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Hepatitis B virus (HBV) is a major cause of liver disease in humans including chronic hepatitis and hepatocellular carcinoma. Domestic cat hepadnavirus (DCH), a novel HBV-like hepadnavirus, was identified in domestic cats in 2018. From 6.5 %-10.8 % of pet cats are viremic for DCH and altered serological markers suggestive of liver damage have been identified in 50 % of DCH-infected cats. DCH DNA has been detected in association with characteristic lesions of chronic hepatitis and with hepatocellular carcinoma in cats, suggesting a possible association. In this study longitudinal molecular screening of cats infected with DCH was performed to determine if DCH can cause chronic infections in cats. Upon re-testing of sera from five DCH-positive animals, 2-10 months after the initial diagnosis, three cats tested negative for DCH on two consecutive occasions using quantitative PCR. Two other cats remained DCH-positive, including an 8-month-old female cat re-tested four months after the initial positive result, and a 9-year-old male cat, which tested positive for DCH on six occasions over an 11-month period. The latter had a history of chronic hepatopathy with jaundice, lethargy and elevated serum alanine transaminase levels (ALT). During the period of observation, DCH titers ranged between 1.64 × 10 5 and 2.09 × 10 6 DNA copies/mL and ALT was persistently elevated, suggesting chronic infection. DCH DNA was not detected in oral, conjunctival, preputial and rectal swabs from the two animals collected at several time points. Long-term (chronic) infection would be consistent with the relatively high number of viremic cats identified in epidemiological investigations, with the possible association of DCH with chronic hepatic pathologies and with what described with HBV in human patients., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Feline leukaemia virus (FeLV) is a retrovirus associated with fatal disease in cats with infection in its progressive form. Although there are numerous reports on the occurrence of FeLV in the feline population worldwide, there is a paucity of data in Asia. In this study, we assessed the circulation of FeLV by ELISA and nested PCR in cats from different countries in Southeast Asia (i.e., Thailand, Malaysia, Singapore, Philippines, Indonesia and Vietnam) and Taiwan during 2017-2018. Forty-seven cats were positive to FeLV by antigen or provirus detection, but 32 samples were considered truly positive on the basis of positive molecular testing. Frequency of occurrence of FeLV proviral DNA ranged from 0% (0/43 positive samples) in Indonesia to 18.5% (22/119 positive samples) in Thailand. A statistically significant association (p < 0.05) was found between country of cats origin, age, lifestyle, abnormal oral mucosa, and FeLV molecular positive results. In-depth studies are needed in other countries in Southeast Asia to elucidate the mosaic of knowledge about FeLV epidemiology., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Coronaviruses (CoVs) cause disease in a range of agricultural and companion animal species, and can be important causes of zoonotic infections. In humans, several coronaviruses circulate seasonally. Recently, a novel zoonotic CoV named SARS-CoV-2 emerged from a bat reservoir, resulting in the COVID-19 pandemic. With a focus on felines, we review here the evidence for SARS-CoV-2 infection in cats, ferrets and dogs, describe the relationship between SARS-CoV-2 and the natural coronaviruses known to infect these species, and provide a rationale for the relative susceptibility of these species to SARS-CoV-2 through comparative analysis of the ACE-2 receptor., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Feline morbillivirus (FeMV) is an emerging virus that was first described in Hong Kong in 2012. Several reports suggested the epidemiological association of FeMV infection with chronic kidney disease (CKD) in cats. The aim of this study was to investigate the presence and the genetic diversity of FeMV as well as the relationship between FeMV infection and CKD in cats from Northern Italy. Urine (n = 81) and kidney samples (n = 27) from 92 cats admitted to the Veterinary Teaching Hospital of the University of Milan between 2014 and 2017 were investigated for FeMV infection. FeMV RNA was detected in one urine sample (1.23%; 95% CI: 0.03-6.68%) and in two kidneys (7.40%; 95% CI: 0.91-24.28%). FeMV RNA was revealed only in urine or kidneys of cats without evidence of CKD. Phylogenetic analysis showed that the three strains clustered with FeMV strains retrieved from public database, forming a distinct sub-cluster of FeMV. The presence of distinct genotypes of FeMV found in this study is in accordance with previous studies demonstrating that FeMV strains are genetically diverse. A clear relationship between the presence of FeMV infection and CKD in the cats from Northern Italy was not observed, confirming recent reports that do not support the hypothesis that FeMV infection is associated with the development of CKD., (Copyright © 2019 Elsevier B.V. All rights reserved.)

