Cloning and sequencing of the gene for a 120-kDa immunodominant protein of Ehrlichia chaffeensis

Xue Jie Yu, Patricia Crocquet-Valdes, David H. Walker

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


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 λZAP 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.

Original languageEnglish (US)
Pages (from-to)149-154
Number of pages6
Issue number2
StatePublished - Jan 15 1997


  • DNA repeat units
  • Ehrlichiosis
  • Obligate intracellular bacterium

ASJC Scopus subject areas

  • Genetics


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