螺杆菌属细菌致病基因系统进化分析

Phylogenetic analysis of pathogenic genes in Helicobacter species

背景螺杆菌属(Helicobacter)与多种消化道疾病相关,除幽门螺杆菌(Helicobacter pylori,H.pylori)外,多种非H.pylori螺杆菌属细菌(non-Helicobacter pylori Helicobacters,NHPH)也从多种动物宿主的肝脏、肠道和胆囊中分离出来,作为潜在的人畜共患病病原体,其感染和致病机制尚不清楚.目的基于H.pylori致病基因探讨螺杆菌属细菌的系统进化关系.方法调取12株H.pylori和38株NHPH的基因组,基于16S rRNA、鞭毛、尿素酶以及毒力因子基因,利用MAGA 11软件进行序列比对并构建系统进化树.结果基于16S rRNA基因的系统进化分析结果显示,胃内螺杆菌(Gastric Helicobacter,GH)和肝肠螺杆菌(Enterohepatic Helicobacter Species,EHS)聚集为2个大支,GH宿主均为哺乳动物,而EHS宿主多为禽类和哺乳动物.基于细菌鞭毛动力相关基因(flaA、flaB、fliP、fliQ、fliR、fliG、fliM、fliN)的系统进化分析支持基于16S rRNA基因所得到的系统发育关系,基于脂多糖(lipopolysaccharide,LPS)合成相关基因(lptA,waaC和waaF)的系统进化关系也具有类似的规律.尿素酶基因存在于12株H.pylori和13株胃内NHPH中,仅在4株EHS(H.hepaticus、H.muridarum、H.bilis、H.anseris)中存在,但7个尿素酶基因的系统进化树未见明显一致性规律.结论螺杆菌属细菌的系统进化受到胃和肝肠定植部位的显著影响.

BACKGROUND Helicobacter bacteria are associated with gastrointestinal diseases,especially Helicobacter pylori(H.pylori).With the isolation of many non-Helicobacter pylori Helicobacters(NHPH)from the liver,intestines,and gallbladder of natural animal reservoirs,NHPH have been potential zoonotic pathogens,but their infection and pathogenic mechanisms are still unclear.AIM To explore the phylogenetic relationship of Helicobacter species based on their pathogenic genes.METHODS The present study collected the genomic sequences of 50 strains in genus Helicobacter,including 12 strains of H.pylori and 38 strains of NHPH.Based on 16S rRNA gene and several pathogenic genes(flagella,urease,and virulence factors),MAGA software(Version 11.0)was used to align their sequences and construct phylogenetic trees.RESULTS The phylogenetic tree of 16S rRNA gene showed that gastric Helicobacter(GH)and enterohepatic Helicobacter species(EHS)were clustered into two large branches,respectively.All of the GH’s hosts were mammals,while the hosts of EHS were many wild poultry and mammals.Based on the flagella motility-related genes(flaA,flaB,fliP,fliQ,fliR,fliG,fliM,and fliN),the phylogenetic trees were divided into two major branches(GH and EHS).Similarly,the phylogenetic trees of lipopolysaccharide(LPS)biosynthesis-related genes(lptA,waaC,and waaF)presented two major branches(GH and EHS),too.The urease genes existed in all of the 12 strains of H.pylori,13 strains of gastric NHPH,and 4 strains of EHS(H.hepaticus,H.muridarum,H.bilis,and H.anseris).However,no significant phylogenetic patterns of GH and EHS were observed in the seven urease genes(ureA,ureB,ureE,ureF,ureG,ureH,and ureI).CONCLUSION The phylogenetic relationship of Helicobacter species’pathogenic genes is dominated distinctly by the special colonization areas including gastric and enterohepatic niches.