Creating highly amplified enzyme-linked immunosorbent assay signals from genetically engineered bacteriophage

Protein nanoparticles as multifunctional biocatalysts and health assessment sensors

“…Chemical conjugation methods are often used to attach inorganic, non-proteinaceous components such as chemical dyes for imaging [28,35], targeting ligands for drug delivery [36], and peptides for immune activation [37]. Typically, well-characterized chemistries can be employed to couple substances to reactive side chains that are either surface exposed or genetically incorporated into the protein monomer backbone.…”

“…The coat protein 3 (p3) located at the tip of the rod-shaped phage was modified to bind to the antibody, and the major protein 8 (p8) covering the entire phage surface was modified with biotin to bind avidin-conjugated enzymes. The resulting VLPs modified with anti-rTNFa (recombinant human tumor necrosis factor alpha) antibodies using this strategy showed approximately 4-fold improvement in the ELISA signal [35]. VLPs have been also modified to bind both Ni nanohairs and troponin antibodies in a three-dimensional structure made from engineered HBV capsids.…”

Virus-based assay for antigen detection using infective growth as signal transduction mechanism

“…To see if this improvement in relative signal intensity achieved by the phage infectivity assay will prove useful at enhancing the detection limits, we examined the sensitivity of glucose oxidase detection both phage infectivity assay and phage ELISA. While the limits of detection for ELISA and phage ELISA detection have been shown to be in the range of 1-10 nM (Brasino et al 2015), a main factor that can limit the sensitivity of ELISA is the affinity of the antibody, nonspecific binding, and experimental variation. To reduce these Fig.…”

“…Recent virusbased sensing systems have also shown detection of small chemicals, including the explosive trinitrotoluene, by using the ability of liquid crystalline filamentous virus films to change color in response to target analyte binding (Oh et al 2014). Other effective virus-based sensors have used modification of a phage ELISA technique in which displayed peptide fragments (Wang et al 2015) or protein A coupled p3 systems (Brasino et al 2015) provide selectivity through antibody binding along with reporter enzymes coupled to the virus main coat to achieve high quality colorimetric detection. Similarly, coupling of the virus major coat with DNAgold nanoparticles has shown the possibility of transduction of the binding event into a colorimetric signal (Lee et al 2012) or alternatively detection through Raman scattering .…”

Aptamer-Phage Reporters for Ultrasensitive Lateral Flow Assays

“…Horseradish peroxidase (HRP), fluorophores), and have been successfully used in various protein or small molecule detection assays, e.g. enzyme-linked immunosorbent assays (ELISA) 14-16 , microarrays 17 or other protein sensors 18,19 . PCR amplification of the phage genetic material has led to the development of ultra-sensitive immuno-phage PCR assays by ourselves and others 20-22 .…”