Reactivity of human sera to different strains of granulocytic ehrlichiae in immunodiagnostic assays

Louis A. Magnarelli, Jacob W. Ijdo, J. Stephen Dumler, Robert Heimer, Erol Fikrig

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18 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1835-1838
Number of pages4
JournalJournal of Infectious Diseases
Issue number6
StatePublished - 1998
Externally publishedYes

Bibliographical note

Funding Information:
Financial support: CDC Emerging Infections Program (HR8/ CCH113382-01, U50/CCU111188-01), NIH (AI-41440), and federal Hatch funds. J.W.IJ. is a Daland Fellow of the American Philosophical Society.


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