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Characterization and Transcriptional Analysis of Gene Clusters for a Type IV Secretion Machinery in Human Granulocytic and Monocytic Ehrlichiosis Agents
- Source :
- Infection and Immunity. 70:2128-2138
- Publication Year :
- 2002
- Publisher :
- American Society for Microbiology, 2002.
-
Abstract
- Anaplasma ( Ehrlichia ) phagocytophila and Ehrlichia chaffeensis , the etiologic agents of granulocytic and monocytic ehrlichioses, respectively, are obligatory intracellular bacteria that cause febrile systemic illness in humans. We identified and characterized clusters of genes for a type IV secretion machinery in these two bacteria, and analyzed their gene expression in cell culture and mammalian hosts. Eight virB and virD genes were found in each bacterial genome, and all of the genes were transcribed in cell culture. Although the gene order and orientation were similar to those found in other bacteria, the eight virB and virD genes were clustered at two separate loci in each genome. Five of the genes ( virB8 , virB9 , virB10 , virB11 , and virD4 ) were located downstream from a ribA gene. These five genes in both A. phagocytophila and E. chaffeensis were polycistronically transcribed and controlled through at least two tandem promoters located upstream of the virB8 gene in human leukemia cell lines. The virB9 gene of A. phagocytophila was transcriptionally active in peripheral blood leukocytes from human ehrlichiosis patients and experimentally infected animals. Three of the remaining genes ( virB3 , virB4 , and virB6 ) of both A. phagocytophila and E. chaffeensis were arranged downstream from a sodB gene and cotranscribed with the sodB gene through one or more sodB promoters in human leukocytes. This suggests that transcription of the three virB genes in these two Anaplasma and Ehrlichia spp. is regulated by factors that influence the sodB gene expression. This unique regulation of gene expression for the type IV secretion system may be associated with intracellular survival and replication of Anaplasma and Ehrlichia spp. in granulocytes or monocytes.
- Subjects :
- Anaplasma
Transcription, Genetic
Virulence Factors
animal diseases
Molecular Sequence Data
Immunology
Biology
Microbiology
Bacterial Proteins
Gene cluster
Humans
Ehrlichia chaffeensis
Promoter Regions, Genetic
Gene
Genetics
Regulation of gene expression
Base Sequence
Ehrlichia
Ehrlichiosis
Chromosome Mapping
Promoter
bacterial infections and mycoses
biology.organism_classification
Molecular Pathogenesis
Anaplasmataceae
Infectious Diseases
Multigene Family
Parasitology
Subjects
Details
- ISSN :
- 10985522 and 00199567
- Volume :
- 70
- Database :
- OpenAIRE
- Journal :
- Infection and Immunity
- Accession number :
- edsair.doi.dedup.....04d9fabec80fbbbaa7c7f933a301c616