CLIA COVID-19 RBD

Coronaviruses belong to the family of enveloped RNA viruses. In humans, they cause diverse clinical pictures, from the common cold to severe respiratory syndromes (MERS, SARS, and COVID-19). SARS-CoV-2, the cause of COVID-19, is a respiratory virus discovered in 2019. It is primarily transmitted to an individual through close contact with an infected person, during which infectious droplets spread to the environment. Symptoms of COVID-19 are highly variable, ranging from none to life-threatening illness.

The SARS-CoV-2 virus contains four structural proteins: spike (S), nucleocapsid (N), envelope (E), and membrane (M) protein. Responding to the infection, the human immune system raises specific antibodies, starting with IgA and IgM. The IgG antibodies represent a later matured response. Serological tests play only a supporting role in COVID-19 diagnosis. However, they are effective in assessing the immune response of an individuum or population.

The used Receptor-Binding Domain (RBD) antigen, a subunit of the spike S1 protein, specifically binds to the angiotensin-converting enzyme 2 (ACE2) of the host cell. This bound highly correlates with the formation of neutralizing antibodies. In all vaccines developed so far, the spike protein is the antigenic substance (either as a protein or as an RNA / DNA sequence). Certainly, the anti-RBD antibodies are a valuable tool to monitor vaccination efficacy.