Comparative Genomics of Rhodococcus equi Virulence Plasmids Indicates Host-Driven Evolution of the vap Pathogenicity Island.
Comparative Genomics of Rhodococcus equi Virulence Plasmids Indicates Host-Driven Evolution of the vap Pathogenicity Island.
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DOI：
10.1093/gbe/evx057
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发表时间：
2017-05-01
影响因子：
3.3
通讯作者：
Vázquez-Boland JA
中科院分区：
文献类型：
--
作者：
MacArthur I;Anastasi E;Alvarez S;Scortti M;Vázquez-Boland JA
接合毒力质粒是马红球菌副基因组的重要组成部分，在致病过程中起着至关重要的作用。已鉴定出三种宿主相关的毒力质粒类型：马的pVAPA和猪的pVAPB环变异体，以及在牛(反刍动物)分离株中发现的线形pVAPN。我们最近描述了马R.pangenome的特征(Anastasi E，et al.致病马红球放线菌的泛基因组和系统发育分析。基因组生物Evol。8：3140-3148。)在此，我们报道了毒力质粒基因组的比较分析。尽管起源不同，但每种寄主相关类型内的质粒高度相似。变异是由分散的单核苷酸多态和短核苷酸INDELs引起的，而较大的INDELs-主要在VAP致病岛(PAI)附近的可塑性区域-定义的质粒基因组亚型。只有一个被分析的pVAPN型质粒由于indels在管家主干中的积累而异常分化。每种宿主相关的质粒型携带不同于vap基因补体的唯一PAI，提示vap多基因家族的动物特异性进化。在每种宿主相关的质粒型中观察到vap PAI的完全保守性。在同一系统亚支中观察到寄主相关质粒型的多样性和特定染色体-质粒型组合的克隆性。我们的数据表明，马立克氏杆菌寄主相关毒力质粒总体上的强保守性是宿主驱动的选择、品系之间的横向转移以及国际家畜交流导致的地理传播的综合结果。
The conjugative virulence plasmid is a key component of the Rhodococcus equi accessory genome essential for pathogenesis. Three host-associated virulence plasmid types have been identified: the equine pVAPA and porcine pVAPB circular variants, and the linear pVAPN found in bovine (ruminant) isolates. We recently characterized the R. equi pangenome (Anastasi E, et al.. Pangenome and phylogenomic analysis of the pathogenic actinobacterium Rhodococcus equi. Genome Biol Evol. 8:3140–3148.) and we report here the comparative analysis of the virulence plasmid genomes. Plasmids within each host-associated type were highly similar despite their diverse origins. Variation was accounted for by scattered single nucleotide polymorphisms and short nucleotide indels, while larger indels—mostly in the plasticity region near the vap pathogencity island (PAI)—defined plasmid genomic subtypes. Only one of the plasmids analyzed, of pVAPN type, was exceptionally divergent due to accumulation of indels in the housekeeping backbone. Each host-associated plasmid type carried a unique PAI differing in vap gene complement, suggesting animal host-specific evolution of the vap multigene family. Complete conservation of the vap PAI was observed within each host-associated plasmid type. Both diversity of host-associated plasmid types and clonality of specific chromosomal-plasmid genomic type combinations were observed within the same R. equi phylogenomic subclade. Our data indicate that the overall strong conservation of the R. equi host-associated virulence plasmids is the combined result of host-driven selection, lateral transfer between strains, and geographical spread due to international livestock exchanges.