Recombinant protein-44-based class-specific enzyme-linked immunosorbent assays for serologic diagnosis of human granulocytic ehrlichiosis

L. Magnarelli, J. IJdo, C. Wu, E. Fikrig

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Recombinant protein 44, expressed and purified as a maltose-binding protein fusion peptide of the human granulocytic ehrlichiosis (HGE) agent (Ehrlichia phagocytophila genogroup), was used as antigen in enzyme-linked immunosorbent assays (ELISAs) to detect total antibodies, immunoglobulin (Ig) M antibodies, and IgG antibodies. Of the 67 human sera obtained from 64 HGE patients 3-5 weeks after the onset of illness and confirmed as having total immunoglobulins to whole-cell antigen by indirect fluorescent antibody analyses, 63 were positive in a polyvalent ELISA. Fifty-six and 61 sera had IgM or IgG antibodies, respectively. Fifty sera had both IgM and IgG antibodies. In specificity tests of 110 sera, one serum sample from a patient who had Lyme borreliosis reacted to the protein 44 antigen in the analysis for IgM antibody (specificity, 99%). There were no false-positive results in an ELISA for IgG antibodies. With their high sensitivity and specificity, class-specific ELISAs can be used in conjunction with indirect fluorescent antibody analyses or immunoblotting methods to help diagnose human granulocytic ehrlichiosis.

Original languageEnglish (US)
Pages (from-to)482-485
Number of pages4
JournalEuropean Journal of Clinical Microbiology and Infectious Diseases
Issue number7
StatePublished - 2001
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgments The authors thank T. Blevins for technical assistance and gratefully acknowledge J. Meek of Yale University and J.L. Hadler and M.L. Cartter of the Connecticut State Health Department for coordinating an emerging infections disease program. This work was supported, in part, by grants (HR8-CCR113382–01, CCU-106581, and U5O/CCU111188–01) from the U.S. Centers for Disease Control and Prevention and Emerging Infections Program, a grant (1R01-AI41440) from the U.S. National Institutes of Health, and by federal Hatch funds administered by the U.S. Department of Agriculture. J.W.I. received support from a Robert Leet and Clara Guthrie Patterson Trust, and E.F. is a recipient of a clinical scientist award in translational research from Burroughs Wellcome.


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