title: Reactivity of human sera to different strains of granulocytic ehrlichiae in immunodiagnostic assays.
abstract: 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.
authors.affiliation: Department of Entomology, Connecticut Agricultural Experiment Station, University School of Medicine, New Haven, Connecticut, USA. louis.magnarelli@po.state.ct.us
authors.forename: L A
authors.initials: LA
authors.lastname: Magnarelli
authors.forename: J W
authors.initials: JW
authors.lastname: IJdo
authors.forename: J S
authors.initials: JS
authors.lastname: Dumler
authors.forename: R
authors.initials: R
authors.lastname: Heimer
authors.forename: E
authors.initials: E
authors.lastname: Fikrig
mesh_terms: D000818:Animals; D002140:California; D003237:Connecticut; D004536:Ehrlichia / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification; D016873:Ehrlichiosis / Q000175:diagnosis* / Q000276:immunology / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect; D006098:Granulocytes / Q000382:microbiology; D006734:Horse Diseases / Q000175:diagnosis / Q000276:immunology; D006736:Horses; D006801:Humans; D009504:Neutrophils / Q000382:microbiology; D011159:Population Surveillance; D018709:Statistics, Nonparametric; D013984:Tick Infestations