All about Test Kits to Detect the Causative Agent of COVID-19 (SARS-CoV-2)

SARS (Severe Acute Respiratory Syndrome) is a kind of acute respiratory syndrome. Coronavirus 2 (SARS-CoV-2) is a single-stranded, enclosed RNA virus belonging to the Coronaviridae family. Coronaviruses are made up of 16 nonstructural proteins and four structural proteins: the spike (S), envelope (E), membrane (M), and nucleocapsid (N) (N). Coronaviruses produce diseases with symptoms ranging from a normal cold to more serious illnesses like Coronavirus Disease 2019 (COVID-19), caused by the SARS-CoV-2 virus.

The SARS-CoV-2 virus infects the respiratory tract. It is spread mostly by respiratory droplets following close contact. Primary viral replication is thought to occur in the upper respiratory tract’s mucosal epithelium (nasal cavity and pharynx)—the viral load in these areas peaks within the first week of symptom onset and, after that, drops. 

A SARS-CoV-2 antigen test identifies the presence of the SARS-CoV-2 virus by detecting a nucleoprotein carried by the virus in swab specimens from the upper respiratory tract. During the acute phase of COVID-19, when the virus is still present in significant amounts in the respiratory tract, the test detects the current infection.

Antigen Testing

Antigen assays, in addition to laboratory PCR testing, can be used for fast testing in near-patient settings. For example, the SARS-CoV-2 Rapid Antigen Test is a chromatographic immunoassay for the qualitative identification of SARSCoV2 specific antigens in nasopharyngeal or combined nasopharyngeal/oropharyngeal samples. This test is designed to identify antigens from the SARSCoV2 virus in people who have been diagnosed with COVID19.

Covid-19 antigen test kits manufacturers stated that professionals in laboratories and Point-of-Care settings only use this product. It identifies a SARS-CoV-2 antigen, the nucleoprotein, in the same way as laboratory equipment does. It may thus be used to determine if a person is infected with SARS-CoV-2 by displaying colourful bands indicating the presence of SARS-CoV-2 antigens in a qualitative result.

Covid-19 antigen test kits are only for humans; for canines, there are canine coronavirus Ag rapid test kit factories that create test kits for dogs.

All about Test Kits to Detect the Causative Agent of COVID-19 (SARS-CoV-2) 3

The Canine Coronavirus (CCV) Antigen Rapid Test

The Canine Coronavirus (CCV) Antigen Rapid Test Device is a lateral flow immunochromatographic test detecting CCV antigens (CCV Ag) in dog faeces or vomit.

If CCV antigens are present in the faeces, they react with the test strip’s pre-coated anti-CCV antibodies. The combination then migrates chromatographically upward on the membrane via capillary action, reacting with anti-CCV antibodies on the membrane in the test line area. Therefore, a colorful line will show in the test line region if the material contains Canine Coronavirus, indicating a positive result.

A colored line will not show in the test line region if the material does not contain CCV antigens, indicating a negative result. However, a colored line will always appear in the control line region to act as procedural control.

Polymerase chain reaction (PCR) test

This test falls under the category of genetics test. Your RNA is analyzed to see if there is some unusual activity. To date, it is regarded as the most accurate test. Although, it cannot be claimed as perfect. Due to its accuracy, many countries are demanding you take this test before entering their border. This test can also be used as proof of your health at formal places like schools, workplaces, and government organizations. 

To take this test a swap is inserted in your nose or throat. Through your mucus, it is established whether you have a virus or not. If you are not comfortable with the swab then you can also give a test through saliva. The only downfall is that it usually takes a day to get your results. As the sample has to be taken to the lab to analyze.

Note: Because of the possibility of false positives and negatives, antigen and antibody (IgG/IgM) detection kits should not be used as the only test for diagnosis; verify with the manufacturer for claimed specificity and sensitivity.