Antigenic Diversity of Granulocytic Ehrlichia Isolates From Humans in Wisconsin and New York and a Horse in California

J Infect Dis. 1997 Oct;176(4):1029-34. doi: 10.1086/516529.


The agent of human granulocytic ehrlichiosis (HGE), Ehrlichia phagocytophila, and Ehrlichia equi are very similar. HGE is of variable severity. Genetic and antigenic differences among 3 human isolates (Webster, Spooner, and NY-8) and 1 horse isolate (MRK) were evaluated. The 16S rRNA gene sequences were identical in all human isolates. By use of 5 homologous antisera from these 3 humans and 1 horse and an additional 5 antisera in heterologous reactions, the immunodominant antigens of each isolate were noted to differ in molecular size: 43 kDa in the Webster (Wisconsin) isolate, 46 kDa in the Spooner (Wisconsin) isolate, 42 and 45 kDa in the NY-8 (New York State) isolate, and a 42 kDa doublet in the E. equi MRK isolate from California. Two sera from a Wisconsin patient reacted weakly or not at all with the NY-8 isolate. Antigenic structural diversity exists among otherwise indistinguishable granulocytic ehrlichial isolates.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Bacterial / analysis
  • Antigens, Bacterial / analysis*
  • Cross Reactions / immunology
  • DNA, Bacterial / analysis
  • Ehrlichia / genetics*
  • Ehrlichia / immunology*
  • Ehrlichia / isolation & purification
  • Ehrlichiosis / blood
  • Ehrlichiosis / genetics*
  • Ehrlichiosis / immunology*
  • Horses
  • Humans
  • Immunoblotting
  • Immunodominant Epitopes / analysis
  • Polymerase Chain Reaction
  • RNA, Ribosomal, 16S / genetics*
  • Sequence Homology, Nucleic Acid


  • Antibodies, Bacterial
  • Antigens, Bacterial
  • DNA, Bacterial
  • Immunodominant Epitopes
  • RNA, Ribosomal, 16S