Real SARS-CoV-2, Real SARS-CoV-2 PLUS and Real SARS-CoV-2/RSV/Flu products are three tests based on the PCR real time technique, that allows the qualitative detection and differentiation up to 3 specific genes (E, N and orf1ab) for SARS-CoV-2 Coronavirus, and also RSV and Flu viruses.
COVID-19 is an infectious disease caused by SARS-CoV-2, a sarcovirus-like coronavirus first detected in the Chinese city of Wuhan, Hubei province, in December 2019. In March 2020, the WHO declared it a pandemic.
As the symptoms of the COVID-19 disease might be similar to those caused by Flu or RSV viruses, it is important to diferentiate the cause of the infection in order to take the appropriate measures.
Most people infected with SARS-CoV-2 will develop mild to moderate symptoms, such as fever, fatigue or dry cough, but can also develop severe disease and even death, especially in older patients and/or those with pre-existing conditions.
Detection of RNA virus by techniques such as real-time RT-PCR is important in such infection because it can help health professionals to isolate infected persons quickly, thus containing the outbreak by preventing it from spreading. As a result, health authorities —such as China CDC, Charité-Germany, or US CD (1,2)— have issued several testing and gene detection protocols for the molecular diagnosis of SARS-CoV-2 infection.
The Real SARS-CoV-2 and Real SARS-CoV-2 PLUS products are tests for the easy and sensitive detection of SARS-CoV-2 virus by real time RT-PCR, with protocols available that do not require nucleic acid extraction. The Real SARS-CoV-2/RSV/Flu product also allows the detection of Flu and RSV viruses.
(1) World Health Organization, https://www.who.int/docs/default-source/coronaviruse/protocol-v2-1.pdf, last accessed January 17, 2020
(2) Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected human cases. Interim guidance 2 March 2020, WHO
Possibility of non-extraction of RNA
Detection of up to 3 genes
Identification of new variants
Endogenous internal control
Dr. María Alejandra Torres, haemato-oncologic and member of the Venezuelan COVID Commission, gives an interesting overview of all the diagnostic tools currently available for the detection of COVID-19.
The recorded webinar is available on demand. If you missed it, feel free to request it!
The assay time is similar in all thermal cyclers, with only small variations due to the time it takes for each device to reach the temperatures of each cycle. In the validated thermal cyclers, the differences are less than 10 minutes. Thus, Quantum Studio and CFX take about 80 min, with ramps of 1.6 ºC/s, and Tianlong’s take about 70 min, with ramps of 6 ºC/s. Lighcycler defaults to 4.4 ºC/s.
The channels are equivalent. Only one, whichever is available, should be selected, as each thermal cycler usually contains only one of each group.
The different genes have similar sensitivity. Differences are mainly due to the design of the assay. In most cases, all genes can be detected in positive samples. Thus, most assays targeting more than one gene require the detection of at least 2 genes to provide a clear positive result. In some cases, only 1 or 2 of them are detected, with the N gene being one of the most frequently detected alone. This may be due to a low amount of viral load (early or late in the infection), but also to false positive results, or to reagent contamination with a specific gene. In most tests, if only the N gene is detected, the result would be considered inconclusive, and further testing would be necessary.
The internal control is endogenous, which means that it does not have to be added. This avoids possible errors in the procedure and ensures that all steps (extraction, retrotranscription, amplification) are correct.