The new highly infectious variants of SARS-CoV-2 have been raising hell in many parts of the world, quickly becoming some of the most dominant strains of the virus in circulation. It turns out, these subtly mutated viruses might also be causing a problem for a bunch of other animals, not just humans.
In one new development, researchers have discovered a possible link between cats and dogs infected with the UK variant B.1.1.7 and a heightened risk of myocarditis, inflammation of the heart muscle. In another breakthrough, another team of scientists has found that the new variants can infect mice, unlike the original strains of the virus that couldn’t produce illness in mice.
Both studies are preliminary preprints, meaning they are yet to be peer-reviewed, but they do highlight the way in which the new variants are shaping the COVID-19 pandemic in strange and interesting ways.
Pets and Possible Heart Problems
Earlier this month, scientists at Texas A&M University documented a dog and a cat from the same household in Brazos County being infected with the UK variant (B.1.1.7) of SARS-CoV-2, in what was thought to be the first known case of the variant being identified in animals.
SARS-CoV-2 infections have been seen in cats and dogs before. Back in March 2020, it was revealed that cats and dogs could both test positive for SARS-CoV-2, although they didn’t appear to fall too sick with the disease. However, veterinarians at a pet hospital in the southeast of England have now highlighted a correlation between pets infected with the UK variant and myocarditis, inflammation of the heart muscle.
They noticed that a small but surprising number of dogs and cats were being admitted with myocarditis at the same time the UK was witnessing its initial surge of the B.1.1.7 variant. After noticing this trend, they tested eight cats and three dogs. Although none had a previous history of heart disease, lab tests revealed cardiac abnormalities. They discovered most owners of these pets with myocarditis had developed COVID-19 symptoms or tested positive in the 3-6 weeks before their pets became ill. Seven of the animals received polymerase chain reaction (PCR) tests and three were found to be infected with the B.1.1.7 variant. Three more were found to have antibodies to SARS-COV-2, which suggests earlier tests may have produced more positive results.
The researchers are keen to point out that their research, which is available to read on the preprint server bioRxiv, should not spark panic. For now, they have only found a hazy correlation, not a causal link — but, they argue, the relationship between the newer UK variant and pet infections is certainly worth further investigation.
Mice Are Not Suspectble to Sars-Cov-2, except for The Variants
A separate research project has highlighted another unusual curiosity of the new SARS-CoV-2 variants in animals. The original SARS-CoV-2 strain does not infect mice as it does not bind well to the ACE2 receptor protein on the animals' cells and, as such, can’t enter the cell. However, a new paper has found that the South African variant (B.1.351) and the Brazilian variant (P.1) have picked up mutations that allow them to bind to the mouse ACE2 receptor and infect their cells.
In other words, the original strains of SARS-CoV-2 can’t infect mice, but the South African variant and the Brazilian variant can. The paper, which is yet to be peer-reviewed, can also be read on the preprint server bioRxiv.
The implications of this are not yet clear, not least because the researchers do not know whether the variants can be transmitted from mouse-to-mouse (or mouse-to-human). However, it does raise the worrying possibility that wild mice, and possibly other wild rodents, can act as natural reservoirs for the variants.
“These results raise major questions on the risk of mice or other rodents living in proximity to humans of becoming secondary reservoirs for SARS-CoV-2 in regions where the B.1.351, P.1 or other specific variants circulate, from where they could evolve separately and potentially spillback to humans,” the paper concludes.