Reactivity of Human Sera to Different Strains of Granulocytic Ehrlichiae in Immunodiagnostic Assays

J Infect Dis. 1998 Dec;178(6):1835-8. doi: 10.1086/314516.


Sera from 35 patients diagnosed with human granulocytic ehrlichiosis in Connecticut were tested by indirect IFA staining methods with 5 strains of Ehrlichia equi or the human granulocytic ehrlichiosis agent to assess the suitability of different strains in laboratory analyses. Antigens included horse-derived infected neutrophils (MRK and BDS strains) and human isolates cultured in human promyelocytic leukemia cells (NCH-1, RCH, and Webster). Of 35 sera, 23 (65.7%) reacted to all 5 strains. Seropositivity was highest (97.1%) in assays that contained the MRK strain from California and lowest (71. 4%) in tests with the NCH-1 strain from Nantucket, Massachusetts. In parallel testing of 32 sera with the NCH-1 strain by indirect IFA and Western blot analyses, results were concordant for 30 samples (93.8%). All strains of ehrlichiae can be used in IFA analyses for antibody detection, but assay sensitivity varied with the strain used.

Publication types

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

MeSH terms

  • Animals
  • California
  • Connecticut
  • Ehrlichia / classification*
  • Ehrlichia / immunology
  • Ehrlichia / isolation & purification
  • Ehrlichiosis / diagnosis*
  • Ehrlichiosis / immunology
  • Ehrlichiosis / veterinary
  • Fluorescent Antibody Technique, Indirect
  • Granulocytes / microbiology
  • Horse Diseases / diagnosis
  • Horse Diseases / immunology
  • Horses
  • Humans
  • Neutrophils / microbiology
  • Population Surveillance
  • Statistics, Nonparametric
  • Tick Infestations