In 25 MonthsThe novel-coronavirus has affected 320 million people in the world, and has claimed the lives of 5.5 million.
However, the SARS-CoV-2 virus might have been even worse. The most recent Omicron variantIt is highly transmissible but not as fatal for those who have been vaccinated. Because it attacks the lungs, rather than staying in the throat like Omicron, the earlier Delta variant is more severe. But mercifully, Delta doesn’t spread as fast as Omicron does.
Now imagine a coronavirus that’s both deadly Highly transmissible. It’s certainly within the realm of possibility.
Changchuan Yin from the University of Illinois at Chicago is on the lookout for warning signs in order to avoid a potentially deadly coronavirus epidemic. There are genetic hints that the plague is coming. Experts warn that the proposed system may be flawed as it assumes that coronaviruses will develop in predictable ways.
There are many coronaviruses in the animal kingdom. Scientists have identified 46. Any one could leap to the human — and a bunch already have. We’ve suffered through outbreaks of SARS-CoV-1, MERS and now SARS-CoV-2 — all coronaviruses with their distinctive spikes and tendency to cause respiratory infections.
Yin and other experts warned it’s inevitable there will be a SARS-CoV-3 that, at some point in the near future, will cross over from animals to people. “We are experiencing a new coronavirus outbreak every eight to 10 years,”Kevin Saunders, director at Duke University’s Human Vaccine Institute, said the following:
If we can see the virus coming, our chances of beating it could increase. We could develop new therapies and vaccines and put in place public-health strategies to limit the pathogen’s spread. This means that we must be able to spot the virus before it spreads from its animal host to the humans.
Identifying the viral culprit most likely to cause the most damage is a difficult task that requires a lot of guesswork. Preprint a new studyYin, who has not yet been peer-reviewed, proposes a system to assess and monitor coronaviruses. One that could give us early warning, provided we have enough genetically-sequenced samples of bats, civets, and other coronavirus prone animals.
The science is complicated, but it boils down to this: viruses that are making peace with their human hosts – infecting them but usually not killing them – tend to accumulate a lot of a certain kind of mutation called a “homopolymeric nucleotide repeat,”Or “HP repeat.”
An HP repeat happens when T-cells and antibodies attack a virus, and the virus adapts their attack. Every HP repeat is a sort of genetic scar from the pathogen’s battle with our immune systems as the two try to strike a truce of sorts.
This is a good evolutionary strategy. Generally speaking, a pathogen evolves to be just virulent enough to thrive and spread, but not so virulent that it kills its hosts … and itself.
“This is basic evolutionary biology where viruses become attenuated or weakened with serial passage through human or animal hosts,”Paul Ananth Tambyah is the president of the Asia Pacific Society of Clinical Microbiology and Infection, Singapore. “That is how live-virus vaccines are — you simply infect and reinfect successive generations of animals until you select for mutations which render the virus relatively harmless.”
A virus with a low number of HP-repeats probably hasn’t been exposed to people, possibly Ever.
“A low HP score suggests that the virus is in a more native state,” Yin explained. That’s a giant red flag. The pathogen has never known human beings so it doesn’t know how to avoid making them really, really sick or killing them. It infects human cells, and it just goes insane.
How many HP repetitions can you tell if a virus is capable of surprising our immune systems and causing a pandemic epidemic? Yin suggests six or fewer. “I think if a virus has lower HP … it could be a dangerous virus,”Yin.
Human-CoV/HKU1 is a coronavirus that causes mild, cold-like symptoms. It has 10 HP-repeats. SARS-CoV-2 has six mutations, which is clearly more dangerous. A coronavirus called SZ3 that’s found in civets, a cat-like tropical mammal, has four of the mutations — meaning it just might be even more dangerous to people than SARS-CoV-2. HKU9-1, the bat coronavirus that is threatening humans, has three mutations. HP continues to repeat.
If virologists find a coronavirus with just a couple HPs — look out. Our antibodies and T-cells aren’t ready to battle that virus all on their own.
But there’s a possible flaw in Yin’s system. Yin points out that Omicron has.2 fewer HP repetitions than the first strain of SARS CoV-2 which infected people in December 2019. Omicron evolved slowly over two years. Yet, it has continued to evolve. Fewer These are the telltale mutations.
Yin believes that a human-infecting viral stacks up more HP repeats with time. Omicron, however, disagrees. It also highlights an important truth about coronaviruses. This is because this type of pathogen can be unpredictable.
Omicron is home to an alarming array of 50 key mutations. About 30 are related to the spike protein that aids the virus in grabbing onto our cells. “These major mutations that have occured with Omicron — people said that can’t happen,”Michael Osterholm, Director of the Center for Infectious Disease Research and Policy (University of Minnesota), said the following: “That was a mega leap.”
If coronaviruses behaved the way we expect viruses in general to behave, they’d become steadily less harmful over time. Omicron, however, muddled our expectations and confused experts by being both more effective and less harmful. worse than Delta – vastly more transmissible and yet somewhat less lethal. “All of us got variant evolution wrong,”Edwin Michael, an epidemiologist from the University of South Florida – Center for Global Health Infectious Disease Research.
Omicron’s lower-than-expected HP-repeat count seems to undermine Yin’s design for a pandemic early-warning system, and has made some of his fellow scientists skeptical. “There are some who would disagree” with Yin’s surveillance design, Osterholm said.
Yin recognizes the limitations of his system. The HP continues “cannot directly infer” a virus’s virulence in people or, by extension, its potential to cause a pandemic. No, it’s an indirect Warning about a Possible nasty pathogen. “It is of importance for tracking, virulence assessment and controlling the outbreak of a coronavirus,”Yin said. But it’s not foolproof.
Given the circumstances, even a flawed system like Yin’s might be better than nothing. SARS-CoV-3 is coming to us eventually. “Therefore, strict epidemic surveillance is indispensable,”Yin wrote. Maybe a false alarm that is based on an imperfect search to find one type of mutation is better then no alarm at all.