SARS-CoV-2—the virus that causes COVID-19—belongs to the family of betacoronaviruses that cause everything from the common cold to Mers (which kills about one in three people infected). Despite causing a wide range of symptoms, these viruses all share similarities. If they’re similar enough, could one vaccine prevent infection from them all? Scientists have certainly been considering it.
Before we explore this question, though, we first need to take a detour into the fascinating anatomy of beta coronaviruses.
Betacoronaviruses are microscopic balls covered in spikes that encapsulate a central core of genetic material. The virus must infect cells in order to replicate, and to do this it must first attach to the cells.
Betacoronaviruses use their spikes to attach to cells by latching onto specific targets on the cells called receptors. Scientists from countries including the US and France have examined these spikes and discovered that they are made up of two pieces, or “domains,” imaginatively called S1 and S2.
These spike domains help the virus attach to host cells in a variety of ways. For example, the viruses that cause COVID-19 and SARS both use a part of the S1 domain called the receptor binding domain (RBD) to stick to the host cell receptor (ACE2). But the cold-causing viruses do not.