Study links COVID-19 to stray dogs eating bat meat

The coronavirus pandemic may have been started by stray dogs eating bat meat, according to a study.

Professor Xuhua Xia, from the University of Ottawa's biology department, has suggested that stray dogs are the most likely intermediate host for the transmission of Sars-CoV-2 into humans.

According to the study, the ancestor of the new

coronavirus

and its nearest relative - a bat coronavirus - infected the intestines of dogs. They then evolved before moving to humans.

Coronavirus: Infection numbers in real time

Humans and mammals can fight viruses through an antiviral protein which stops the infection multiplying. Meanwhile, regions of DNA - CpG dinucleotides - tell the immune system to attack the virus.

But single-strand coronaviruses can avoid the body's natural defences by reducing the CpG.

Prof Xia analysed betacoronavirus genomes and found that Sars-CoV-2 and its closest relative - a bat coronavirus - have the lowest amount of CpG.

Only genomes from canine coronaviruses have similar genomic values, the study says.

The cellular receptor for Sars-CoV-2 is "pervasively expressed in the human digestive system", the study says, adding: "This is consistent with the interpretation that the low CpG in Sars-CoV-2 was acquired by the ancestor of Sars-CoV-2 evolving in mammalian digestive systems.

"The interpretation is further corroborated by a recent report that a high proportion of Covid-19 patients also suffer from digestive discomfort.

"In fact, 48.5% presented with digestive symptoms as their chief complaint."

Coronavirus: Race for the vaccine

Prof Xia said the results suggested "the importance of monitoring Sars-like coronaviruses in feral dogs in the fight against Sars-CoV-2".

But Professor James Wood, head of the department of Veterinary Medicine and researcher in infection dynamics at the University of Cambridge, was not convinced.

He said: "There is far too much inference and far too little direct data. I do not see anything in this paper to support this supposition and am concerned that this paper has been published in this journal.

"I do not believe that any dog owners should be concerned as a result of this work."

Nearly two million people worldwide have been infected by the virus.

The findings are published online in the journal Molecular Biology and Evolution.