title: Genetic relationship between Francisella tularensis strains from China and from other countries.
abstract: OBJECTIVE
  To study the types of subspecies of Francisella tularensis from China and to investigate the genetic relationships between F. tularensis strains from China and from other countries.
  
  
  METHODS
  Ten strains of F. tularensis isolated from China were amplified by using typing primers C1/C4 and RD1. On the basis of the lengths of the polymerase chain reaction (PCR) products, it was concluded that these strains of F. tularensis belonged to the same subspecies. At the same time, the fopA, tul4, and 16S rRNA genes of the 10 strains were amplified, and a three-gene based phylogenetic analysis was performed using the Molecular Evolutionary Genetics Analysis software version 4.0.
  
  
  RESULTS
  The 10 strains of F. tularensis from China were all identified as belonging to subspecies holarctica (type B). We found no direct relationship between the genotypes of F. tularensis subsp. holarctica and the geographical area from where they were isolated.
  
  
  CONCLUSIONS
  The F. tularensis strains isolated from North China mainly belong to subspecies holarctica (type B). The strains of F. tularensis subsp. holarctica from China may have evolved earlier than those from Europe and North America.
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Wang
authors.forename: Rong
authors.initials: R
authors.lastname: Hai
authors.forename: Zhikai
authors.initials: Z
authors.lastname: Zhang
authors.forename: Lianxu
authors.initials: L
authors.lastname: Xia
authors.forename: Hong
authors.initials: H
authors.lastname: Cai
authors.forename: Ying
authors.initials: Y
authors.lastname: Liang
authors.forename: Xiaona
authors.initials: X
authors.lastname: Shen
authors.forename: Dongzheng
authors.initials: D
authors.lastname: Yu
mesh_terms: D002681:China; D005604:Francisella tularensis / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny