Improved immunoglobulin M serodiagnosis in Lyme borreliosis by using a μ-capture enzyme-linked immunosorbent assay with biotinylated Borrelia burgdorferi flagella

Abstract

A μ-capture enzyme-linked immunosorbent assay (ELISA) for detection of serum immunoglobulin M (IgM) antibodies to Borrelia burgdorferi by using biotinylated purified B. burgdorferi flagella was developed. The diagnostic performance of the μ-capture ELISA was compared with that of a conventional indirect ELISA. Sera from untreated patients with erythema migrans (N = 50), neuroborreliosis (n = 100), and acrodermatitis chronica atrophicans (ACA; n = 48) were investigated. The cutoff of the ELISAs was adjusted to a diagnostic specificity of 98% on the basis of examination of 200 serum specimens from healthy controls. The μ-capture ELISA increased the diagnostic sensitivity in patients with erythema migrans from 32 to 48% (P < 0.01) and in patients with neuroborreliosis from 37 to 57% (P < 0.001). Because of an increased signal/noise ratio, the μ-capture ELISA yielded a significantly better quantitative discrimination of individual positive measurements from the cutoff (P < 0.001). The increased signal/noise ratio was most likely a consequence of the elimination of IgG competition for the test antigen. This may also explain why 12% of patients with ACA showed significantly increased specific IgM levels only by the μ-capture ELISA. Of patients with ACA, 27% had IgM rheumatoid factor. The μ-capture principle with a directly labeled antigen showed no interference with IgM rheumatoid factor, in contrast to the indirect ELISA. The high diagnostic performance and ease of this three-step μ-capture ELISA make it suitable for routine anti-B. burgdorferi IgM serodiagnosis.