title: Cloning and sequencing of the gene for a 120-kDa immunodominant protein of Ehrlichia chaffeensis.
abstract: Ehrlichia chaffeensis is the tick-borne, obligately intracellular bacterium that causes human monocytic ehrlichiosis. A 120-kDa protein is one of the immunodominant proteins of E. chaffeensis that stimulates production of specific antibodies in infected humans. A genomic library of E. chaffeensis was constructed in a lambda ZAP II phage vector, and a clone expressing the 120-kDa protein of E. chaffeensis was identified using canine anti-E. chaffeensis serum. DNA sequence analysis of the cloned 120-kDa protein gene of E. chaffeensis identified a 1884-bp open reading frame with an ehrlichial promoter. Five identical 240-bp tandem repeat units were identified in the 120-kDa protein gene of E. chaffeensis, comprising 60% of the entire gene. Aside from the first repeat unit, all the other repeat units are identical. In the first repeat unit there are four nucleotides that are different from the other repeats. Hydropathy analysis of the deduced amino-acid sequence demonstrated that the repeat domain contains highly hydrophilic segments. The 120-kDa protein should be evaluated for a role in stimulating protective immunity.
authors.affiliation: Department of Pathology, University of Texas Medical Branch, Galveston 77555-0609, USA.
authors.forename: X J
authors.initials: XJ
authors.lastname: Yu
authors.forename: P
authors.initials: P
authors.lastname: Crocquet-Valdes
authors.forename: D H
authors.initials: DH
authors.lastname: Walker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics* / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004285:Dogs; D018469:Ehrlichia chaffeensis / Q000235:genetics* / Q000276:immunology; D004926:Escherichia coli; D005798:Genes, Bacterial; D005822:Genetic Vectors; D016056:Immunodominant Epitopes / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
chemical_list: C104346:120-kDa immunodominant protein, Ehrlichia chaffeensis; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D016056:Immunodominant Epitopes; D011994:Recombinant Proteins