Feline Virome-A Review of Novel Enteric Viruses Detected in Cats

Identification of Aichivirus in a Pet Rat (Rattus norvegicus) in Italy

We investigated the occurrence of eight potential zoonotic viruses in 91 exotic companion mammals from pet shops in southern Italy via real-time PCR and end-point PCR. The animals were screened for aichivirus, sapovirus, astrovirus, hepatitis A, noroviruses (GI and GII), rotavirus, circovirus, and SARS-CoV-2. Among the nine species of exotic pets studied, only one rat tested positive for aichivirus. The high sequence similarity to a murine kobuvirus-1 strain previously identified in China suggests that the virus may have been introduced into Italy through the importation of animals from Asia. Since exotic companion mammals live in close contact with humans, continuous sanitary monitoring is crucial to prevent the spread of new pathogens among domestic animals and humans. Further investigations on detecting and typing zoonotic viruses are needed to identify emerging and re-emerging viruses to safeguard public health.

Viral pathogens in domestic cats in southern Italy: A retrospective analysis in Sicily, 2020-2022

A retrospective study was carried out on selected feline viral pathogens detected in domestic cat in Sicily, southern Italy. Samples from 64 cats, collected from 2020 to 2022, were analysed for the presence of feline panleukopenia virus, canine parvovirus type 2 (CPV-2), feline coronavirus (FCoV), feline calicivirus (FCV), feline herpesvirus type 1, norovirus (NoV), and rotavirus (RoV). Single (45 %) or mixed (38 %) viral infections were detected. FPV, related with other Italian FPV strains, remains the main viral cause of infection (66 %). CPV-2c Asian lineage strains (3 %) were detected for the first time in domestic cats in Europe. FCoV (29.6 %), either enteric or systemic, and systemic FCV (18.7 %) infections were detected in positive cats. Less commonly reported viruses (GIV.2/GVI.2 NoVs, RoV), potentially related to the animal/human interface, were detected at lower rates as well (5 %). The present epidemiological data suggest the need to improve disease prevention, immunization, and biosecurity strategies.

Genetic Diversity and Evolution of Viruses Infecting Felis catus: A Global Perspective

Cats harbor many important viral pathogens, and the knowledge of their diversity has been greatly expanded thanks to increasingly popular molecular sequencing techniques. While the diversity is mostly described in numerous regionally defined studies, there lacks a global overview of the diversity for the majority of cat viruses, and therefore our understanding of the evolution and epidemiology of these viruses was generally inadequate. In this study, we analyzed 12,377 genetic sequences from 25 cat virus species and conducted comprehensive phylodynamic analyses. It revealed, for the first time, the global diversity for all cat viruses known to date, taking into account highly virulent strains and vaccine strains. From there, we further characterized and compared the geographic expansion patterns, temporal dynamics and recombination frequencies of these viruses. While respiratory pathogens such as feline calicivirus showed some degree of geographical panmixes, the other viral species are more geographically defined. Furthermore, recombination rates were much higher in feline parvovirus, feline coronavirus, feline calicivirus and feline foamy virus than the other feline virus species. Collectively, our findings deepen the understanding of the evolutionary and epidemiological features of cat viruses, which in turn provide important insight into the prevention and control of cat pathogens.

Old and Novel Enteric Parvoviruses of Dogs

Parvovirus infections have been well known for around 100 years in domestic carnivores. However, the use of molecular assays and metagenomic approaches for virus discovery and characterization has led to the detection of novel parvovirus species and/or variants in dogs. Although some evidence suggests that these emerging canine parvoviruses may act as primary causative agents or as synergistic pathogens in the diseases of domestic carnivores, several aspects regarding epidemiology and virus-host interaction remain to be elucidated.

The discovery of novel papillomaviruses in cats in Southwest China

Feline viral diarrhea is a significant cause of death in kittens. In this study, 12 mammalian viruses were identified by metagenomic sequencing in diarrheal feces in 2019, 2020, and 2021, respectively. Interestingly, a novel of felis catus papillomavirus (FcaPV) was identified for the first time in China. Subsequently, we investigated the prevalence of FcaPV in 252 feline samples, including 168 diarrheal feces and 84 oral swabs, with a total of 57 (22.62%, 57/252) samples detected positive. Of the 57 positive samples, FcaPV genotype 3 (FcaPV-3) was detected at high prevalence rate (68.42%, 39/57), followed by FcaPV-4 (22.8%, 13/57), FcaPV-2 (17.54%, 10/57), and FcaPV-1 (1.75%, 1/55), while no FcaPV-5 and FcaPV-6. In addition, two novel putative FcaPVs were identified, which were the highest similarity to Lambdapillomavirus from Leopardus wiedii or canis familiaris, respectively. Therefore, this study was the first characterization of the viral diversity in feline diarrheal feces and the prevalence of FcaPV in Southwest China.

