Genetic boundaries to delineate the typhoid agent and other Salmonella serotypes into distinct natural lineages.
The deadly human typhoid agent was initially classified as a species called Salmonella typhi but later reclassified as a serovar of Salmonella enterica together with other pathogenically diverse serovars. The dynamic changes of Salmonella taxonomy reflect the need to clarify the phylogenetic status of the Salmonella serovars: are they discrete lineages or variants of a genetic lineage? To answer this question, we compared S. typhi and other Salmonella serotypes. We found that the S. typhi and Salmonella typhimurium strains had over 90% and ca. 80%, respectively, of their genes identical; however, between S. typhi and S. typhimurium, this percentage dropped to 6%, suggesting the existence of genetic boundaries between them. We conclude that S. typhi and the other compared Salmonella serovars have developed into distinct lineages circumscribed by the genetic boundary. This concept and methods may be used to delineate other Salmonella serotypes, many of which are polyphyletic, needing differentiation.
Genomics Research Center (one of The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, China.
Le
L
Tang
Chun-Xiao
CX
Wang
Song-Ling
SL
Zhu
Yang
Y
Li
Xia
X
Deng
Randal N
RN
Johnston
Gui-Rong
GR
Liu
Shu-Lin
SL
Liu
D019143:Evolution, Molecular; D005798:Genes, Bacterial; D049810:Genetic Speciation; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D019779:Salmonella enterica / Q000145:classification* / Q000235:genetics*; D012485:Salmonella typhi / Q000145:classification / Q000235:genetics; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics; D017385:Sequence Homology; D012703:Serotyping; D014435:Typhoid Fever / Q000382:microbiology* / Q000473:pathology
Bacterial species; Genetic boundary; Genomic divergence