Method Developed to Speed Up Detection of Infectious Diseases

A method to speed and simplify the detection of proteins in blood and plasma has been described opening up the potential for diagnosing the early presence of infectious diseases or cancer during a doctor’s office visit.

The new approach overcame several key challenges in detecting proteins that are biomarkers of disease. First, these proteins are often at low abundance in body fluids and accurately identifying them requires amplification processes. The new test takes about 10 minutes as opposed to two to four hours for current state-of-the-art tests.

Scientists at the University of California, Los Angeles (CA, USA) devised an approach to amplify a protein signal without any enzymes, thus eliminating the need for a complex system to wash away excess enzymes, and that would work only in the presence of the target protein. This novel approach made use of a molecular chain reaction that was strongly triggered only in the presence of a target protein.

The team designed a transduction mechanism whereby a protein signal is transduced into an amplified nucleic acid output using DNA nanotechnology. In this system, a protein is recognized by nucleic acid bound recognition elements to form a catalytic complex that drives a hybridization/displacement reaction on a multicomponent nucleic acid substrate, releasing multiple target single-stranded oligonucleotides in an amplified fashion. The team demonstrated the approach with two target proteins, streptavidin, widely used as a test protein for new diagnostic assays, and influenza nucleoprotein, which is a protein associated with the influenza virus.

In the long term the team aims to combine the technique with portable readers that could be particularly beneficial in clinics in resource-poor areas. The scientists demonstrated a synergistic handheld microplate reader suitable for protein diagnostic assays based on a cellphone’s optical and computational systems earlier this year. In addition, they demonstrated the assay in a microfluidic digital assay format leading to improved quantification and sensitivity approaching single-molecule levels. The present scheme they believe will have a significant impact on a range of applications from fundamental molecular interaction studies to design of artificial circuits in vivo to high-throughput, multiplexed assays for screening or point-of-care diagnostics.

Omai B. Garner, PhD, an Assistant Clinical Professor and Associate Director of Clinical Microbiology and co-author of the study, said, “Although demonstrated initially in detecting protein associated with flu, we envision the approach can be generalized to a range of protein biomarkers associated with infectious diseases and cancer.” He noted it could be configured to detect diseases such as Zika or Ebola. The study was published on July 27, 2016, in the journal ACS Nano.

Related Links:
University of California, Los Angeles