The evolutionary journey of Omicron.

A never-ending story?

Agustín Muñoz-Sanz
ILLUMINATION
Published in
18 min readMar 4, 2022

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Zoonoses are human infections caused by microbes originating from the animal world. More than 60% of the 400 emerging human diseases identified since 1943 are zoonotic (The Lancet).

Figure 1. Dynamics of zoonoses showing the direct transfer of microorganisms between wild animals, from wild animals to domestic and to humans. In many zoonoses the transfer is indirect because insect vectors are involved. Credit: Karesh, et al, The Lancet.

Many kinds of microbe cause zoonosis. Bats (order Chiroptera) occupy a privileged position among mammalian animals. Viruses stand out among microbes. I highlight the importance of the coronaviruses-bats binomial in veterinary and human medicine. It is an inseparable couple since the beginning of time. Long before animal domestication.

But we only know the tip of the iceberg. A 2017 study by PREDICT (EcoHealth Alliance) described the active search for viruses in nature. The investigators analyzed bats, rodents, monkeys, and humans in Bangladesh. The work led to the detection of more than 100 different coronaviruses, 98% of which were in bats. The authors suppose there must be more than 3,000 coronaviruses. Most of them are still undiscovered. They live among the more than 1,420 cataloged species of bats. Although only a few dominate. Bats of the genus Rhinolophus are the most frequent, but not the only ones.

After rodents, bats are the most abundant (22%) mammals. Not to be overlooked, distracted by bats, the role of rodents in this story. And if the coronaviruses-bats pairing were not enough, there are about 5,500 known species of mammals. Many may be candidates for receiving and exporting coronaviruses. To individuals of the same or different species. Including Homo sapiens.

Comparative genomics and protein structural analysis permit to do profound studies (PNAS, June 2020). Among 410 vertebrates analyzed, 252 (61.4%) of which were mammals, only these (mammals) are at high risk of receiving coronavirus, especially bats. The reason lies in the affinity of coronaviruses for a region of the cellular receptor ACE2.

Mathematical models estimate 11.5 times more coronavirus-host associations. Also, more than 30 times more potential SARS-CoV-2 recombination hosts. And more than 40 times more host species with four or more different subgenera of coronaviruses have been observed so far. We have known some of the…

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Agustín Muñoz-Sanz
ILLUMINATION

Medical Doctor (Infectious Diseases specialist/Professor of Medicine) and writer (narrative, theater).