Genetic heterogeneity of canine bufaviruses

Genetic and recombination heterogeneity of canine bufaviruses detected in diarrheal dogs in China

Bufavirus (BuV) was first identified in feces from children with acute diarrhea, and a genetically related Canine bufavirus (CBuV) was first reported in Italy in 2018. In this study, through the investigation of CBuV in 622 anal swabs from dogs with diarrhea symptoms collected from various provinces in northern, central and eastern China during 2018-2022, 14 samples were detected to be positive. And 5 samples were from dogs co-infected with other canine diarrhea related viruses, which consist of CPV-2, CDV and CCoV. The complete genome sequences (4219 nt) of the fourteen strains were amplified and sequenced. Through comparative analysis with 51 reference BuV strains, six strains might recombinate from the CBuV strains (HUN/2012/22, CaBuV/9AS/2005/ITA and CaBuV/35/2016/ITA) in Hungary and Italy as the parents, and two genetic recombination events from various parents were predicted to occur on the BUV-422 strain. Combined analyzing the phylogenetic tree and sequence alignment, it was found that these CBuVs are highly conserved in the nonstructural protein NS1, but indeed various amino acid mutation sites in the capsid protein VP2, and even some amino acid sites coincide with putative protein plastic regions and potential epitopes. The BUV-422 and BUV-512 strains show sequential mutation sites identical to the divergent strains of CaBuV/9AS/2005/ITA and CaBuV/35/2016/ITA. This study would enrich the molecular data of CBuV in China and provide essential reference for the epidemiological research and vaccine development of CBuV in the future.

Canine bufavirus (Carnivore protoparvovirus-3) infection in dogs with respiratory disease

Canine bufavirus (CBuV) or Carnivore protoparvovirus-3, a nonenveloped DNA virus belonging to the genus Protoparvovirus, family Parvoviridae, has been identified in dogs with respiratory and enteric diseases. Although CBuV detection has been reported in multiple countries, descriptions of pathologic findings associated with infection have not yet been provided. In this study, the authors necropsied 14 dogs (12 puppies and 2 adult dogs) from a breeding colony that died during multiple outbreaks of respiratory diseases. Postmortem investigations revealed extensive bronchointerstitial pneumonia with segmental type II pneumocyte hyperplasia in all necropsied puppies but less severe lesions in adults. With negative results of common pathogen detection by ancillary testing, CBuV DNA was identified in all investigated dogs using a polymerase chain reaction (PCR). Quantitative PCR demonstrated CBuV DNA in several tissues, and in situ hybridization (ISH) indicated CBuV tissue localization in the lung, tracheobronchial lymph node, and spinal cord, suggesting hematogenous spread. Dual CBuV ISH and cellular-specific immunohistochemistry were used to determine the cellular tropism of the virus in the lung and tracheobronchial lymph node, demonstrating viral localization in various cell types, including B-cells, macrophages, and type II pneumocytes, but not T-cells. Three complete CBuV sequences were successfully characterized and revealed that they clustered with the CBuV sequences obtained from dogs with respiratory disease in Hungary. No additional cases were identified in small numbers of healthy dogs. Although association of the bufavirus with enteric disease remains to be determined, a contributory role of CBuV in canine respiratory disease is possible.

First detection and genetic characterization of canine bufavirus in domestic dogs, Thailand

