The severe acute respiratory syndrome, SARS-CoV-2, the causative agent of COVID-19 infection, is believed to transfer from animals to humans in a process called zoonosis.
A News-Medical.net report specified that this coronavirus type naturally affects nonhuman primates, canids, minks, and felids.
Experimental contagions have proven the vulnerability of SARS-CoV-2 infection in various other species, including wildlife and laboratory animals.
COVID-19 is believed to have come from wildlife and perhaps, introduced to humans in December 2019 in a live animal market-based in Wuhan, China. Nevertheless, there is still no absolute scientific consensus in terms of species of origin.
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Scientists published reports on initial research evaluating the vulnerability of common domestic livestock, including sheep, to intranasal infection with SARS-CoV-2.
Susceptibility of Domestic Livestock
While bats are a possible source of COVID-19 given the sequence similarity to other bat coronaviruses, investigational research in bats thus far does not validate such a theory.
Consequently, the reservoirs of COVID-19 infection are yet to be determined, and researchers need to resort to the so-called "serosurveillance" and investigational infection research to elucidate probable reservoir hosts.
Scientists recently published reports on initial research evaluating the vulnerability of common domestic livestock, including sheep, cattle, alpaca, goat, horse, and rabbit, to intranasal infection with SARS-CoV-2. Findings were published in the Emerging Microbes & Infections journal.
In their research, the study authors injected animals from representative livestock species such as sheep, goats, alpaca, cattle, rabbits, and one horse intranasally to closely observe clinical illness, gather samples for viral shedding through the rectal, nasal, or oral method, viral titer's measurement in respiratory organs from acute-stage necropsies, and identifying the production of antibodies over the one month in most species.
Plaque Reduction Neutralization Test
Isolation of the virus from swabs and tissues was tested using inscription assays on Vero, and actual-time RT-PCR was carried out on specimens and tissues three days after injection.
Tissues collected on the third day after infection were also fixed in formalin for histopathological assessment by a veterinary pathologist. Essentially, terminal sera were tested for "virus-neutralizing antibodies," the so-called PRNT or plaque reduction neutralization test.
Study findings showed that the animals that shed identifiable contagious virus during the course of the research. One calf, a pair of goats, and a single rabbit underwent RT-PCR positive oral and nasal swabs suggesting these animals could be slightly tolerant to infection.
Results Contribute to Analysis of Zoonosis
The study findings were consistent with other livestock research signifying low-level viral replications specifically in cattle, rabbits, and pigs.
Such research identifying the host range, pathogenesis, and an emerging pathogen's transmissibility is critical in understanding the epidemiology of the resulting illness and target surveillance, not to mention mitigation initiatives.
Lastly, the study results may contribute to the risk analysis of zoonosis, detailed in Healthline as an infection of humans by animals, and reverse zoonosis, infection of animals by humans, of the said species that are in close contact with humans.
This contributes to the understanding of the reaction of domestic animals to SARS-CoV-2 infection and what danger such animals might play in resulting in more human contact with the virus.
Related information about the transmission of COVID-19 from animals to humans is shown on CBC News's YouTube video below:
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