Is the pig the new bat?
The experiences with Sars, Mers and Sars-CoV-2 show: Humanity should be prepared for new pandemics. Researchers can now identify another coronavirus as a source of danger: Sads-CoV. The virus is not new, but has so far only been detected in pigs. In experiments it has now also been able to infect human cells. But there is hope.
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Viruses jump from animals to humans
Many experts are convinced: the current pandemic will probably not be the last. There is a risk of further zoonoses – infectious diseases that spread from animals to humans. Like Sars-CoV-2, some of them can cause global outbreaks. In the past 18 years, there have already been three coronavirus pandemics, Sars and Mers. Researchers from the USA have now identified another potential candidate: It is also a coronavirus, which, however, has so far only been detected in pigs.
For the first time, this coronavirus triggered major outbreaks on pig farms in China in 2016. The pathogen strain was named Sads-CoV – the abbreviation Sads stands for “Swine Acute Diarrhea Syndrome” (German: “acute diarrhea syndrome in pigs”). Because Sads-CoV mainly attacks the digestive tract in pigs. Symptoms include severe diarrhea and vomiting.
The virus can be very dangerous, especially for young piglets. Of the sick animals that were less than six days old, 90 percent died in large outbreaks on three Chinese farms. However, from the age of eight days, the mortality fell to only 5 percent. At that time, a total of almost 25,000 piglets succumbed to the coronavirus. What stands out: For the first time, Sads-CoV broke out on a farm in the Chinese province of Guangdong. The Sars pathogen, which triggered a pandemic in 2002/03, first appeared in the same province.
Pathogens can multiply in human cells
Transmission of Sads-CoV to humans has not yet been observed. However, scientists from the University of North Carolina at Chapel Hill have now found that the pathogen can also multiply in human cells. Tests on cell samples in the laboratory showed that Sads-CoV infected human airway cells and intestinal cells, the authors write in their study.
Caitlin Edwards and his team had exposed different cell types to a synthetic variant of Sads-Cov. It turned out that the pathogen can infect a wide range of cells found in mammals. In humans, the virus multiplied – unlike Sars-CoV-2 – but more strongly in cells of the digestive tract. How exactly Sads-CoV gains access to the cells is still unclear.
Although it is “impossible” to predict whether Sads-CoV and related viruses could jump to humans and cause a new pandemic, Edwards emphasizes, according to the university. In their work, however, she and her colleagues speak of a pathogen with a “higher risk”, which could not only endanger human health, but also the global economy.
Covid-19 agent Remdesivir shows effect on Sads-CoV
However, the researchers also have good news: Tests with the antiviral agent remdesivir, which is effective against Sars-CoV-2, showed that Sads-CoV can also be contained by it. So if there is a jump to humans, there may already be “a potential treatment option,” said Edwards. However, more tests are needed to confirm this.
The origin of Sads-CoV is – as presumably also with Sars, Mers and Sars-CoV-2 – in bats. In contrast to the Sars-CoV-2 beta coronavirus, however, it is an alphacoronavirus. “While many researchers focus on the potential hazard of beta coronaviruses such as Sars and Mers, the alphacoronaviruses may pose just as, if not greater, a threat to human health,” warns epidemiologist Ralph Baric, who also participated in the study would have. The alphacoronaviruses also include the comparatively harmless human coronaviruses HCoV-229E and HCoV-NL63.
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