With the increase of blood transfusion in veterinary medicine, the presence of endemic viral agents in the blood should be carefully investigated. For this reason, the blood of feline and canine blood donors was screened to detect the presence of herpesviruses, especially gammaherpesviruses and parvoviruses, and to characterize the viruses detected. A retrospective cross-sectional study was performed on 31 cats and 54 dogs, enrolled as voluntary blood donors. Nested PCR was carried out to detect herpesvirus and parvovirus DNA. Sequencing and real-time PCR were used to confirm and quantify positive samples. The feline and canine samples were negative for the presence of herpesviruses. Fourteen specimens of blood (45.16%, 95% confidence interval, CI: 27.78-63.70) from feline blood donors and two (3.7%, 95% CI: 0.64-13.84) from canine blood donors were positive for parvovirus DNA. The percentage positivity was significantly different in cats and dogs (P < 0.0001), giving an odds ratio of 21.41 (95% CI: 4.4-103.9). The lack of detection of herpesviral DNA confirms previous results obtained in dogs, but contrasts with the evidence of the worldwide distribution of gammaherpesviruses in cats. Selection of blood donors is a useful tool adopted to reduce the risk of transfusion-transmitted infections for the majority of known microorganisms. The results obtained for parvovirus, however, confirm the presence of this pathogen in the blood of healthy cats, with a significant difference from dogs. The implications of the detection of parvoviral DNA in the blood of donors must be clarified in order to exclude the risk of transmission., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Feline infectious peritonitis (FIP) is a common and highly lethal coronavirus disease of domestic cats. Recent studies of diseases caused by several RNA viruses in people and other species indicate that antiviral therapy may be effective against FIP in cats. The small molecule nucleoside analog GS-441524 is a molecular precursor to a pharmacologically active nucleoside triphosphate molecule. These analogs act as an alternative substrate and RNA-chain terminator of viral RNA dependent RNA polymerase. We determined that GS-441524 was non-toxic in feline cells at concentrations as high as 100 uM and effectively inhibited FIPV replication in cultured CRFK cells and in naturally infected feline peritoneal macrophages at concentrations as low as 1 uM. We determined the pharmacokinetics of GS-441524 in cats in vivo and established a dosage that would sustain effective blood levels for 24 h. In an experimental FIPV infection of cats, GS-441524 treatment caused a rapid reversal of disease signs and return to normality with as little as two weeks of treatment in 10/10 cats and with no apparent toxicity., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Canine parvovirus (CPV) and feline panleukopaenia virus (FPLV) are two closely related viruses, which are known to cause severe disease in younger unvaccinated animals. As well as causing disease in their respective hosts, CPV has recently acquired the feline host range, allowing it to infect both cats and dogs. As well as causing disease in dogs, there is evidence that under some circumstances CPV may also cause disease in cats. This study has investigated the prevalence of parvoviruses in the faeces of clinically healthy cats and dogs in two rescue shelters. Canine parvovirus was demonstrated in 32.5% (13/50) of faecal samples in a cross sectional study of 50 cats from a feline only shelter, and 33.9% (61/180) of faecal samples in a longitudinal study of 74 cats at a mixed canine and feline shelter. Virus was isolated in cell cultures of both canine and feline origin from all PCR-positive samples suggesting they contained viable, infectious virus. In contrast to the high CPV prevalence in cats, no FPLV was found, and none of 122 faecal samples from dogs, or 160 samples collected from the kennel environment, tested positive for parvovirus by PCR. Sequence analysis of major capsid VP2 gene from all positive samples, as well as the non-structural gene from 18 randomly selected positive samples, showed that all positive cats were shedding CPV2a or 2b, rather than FPLV. Longitudinally sampling in one shelter showed that all cats appeared to shed the same virus sequence type at each date they were positive (up to six weeks), despite a lack of clinical signs. Fifty percent of the sequences obtained here were shown to be similar to those recently obtained in a study of sick dogs in the UK (Clegg et al., 2011). These results suggest that in some circumstances, clinically normal cats may be able to shed CPV for prolonged periods of time, and raises the possibility that such cats may be important reservoirs for the maintenance of infection in both the cat and the dog population., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A molecular epidemiology study was performed on a selection of 30 rabies-positive brain samples collected between 1994 and 2010 in Slovenia and originating from the red fox (n=19), badger (n=3), cattle (n=3), dog (n=2), cat (n=1), marten (n=1) and horse (n=1). Based on the comparison of 1092 and 672 nucleotide sequences of nucleoprotein (N) and partial glycoprotein (G) gene regions, a low genetic diversity of the circulating strains was detected, but both phylogenetic trees were consistent with the topology where partial nucleoprotein or glycoprotein genes were used. A high sequence identity in the N and G gene to rabies virus isolates from neighbouring countries was found. The Slovenian strains were clearly different from the vaccine strains SAD B19 and SAD Bern, which have been used in Slovenia since 1988., (Copyright © 2011 Elsevier B.V. All rights reserved.)

