Canine circovirus and Canine adenovirus type 1 and 2 in dogs with parvoviral enteritis

The PB subunit vaccine evokes immune response against fox encephalitis

Canine adenovirus type 1 (CAdV-1) is an important pathogen for fox encephalitis, and posing a severe threat to the global fox farming industry. Although live CAdV-2 vaccines are currently available, its defect remains a considerable challenge. It is vital to develop a safe subunit vaccine. This study aimed to evaluate the immunogenicity and safety of the penton base (PB) subunit vaccine in fox with CAdV-1, for which little is known. Bioinformatics methods were used to design a recombinant protein vaccine based on conserved regions of protein consensus sequences in PB protein. The E.coli prokaryotic expression system was utilized to enhance protein expression, solubility and immunogenicity. After the PB proteins of CAdV-1 were successfully expressed, the mice and silver foxes were immunized. The specific antibody, neutralizing antibody titters, T lymphocyte proliferation, cytokine, tissue histopathology, virus shedding, and the survival rate were investigated. The results showed that the PB subunit vaccine induced the production of antibodies in mice at 7, 14, 21, 30, 60 d post-vaccination (dpv). Moreover, the neutralizing antibody level of the PB group was higher than that in the Knob group at 21 and 28 dpv. It indicates that PB subunit vaccine elicits immunity. In the silver fox, PB subunit vaccine induced the production of antibodies at 30 dpv. Moreover, the neutralizing antibody level in PB group was higher than that in the CAdV-2 vaccine group at 30 dpv. PB subunit vaccine conferred complete protection in fox against CAdV-1. The tissue histopathology suggested that the PB subunit vaccine was more effective in blocking the pathogenicity of CAdV-1. In addition, the PB subunit vaccine further reduced the virus shedding in silver foxes than the CAdV-2 vaccine. The results suggest that this vaccine could be a promising candidate for preventing CAdV-1 in foxes.

Canine circovirus: emergence, adaptation, and challenges for animal and public health

Introduction

Canine circovirus (CanineCV) is an emerging pathogen with a significant impact on animal health and potential zoonotic risks. This study addresses its characterization, epidemiology, pathogenesis, and diagnostics, emphasizing its relevance within the One Health approach.

Background

The increasing detection of CanineCV across various species and regions highlights its genetic adaptability and cross-species transmission potential. Furthermore, growing interactions among domestic animals, wildlife, and humans amplify the need to understand its public and animal health implications.

Objective

To analyze the biology, epidemiology, and diagnostic challenges of CanineCV, focusing on its genetic evolution, interactions with co-infections, and implications for control strategies.

Methods

A systematic literature review was conducted, synthesizing data from epidemiological, genomic, and clinical studies. Molecular techniques, such as PCR and qPCR, were evaluated for their efficacy in virus detection and quantification.

Results

Canine circovirus exhibits high genetic variability and has been detected in diverse species and tissues. Co-infections, including parvovirus and adenovirus, exacerbate clinical signs, primarily gastrointestinal, and respiratory. Advances in diagnostics, such as real-time PCR and in situ hybridization, have demonstrated increased sensitivity in viral detection.

Conclusion

Canine circovirus poses a growing challenge to animal health and a potential threat to public health due to its genetic plasticity and adaptability to multiple hosts. Continuous research is essential to understand its pathogenesis, develop effective control measures, and mitigate risks in diverse ecosystems.

Canine Adenoviruses in Wildlife: Role in At-Risk Species Conservation and Interface with Domestic Animals

Canine adenovirus type 1 (CAdV-1) and type 2 (CAdV-2) are well known pathogens of domestic dogs but are little investigated in wild animals. The few available studies about CAdV-1 in wild animals show that it circulates in various species and that transmission of the virus in the interface between wildlife and domestic animals is a frequent event. Furthermore, wild animals are usually subject to asymptomatic infections, but cases of serious and fatal diseases have been documented, with possible effects on the conservation of the species. In contrast, CAdV-2 infection was reported only recently and sporadically in some wild animals, with few data regarding its pathogenic role in these species. However, the real prevalence of these viruses in wildlife is still uncertain due to the use of serological tests that are largely unable to distinguish antibodies against CAdV-1 and CAdV-2. This review, reporting all the data currently available on CAdV-1 and CAdV-2 infection in wild animals, highlights the importance of these pathogens for wildlife conservation and their role in the potential transmission of the infection to domestic dogs.

