摘要
以广东省内5个罗非鱼Oreochromis niloticus主要养殖区内分离的无乳链球菌Streptococcus agalactiae为研究目标,通过毒力基因PCR检测、多位点序列分型、脉冲场凝胶电泳技术研究广东地区感染罗非鱼的无乳链球菌分子特征。结果发现170株分离无乳链球菌中毒力基因的携带率介于60.59%~100%之间,毒力基因携带形成10个谱系,dltR-bca-sod A-spb1-cfb-bac（38.24%,65/170）,dltr-bca-sod A-spb1-bac（23.53%,40/170）和dltr-bca-sod A-spb1-cfb-bac-scp B（22,35%,38/170）为主要的谱系,dltr-bca-sod A-spb1-bac-scpb（8.24%,14/170）和dltr-bca-sod A-spb1（4.71%,8/170）次之。多位点序列分型研究证实170株菌在7个位点均为单一的等位基因,为adh P（10）,phe S（1）,atr（2）,gln A（1）,sdh A（3）,glc K（2）,tkt（2）,序列型为ST7型。146株菌脉冲场凝胶电泳结果表明146株菌分为6个簇（A-D,F,G）,相似性介于86%~100%之间。A（18）,B（16）,C（103）,D（7）为主要的遗传簇,占菌株数的98.63%（144/146）。基因簇A,C在4个采样区均有发现;基因簇B分布在吴川、茂名和阳江;基因簇D分布在茂名、珠海和阳江;基因簇F和G分别来自茂名和珠海。在A-D遗传簇中均有发现来自不同地区的菌株呈现100%的相似性,为同一克隆株。结果表明广东省主要罗非鱼养殖区内感染链球菌携带毒力基因比率高,序列型均为高致病的ST7型别,不同地区间具有相同的PFGE型别,不同地区间交叉传播感染的可能高。
Tilapia samples were collected from five main tilapia farms in Guangdong. The characteristics of the isolates were determined by virulence gene detection,Multilocus Sequencing Type（ MLST）,and Pulsed-Field Gel Electrophoresis（ PFGE）. The frequency of virulence gene in all isolates varied from60. 59% to 100%. Ten distribution patterns of virulence gene were identified,dltR-bca-sod A-spb1-cfb-bac（ 38. 24%,65 /170）,dltr-bca-sod A-spb1-bac（ 23. 53%,40 /170）,and dltr-bca-sod A-spb1-cfbbac-scp B（ 22,35%,38 /170） were the predominant patterns,followed by dltr-bca-sod A-spb1-bacscpb（ 8. 24%,14 /170） and dltr-bca-sod A-spb1（ 4. 71%,8 /170）. The single allele was observed in each of seven loci,adh P（ 10）,phe S（ 1）,atr（ 2）,gln A（ 1）,sdh A（ 3）,glc K（ 2）,tkt（ 2） and result in unique ST 7（ Sequencing Type 7）. One hundred and forty-six isolates were assigned to six clusters based on the PFGE results. The similarity between these clusters ranged from 86% to 100%. Cluster A（ 18）,B（ 16）,C（ 103） and D（ 7） were the predominant clusters,account for 98. 63% of all isolates. Cluster A and C were distributed in all four areas,Cluster B were mainly isolated from Wuchuan,Maoming and Yangjiang,whereas Cluster D were isolated from Maoming,Zhuhai and Yangjiang. The unique clusters F and G were isolated from Maoming and Zhuhai,respectively. In addition,the clones in Clusters A--D isolated from different areas in Guangdong showed 100% similarity. High proportion of strains with virulence gene was observed in Streptococcus agalactiae strains isolated from tilapia farm in Guandong. All of isolates belonged to the unique ST7. The clones with 100% similarity were identified in different area suggesting the cross infection and transmission in Guangdong,China.
出处
《中山大学学报（自然科学版）》
CAS
CSCD
北大核心
2016年第2期97-101,110,共6页
Acta Scientiarum Naturalium Universitatis Sunyatseni
基金
广东省鱼病专项基金资助项目(粤财农〔2014〕89号)
