A biochip-based combined immunoassay for detection of serological status of Borrelia burgdorferi in Lyme borreliosis.

Background: Dithiobis (succinimidyl undecanoate) modified gold surface biochip were used as a combined immunoassay platform for concurrently detecting immune responses to Borrelia burgdorferi (B. burgdorferi) sensu lato antigens, flagellin, outer surface protein C, variable major protein-like sequence proteins, and 3 VlsE protein IR peptides. The peptides represented intrinsic Borrelia genospecies: B. burgdorferi sensu stricto, B. garinii, and B. afzelii, respectively.

Methods: Fourier transform infrared spectroscopy was utilized to validate the surface chemical characteristics on the modified gold surface.

Results: The limits in detection of IgG antibody on the biochips were as little as 0.39μg/ml for anti-VlsE and 0.78μg/ml for anti-flagellin and anti-OspC, respectively. Samples from 56 neuroborreliosis (NB) patients and 114 healthy individuals were analyzed by the combined biochip. We found that the seroprevalences of IgM or IgG antibody against the 6 antigens were contributed to increased overall sensitivity by the multiplex immunobiochip assay. Serum combined positive rates of the 6 antigens in the patients were 92.86% for IgM antibody and 91.07% for IgG antibody. Part of the patients bore antibody responses against the 3 VlsE IR variant peptides, indicating that Lyme borreliosis would attribute to consequence of multiple infections by one or more Borrelia burgdorferi strains. Concurrent assessment for both IgM and IgG antibodies against the protein antigens and B. burgdorferi IR peptides in the sera of NB patients was beneficial from the biochip format, enabling detection of expanded serologic infection status and therapy strategy-making more efficiently.

Conclusions: The combined biochip-based immunoassay, as a potential substitution of ELISA, provided a promising approach to extend the detection spectrum of infectious antibodies against a panel of Borrelia antigens.