1. Introduction
Feline parvovirus (FPV), a small non-enveloped linear ssDNA virus with a
5.1 kb genome is a variant of the species Carnivore
Protoparvovirus 1 ( family Parvoviridae). Feline parvovirus
causes an enteric and systemic disease known as feline panleukopenia
(FPL) and can also infect cats subclinically (Barrs 2019). The virus is
shed in high copy numbers in all secretions of infected cats and is
transmitted faeco-orally, especially via fomites. Infection by this
remarkably environmentally resilient virus occurs most commonly in
unvaccinated kittens that first encounter the virus, especially in
animal shelters, after maternal antibodies wane. Disease in susceptible
cats is characterised by vomiting, diarrhoea, dehydration, sepsis and in
severe cases, death (Barrs 2019).
Co-infections of FPV with other enteric viruses have been detected in
sick and/or healthy cats including viruses in the familiesParvoviridae (Genus Bocaparvovirus andChaphamaparvovirus ), Astroviridae (GenusMamastrovirus ), Coronaviridae (Genus Alphacoronavirus),Caliciviridae (Genus Vesivirus, Norovirus ) andPicornaviridae (Genus Kobuvirus) (Brussel et al., 2020; Castro et
al., 2015; Di Profio et al., 2021; Ji et al., 2020; Piewbang et al.,
2019).
A host can be exposed to multiple viruses with similar routes of
transmission and high prevalence at the same or within a short space of
time. In young children, co-infection and simultaneous detection of
enteropathogens is common (Makimaa et al., 2020). Interactions among
co-infecting viruses may be synergistically pathogenic and enteric virus
co-infections are commonly identified for all viruses linked to acute
gastroenteritis in humans (Simsek et al., 2021). Similarly, enteric
co-pathogen infections may play a role in determining clinical outcomes
in cats infected with FPV. Since FPV damages gastrointestinal epithelium
and bone-marrow to cause local and systemic immunocompromise, the
abundance of viral co-infections might be higher in cats with FPL than
among healthy cats.
We incorporated both metatranscriptomics, the analysis of non-ribosomal
RNA (rRNA) transcripts, and viral particle enrichment metagenomics in
this study to characterise the enteric virome of sick FPV-infected and
clinically healthy cats. Our specific aim was to reveal any differences
in the gut virome of FPV-infected cats, particularly enteric viruses
that are absent from the enteric virome of healthy control cats.