After analysing coronavirus across different species, a top biology researcher in Canada concluded that feral dogs may have helped transmit the new Sars-CoV-2 disease – which causes Covid-19 – into humans.
The ancestor of the virus and its nearest relative, a bat coronavirus, could have infected the intestines of canines where it evolved before jumping to humans, Professor Xuhua Xia’s study suggests.
The findings of Prof Xia, from the University of Ottawa’s biology department, are published online in the advanced access edition of the journal Molecular Biology and Evolution.
In his study, Prof Xia analysed 1,252 full-length betacoronavirus genomes shared via an open access database.
He said that Sars-CoV-2 and its closest known relative, the bat coronavirus BatCoV RaTG13, which shares 96 per cent sequence similarity, have the lowest amount of a particular region of DNA which help the immune system tackle disease.
Only genomes from canine coronaviruses, which have already caused a highly contagious intestinal disease worldwide in dogs, have similar genomic values, the study found.
Dogs also have coronaviruses which affect their respiratory systems as well as their digestive systems, the paper notes.
Prof Xia wrote that the suggested link between canines and humans is “further corroborated by a recent report that a high proportion of Covid-19 patients also suffer from digestive discomfort.”
“In fact, 48.5 per cent presented with digestive symptoms as their chief complaint,” he states in the report.
“These observations are consistent with the hypothesis that Sars-CoV-2 has evolved in mammalian intestine or tissues associated with the intestine.”
However, the paper was criticised by professor James Wood, head of the department of Veterinary Medicine and researcher in infection dynamics at the University of Cambridge.
He said: “I find it difficult to understand how the author has been able to conclude anything from this study, or to hypothesise much, let alone that the virus causing Covid-19 may have evolved through dogs.
“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.”
Prof Xia said: “Our observations have allowed the formation of a new hypothesis for the origin and initial transmission of Sars-CoV-2.
“The ancestor of Sars-CoV-2 and its nearest relative, a bat coronavirus, infected the intestine of canids, most likely resulting in a rapid evolution of the virus in canids and its jump into humans.
“This suggests the importance of monitoring Sars-like coronaviruses in feral dogs in the fight against Sars-CoV-2.”
Nearly two million people have contracted Sars-CoV-2 since it first appeared at a seafood market in Wuhan, China, in late 2019, according to a global tracker by Johns Hopkins University.
More than 120,000 people have so far died after developing Covid-19.
Source: Evening Standard UK