Coronavirus (CoVs) infection in animals and humans isn’t new. The earliest papers in scientific literature of coronavirus infection date to 1966. However, before SARS-CoV, MERS-CoV, and SARS-CoV-2, little or no attention had been paid to coronaviruses.
Suddenly, coronaviruses changed everything we all know about personal and public health, and societal and economic well-being. The change led to rushed analyses to know the origins of coronaviruses in humans. This rush has led to a so far fruitless look for intermediate hosts (e.g., civet in SARS-CoV and pangolin in SARS-CoV-2) instead of that focusing on important work, which has always been surveillance of SARS-like viruses in bats.
To clarify the origins of coronavirus’ infections in humans, researchers from the Bioinformatics research facility (BRC) at the University of North Carolina at Charlotte (UNC Charlotte) performed the most important and most comprehensive evolutionary analyses so far . The UNC Charlotte team analyzed over 2,000 genomes of diverse coronaviruses that infect humans or other animals.
“We wanted to conduct evolutionary analyses based on the foremost rigorous standards of the sector ,” said Denis Jacob Machado, first author of the paper. “We’ve seen rushed analyses that had different problems. for instance , many analyses had poor sampling of viral diversity or placed excessive emphasis on overall similarity instead of on the characteristics shared due to common evolutionary history. it had been vital to us to avoid those mistakes to produce a sound evolutionary hypothesis that would offer reliable information for future research.”
The study’s major conclusions are:
1) Bats are ancestral hosts of human coronaviruses in case of SARS-CoV and SARS-CoV-2. Bats also were the ancestral hosts of MERS-CoV infections in dromedary camels that spread rapidly to humans.
2) Transmission of MERS-CoV among camels and their herders evolved after the transmission from bats to those hosts. Similarly, there was transmission of SARS-CoV after the bat to human transmission among human vendors and their civets. These events are almost like the transmission of SARS-CoV-2 by fur farmers to their minks. The evolutionary analysis during this study helps to elucidate that these events occurred after the orignal human infection from lineages of coronaviruses hosted in bats. Therefore, these secondary transmissions to civet or mink didn’t play a role in fundamental emergence of human coronaviruses.
3) The study corroborates the animal host origins of other human coronaviruses, like HCoV-NL63 (from bat hosts), HCoV-229E (from camel hosts), HCoV-HKU1 (from rodent hosts) and HCoV-OC43 and HECV-4408 (from cow hosts).
4) Transmission of coronaviruses from animals to humans occurs episodically. From 1966- 2020, the scientific community has described eight human-hosted lineages of coronaviruses. Although it’s difficult to predict when new human hosted coronavirus could emerge, the info indicate that we should always steel oneself against that possibility.
“As coronavirus transmission from animal to human host occurs episodically at unpredictable intervals, it’s not knowing plan to time once we will experience next human coronavirus,” noted professor Daniel A. Janies, Carol Grotnes Belk Distinguished Professor of Bioinformatics and Genomics and team leader for the study. “We must conduct research on viruses which will be transferred from animals to humans on endless instead of reactionary basis.”
4) Transmission of coronaviruses from animals to humans occurs episodically. From 1966 to 2020, the scientific community has described eight human-hosted lineages of coronaviruses. Although it is difficult to predict when a new human hosted coronavirus could emerge, the data indicate that we should prepare for that possibility.
“As coronavirus transmission from animal to human host occurs episodically at unpredictable intervals, it is not wise to attempt to time when we will experience the next human coronavirus,” noted professor Daniel A. Janies, Carol Grotnes Belk Distinguished Professor of Bioinformatics and Genomics and team leader for the study. “We must conduct research on viruses that can be transferred from animals to humans on a continuous rather than reactionary basis.”
The findings were reported in University of North Carolina at Charlotte