Originally from The Conversation

Ruben Cloete, Lecturer in Bioinformatics, University of the Western Cape, Burtram C. Fielding, Dean Faculty of Natural Sciences and Professor, University of the Western Cape, and Dewald Schoeman, PhD Candidate, Molecular Biology and Virology, University of the Western Cape

It’s hard to imagine a time when “coronavirus” wasn’t a household word. But for a long time, this family of viruses had merited very little attention. Believed to be ubiquitous among animals and avian species, the first coronavirus to infect and cause disease in humans was only isolated and identified in the 1960s.

Seven human coronaviruses have been identified since then.

Most cause only relatively minor health concerns: the common cold and seasonal respiratory infections that come around every year. But the 2003 outbreak in China and other parts of Asia of severe acute respiratory syndrome (SARS), caused by SARS-CoV (now renamed as SARS-CoV-1), propelled the virus onto the global stage. Coronaviruses gained further infamy when, in 2012, cases of the much more severe Middle East respiratory syndrome (MERS) were identified in Saudi Arabia.

Both outbreaks were relatively contained. Not surprisingly, the concern over coronavirus diseases largely faded from the minds of ordinary people. The same was true for virologists, who focused their time and funding on more pressing viruses. Then in late 2019 came SARS-CoV-2, the causative agent of COVID-19.

Fortunately, some researchers had retained an interest in coronaviruses. After all, viruses can mutate and reappear, causing new outbreaks. One such cohort, ourselves among them, works at the University of the Western Cape in South Africa. Our laboratory had, among other things, been studying some of the structural proteins that are the building blocks of coronaviruses. These proteins – named spike, nucleocapsid, membrane, and envelope proteins – have different roles, but are essential to how coronaviruses reproduce, spread and cause disease.

In our most recent paper, we examined what possibly sets the human coronaviruses that cause SARS, MERS and COVID-19 apart from the other human coronaviruses that cause milder diseases like seasonal colds. The answer, we argue, lies with the envelope protein.

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