Evaluation of the C6 Lyme Enzyme Immunoassay for the Diagnosis of Lyme Disease in Children and Adolescents

Abstract

5Pediatric Physicians' Organization at Children's, Brookline, MassachusettsBackground. The commercially-available C6 Lyme enzyme immunoassay (EIA) has been approved to replace the standard whole-cell sonicate EIA as a first-tier test for the diagnosis of Lyme disease and has been suggested as a stand-alone diagnostic. However, the C6 EIA has not been extensively studied in pediatric patients undergoing evaluation for Lyme disease.Methods. We collected discarded serum samples from children and adolescents (aged ≤21 years) undergoing conventional 2-tiered testing for Lyme disease at a single hospital-based clinical laboratory located in an area endemic for Lyme disease. We performed a C6 EIA on all collected specimens, followed by a supplemental immunoblot if the C6 EIA result was positive but the wholecell sonicate EIA result was negative. We defined a case of Lyme disease as either a clinician-diagnosed erythema migrans lesion or a positive standard 2-tiered serologic result in a patient with symptoms compatible with Lyme disease. We then compared the performance of the C6 EIA alone and as a first-tier test followed by immunoblot, with that of standard 2-tiered serology for the diagnosis of Lyme disease.Results. Of the 944 specimens collected, 114 (12%) were from patients with Lyme disease. The C6 EIA alone had sensitivity similar to that of standard 2-tiered testing (79.8% vs 81.6% for standard 2-tiered testing; P = .71) with slightly lower specificity (94.2% vs 98.8% 2; P < .002). Addition of a supplemental immunoblot improved the specificity of the C6 EIA to 98.6%.Conclusions. For children and adolescents undergoing evaluation for Lyme disease, the C6 EIA could guide initial clinical decision making, although a supplemental immunoblot should still be performed.

Evaluation of Modified 2-Tiered Serodiagnostic Testing Algorithms for Early Lyme Disease

“…One of the MTTT protocols, a WCS EIA followed by a C6 EIA, has been evaluated by several independent groups with similar findings to those reported here [3,5,6,8,21]. Our study furnishes additional evidence that this algorithm provides similar or greater sensitivity in acute-or convalescent-phase EM, compared with any 2-tiered protocol involving WBs, while maintaining the specificity of algorithms involving WBs.…”

“…Assays using full-length VlsE may be orthogonal to assays using the C6 peptide, at least to some degree. The resolved 3-dimensional structure of VlsE demonstrates that its sixth invariable region (IR 6 ) is buried within the parent molecule, and anti-IR 6 antibodies are predicted to have minimal interaction with full-length VlsE [22]. There is also direct evidence that anti-IR 6 antibodies often do not react with VlsE and vice versa [23].…”

“…Next-generation first-tier assays have been approved for diagnostic use in the United States [3][4][5][6]. These assays are prepared from recombinant proteins or synthetic peptides that correspond to spirochetal antigens known to induce relatively early and robust humoral immune responses [7].…”

“…These assays are prepared from recombinant proteins or synthetic peptides that correspond to spirochetal antigens known to induce relatively early and robust humoral immune responses [7]. Because they contain far fewer antigens than WCS assays, these alternative first-tier assays are typically more specific [3,5,6,8], although none is completely specific. At present, these assays must still be used in the first tier of a 2-tiered testing protocol, with WBs used in the second tier.…”

Evaluation of a sequential enzyme immunoassay testing algorithm for Lyme disease demonstrates lack of test independence but high diagnostic specificity

“…Unpublished data collected in four previously reported studies that evaluated the specificity of WCS EIAs and the C6 peptide EIA were analyzed (Branda et al, 2011; Lipsett et al, 2016; Molins et al, 2016; Wormser et al, 2013b). Two analyses were performed: one that compared the specificity of the C6 peptide EIA with WCS EIA reactive versus WCS EIA negative control sera, and a second that excluded those control serum samples that were reactive by a WCS EIA and also positive by an IgG immunoblot assay, with the IgG immunoblot assay interpreted using the criteria recommended by the Centers for Disease Control and Prevention (CDC, 1995).…”