The researchers created a synthetic clone of the SADS-CoV virus and infected human sample cells with this derivative recombinant SADS-CoV or rSADS-CoV to see if virus transmission, replication and in vitro gene expression was possible.
Given the increase in knowledge about coronaviruses since the beginning of the COVID-19 pandemic, it is now well known that there are many strains of coronaviruses in the world and that not all of them infect humans. The US Centers for Disease Control and Prevention (CDC) lists seven types of alpha and beta coronavirus strains that infect humans including MERS-CoV, SARS-CoV and SARS-CoV-2 viruses. Similarly, there are many types of coronaviruses that infect only animals.
Of these, a particular strain of coronavirus that infects pigs or swine have recently caused immense concern in the swine industry and new research published in the Proceedings of the National Academy of Sciences (PNAS) suggests that this strain might even be transmissible to humans.
What is SADS-CoV?
Before we jump into the findings of the PNAS study, here’s what you should know about this strain of the coronavirus, which is known as swine acute diarrhoea syndrome coronavirus (SADS-CoV). A study published in Virus Research in August 2020 reveals that SADS-CoV was discovered in 2017 and is also known as swine enteric alphacoronavirus (SeACoV) and porcine enteric alphacoronavirus (PEAV).
This study also mentions that to date there have been five different species of coronaviruses that naturally infect pigs. SADs-CoV was discovered in the Guangdong province of China, where outbreaks of severe diarrhoea in suckling piglets occurred primarily in four swine herds. Research indicated that SADS-CoV was closely related to the species Rhinolophus bat coronavirus HKU2 (meaning it originated in bats) and was able to infect the pigs orally. This study suggested, however, that the actual pathogenicity (the ability to cause disease) of SADS-CoV was controversial due to the lack of current evidence. The findings of the new PNAS study may lay this controversy to rest.
Can SADS-CoV infect humans?
The goal of the PNAS study was to evaluate the human susceptibility for SADS-CoV cross-species transmission and replication. The researchers created a synthetic clone of the SADS-CoV virus and infected human sample cells with this derivative recombinant SADS-CoV or rSADS-CoV to see if virus transmission, replication and in vitro gene expression was possible.
The researchers found that SADS-CoV replicated efficiently in primary human cells derived from both the lungs and the intestines. This highlights the intrinsic potential of the SADS-CoV virus for cross-species transmission, especially from pigs to humans. The researchers concluded that given the risk of pathogenicity in humans due to SADS-CoV — and especially observing the global effect SARS-CoV-2 has had — mechanisms to block this transmission and replication need to be devised urgently.
They then evaluated the ability of small-cell inhibitors to impede the spread of SADS-CoV in human cells and found that the drug remdesivir is a key broad-spectrum antiviral that can potentially block the transmission and pathogenesis of SADS-CoV in humans.
The researchers pointed out that while more clinical trials need to be conducted to ascertain this effectiveness of remdesivir, it can provide a treatment option in case there’s a spillover outbreak from pigs to humans. They also called for better supervision of the health of swine industry workers as they could be potential carriers who can spread the infection further in case of an outbreak.
For more information, read our article on Coronavirus infection.
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