Homology analysis and historical tracing for inter-continental Burkholderia pseudomallei strains of sequence type 562 / 中华流行病学杂志

ABSTRACT

Objective To understand the homology of sequence type 562 (ST562) strains of Burkholderia pseudomallei which circulated in two separate continents (Asia and Australia) at different times.Methods Spe Ⅰ restriction fragments and 4-locus multiple locus variable number tandem repeat analysis (MLVA-4) profiles were extracted from MSHR5858 (ST562 Australia strain) and 350105 (ST562 historical strain of Hainan) genomes respectively by in silico analysis and then compared with the PFGE and MLVA-4 results of five ST562 clinical isolates from Hainan to test their homology.Synteny and homology between MSHR5858 and 350105 genomes were evaluated with bioinformatics methods.Results Five ST562 clinical strains from Hainan shared same PFGE pattern (similarity ＞97％) and this pattern coincided to the map of Spe Ⅰ restriction fragments of Australian strain MSHR5858.The amounts of genomic restriction fragments (Spe Ⅰ) for MSHR5858 and 350105 were 31 and 34 respectively,with 31 of them matched by each other.Five ST562 clinical strains of Hainan were distinct by MLVA-4 profiles,among which HPPH43 (MLVA-4 profile10,8,10,8) was close to Australia strain MSHR5858 (10,8,8,6),containing identical repeat numbers at VNTR loci 2341k and 1788k;while HK003 (11,8,15,7) and HK061 (11,8,17,7) similar to Hainan historical strain 350105 (11,8,11,8),with same repeat numbers at loci 2341k and 1788k also.High-degree synteny and consistency on genomic contents were observed between 350105 and MSHR5858,indicating a similar origin for the 2 strains.Conclusion All inter-continental and historical ST562 strains ofB.pseudomallei had similar genomic characteristics,supporting the assumption that they had a common origin.Also,it is possible that Hainan historical strain 350105 is the ancestor of all circulating ST562 strains.