But as soon as it gets into a human airway, the virus hijacks our cells to create millions more versions of itself.
‘Between chemistry and biology’
It is, in other words, just sneaky enough to wreak worldwide havoc.
When viruses encounter a host, they use proteins on their surfaces to unlock and invade its unsuspecting cells. Then they take control of those cells’ molecular machinery to produce and assemble the materials needed for more viruses.
“Let’s say dengue has a tool belt with only one hammer,” said Vineet Menachery, a virologist at the University of Texas Medical Branch. This coronavirus has three different hammers, each for a different situation.
Scientists believe that the SARS virus originated as a bat virus that reached humans via civet cats sold in animal markets. This current virus, which can also be traced to bats, is thought to have had an intermediate host, possibly an endangered scaly anteater called a pangolin.
Funding for research on coronaviruses increased after the SARS outbreak, but in recent years that funding has dried up, Taubenberger said. Such viruses usually simply cause colds and were not considered as important as other viral pathogens, he said.
Andrew Pekosz, a virologist at Johns Hopkins University, compared viruses to particularly destructive burglars: They break into your home, eat your food, use your furniture and have 10,000 babies. “And then they leave the place trashed,” he said.
Unfortunately, humans have few defenses against these burglars.
For this reason, antiviral drugs must be extremely targeted and specific, said Stanford virologist Karla Kirkegaard. They tend to target proteins produced by the virus (using our cellular machinery) as part of its replication process. These proteins are unique to their viruses. This means the drugs that fight one disease generally don’t work across multiple ones.
“Modern medicine is constantly needing to catch up to new emerging viruses,” Kirkegaard said.
Understanding these proteins could be critical to developing a vaccine, said Alessandro Sette, head of the center for infectious disease at the La Jolla Institute for Immunology. Previous research has shown that the spike proteins on SARS are what trigger the immune system’s protective response. In a paper published this month, Sette found the same is true of SARS-CoV-2.
This gives scientists reason for optimism, according to Sette. It affirms researchers’ hunch that the spike protein is a good target for vaccines. If people are inoculated with a version of that protein, it could teach their immune system to recognize the virus and allow them to respond to the invader more quickly.
“It also says the novel coronavirus is not that novel,” Sette said.
And if SARS-CoV-2 is not so different from its older cousin SARS, then the virus is probably not evolving very fast, giving scientists developing vaccines time to catch up.
In the meantime, Kirkegaard said, the best weapons we have against the coronavirus are public health measures, such as testing and social distancing, and our own immune systems.
For all its evil genius and efficient, lethal design, Kirkegaard said, “the virus doesn’t really want to kill us. It’s good for them, good for their population, if you’re walking around being perfectly healthy.”
Evolutionarily speaking, experts believe, the ultimate goal of viruses is to be contagious while also gentle on their hosts — less a destructive burglar and more a considerate house guest.
That’s because highly lethal viruses like SARS and Ebola tend to burn themselves out, leaving no one alive to spread them.
But a germ that’s merely annoying can perpetuate itself indefinitely. One 2014 study found that the virus causing oral herpes has been with the human lineage for 6 million years.
Seen through this lens, the novel coronavirus that is killing thousands across the world is still early in its life. It replicates destructively, unaware that there’s a better way to survive.
But bit by bit, over time, its RNA will change. Until one day, not so far in the future, it will be just another one of the handful of common cold coronaviruses that circulate every year, giving us a cough or sniffle and nothing more.
That would be nice.