Origin of coronaviruses: what scientists have discovered so far

In seeking to clarify the origins of coronavirus infections in humans, researchers at the Bioinformatics Research Center (BRC) at the University of North Carolina (UNC) in Charlotte, United States, carried out one of the largest and most comprehensive evolutionary analyzes carried out to date. . The team analyzed more than 2,000 genomes of several coronaviruses that infect humans or other animals.

More than two thousand genomes have been analyzed.Source: Pixabay

The Brazilian PhD Denis Jacob Machado – main author of the article – stated, in a text released by the university, that the analyzes made by the scientific community shortly after the emergence of the new coronavirus were rushed and presented different problems. The study organized by his team carried out evolutionary analyzes based on the most rigorous standards in the area.

“Many previous analyzes had a poor sampling of viral diversity or an excessive emphasis on general similarity, rather than focusing on shared characteristics due to the common evolutionary history. It was very important for us to avoid these errors in producing a solid evolutionary hypothesis that would offer information reliable for future research, “said Machado.

Coronavirus in humans

Coronavirus (CoVs) infection in animals and humans is nothing new. The first articles in the scientific literature were published in 1966. However, before the outbreaks of SARS-CoV (severe acute respiratory syndrome – or SARS, which occurred between 2002 and 2003); MERS-CoV (Middle East respiratory syndrome, active since 2012) and SARS-CoV-2 (which causes covid-19), very little attention had been paid to coronaviruses.

But suddenly, coronaviruses changed everything: from concepts of personal and public health to levels of social and economic well-being. This change led to hasty analyzes, which sought to find intermediate hosts (for example, the civet in the case of SARS-CoV and the pangolin in SARS-CoV-2), rather than watching for SARS-like viruses in bats, which, according to the result of the new research, it would be more important.

Scientific conclusions

Machado’s team attested that bats have been ancestral hosts for human coronaviruses in the case of SARS-CoV and SARS-CoV-2. These animals were also the ancestral hosts of MERS-CoV infections in dromedary camels – which quickly migrated to humans.

The transmission of MERS-CoV between camels and their shepherds occurred after the contact of bats with these hosts (the camels). Likewise, SARS-CoV was transmitted to humans – first among civet sellers – after contact between bats and civets. These events are similar to the transmission of SARS-CoV-2 between mink breeders and their animals, but these secondary infections have not had relationship with the emergence of coronaviruses in humans.

The study also confirms the origins of animal hosts from other human coronaviruses, such as HCoV-NL63 (from bat hosts), HCoV-229E (from camel host), HCoV-HKU1 (from rodent hosts) and HCoV-OC43 and HECV-4408 ( host cows).

Camel is appointed as an intermediate host of the MERS-CoV virus.Camel is appointed as an intermediate host of the MERS-CoV virus.Source: Pixabay

The researchers say that the transmission of coronavirus from animals to humans occurs episodically. From 1966 to 2020, scientists described eight strains of coronavirus hosted in humans. Although it is difficult to predict when a new coronavirus like this may appear, the data indicate that we must prepare for this possibility.

“As transmission between animals and humans occurs at unpredictable intervals, it is not advisable to wait for the moment when we will experience the next human coronavirus,” said Professor Daniel A. Janies, the study’s leading professor of Bioinformatics and Genomics. “We should conduct research on viruses that can be transferred from animals to humans on an ongoing basis, rather than just reacting when an outbreak happens,” he concluded.

But what if it is a laboratory virus?

There are also those who believe that SARS-CoV-2 has escaped from a virology institute that is a world leader in coronavirus research, located in Wuhan, China. The writer Nicholas Wade, specialized in science, says in a text on the website Medium that the possibility should not be treated as a conspiracy, but as a possible scenario – and that it should also be analyzed so that, if this is the origin, another case similar situation does not occur again.

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