Evolutionary Origin, Genetic Recombination, and Phylogeography of Porcine Kobuvirus

The newly identified porcine Kobuvirus (PKV) has raised concerns owing to its association with diarrheal symptom in pigs worldwide. The process involving the emergence and global spread of PKV remains largely unknown. Here, the origin, genetic diversity, and geographic distribution of PKV were determined based on the available PKV sequence information. PKV might be derived from the rabbit Kobuvirus and sheep were an important intermediate host. The most recent ancestor of PKV could be traced back to 1975. Two major clades are identified, PKVa and PKVb, and recombination events increase PKV genetic diversity. Cross-species transmission of PKV might be linked to interspecies conserved amino acids at 13-17 and 25-40 residue motifs of Kobuvirus VP1 proteins. Phylogeographic analysis showed that Spain was the most likely location of PKV origin, which then spread to pig-rearing countries in Asia, Africa, and Europe. Within China, the Hubei province was identified as a primary hub of PKV, transmitting to the east, southwest, and northeast regions of the country. Taken together, our findings have important implications for understanding the evolutionary origin, genetic recombination, and geographic distribution of PKV thereby facilitating the design of preventive and containment measures to combat PKV infection.

The enteric virome of cats with feline panleukopenia differs in abundance and diversity from healthy cats

Feline panleukopenia (FPL) is a severe, often fatal disease caused by feline panleukopenia virus (FPV). How infection with FPV might impact the composition of the entire eukaryotic enteric virome in cats has not been characterized. We used meta-transcriptomic and viral particle enrichment metagenomic approaches to characterize the enteric viromes of 23 cats naturally infected with FPV (FPV-cases) and 36 age-matched healthy shelter cats (healthy controls). Sequencing reads from mammalian infecting viral families largely belonged to the Coronaviridae, Parvoviridae and Astroviridae. The most abundant viruses among the healthy control cats were feline coronavirus, Mamastrovirus 2 and Carnivore bocaparvovirus 3 (feline bocavirus), with frequent coinfections of all three. Feline chaphamaparvovirus was only detected in healthy controls (6 out of 36, 16.7%). Among the FPV-cases, in addition to FPV, the most abundant viruses were Mamastrovirus 2, feline coronavirus and C. bocaparvovirus 4 (feline bocaparvovirus 2). The latter and feline bocaparvovirus 3 were detected significantly more frequently in FPV-cases than in healthy controls. Feline calicivirus was present in a higher proportion of FPV-cases (11 out of 23, 47.8%) compared to healthy controls (5 out of 36, 13.9%, p = 0.0067). Feline kobuvirus infections were also common among FPV-cases (9 out of 23, 39.1%) and were not detected in any healthy controls (p < .0001). While abundant in both groups, astroviruses were more frequently present in FPV-cases (19 out of 23, 82.6%) than in healthy controls (18 out of 36, p = .0142). The differences in eukaryotic virome composition revealed here indicate that further investigations are warranted to determine associations between enteric viral co-infections on clinical disease severity in cats with FPL.

Immunodominant B-Cell Linear Epitope on the VP1 P Domain of a Feline Norovirus Cat Model

Norovirus (NoV) infection remains a major public health concern worldwide. Appropriate animal models are essential for the development of effective NoV vaccines. We previously established the feline NoV (FNoV)-cat model as a surrogate animal model for human NoV infection. In the present study, we analyzed the B-cell linear epitope in the P domain of FNoV to confirm the basic immunological features of the FNoV-cat model. B-cell linear epitopes were present in the P2 subdomain. We compared antibody levels to peptides containing the B-cell linear epitope (P-10) in three FNoV-infected cats with time-course changes in viral load and symptom scoring. After FNoV infection, viral shedding and clinical symptoms were shown to improve by elevated levels of antibodies against P-10 in the plasma. This report provides important information for understanding NoV infections in humans and cats.

Novel parvovirus in cats, China

Parvovirus is a common element of the feline virus group and usually causes gastroenteritis and leukopenia in cats. In this study, we identified a novel protoparvovirus from the Chinese domestic cats, which is genetically similar to canine bufavirus (98.0%-99.8%), but sharing low amino acid identities in the viral structural proteins 2 (VP2) (36.1-37.2%) to the well-known canine parvovirus type 2 and feline panleukopenia virus. This virus was provisionally designated as feline bufavirus (FBuV). Screening of fecal samples revealed a prevalence of 7.4% (19/257) in domestic cats. Diarrhea was present in 52.6% (10/19) of cats positive for FBuV. However, statistical analysis showed no association between FBuV and clinical signs. VP2 gene of the 19 field FBuV was sequenced and phylogenetic analysis demonstrated that FBuV determined from China had a genetic diversity. This study will strengthen the understanding of the epidemiology and genetic diversity of bufavirus and provide a foundation for further studies.

