Detection of SARS-CoV-2 Delta mutant infection in domestic cats

The first published case explaining a delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in domestic cats in the United States is a spillover infection with a new viral variant that threatens human and animal health. Highlights a realistic scenario of. The research paper is currently bioRxiv Preprint * server while undergoing peer review.

study: Detection and interspecific comparison of SARS-CoV-2 delta variant (AY.3) in feces from domestic cat and human samples.. Image credit: NIAID

Infection with SARS-CoV-2, the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic, has spread from humans to countless animal species. This includes not only domestic cats and dogs, but also large untamed felines, white-tailed deer and mink.

One of the more threatening subspecies has been identified so far in one dog in the United States (related to a particular AY.3 strain), several Asian lions in India, and three domestic cats in China. It is a delta subspecies.

This subspecies is zoonotic because it spreads more easily among humans, is associated with more serious illnesses, and has a much higher incidence of vaccine breakthrough infections compared to strains that appeared early in the pandemic. Reservoir that needs to be tracked in the natural host range to reveal the possibility of an infectious disease.

In this paper, a research group at the University of Pennsylvania (led by Dr. Olivia C. Renz and Dr. Andrew D. Marques) reported a SARS-CoV-2 delta variant (AY.3) in domestic home fecal specimens. .. A cat in the Delaware Valley region of southeastern Pennsylvania.

Molecular testing and whole genome sequencing

In this study, an 11-year-old female cat had several days of drowsiness, loss of appetite, loose stools, and vomiting, and known exposure to SARS-CoV-2 (one of the cat owners was positive before the onset of symptoms). Because there was).

Fecal samples were sent to the polymerase chain reaction (PCR) test for infectious pathogens associated with gastrointestinal disease in cats (specific bacteria, viruses, parasites, etc.), but all returned negative.

Next, we tested the fecal sample SARS-CoV-2 using the new coronavirus real-time PCR (RT-PCR) diagnostic panel from Centers for Disease Control 2019.Since the test result was positive, the SARS-CoV-2 whole genome sequence was used. Phylogenetic analysis Immediately pursued to obtain the genetic profile of the virus.

High levels of SARS-CoV-2 in cat fecal specimens

In short, two cat fecal samples collected at 7-day intervals both had a cycle threshold of 26-28 SARS-CoV-2 detection. This indicates that there is a relatively high level of genomic replication and a high level of viral revolving nuclei. Acid (RNA).

In addition, detailed sequencing of the cat-derived viral genome revealed that the two were indistinguishable, and pairwise comparisons with human-derived strain AY.3 sequences revealed that 4-14 single nucleotide polymorphisms differed. I did. period.

However, while the fecal samples of infected cats contained relatively high levels of viral genetic material, SARS-CoV-2 was not found in the oropharyngeal swab taken on the day of presentation to the veterinary hospital. ..

Pairwise distance between AY.3 sequences in the Deladelphia Valley. Contains sequences from cats (VSP3509) and sequences from humans. The number of SNPs that separate each pair of strains is indicated by a color code (key on the right side of the figure).

Importance of interspecific transmission

The discovery of the SARS-CoV-2 delta mutant line AY.3 sequence in a cat sample, together with the detection of the delta mutant line B.1.617.2 in non-human animal species, implies infection with SARS-CoV-2. To do. Interspecies can occur between multiple delta variants.

“Domestic cats can support relatively efficient replication of the SARS-CoV-2 virus genome, similar to those that infect humans, and can infect the SARS-CoV-2 virus into a naive allogeneic, often. Due to its high contact with humans, it can become an enzymatic reservoir of the virus, “says the author of this study. bioRxiv paper.

Therefore, the transmission of non-human animal species and the formation of reservoirs of SARS-CoV-2 represent a threat to livestock, wildlife, and human health. Therefore, it is necessary to carefully track the SARS-CoV-2 mutant in domestic cats to elucidate the interrelated properties of animal and human health in this pandemic.

*Important Notices

bioRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.