StaphAIR: A Label-Free Antigen Microarray Approach to Detecting Anti-Staphylococcus aureus Antibody Responses in Orthopedic Infections

Abstract

Arrayed imaging reflectometry (AIR) is an optical biosensor platform for simple, multiplex measurement of antigenspecific antibody responses in patient blood samples. Here, we report the development of StaphAIR, an 8-plex Staphylococcus aureus antigen array on the AIR platform for profiling antigenspecific anti-S. aureus humoral immune responses. Initial validation experiments with mouse and humanized monoclonal antibodies against the S. aureus autolysin glucosaminidase (Gmd) domain, and subsequent testing with dilution series of pooled positive human serum confirmed analytically robust behavior of the array, with all antigens displaying Langmuir-type dose−response curves. Testing a cohort of 82 patients with S. aureus musculoskeletal infections (MSKI) and 30 healthy individuals enabled discrimination of individual patient responses to different S. aureus antigens, with statistical significance between osteomyelitis patients and controls obtained overall for four individual antigens (IsdA, IsdB, Gmd, and SCIN). Multivariate analyses of the antibody titers obtained from StaphAIR revealed its utility as a potential diagnostic tool for detecting S. aureus MSKI (area under the receiver operating characteristic curve (AUC) > 0.85). We conclude that StaphAIR has utility as a high-throughput immunoassay for studying and diagnosing osteomyelitis in patients.

Arrayed Imaging Reflectometry monitoring of anti-viral antibody production throughout vaccination and breakthrough Covid-19

“…Here the data are reported as simply thickness (Å) where negative control information is not subtracted but is instead plotted independently. The standard deviation of serum samples was calculated from replicate probe spots on each array [21]. Positive samples were determined as those significantly different from control by one-tailed two-sample t-test with p < 0.01.…”

“…AIR provides reflectivity data in an image, where the intensity of each pixel may be converted to thickness via well-established algorithms [21]. Thickness in turn may be converted to concentration if desired with reference to a calibration curve.…”

“…For several years, we have worked to develop array-based methods based on Arrayed Imaging Reflectometry (AIR) for rapidly assessing immunity to upper respiratory viruses [19]. AIR relies on the quantitative perturbation of a near-perfect antireflective condition on a silicon/silicon dioxide chip as targets bind to the arrayed probes [20,21]. As an imaging technique, AIR can quantify binding of more than 100 targets on an array independently and simultaneously [22].…”

Label-free OIRD microarray chips with a nanostructured sensing interface: enhanced sensitivity and mechanism

“…9,10 A great diversity of label-free techniques, including interferometry, reflectometry, and surface plasmon resonance (SPR), have been developed. 11–13…”

“…9,10 A great diversity of label-free techniques, including interferometry, reflectometry, and surface plasmon resonance (SPR), have been developed. [11][12][13] Oblique-incidence reflectivity difference (OIRD) is a new kind of non-invasive optical technique developed in the last three decades for real-time monitoring the surface change. [14][15][16][17] It achieves label-free probing of interfacial processes by measuring the change of the difference between two polarized light components (s and p) of the obliquely reflected light from this interface.…”