Another coronavirus infecting pigs may be even more dangerous to humans


Researchers warn that swine acute diarrhea syndrome coronavirus (SADS-CoV) could cripple the pork industry and be just as problematic for people as COVID-19.


CHAPEL HILL, N.C. — As scientists continue working on a vaccine for COVID-19, another coronavirus strain has some very worried. Researchers from the University of North Carolina say an illness currently infecting swine is capable of making humans sick too. They warn that an outbreak of this coronavirus would not only endanger people, but devastate the pork industry as well.

According to the study, swine acute diarrhea syndrome coronavirus (SADS-CoV) originated in bats before migrating to pig herds in China. This is very similar to way COVID is believed to have started prior to the global pandemic. Researchers say SADS-CoV causes severe diarrhea and vomiting in patients and is particularly deadly to young piglets.

Unlike COVID-19, this swine coronavirus has been known to scientists since 2016. Another difference between the strains is SADS-CoV is an alphacoronavirus, which mainly causes gastrointestinal sickness. SARS-CoV-2, the virus producing COVID-19, is a betacoronavirus that primarily causes respiratory illness in humans.

More infectious than COVID-19?

The UNC team experimented with SADS-CoV in lab tests, seeing if the virus could potentially jump into the human population. Their results show swine coronavirus can effectively replicate inside human liver and gut cells. It can also spread through the airways like SARS-CoV-2 as well.

“While many investigators focus on the emergent potential of the betacoronaviruses like SARS and MERS, actually the alphacoronaviruses may prove equally prominent — if not greater — concerns to human health, given their potential to rapidly jump between species,” says professor of epidemiology Ralph Baric in a university release.

Although the study notes there aren’t any human infections on record, the COVID pandemic serves as a clear warning that viruses can easily move from one species to another. The Chapel Hill team also reports SADS-CoV could be just as problematic for people as COVID-19.

Experiments on a wide variety of mammal cells reveals swine coronavirus has a higher growth rate in human intestinal cells than SARS-CoV-2. While herd immunity usually stops animal viruses from jumping into people, humans do not have an immunity to SADS-CoV yet.

“SADS-CoV is derived from bat coronaviruses called HKU2, which is a heterogenous group of viruses with a worldwide distribution,” explains research specialist Caitlin Edwards. “It is impossible to predict if this virus, or a closely related HKU2 bat strain, could emerge and infect human populations. However, the broad host range of SADS-CoV, coupled with an ability to replicate in primary human lung and enteric cells, demonstrates potential risk for future emergence events in human and animal populations.”

Can humans defend against swine coronavirus?

One promising finding from the study is that a drug currently fighting COVID-19 may also fight swine coronavirus. Study authors say remdesivir produces a strong effect when introduced to SADS-CoV.

“Promising data with remdesivir provides a potential treatment option in the case of a human spillover event,” Edwards adds. “We recommend that both swine workers and the swine population be continually monitored for indications of SADS-CoV infections to prevent outbreaks and massive economic losses.”

The drug is already in widespread use across the United States, including use on President Trump after his infection. Although researchers caution that more tests are needed, they say proven treatments will be vital to prevent a devastating outbreak.

For the food industry, an outbreak in the U.S. could cripple global pork production. One-third of all pork products came from America in 2019.

“We are currently looking for partners to investigate the potential of SADS-CoV vaccine candidates to protect swine,” Baric says. “While surveillance and early separation of infected piglets from sows provide an opportunity to mitigate larger outbreaks and the potential for spillover into humans, vaccines may be key for limiting global spread and human emergence events in the future.”

The study appears in Proceedings of the National Academy of Sciences.

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