OBJECTIVETo evaluate the significance of traditional index on the identification of Bacillus anthracis and its correlation with pathogenic strains.

METHODSRoutine bacteriologic methods and PCR of virulence genes were used to determine the difference on traditional identification index between pathogenic and nonpathogenic Bacillus.

RESULTSThe characteristics of colony, with hemolysis and mobility both negative are the important interrelated characters of pathogenic strains of Bacillus anthracis.

CONCLUSIONTo judge the risk of anthrax, virulence of genes must be first defined. Some traditional methods for identification are still useful when molecular biological methods are not available.

Animals ; Bacillus anthracis ; genetics ; isolation & purification ; pathogenicity ; Hemolysis ; Sheep ; Virulence ; genetics

OBJECTIVETo 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.

METHODSTen 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.

RESULTSThe 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.

CONCLUSIONThe 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.

China ; Francisella tularensis ; classification ; genetics ; Molecular Sequence Data ; Phylogeny

Objective To compare the coding sequences (CDS) of Yersinia pestis D106004 strain from Yulong County in Yunnan Province and Z176003 strain from Qing-Tibet Plateau in order to find the differences between their genomes and the genetic characteristics. Methods The CDS of Yersinia pestis D106004 strain and Z176003 strain were searched and compared by BLAST. Twenty-two differential CDS were selected to design 22 pairs of primers. PCR amplification was carried out in 119 representative plague strains from different isolation sources (natural foci of Himalayan marmot plague in the Qinghai-Tibet Plateau, natural foci of Apodemus chevrieri and Eothenomys miletus plague in Yunnan), time span of about 50 years, and distribution in six ecological types including Tibet, Qinghai, Sichuan, Gansu and Yunnan, and PCR products were sequenced and verified. The strains were all from the State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Infectious Disease Control and Prevention, Chinese Center for Disease Control and Prevention. Results In 119 representative plague strains of 6 ecological types, the cumulative sequence length of 22 differential CDS PCR amplification products was 2.13 × 106 bp. Among the 119 representative plague strains in the foci of Yulong D106004 strain and Qinghai-Tibet Plateau Z176003 strain, 22 differential CDS had high homology, there was no difference in 78.2％ (2047/2618) sequences of differential CDS, and 21.8％ (571/2618) sequences had three types of gene mutations ( deletion , missense and frameshift mutations). The characteristics of the differences were stable in the 6 ecological plague strains of the foci, and they were divided into 6 geographical distributions. Conclusion Yulong D106004 strain and Qinghai-Tibet Plateau Z176003 strain have high homology, close genetic relationship, and little difference in genome, but the genetic characteristics of different ecotype strains are stable.