Viral RNA
The testing of SARS-CoV-2 is grouped into molecular testing and serology
testing. The molecular testing includes nucleic acid amplification test
(NAAT) such as real-time RT-PCR [7]. According to WHO interim
guidance on laboratory testing of COVID-19 in suspected human [7],
the respiratory materials were required to collect to perform NAAT. The
unique sequence RNA of the virus including nucleocapsid (N), envelope
(E), spike protein (S) and RNA-dependent RNA-polymerase (RdRP) genes are
targeted to analyze using real-time reverse-transcription polymerase
chain reaction (rRT-PCR) [8]. On 23rd January
2020, the first COVID-19 detection kit using rRT-PCR was published which
targeted RdRP, N and E gene of SARS-CoV-2 [8]. Up to present, there
are many in-house or commercial COVID-19 molecular assays
available from worldwide, for instance, 1. ’CDC 2019-nCoV real-time
reverse transcriptase PCR diagnostic panel’ was developed by United
State Centers for Disease Control and Prevention (US CDC). This
diagnostic panel is working with Applied Biosystems 7500 Fast DX
Real-Time PCR Instrument with SDS 1.4 software; 2. ‘New coronavirus
nucleic acid assay’ which targeted on ORF1ab and N gene was developed by
Chinese National Institute for Viral Disease Control and Prevention; 3.
Molecular test kits from four companies such as Seegene Inc., Kogene
Biotech Co. Ltd., Sd Biosensor Inc., and Solgent Co. were approved by
Ministry Food and Drug Safety (MFDS) and Korea Centers for Disease
Control and Prevention (KCDCP) which are now widely being used in South
Korea [9]. Primer and probe design are critical for the detection of
or viral RNA that is easy to mutate. Taiwan Centers for Disease Control
provides real-time RT-PCR primers targeting E, RdRp and N gene for
first-line screening, confirmatory and additional confirmatory assay,
respectively.
The outbreaks of the COVID-19 pandemic have led to the increasing of
thousands of active cases every day all over the world, so worldwide are
racing against time to find a test to quickly detect the virus and
isolate the infected patient from healthy population to stop virus
transmission from the further outbreak. The United States Food and Drug
Administration (US FDA) is moving fast to approve a few COVID-19
molecular test kits under Emergency Use Authorization (EUA) powers.
Cepheid Inc, Mesa Biotech Inc and BioFire Defense LLC were recently
granted FDA approval of their rapid diagnostic test that could give the
test result reduced to an hour compared to traditional RT-PCR methods
that required 3 to 4 hours. On March 27, 2020, Abbott announced the
launch of a molecular point-of-care test, which uses an isothermal RNA
amplification method to deliver positive results in five minutes and
negative results in 13 minutes. It is expected to produce about 5
million tests per month
(https://www.abbott.com/corpnewsroom/product-and-innovation/detect-covid-19-in-as-little-as-5-minutes.html).