To expand the epidemiological understanding of feline calicivirus (FCV) in dogs, genotypic and phenotypic characterizations of a FCV strain isolated from a puppy showing enteritis were performed. After isolation in cell culture, the novel isolate was analysed by RT-PCR and the amplicons obtained were sequenced. In order to characterize the growth properties of the isolate, the size of the plaques, the temperature of inactivation and the kinetics of growth were evaluated. Moreover, the novel strain was used to perform a serological study on 86 canine serum samples and 81 feline sera by virus-neutralization assay. The comparative analysis of nucleotide and amino acid sequences of the isolate, named FCV-Te/10/07, revealed the highest identity to strain FCV-F65. The growth kinetic revealed that strain Te/10/07 grew more rapidly than F9 strain. By virus-neutralization assay, dogs from the same region of the isolate showed antibodies against the FCV-F9 vaccinal strain in 63.9% (55/86) of sera, while antibodies against the Te/10/07 were found in seven sera (8.13%). In cats neutralizing antibodies against Te/10/07 strain were recovered in 50.62% (41/81) of samples tested, even if 38 sera were positives for F9 strain with similar titres or higher. In three cats neutralization to Te/10/07 alone was seen. Our results confirmed the interspecific circulation of FCV strains among different animal species, but new investigations are needed to establish whether FCV is pathogenic in the dog and the role of interspecies circulation in pathogen spreading.

The susceptibility of cats and dogs to Australian bat lyssavirus (ABLV; genotype VII) was investigated by intramuscular (IM) inoculation of 10(3.7)-10(5) 50% tissue culture infective doses (TCID(50)) of virus followed by observation of experimental animals for up to 3 months post-inoculation (pi). Each experiment also included positive and negative controls, animals inoculated with a bat variant of rabies virus (Eptesicus I, genotype I), or a 10% suspension of uninfected mouse brain, respectively. Each of the ABLV-inoculated cats showed occasional abnormal clinical signs, but none died. Necropsies performed at 3 months pi revealed no lesions, and no viral antigen, in the central nervous system of any cat. ABLV could not be recovered from any cats. However, rabies virus-neutralizing antibodies were detected between 4 and 14 weeks pi in the sera of all three ABLV-inoculated cats. At 2-3 weeks pi, three of the five ABLV-inoculated dogs showed very mild abnormal clinical signs that persisted for 1-2 days, after which the dogs recovered. At 3 months pi, when all dogs were necropsied, neither lesions nor ABLV antigen were detected in, and virus was not isolated from, any dog. No ABLV RNA was detected by polymerase chain reaction (PCR) in clinical or necropsy samples from the three ABLV-affected dogs. However, all ABLV-inoculated dogs seroconverted by 2 weeks pi, and serum antibody titres were higher than those observed in cats. CSF, collected at 3 months pi, was positive for rabies virus-neutralizing antibody in two ABLV-inoculated dogs.

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the detection of the feline coronavirus (FCoV) genome and a co-cultivation method for the isolation of field strains of FCoV are described. Using the RT-PCR assay to assess blood samples from cats with feline infectious peritonitis (FIP) (n = 47) and healthy cats from households with endemic FCoV (n = 69) it was shown that approximately 80% of the cats were viraemic, irrespective of their health status. It was also shown that, over a 12-month period, a similar percentage of healthy cats remained viraemic, and that the presence of viraemia did not appear to predispose the cats to the development of FIP. The co-cultivation system proved to be a suitable method for the culture of field strains of FCoV from blood samples, so long as the cultures were maintained for at least 4 weeks. Using this system, followed by the RT-PCR, viraemia was detected as frequently as by RT-PCR on RNA extracted directly from peripheral blood mononuclear cells.

Following the isolation of a group I Aujeszky's disease virus from a wild boar in 1993, an investigation was carried out on 30 Italian Aujeszky's disease viruses (ADV's), isolated over a 23-yr period in 12 Italian regions, by means of restriction endonuclease analysis. All strains isolated between 1972 and 1984 belong to group I. From 1984 onwards group II isolates (II and II intermediate) replace group I isolates. The isolation of a group I virus in 1993 from a wild boar supports the hypothesis that ADV's may persist for several years in wild boar populations and that wild boars should therefore be considered reservoirs of Aujeszky's disease virus.