An unknown family of viruses, already widespread in wild African primates and known to cause lethal Ebola-like symptoms in certain monkeys, is “poised for spillover” to humans, according to the authors of new study published by University of Colorado Boulder in the journal Cell today.
Even though these arteriviruses are already thought to be a major threat to macaque monkeys, no infections in humans have been reported as of yet. And it’s not clear what effect the virus would have on humans if it spreads from animals to humans.
But the authors still want people to be careful by drawing comparisons to HIV, whose ancestor came from African monkeys. By keeping an eye out for arteriviruses in both animals and people, the global health community may be able to prevent another crisis, scientists said.
“This animal virus has figured out how to gain access to human cells, multiply itself, and escape some of the important immune mechanisms we would expect to protect us from an animal virus. That’s pretty rare,” added senior author Sara Sawyer, a professor of molecular, cellular and developmental biology at CU Boulder. “We should be paying attention to it.”
Animals all across the world are infected with thousands of different viruses, the majority of which show no symptoms. The Middle Eastern Respiratory Syndrome (MERS) in 2012, Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) in 2003, and SARS-CoV-2 (the virus that causes COVID-19) in 2020 are just a few examples of how an increasing number of viruses have jumped to humans in recent decades, wreaking havoc on foolish immune systems with no experience fighting them off.
For 15 years, Sawyer’s team has investigated whether animal viruses may be likely to infect people by using laboratory procedures and tissue samples from wildlife from all over the world.
She and the study’s first author, Cody Warren, who was at the time a postdoctoral fellow at the BioFrontiers Institute at Colorado University, focused on arteriviruses, which are widespread in pigs and horses but less known in nonhuman primates. They focused on the simian hemorrhagic fever virus (SHFV), which has been responsible for catastrophic outbreaks in confined macaque colonies since the 1960s and causes a fatal illness similar to the Ebola virus disease.
The study shows that a molecule or receptor called CD163 is a key part of the way simian arteriviruses work, allowing them to get into target cells and make them sick. Researchers were surprised to discover, through a series of laboratory studies, that the virus was also highly effective at attaching to the human form of CD163, entering human cells, and rapidly replicating itself.
Simian arteriviruses appear to attack immune cells similarly to human immunodeficiency virus (HIV) and its predecessor simian immunodeficiency virus (SIV), compromising vital defense mechanisms and establishing a long-lasting presence in the body.
“The similarities are profound between this virus and the simian viruses that gave rise to the HIV pandemic,” highlighted Warren, now an assistant professor in the College of Veterinary Medicine at The Ohio State University.
The authors emphasize that a new pandemic is not coming soon, so people don’t need to worry.
However, they do recommend that the science of global health focus more research on simian arteriviruses, create blood tests for them, and think about surveillance of human populations that have intimate contact with animal carriers.
Many different African monkey species already have significant viral loads of different arteriviruses, frequently without any symptoms, and certain species are known to bite and scratch humans.
“Just because we haven’t diagnosed a human arterivirus infection yet doesn’t mean that no human has been exposed. We haven’t been looking,” remarked Warren.
According to Warren and Sawyer, no one had ever heard of HIV in the 1970s either.
The SIVs that infected nonhuman primates in Africa are thought to be the source of HIV, which spread to humans sometime in the early 1900s.
There was no serology test available and no treatments were being developed when it started killing young men in the 1980s in the United States.
According to Sawyer, there is no assurance that these simian arteriviruses will spread to people. However, one thing is certain: More viruses will infect humans and spread disease.
“COVID is just the latest in a long string of spillover events from animals to humans, some of which have erupted into global catastrophes,” Sawyer added. “Our hope is that by raising awareness of the viruses that we should be looking out for, we can get ahead of this so that if human infections begin to occur, we’re on it quickly.”
Source: 10.1016/j.cell.2022.09.022
Image Credit: Getty
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