Canine bufavirus (CBuV) was reported in domestic dogs worldwide. We conducted a survey of canine bufavirus in domestic dogs in Thailand from September 2016 to October 2022. Rectal swab samples (n = 531) were collected from asymptomatic dogs and dogs with gastroenteritis signs. The samples were tested for CBuV using PCR with specific primers to the VP1/VP2 gene, and 9.42% (50/531) was CBuV positive. Our findings showed that CBuVs could be detected in both symptomatic and healthy dogs. The Thai CBuVs were found in dogs from different age groups, with a significant presence in those under 1 year (12.60%) and dogs aged 1-5 years (7.34%) (p < 0.05), suggesting a high prevalence of Thai CBuVs in dogs under 5 years of age. We performed complete genome sequencing (n = 15) and partial VP1/VP2 sequencing (n = 5) of Thai CBuVs. Genetic and phylogenetic analyses showed that whole genomes of Thai CBuVs were closely related to Chinese and Italian CBuVs, suggesting the possible origin of Thai CBuVs. The analysis of VP1 and VP2 genes in Thai CBuVs showed that 18 of them were placed in subgroup A, while only 2 belonged to subgroup B. This study is the first to report the detection and genetic characterization of CBuVs in domestic dogs in Thailand. Additionally, surveillance and genetic characterization of CBuVs in domestic animals should be further investigated on a larger scale to elucidate the dynamic, evolution, and distribution of CBuVs.

Molecular Surveillance for Bocaparvoviruses and Bufaviruses in the European Hedgehog (Erinaceus europaeus)

The presence of bocaparvoviruses (BoVs) and bufaviruses (BuVs) in the European hedgehog (Erinaceus europaeus) was investigated by screening duodenal and liver samples collected from 183 carcasses, delivered to wildlife rescue centers located in northwestern Italy. BoV DNA was detected in 15 animals (8.2%), with prevalences of 7.1% (13/183) and 2.7% (5/183) in intestine and liver samples, respectively. Upon the sequence analyses of the NS1 gene, two highly divergent BoVs (65.5-67.8% nt identities) were identified. Fourteen strains showed the highest identity (98.3-99.4% nt) to the hedgehog BoV strains recently detected in China in Amur hedgehogs (Erinaceus amurensis), whilst four strains were genetically related (98.9-99.4% nt identities) to the porcine BoVs identified in pigs and classified in the species Bocaparvovirus ungulate 4, which included related viruses also found in rats, minks, shrews, and mice. BuV DNA was detected in the duodenal samples of two hedgehogs, with a prevalence rate of 1.1%. The nearly full-length genome of two BuV strains, Hedgehog/331DU-2022/ITA and Hedgehog/1278DU/2019/ITA, was reconstructed. Upon phylogenetic analysis based on the NS and VP aa sequences, the Italian hedgehog BuVs tightly clustered with the BuVs recently identified in the Chinese Amur hedgehogs, within a potential novel candidate species of the genus Protoparvovirus.

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.

Investigation of canine chaphamaparvovirus, canine bufavirus, and canine adenovirus in dogs with diarrhea: First report of novel canine bufavirus in Turkey

Viral enteritis is a significant cause of death among dogs younger than 6 months. In this study, the presence of canine chaphamaparvovirus (CaChPV), canine bufavirus (CBuV), and canine adenovirus (CAdV) was investigated in 62 diarrheal dogs previously tested for other viral pathogens (canine parvovirus type 2, canine coronavirus, and canine circovirus). CBuV was detected in two dogs (3.22%) and CaChPV in one dog (1.61%). One dog tested positive for three parvoviruses (CPV-2b, CBuV, and CaChPV). All dogs tested negative to CAdV-1/CAdV-2. A long genome fragment of one of the two identified CBuVs and of the CaChPV was obtained and analyzed. New Turkish CBuVs had high identity rates (96%-98% nt; 97%-98% aa) with some Italian CBuV strains (CaBuV/9AS/2005/ITA and CaBuV/35/2016/ITA). The phylogenetic analysis powerfully demonstrated that these viruses belonged to a novel genotype (genotype 2). A part of the genome ChPV-TR-2021-19 revealed high identity rates (> 98% nt and > 99% aa) with some Canadian CaChPV strains (NWT-W88 and NWT-W171) and the Italian CaChPV strain Te/37OVUD/2019/IT. This study is the first report on the detection of CBuV-2 and the concomitant presence of three canine parvoviruses in Turkey. The obtained data will contribute to the molecular epidemiology and the role in the etiology of enteric disease of new parvoviruses.

