By Sahana Shankar, Ph.D. Candidate
Researchers from Taiwan’s preeminent academic institution, Academia Sinica have developed a rapid immune-based diagnostic kit to identify COVID-19 infected samples within 15 to 20 minutes. The monoclonal antibodies do not cross-react with other coronaviruses and are quite specific in detecting the nucleocapsid protein of the COVID-19 causing coronavirus.
A huge breakthrough in our understanding of the COVID-19 outbreak was the analysis of the causal coronavirus SARS-CoV-2’s genome and its sequence similarity with SARS and MERS viruses. Since the genome sequence was made available by a consortium of scientists on January 10, 2020, various labs developed diagnostic protocols for the detection of the virus in clinical respiratory samples. The World Health Organization (WHO)-recommended standard diagnostic is an RT-PCR test, testing for sequences from ‘E’ and ‘RdRp’ genes of the SARS-CoV-2 coronavirus. The US Centers for Disease Control and Prevention (CDC) has instituted a slightly modified RT-PCR where 3 sequences of the nucleocapsid N gene and multiple regions of the RdRp genes are probed.
If a patient tests positive, further confirmatory tests like whole viral genome sequencing or viral culture may be carried out. The turnaround time for a typical RT-PCR is around 4-6 hours. However, since most diagnostic labs are overwhelmed by the volume of cases at the moment, turnaround time varies from 12-72h. With the number of cases and cluster infections increasing worldwide, RT-PCR based protocols may be time-consuming and limited by the availability of appropriate primers though the scientific community has been very proactive in making relevant literature and reagents available for everyone. In this regard, two new detection protocols have been proposed to ensure effective and timely diagnosis to help clinicians- one is a high-throughput molecular diagnostic kit from Hologic Inc, San Diego and the other is an antibody-based immune test developed in Academia Sinica, Taipei.
Hologic’s Panther Fusion
Hologic, a medical technology company based in San Diego, California, launched an automated high throughput PCR system called Panther Fusion in 2017 as an accredited medical diagnostic tool. Over the years, Hologic has added a broad spectrum of molecular tests for many bacterial and viral infections to its repertoire. In collaboration with clinicians from the Hannover Medical School, Germany, Hologic has developed a molecular assay for the detection of SARS-CoV-2. The pilot study demonstrated fully automated processing of patient samples right from RNA extraction, amplification of target sequences and real-time detection of amplicons in under 4h.
The US Department of Health and Human Services funded this diagnostic kit to the tune of $700,000 to be developed into a full-fledged diagnostic test for COVID-19 wherein 1000 samples can be tested in 24h. Kevin Thornal, president of the Diagnostic Solutions division at Hologic said “It’s extremely gratifying to see our instrument system being used to quickly develop a response to an urgent public health threat. We specifically designed Panther Fusion and Open Access functionality to give diagnostic lab customers maximum flexibility, both for their day-to-day needs and to respond quickly to emerging threats.” Hologic will further develop the assay in the coming weeks to be submitted to the US FDA for emergency use authorization (EUA).
Academia Sinica’s Rapid Immune-Based Diagnostic Kit
Dr. An-Suei, Yang and his team at the Genomics Research Center in Academia Sinica have identified a monoclonal antibody that specifically recognizes the nucleocapsid (N) protein of COVID-19 causing coronavirus SARS-CoV-2. Dr.Yang and his team generated anti-N protein antibodies from 7 different viral species, screened dozens of candidates to yield a SARS-CoV-2 specific antibody in 19 days. They were also able to generate monoclonal antibodies against nucleocapsid (N) proteins of other coronaviruses such as SARS and MERS. An added advantage of the SARS-Cov-2 monoclonal antibody is that it does not recognize the N protein of 5 other strains of coronavirus that can cause the common cold and hence prevents cross-reactivity and false positives.
Dr. Yang is the Division Director of Physical and Computational Genomics, and his work is based on AI-assisted antibody engineering. A typical workflow in his lab involves a reiterative process of identification of antibody repertoires in human immune response; computational design based on bioinformatics and protein interaction data; chemical synthesis of antibody libraries; bacteriophage display of antibody gene libraries to screen functional candidates and analysis of their therapeutic abilities. Since the antibody library does not need expensive animal facilities, screening multiple candidates to obtain a broad spectrum of drugs was achieved with minimal costs and reduced environmental impact. Dr. Yang had previously applied this approach to combat the African swine flu last year.
Dr. Yang is currently in talks with diagnostic manufacturers and the Ministry of Economic Affairs to develop a prototype kit after which they will approach Taiwan FDA for product qualification and certification. Upon approval from the Ministry of Health and Welfare, this rapid immune-based diagnostic kit will be able to provide COVID-19 test results within 15 – 20 minutes, much like a rapid influenza test. This should lift a significant burden off of many medical diagnostics that are currently working at full capacity.
With the emergence of these new diagnostic tools in the coming months, clinicians worldwide hopefully will have more technological support to manage the COVID-19 outbreak.
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