海南省类鼻疽伯克霍尔德菌临床分离株的基因岛特征和毒力因子分析

Characterization of genomic islands and virulence factors of clinical isolates of Burkholderia pseudomallei in Hainan Province,China

目的分析类鼻疽伯克霍尔德菌(Burkholderia pseudomallei)临床分离株的基因岛(genomic island,GI)特征和毒力因子差异,为类鼻疽病的诊疗研究提供依据。方法收集B.pseudomallei临床分离株,PCR检测和测序分析毒力相关GI,在Islandviewr 4平台上提交全基因组序列注释格式文件,整合SIGI-HMM与IslandPath-DIMOB两种算法预测GI,通过序列比对分析GI独特性和毒力因子差异。结果共收集到52株B.pseudomallei临床分离株,结果显示,52个基因组按进化距离分为3个分枝,其中82.69%(43/52)菌株集中在分枝1。52个B.pseudomallei基因组共识别出828个GI,按序列相似性聚类为157个GI cluster。GI在基因组中占比达2.05%~6.38%。GI cluster1和2存在全部菌株中,但84个(53.50%)GI cluster只聚类到单个基因组。10个GI cluster很可能是特有的,其中5个来源同属细菌,2个来源其他属,3个来源不确定。25个GI cluster与毒力相关,B.pseudomallei BP76和BP169含有其中8个,是所有菌株中毒力相关GI最多的。52株B.pseudomallei的毒力基因除了fhaB1、fhaB2、BPSL1661、cheY1、wzM、tssH-5/clpV、tssA-5、boaA和boaB存在差异,其余都表现一致。与泰国和澳大利亚B.pseudomallei临床菌株比较,boaA、boaB、cheY1和chbp在两个国家的菌株中都表现出差异,同时fhaB1、fhaB3和bimA在澳大利亚菌株中表现出差异。结论海南地区B.pseudomallei GI具有保守性和独特性,通过特有GI和毒力因子研究,可以发现菌株水平基因转移(Horizontal gene transfer,HGT)的来源和分子水平的毒力差异。

The genomic island(GI)characteristics and virulence factor differences of clinical isolates of Burkholderia pseudomallei in Hainan Province,China were analyzed to provide a scientific basis for diagnosis and treatment of melioidosis.In total,52 B.pseudomallei isolates were collected for detection of virulence-related GIs by PCR.The whole genome sequence annotation format file was submitted on Islandviwer 4 platform,and the genomes of the same species and close relatives were added for comparison.Two algorithms,SIGI-HMM and IslandPath-DIMOB,were integrated to predict GIs and sequence alignments were conducted to identify specific GIs and differences in virulence factors.The genomes of 52 clinical strains could be divided into three branches based on evolutionary distance,with 82.69%(43/52)of strains concentrated in branch 1.In total,828 GIs were identified among the 52 B.pseudomallei genomes,which formed 157 GI clusters based on sequence similarity.GIs accounted for 2.05%-6.38%of the genome content.While GI clusters 1 and 2 were present in all strains,a total of 84(53.50%)GI clusters only clustered within a single genome isolate.Of 10 GI likely specific clusters,five were from the same genus,two from another genus,and three with uncertain origins.Moreover,25 GI clusters were associated with virulence,which included eight shared by B.pseudomallei BP76 and BP169,which had the highest number of virulence-associated GIs among all isolates.O the 52 B.pseudomallei isolates,variations were identified in the virulence genes fhaB1,fhaB2,BPSL1661,cheY1,wzM,tssH-5/clpV,tssA-5,boaA,and boaB.Comparisons of these findings with clinical isolates from Thailand and Australia showed that B.pseudomallei isolates from Hainan had significant differences in the sequences of boaA,boaB,cheY1,and chbp.Additionally,fhaB1,fhaB3,and bimA displayed significant variations specifically within the Australian isolates.B.pseudomallei GI was conserved and specific to Hainan.The identification of specific GI and virulence factors was useful to clarify the source of horizontal gene transfer and differences in virulence at the molecular level.