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In the past decade, Sarbecoviruses crossed into humans twice, resulting in the SARS-1 virus-related pandemic in 2002-04, and the SARS-2 virus-related COVID-19 pandemic in 2019. Today's Oxford University study shows that the virus' most recent common ancestor was more than 21,000 years old, which is nearly 30 times longer than previously estimated.
Despite their rapid evolution rate, viruses must be adapted to their host to survive. This limits their ability to acquire mutations and does not affect their fitness. The apparent rate of virus evolution slows down over time. This new research recreates for the first-time the patterns of observed rate decay in viruses.
"We have developed a new method to recover the age and magnitude of viruses over longer time periods. This correction corrects for an underlying phenomenon called evolutionary relativity, where the rate of evolution is dependent on the measurement time. Mahan Ghafari from Oxford University said that our estimate, based on viral sequence data dating back more than 21,000 years, is in striking agreement with a recent analysis of human genomic data that suggests an ancient coronavirus infection around the same period."
This study also shows that existing evolutionary models often fail to measure divergence between viruses species over long periods, ranging from a few hundred years to a few thousand of years. The evolutionary framework created in this study will allow reliable estimations of virus divergence over large timescales and possibly over the entire history of animal and plant evolutionary.
This new model allows us to reconstruct not only the evolutionary history of viruses associated with SARS-CoV-2 but also to identify RNA viruses and DNA viruses that occurred at more distant times in the past.
Model predictions for the hepatitis C virus, a leading cause of liver disease worldwide, are consistent with the notion that it has circulated for almost half a million years. The possibility that HCV spread to the rest of the world as an integral part of the "Out-of-African" migration of modern humans about 150,000 years ago is possible.
This extended period may have been the source of different HCV genotypes that are now found in South, South-East Asia, and Central Africa. The revised timeframe may help to resolve the long-standing mystery of their global distribution.
Professor Simmonds from Oxford University says, "With this new technology we can look more broadly at other viruses; reevaluate their deeper evolution timescales and gain insight into host relationships that are crucial to understanding their ability cause disease."
Continue reading Understanding the evolution of SARS type viruses and COVID-19 types viruses
Mahan Ghafari and colleagues, A mechanistic evolution model that explains the time-dependent pattern in substitution rates for viruses, Current Biology (2021). Information from the Journal: Current Biology Mahan Ghafari and colleagues, A mechanistic evolutionary modeling explains time-dependent substitution rates in viruses (2021). DOI: 10.1016/j.cub.2021.08.020
