Papillomavirdae.
Despite the relatively small sample size, several viruses were
significantly more likely to be detected in FPV-cases compared with
healthy controls including feline kobuvirus, feline astroviruses,Feline calicivirus , feline bocaparvovirus 2 and feline
bocaparvovirus 3. Indeed, it is notable that feline kobuvirus was only
detected in FPV-cases (Figure 2) and the prevalence of detection
(39.1%) is the highest reported to date (Chung et al., 2013; Di Martino
et al., 2015; Lu et al., 2018). In previous reports, co-infections of
FPV, feline coronavirus and/or feline bocavirus 1 were common in cats
naturally infected with feline kobuvirus (Chung et al., 2013; Di Martino
et al., 2015; Lu et al., 2018; Niu et al., 2019). However, in those
investigations targeted conventional PCR was used to screen for a few
common enteric viruses only. The use of unbiased sequencing techniques,
as performed here, demonstrates that
other enteric viruses including
feline astroviruses, feline bocaparvovirus 2 and feline bocaparvovirus
3, as well as Feline calicivirus are also common co-infections
(Figure 2). The feline kobuvirus sequences detected here are the first
in Australia, suggesting active circulation among Australian cats and
highlighting the importance of screening for this virus in Australian
cats with gastroenteritis of unknown cause. Similarly, here we
documented the first Australian sequences of Feline picornavirus .
Feline astrovirus infections have been identified in both healthy and
sick cats (Brussel et al., 2020; Zhang et al., 2019; Zhang et al.,
2014), although experimental infection of specific-pathogen kittens with
feline astrovirus induces acute enteritis and viral shedding (Harbour et
al., 1987). Here, although astrovirus shedding was detected in healthy
controls, the prevalence of astrovirus in FPV-cases was significantly
higher. Recently feline astrovirus infection was associated with acute
gastroenteritis in shelter-housed cats, where 91% of affected cats and
56% of healthy cats were found to be shedding feline astrovirus, using
a metagenomics approach (Li et al., 2021).
We detected Feline calicivirus at a significantly higher rate in
FPV-cases than in healthy control cats. Although primarily a feline
respiratory pathogen, evidence is mounting for an aetiological role in
naturally occurring viral gastroenteritis (Castro et al., 2015; Di
Martino et al., 2020). Experimental infection of cats with Felinecalicivirus causes diarrhoea (Povey et al., 1974) and enteric
strains of Feline calicivirus are resistant to low pH, trypsin
and bile salts (Di Martino et al., 2020). In a previous study,Feline calicivirus was not detected in healthy cat faeces but was
found in 25.9% of diarrhoeic faeces and co-infections with FPV or
feline coronavirus were common (Di Martino et al., 2020). In the cats
shedding Feline calicivirus here, enteric co-infections,
especially with feline astroviruses were common in both FPV-cases and
healthy control cats (Figure 2).
There are conflicting reports on the prevalence of detection of
bocaparvoviruses in cats with enteritis. These viruses have been
detected in the faeces of cats with and without diarrhoea and in the
oropharynx of healthy cats (Abayli et al., 2021; Li et al., 2020; Yi et
al., 2018). Here, feline bocaparvovirus 2 and feline bocaparvovirus 3
were both detected at a significantly higher prevalence in the faeces of
FPV-cases compared to healthy controls. Although, evidence for an
association between feline bocavirus 1 infection and gastroenteritis in
cats is accumulating, we found no significant difference in the
prevalence of feline bocavirus 1 in FPV-cases and healthy control cats.
One study reported a prevalence of 24.8% in 105 cats with diarrhoea
compared to 9.8% in 92 healthy cats (Yi et al., 2018). Two other
reports concluded there was an association between feline bocavirus 1
infection and severe gastroenteritis in cats, although sample numbers
were small and co-infections with other pathogenic enteric viruses
including FPV were common (Liu et al., 2018; Piewbang et al., 2019).