL、FBPS、GAPDH、ORF2和Ssn A)进行克隆测序,比较这9个毒力相关基因在该37株SS2分离株中的分布差异和突变情况。结果显示各个毒力相关基因在来自临床健康猪群的32个分离株和5个强毒参考株中呈现不均等的分布,在强毒参考菌株中谷氨酸脱氢酶(GDH)、38KD蛋白、分泌性核酸酶(Ssn A)基因的检测阳性率达到100%,在健康猪群分离株中它们的阳性率也超过90%。纤维蛋白原结合蛋白(FBPS)和溶血素(SLY)基因在强毒参考菌株中阳性率为100%,而在健康猪群分离株中FBPS和Sly基因检测率分别为68.75%和65.63%。透明质酸裂解酶(HYL)基因在两类菌株间阳性率相差较大,在强毒参考株中其阳性率约为60%,在健康猪群分离株中HYL阳性率仅为18.75%。通过测序和Blast比对分析显示,健康猪分离株中毒力相关基因突变情况非常少,而SS2强毒参考株中其突变位点较多,并呈现多种突变方式,GAPDH、HYL、Ssn A基因属于保守序列,突变较少。SLY和GDH基因也是保守序列,在健康猪群分离株中只发现一株无意义突变,但在强毒参考株中却发现多个导致氨基酸改变的突变位点和突变方式。OFS、ORF2和FBPS基因在两组菌中均有突变,但在强毒参考株中存在较多的突变,并且可造成其编码的氨基酸序列改变。提示SS2毒力相关因子复杂,仅仅依据毒力基因是否存在不能判断其毒力的强弱,其突变位点及突变方式对毒力的判断也具有一定的参考意义。
Streptococcus suis type 2 （SS2） is an important zoonosis pathogen. There are different correlations between pathogenicity and virulence factors in different strains based on previous studies. In order to explore the relevance between virulence factors and pathogenicity, and to determine whether virulence factors can be used to evaluate pathogenicity, PCR method was used to acquire the virulence-associated genes of all the 32 SS2 isolates from healthy pigs of nine pig farms with differernt scale and management modes and 5 virulent reference strains. The results of gene squencing analysis found the difference of distribution and the mutation status of these 9 virulence factors among 37 SS2 isolated strains and demonstrated that the distribution was unequal of every virulence-associated genes in the 32 SS2 isolates and 5 virulent reference strains. In virulent reference strains, the positive rates of GDH, 38KD protein, SsnA genes were reached to 100% and in the isolates, the positive rates also exceeded to 90%. The positive rates of FBPS and SLY genes were 100% in virulent reference strains, however, they were only 68.75% and 65.63% respectively in the isolates. The positive rate of HYL was about 60% in virulent reference strains and was only 18.75% in the isolates. Meanwhile, the sequencing and comparative analysis showed that the mutation phenomenon was rarely found in the isolates, however, the multiple mutations were found in virulent reference strains. GAPDH, HYL and SsnA genes were relatively conservative. SLY and GDH genes were also conservative, and only one nonsense mutation in the two genes was found in the isolates from healthy pigs. However, the mutations of the two genes were found in many sites with variety mutation modes in virulent reference strains. The mutations of the OFS, ORF2 and FBPS genes were exist in all strains and more mutations were found in virulent reference strains which caused the changes of the amino acid sequences deduced by these genes. The results showed that SS2 virulence factors were complicated and the virulence of SS2 strains couldn’t be decided only by virulence-associated genes. However the mutation sites and the mutation modes still have referenced significance to determimate the virulence of the SS2 strains.
出处
《中国预防兽医学报》
CAS
CSCD
北大核心
2018年第1期50-54,共5页
Chinese Journal of Preventive Veterinary Medicine
基金
国家自然科学基金国际合作重点项目(31520103917)
关键词
猪链球菌2型
毒力相关基因
分布
突变
Streptococcus suis type 2
virulence-associated genes
distribution
mutation