Emerging Respiratory Viruses of Cats

In recent years, advances in diagnostics and deep sequencing technologies have led to the identification and characterization of novel viruses in cats as protoparviruses and chaphamaparvoviruses, unveiling the diversity of the feline virome in the respiratory tract. Observational, epidemiological and experimental data are necessary to demonstrate firmly if some viruses are able to cause disease, as this information may be confounded by virus- or host-related factors. Also, in recent years, researchers were able to monitor multiple examples of transmission to felids of viruses with high pathogenic potential, such as the influenza virus strains H5N1, H1N1, H7N2, H5N6 and H3N2, and in the late 2019, the human hypervirulent coronavirus SARS-CoV-2. These findings suggest that the study of viral infections always requires a multi-disciplinary approach inspired by the One Health vision. By reviewing the literature, we provide herewith an update on the emerging viruses identified in cats and their potential association with respiratory disease.

First report of canine bufavirus in India

Canine bufavirus (CBuV), a novel protoparvovirus of dogs that is associated with enteric and respiratory symptoms, has been reported only in Italy and China. The enteric prevalence of CBuV in India was investigated, and the nearly complete genome sequence (4292 bp) was amplified and reconstructed for one strain. A nucleotide sequence alignment indicated 93.42–98.81% identity to the other available CBuV sequences and 70.88–73.39% and 54.4–54.8% identity to human bufavirus and canine parvovirus 2 (CPV-2), respectively. The current strain is most closely related to Chinese CBuV strains, which together form an Asian lineage. This first report of the prevalence of CBuV in India emphasizes the need for further epidemiological surveillance.

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

A SYBR Green I-based real-time polymerase chain reaction assay for detection and quantification of canine bufavirus

Canine bufavirus (CBuV) was first discovered in puppies in Italy in 2016, and subsequent studies have reported its possible relationship with acute enteritis. Currently, there is no specific and quantitative detection method for CBuV. This study examined the conserved NS1 gene and used a pair of specific primers to establish a direct SYBR Green I-based real-time quantitative polymerase chain reaction (qPCR) method for the detection and quantification of CBuV. In the sensitivity experiment, the detection limit of SYBR Green I-based real-time qPCR was 4.676 × 10¹ copies/μL and that of conventional PCR (cPCR) was 4.676 × 10³ copies/μL. Furthermore, the qPCR method did not detect other viruses in dogs, indicating good specificity. The intra-assay coefficient of variation was 0.07-0.55% and the inter-assay coefficient of variation was 0.03-0.11%, indicating good repeatability. In clinical sample testing, the detection rate of qPCR was 5.0% (6/120), higher than that of cPCR (2.5%, 3/120). In addition, the samples that tested CBuV-positive in this experiment were all from dogs with acute enteritis. In summary, the SYBR Green I-based qPCR method established in this study has good sensitivity, specificity, and reproducibility for clinical sample detection and can also assist in future research on CBuV.

Icariin, Formononetin and Caffeic Acid Phenethyl Ester Inhibit Feline Calicivirus Replication In Vitro

Cats infected with feline calicivirus (FCV) often display oral ulcers and inflammation of the upper respiratory tract, which can lead to death in severe cases. Antiviral therapy is one of the most effective ways to control FCV infection. Natural compounds in Chinese herbal medicines and medicinal plants provide abundant resources for research on antiviral drugs. In this study, we found that icariin (ICA), formononetin (FMN) and caffeic acid phenethyl ester (CPAE) show low cytotoxicity towards F81 cells, that the three natural compounds have apparent antiviral effects on FCV in vitro, and that they can inhibit different FCV strains. Then, we found that ICA and FMN mainly function in the early stage of FCV infection, while CAPE can function in both the early and late stages of FCV infection. Finally, we found that ICA has an antagonistic effect on FMN and CAPE in FCV infection, and FMN has a synergistic effect with CAPE against FCV infection. Our results showed that ICA, FMN and CAPE may be potential drug candidates for FCV-induced diseases.