Biomarkers that predict of S. aureus and S. pyogenes-caused sepsis are bacterial toxins, superantigens. S. aureus causes most deaths from infectious diseases in high-income countries. This situation is exacerbated by spread of multiple antibiotic resistant S. aureus (MRSA) in the community and hospitals.
Superantigens are commonly found in the serum in the absence of bacteraemia. It is hence not appropriate to detect them by PCR of the toxin-coding DNA sequences. The key to our innovation is detection of superantigen protein using novel DNA-containing detector nanorods. Binding of the detector particles to the analyte will be quantified via the nanorod DNA. This strategy (immune-PCR) combines immunodetection with sensitivity of PCR to achieve ultrasensitive detection.
The system devised in this action be a prototype for a novel class of devices for ultrasensitive detection of wide array of molecules, including explosives, hormones, or chemical pollutants. The affordable all-in-one plug and play design will allow use in the general practitioner’s office (point of care), at home, or even in the war zones or disaster areas.
Development of fully integrated point-of-care lab-on-chip prototype will require multidisciplinary effort where ER’s novel detector nanorods will be combined with the Eden’s expertise in design and engineering of microfluidic systems.
Objective: development of novel diagnostic tools for detection of superantigens
To overcome the limitations of current diagnostic assays for sepsis in the terms of sensitivity, speed and ease of use, we propose to produce a fully integrated system for highly sensitive detection of superantigens. Major increase in sensitivity will be achieved by using immune-PCR (iPCR), a method that combines immune detection of proteins with sensitivity of quantitative PCR, while the ease of use and speed are based on the microfluidic assay design. Our fully integrated lab-on-chip point-of-care device will have several advantages over the existing systems. Firstly, it will use, as detector particles, Experienced Researcher (ER)-developed DNA-protein nanorods displaying TCR Vβ. The protein-DNA link in these detector particles is essential for iPCR and it is achieved by natural production of the particles, rather than more expensive chemical coupling. Secondly, the assay will use immobilised MHC II to capture the superantigen-nanorod complex. Given that all superantigens bind MHC II, this approach will allow capture of all superantigen-nanorod complexes. The assay will allow specific detection of each superantigen by using, for superantigen-specific detection, a mixture of bar-coded nanorods, each displaying a TCR Vβ domain which preferentially binds a specific superantigen. The bar-coding of the nanorod DNA will in turn permit multiplexing of the assay at the PCR stage.
