title: Comparative genomics of Rickettsia prowazekii Madrid E and Breinl strains.
abstract: Rickettsia prowazekii, the causative agent of epidemic typhus, has been responsible for millions of human deaths. Madrid E is an attenuated strain of R. prowazekii, while Breinl is a virulent strain. The genomic DNA sequence of Madrid E has recently been published. To study the genomic variations between Madrid E (reference) and Breinl (test) DNAs, cohybridization experiments were performed on a DNA microarray containing all 834 protein-coding genes of Madrid E. Of the 834 genes assessed, 24 genes showed 1.5- to 2.0-fold increases in hybridization signals in Breinl DNA compared to Madrid E DNA, indicating the presence of genomic variations in approximately 3% of the total genes. Eighteen of these 24 genes are predicted to be involved in different functions. Southern blot analysis of five genes, virB4, ftsK, rfbE, lpxA, and rpoH, suggested the presence of an additional paralog(s) in Breinl, which might be related to the observed increase in hybridization signals. Studies by real-time reverse transcription-PCR revealed an increase in expression of the above-mentioned five genes and five other genes. In addition to the elevated hybridization signals of 24 genes observed in the Breinl strain, one gene (rp084) showed only 1/10 the hybridization signal of Madrid E. Further analysis of this gene by PCR and sequencing revealed a large deletion flanking the whole rp084 gene and part of the rp083 gene in the virulent Breinl strain. The results of this first rickettsial DNA microarray may provide some important information for the elucidation of pathogenic mechanisms of R. prowazekii.
authors.affiliation: Rickettsial Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, Maryland 20910, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Ge
authors.forename: Yao-Yu Eric
authors.initials: YY
authors.lastname: Chuang
authors.forename: Shuping
authors.initials: S
authors.lastname: Zhao
authors.forename: Min
authors.initials: M
authors.lastname: Tong
authors.forename: Mong-Hsun
authors.initials: MH
authors.lastname: Tsai
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Temenak
authors.forename: Allen L
authors.initials: AL
authors.lastname: Richards
authors.forename: Wei-Mei
authors.initials: WM
authors.lastname: Ching
mesh_terms: D015139:Blotting, Southern; D002238:Carbohydrate Epimerases / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry; D016680:Genome, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012283:Rickettsia prowazekii / Q000235:genetics* / Q000472:pathogenicity; D012808:Sigma Factor; D000637:Transaminases / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32; D000637:Transaminases; D002238:Carbohydrate Epimerases; C061272:perosamine synthetase