Comprehensive seroprofiling of sixteen B. burgdorferi OspC: implications for Lyme disease diagnostics design

Abstract

Early diagnosis of Lyme disease (LD) is critical to successful treatment. However, current serodiagnostic tests do not reliably detect antibodies during early infection. OspC induces a potent early immune response and is also one of the most diverse proteins in the Borrelia proteome. Yet, at least 70% of the amino acid sequence is conserved among all 21 known OspC types. We performed a series of comprehensive seroprofiling studies to select the OspC types that have the most cross-reactive immunodominant epitopes. We found that proteins belonging to seven OspC types detect antibodies from all three infected host species regardless of the OspC genotype of the infecting strain. Although no one OspC type identifies all seropositive human samples, combinations of as few as two OspC proteins identified all patients that had anti-OspC antibodies.

Figure 1

OspC seroprofiling of laboratory infected mice. ELISA immunoarrays of five rOspC proteins detect anti-OspC antibodies in all infected mice, regardless of the OspC-type of the B. burgdorferi with which the mouse was infected. All other rOspC proteins failed to detect anti-OspC antibodies from at least one B. burgdorferi-infected mouse (i.e. rOspC-type A did not detect mice infected with B. burgdorferi strains having either OspC-type D or M). Anti-mouse IgG HRP secondary antibody was used. ELISA readings below the detection cutoff (negative) have been highlighted in red.

Figure 2

Variation among naturally-infected white-footed mice in the amount of antibodies detected by each rOspC protein. Each graph represents the frequency distribution of OD values obtained from the reaction of IgG in serum from naturally-infected white-footed mice (P. leucopus) to each type-specific-rOspC protein by ELISA. Serum panel tested positive for B. burgdorferi infection by the C6 ELISA assay.

Figure 3

Variation among naturally-infected dogs in the amount of antibodies detected by each rOspC protein. Each graph represents the frequency distribution of OD values obtained from the reaction of IgG in serum from naturally-infected dogs (Canis lupus familiaris) to each type-specific-rOspC protein by ELISA. Serum panel tested positive for B. burgdorferi infection by the whole cell sonicate ELISA assay.

Figure 4

Variation among naturally-infected humans from North America in the amount of antibodies detected by each rOspC protein. Each graph represents the frequency distribution of OD values obtained from the reaction of IgG in serum from naturally-infected humans (Homo sapiens) to each type-specific-rOspC protein by ELISA. Serum panel tested positive for B. burgdorferi infection by the C6 ELISA assay.

Figure 5

Variation among naturally-infected humans from Europe in the amount of antibodies detected by each rOspC protein. Each graph represents the frequency distribution of OD values obtained from the reaction of IgG in serum from naturally-infected humans (Homo sapiens) to each type-specific-rOspC protein by ELISA. Serum panel tested positive for B. burgdorferi infection by the whole cell sonicate ELISA assay.