Class and isotype of VlsE-specific antibody differentiates Lyme disease stage.

Abstract

Establishment of immunoglobulin diversity is contingent on recombination that occurs both at the Fab and at the Fc regions of the immunoglobulin, and this process is time dependent. Based on this principle, we questioned whether Lyme disease stage can be distinguished by quantification of immunoglobulin class and IgG isotype specific to VlsE in serum from clinically characterized patients. We used an enzyme immunoassay to categorize serologic antibodies to VlsE antigen as well as machine-learning techniques to train and integrate multiple predictors to identify likely disease stage. We found that IgM/IgG3/IgG1/IgA1 was enriched in serum obtained in the earliest stages, whereas IgG3/IgG1/IgG4 was enriched in Lyme arthritis. IgG2 detection was unremarkable across all disease stages. Post-Treatment Lyme Disease Syndrome (PTLDS) serum was enriched in IgG3/IgG1/IgA1 but lacked IgM. The multivariable models showed better predictive accuracy than any single immunoglobulin model, with more than half of panels perfectly identified by random forest under cross validation (56%) vs a maximum of 38% for a model using IgG1 alone. The findings suggest a characteristic succession of VlsE-specific antibody switching between immunoglobulin class and IgG isotype as Lyme disease progresses from early to late stages. The data also suggest that immunoglobulin class and IgG isotyping are likely more helpful to distinguish early Lyme disease cases. Comprehensive evaluation of immunoglobulin class (M, G, A) and IgG isotypes (1/2/3/4) provides time-dependent pathogen-induced host response information to current Lyme disease antibody detection and may be useful for differentiation of disease stage.

Importance: The order of switching between the immunoglobulin heavy chain (Fc) is time dependent, progressing from IgM/D to IgG3/IgG1/IgA1/IgG2/IgG4 and later to IgE/IgA2. In this study, we show that B. burgdorferi-VlsE-specific antibody switching proceeds in a predictable sequence between class (Ig M/G/A) and IgG isotype (IgG 1/2/3/4) as Lyme disease progresses from early to late stage and that antibody class and isotype may be more helpful to distinguish the early stages of Lyme disease. This study advances our understanding of the tempo and structure of the humoral immune response to B. burgdorferi and is applicable to the development of new diagnostic assays for Lyme disease.