Viruses that jump from animal populations to humans frequently do not necessitate specialized adaptations to ignite an epidemic or pandemic, according to researchers at the University of California San Diego. Their findings have been featured in the journal Cell.
The research group conducted an examination of various viral genomes, encompassing influenza A, Ebola, Marburg virus disease, SARS, and SARS-CoV-2, specifically focusing on the genetic sequences immediately preceding transmission to humans. The expectation among the scientists was to uncover evidence of adaptations grooming the virus for human infection. Nevertheless, phylogenetic analysis revealed that prior to making the leap to humans, these viruses underwent no atypical natural selection nor acquired any significant evolutionary alterations.
“Our results challenge the notion that pandemic-capable viruses possess unique characteristics before they ever encounter humans. The majority of viruses are inherently equipped to infect and spread among people; the primary risk factor is simply direct contact between humans and animals, alongside alterations in their shared habitats,” the scientists state.
This study further corroborated that the spread of SARS-CoV-2 occurred naturally. No signatures indicative of laboratory manipulation were detected within the virus’s genome. An exception was the H1N1 influenza virus, responsible for the 1977 pandemic following a two-decade hiatus. This particular virus displayed a selection pressure pattern consistent with lab adaptation, lending credence to the long-standing theory of a potential lab leak in that instance.
These conclusions are crucial for averting future outbreaks, in the view of the researchers. They advocate that efforts to manage zoonotic viruses should concentrate on mitigating human-animal interaction and addressing ecosystem shifts, rather than searching for what they term “super-mutations” in viruses.
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