Pathogenic Yersinia bacteria, including Y. pseudotubuclosis Y. enterocolitica, and Y. pestis, contain the mosaic plasmid pYV that encodes for, among other things, a number of proteinaceous virulence factors. While the evolutionary histories of many of the biovars and strains of pathogenic Yersinia species are well documented, the origins of many of the individual virulence factors have not been comprehensively examined. Here, the evolutionary origins of the genes coding for a set of Yersinia outer protein (Yop) virulence factors were investigated through phylogenetic reconstruction and subsequence analysis. It was found that many of these genes had only a few sequenced homologs and none of the resolved phylogenies recovered the same relationships as was resolved from chromosomal analyses. Many of the evolutionary relationships differ greatly among genes on the plasmid, and variation is also found across different domains of the same gene, which provides evidence of the mosaic nature of the plasmid as well as multiple genes on the plasmid. This mosaic aspect also relates to patterns of selection, which vary among the studied domains.

致病性耶尔森氏菌，包括小肠结肠炎耶尔森耶尔森氏菌和鼠疫耶尔森氏菌，含有嵌合质粒 pYV，其编码除其他外，许多蛋白质毒力因子。虽然致病性耶尔森菌属物种的许多生物变种和菌株的进化历史有据可查，但许多个体毒力因子的起源尚未得到全面研究。在这里，编码一组耶尔森氏菌的基因的进化起源通过系统发育重建和亚序列分析研究了外蛋白（Yop）毒力因子。发现这些基因中的许多基因只有少数已测序的同源物，并且解析的系统发育中没有一个恢复与染色体分析解析相同的关系。许多进化关系在质粒上的基因之间差异很大，并且在同一基因的不同域中也发现了变异，这为质粒的镶嵌性质以及质粒上的多个基因提供了证据。这种马赛克方面也与选择模式有关，这在所研究的领域之间有所不同。