Emerging Parvoviruses in Domestic Cats

Parvovirus infections in cats have been well known for around 100 years. Recently, the use of molecular assays and metagenomic approaches for virus discovery and characterization has led to the detection of novel parvovirus lineages and/or species infecting the feline host. However, the involvement of emerging parvoviruses in the onset of gastroenteritis or other feline diseases is still uncertain.

Astrovirus Outbreak in an Animal Shelter Associated With Feline Vomiting

An outbreak of cat vomiting was observed in an animal shelter. Testing for known enteric feline pathogens did not identify a causative agent. Viral metagenomics on four mini pools of feces from cases and controls housed in the same area revealed the presence of feline astrovirus in all pools. Also found with fewer reads in one pool each were rotavirus I, carnivore bocaparvovirus 3, norovirus (NoV) GVI, and a novel dependovirus. The genome of the highly prevalent astrovirus was sequenced and classified into mamastrovirus species two, also known as feline astrovirus. Real-time RT-PCR on longitudinally acquired fecal samples from 11 sick cases showed 10 (91%) to be shedding astrovirus for as long as 19 days. Affected cats were sick for an average of 9.8 days, with a median of 2.5 days (range = 1–31 days). Unaffected control cats housed in the same areas during the outbreak showed five out of nine (56%) to also be shedding astrovirus. Feline fecal samples collected from the same animal shelter ~1 year before (n = 8) and after (n = 10) showed none to be shedding astrovirus, indicating that this virus was temporarily associated with the vomiting outbreak and is not part of the commensal virome for cats in this shelter. Together with the absence of highly prevalent known pathogens, our results support a role for feline astrovirus infection, as well as significant asymptomatic shedding, in an outbreak of contagious feline vomiting.

Feline chaphamaparvovirus in cats with enteritis and upper respiratory tract disease

Feline chaphamaparvovirus (FeChPV) is a novel parvovirus, first discovered in a multi-facility feline shelter in Canada in 2019, during an outbreak of acute gastro-enteritis (AGE) in cats, and detected at high prevalence (47.0%) in faecal samples. Whether this finding was anecdotal or similar viruses are common components of feline virome is still unclear. Also, the potential impact of this virus on feline health is uncertain. Herewith, a case-control study was performed to investigate whether this novel parvovirus may play a role as enteric pathogen, screening samples collected from cats with and without AGE signs. Furthermore, we extended the research by testing archival paired oropharyngeal and ocular samples collected from cats with or without upper respiratory tract disease (URTD). FeChPV DNA was detected at high prevalence rate (36.8%, 14/38) in clinical cases, representing the most frequently identified enteric virus, followed by feline panleukopenia parvovirus (23.7%, 9/38), feline coronavirus (5.3%, 2/38), feline kobuvirus (5.3%, 2/38) and noroviruses (5.3%, 2/38). The different prevalence rates of FeChPV between the case and control group were statistically significant, suggesting a possible association of the virus with acute gastro-enteric disease. The virus was also detected at low rate in the respiratory samples of cats with (3.3%, 6/183) or without URTD (4.3%, 6/140), although there was no significant association between FeChPV and URTD. The complete VP encoding gene was determined for five viruses and the nearly full-length genome was reconstructed for three viruses, namely 313R/2019/ITA, 284R/2019/ITA and 49E/2019/ITA. In the NS1-based tree, the Italian strains clustered tightly with the two FeChPV prototypes detected in Canada, within a monophyletic cluster related to but clearly distinct from canine chaphamaparvovirus, currently classified in the species Carnivore chaphamaparvovirus 1 (CaChPV-1).

Virome of a Feline Outbreak of Diarrhea and Vomiting Includes Bocaviruses and a Novel Chapparvovirus

An unexplained outbreak of feline diarrhea and vomiting, negative for common enteric viral and bacterial pathogens, was subjected to viral metagenomics and PCR. We characterized from fecal samples the genome of a novel chapparvovirus we named fechavirus that was shed by 8/17 affected cats and identified three different feline bocaviruses shed by 9/17 cats. Also detected were nucleic acids from attenuated vaccine viruses, members of the normal feline virome, viruses found in only one or two cases, and viruses likely derived from ingested food products. Epidemiological investigation of disease signs, time of onset, and transfers of affected cats between three facilities support a possible role for this new chapparvovirus in a highly contagious feline diarrhea and vomiting disease.