Seroreactivity to the C6 Peptide in Borrelia miyamotoi Infections Occurring in the Northeastern United States

Clin Infect Dis. 2018 Apr 17;66(9):1407-1410. doi: 10.1093/cid/cix1023.


Background: There are no US Food and Drug Administration (FDA)-approved diagnostic tests for Borrelia miyamotoi infection, an emerging tick-borne illness in the United States. The purpose of this study was to evaluate whether the FDA-approved C6 peptide enzyme-linked immunosorbent assay (ELISA) currently used to diagnose Lyme disease may potentially serve as a diagnostic test for B. miyamotoi infections.

Methods: Serum specimens from 30 patients from the northeastern United States with B. miyamotoi infection established by a polymerase chain reaction assay of a blood specimen were tested using the C6 ELISA. To reduce confounding with Borrelia burgdorferi coinfection, 6 sera were excluded: 3 from patients with a positive Western immunoblot for antibodies to B. burgdorferi and 3 from patients for whom immunoblot testing had not been performed.

Results: Twenty-two of 24 (91.7% [95% confidence interval, 73.0%-98.8%]) evaluable B. miyamotoi patients were C6 ELISA reactive, principally on a convalescent-phase serum specimen. C6 ELISA index values were often well above the positive cutoff value of 1.1, exceeding 4 in 11 of the 22 (50.0%) C6 ELISA-reactive patients.

Conclusions: Although previously regarded as a highly specific test for Lyme disease, the C6 ELISA is also regularly reactive on convalescent-phase serum samples of patients from the northeastern United States with B. miyamotoi infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / blood*
  • Bacterial Proteins / immunology*
  • Borrelia / classification
  • Borrelia / immunology*
  • Borrelia Infections / diagnosis*
  • Borrelia Infections / immunology
  • Communicable Diseases, Emerging / epidemiology
  • Communicable Diseases, Emerging / microbiology
  • Enzyme-Linked Immunosorbent Assay / standards*
  • Humans
  • Immunoglobulin G / blood
  • Lyme Disease / diagnosis
  • Lyme Disease / immunology
  • New England
  • Peptides / immunology
  • Polymerase Chain Reaction
  • Reagent Kits, Diagnostic / standards*


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Immunoglobulin G
  • Peptides
  • Reagent Kits, Diagnostic