Intro: UCLA researchers in the Department of Molecular and Medical Pharmacology have discovered high affinity binding affibodies to COVID-19’s nucleocapsid protein that provide the basis for an ELISA-based diagnostic platform. The researchers are currently developing affibody-coated test strips for saliva detection of COVID-19 in high population settings or at home testing.
BACKGROUND: COVID-19 is a highly contagious viral pneumonia causing fever and shortness of breath and since December 2019, there has been an ongoing global outbreak of the virus. The disease originates from Wuhan, China and has quickly spread to more than twenty countries within two months. As of 14 February 2019, there have been 64544 cases of infection and 1380 deaths reported. While the worldwide epidemic is expected to last until the first half of 2020, a sensitive and quick viral detection method will be essential to early diagnosis and disease control of COVID-19. Unfortunately, current RT-PCR diagnostic tests have poor sensitivity, are time-consuming, and do not enable population-wide screening in a cost-effective manner.
INNOVATION: UCLA researchers have developed two sensitive antibody mimetics (affibody) for detecting nucleocapsid protein (NP) of COVID-19. The affibodies were developed, using an mRNA display method and can be mass-produced and purified from E. coli. The two affibodies bind SARS NP with Kd of 3.7nM and 400pM affinities. COVID-19 and SARS nucleotide sequences have 94% similarity and amino acid sequence and structural conservation level of NP N-terminal and C-terminal domains was investigated and confirmed in silico and in vitro with purified COVID-19-NP. Indeed, in vitro studies show a slightly diminished but still strong affinity of the two affibodies towards COVID-19-NP. Efforts to further increase the binding affinity for COVID-19-NP are underway. The affibodies can be detected using an ELISA- based detection method developed by the UCLA researchers. The assay has a limit of detection is around 1 to 5 pg/ml for the two affibodies rendering it a reliable, fast and facile diagnostic tool for COVID-19. Studies to prove the superiority of this method against current PCR-based methods are ongoing and so is the development of lateral flow test strips for viral detection in patient saliva. Overall, this technology provides a much-needed rapid diagnostic for COVID-19 that upon commercialization will aid in the timely detection and control of viral dissemination.
POTENTIAL APPLICATIONS:
• Viral detection
• COVID-19 diagnostic
ADVANTAGES:
• Fast and easy detection
• Sensitive
• Scalable production using Ecoli
• High affinity for virus nucleocapsid protein
DEVELOPMENT-TO-DATE:
Two affibodies have been discovered, synthesized, purified and tested against purified COVID-19-NP. Both affibodies bind COVID-19-NP with low nanomolar affinities. The researchers have developed an accompanying ELISA-based detection method for the affibodies which results in lower limits of detection around 1 to 5 pg/ml.