SARS-CoV-2 Research Antibodies

SARS-CoV-2, the causative viral agent of the disease COVID-19, is a coronavirus which bears the transmembrane glycoprotein spikes (S protein) typical of viruses in its clade. These spikes are a prominent target of human immune responses and have been found to be highly immunogenic. The receptor-binding domain (RBD) of the S protein is particularly targeted by neutralising antibodies.

The spike protein is a heavily-glycosylated, cell-surface protein which mediates viral entry into host cells. The spikes on SARS-CoV-2 allows the virus to enter host cells through the human receptor angiotensin converting enzyme 2 (ACE2), present in alveolar epithelial cells. ACE2, a carboxypeptidase, is part of the renin-angiotensin system (RAS), and has been shown to be a functional receptor of the human coronaviruses SARS-CoV and SARS-CoV-2.The S protein RBD and ACE2 interaction is explained in great detail in this article.

Spike protein is necessary for attachment to susceptible cells. The spike protein is composed of both an S1 domain and S2 domain. S1 contains a receptor-binding domain. The receptor-binding domain of the spike protein mediates an interaction with angiotensin-converting enzyme 2 (ACE2). Neutralising antibody responses, mainly to the Spike protein, begin to develop by week 2 of infection onset and most patients develop neutralising antibodies by week 3.

The time between initial viral exposure and symptom onset is known as the incubation period. For COVID-19, the average incubation period has been reported to be between five and six days, however, there is considerable variation in incubation time.

In patients with SARS-CoV infection, B cell responses are activated firstly against the nucleocapsid (N) protein of SARS-CoV-2. The N protein is one of the most abundant structural proteins during SARS-CoV-2 infection. The role of the N protein is to package the positive strand viral genome RNA into a helical ribonucleocapsid (RNP). The SARS-CoV-2 N protein also plays a role during virion assembly through its interactions with the viral genome and membrane protein M.

Within 4–8 days after symptoms present, antibody responses against the spike (S) protein of the virus are found. Neutralising antibody responses, mainly to the S protein, begin to develop by week 2 of infection onset and most patients develop neutralising antibodies by week 3.

To support the efforts of researchers across the globe, ELISA Genie has developed SARS-CoV-2 receptor ACE2 antibodies, spike protein antibodies, nucleoprotein antibodies and more. These antibody research tools will contribute to understanding and combating COVID-19 virus SARS-COV-2 and other coronaviruses.