Canine circovirus: an emerging virus of dogs and wild canids

Canine Circovirus (CanineCV) is an emerging viral pathogen affecting dogs and wild canids worldwide. Belonging to the Circoviridae family, CanineCV exhibits genetic variability and has been associated with various clinical manifestations, including gastroenteritis, respiratory symptoms, and neurological disorders. While its prevalence is notable, gaps persist in understanding its pathogenicity and evolutionary origins. CanineCV often co-infects with other canine viruses, complicating diagnosis and treatment. Prevention strategies are hindered by the lack of targeted vaccines and the virus's resilience in the environment. This review paper summarizes the current knowledge on CanineCV and discusses the virus's genetic features and taxonomy, epidemiology in both domestic and wild populations, clinical manifestations, diagnosis methods, and prevention strategies. Additionally, the article highlights gaps in knowledge regarding CanineCV's pathogenicity, evolutionary aspects, and potential zoonotic transmission risks. Overall, it underscores the importance of further research to better understand and mitigate the impact of CanineCV on canine health and public health.

Establishment of a chip digital PCR detection method for canine circovirus

Canine circovirus (CanineCV), which is a new mammalian circovirus first reported in the United States in 2012, mainly causes diarrhea and vomiting in dogs. As CanineCV evolves and new subtypes emerge, there is an urgent need for new detection technologies to improve the sensitivity and detection rates of viruses in complex scenarios. A chip digital PCR(cdPCR) assay was established for the detection of CanineCV in this study. The results showed good reproducibility, specificity and a linear relationship; the minimum detection limit of CanineCV by cdPCR was 6.62 copies/μL, which is 10 times more sensitive than quantitative real-time PCR (qPCR). The qPCR-positive detection rate was 1 %, while CanineCV cdPCR (2.1 %) exhibited a greater positive detection rate. Fifteen complete genomes were sequenced and subdivided into CanineCV-1 and CanineCV-3. In conclusion, we developed a rapid, reliable, and specific cdPCR method for screening and monitoring canine CV.

Molecular analysis of canine circovirus in dogs from animal shelters in Belém, Pará, northern Brazil: first detection at the amazon region

The canine circovirus (CanCV) is a single-stranded DNA virus that has become an important emerging virus associated with gastroenteritis in dogs worldwide. In the present study, the CanCV was detected by PCR in 15% (22/147) of dogs from animal shelters in Belém, between 2019 and 2020. We observed an association between the CanCV infection and the presence of diarrhea in animals younger than one year of age (p > 0.01). The Brazilian strains were grouped in Chinese genotypes, with 99.54 to 100% nucleotilde homology. The GMRF Bayesian Skyride used the molecular clock model, which was the best suited technique to plot the dataset. The most recent common ancestor (TMRCA) was estimated in 2017, with the evolution rate of 1.6 x 10-3 s/s/y. The viral family diversity was also investigated, with emphasis on the families of the enteric pathogenic viruses Parvoviridae, Picornaviridae and Astroviridae, which were detected in the CanCV positive pooled samples. This study highlights the importance of the CanCV as an emergent virus that causes diarrhea in Brazilian dogs. The results found herein contribute to the understanding of the role of CanCV in enteric diseases and in the evolutionary molecular characterization of the circulating genotypes. Furthermore, we increased the understanding of the fecal virome in dogs with diarrhea, providing data for the monitoring and prevention viral gastroenteric diseases in domestic animals.

Epidemiology and genotypic diversity of canine circovirus identified in pet dogs in Harbin, China

Canine circovirus (CanineCV) is a single-stranded DNA virus that circulates in dogs and wild carnivores around the world. It has been suggested to be associated with diseases of respiratory and gastrointestinal systems, though its pathogenic potential remains unclear. Currently, CanineCV is divided into six genotypes (genotype 1-6), and genotypes 2, 3, and 4 have been described in China. In this study, 359 blood samples from pet dogs with or without clinical signs were collected in Harbin city. After PCR screening, a total of 34 samples were tested positive for CanineCV, and nine full-length genome sequences were recovered from positive samples. Pairwise sequence comparison showed that they shared 82.4-99.3% genome-wide identity with other CanineCVs available in GenBank. Additionally, recombination events were detected, all of which were determined to be associated with sequences obtained in China. The reconstructed phylogenetic tree based on the recombination-free complete genome sequences revealed that the complete genome sequences generated herein were clustered into genotypes 1 and 3. Furthermore, purifying selection was the dominant evolutionary pressure acting on the genomes of CanineCV. These results expand the knowledge about the genetic diversity of CanineCV circulating in China, and also promote us to better understand the evolution of CanineCV.

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.

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Canine vaccination is the main tool for preventing dangerous and widespread diseases. The strongly recommended (core) dog vaccines are against Canine Parvovirus type 2 (CPV-2), Canine Distemper Virus (CDV), and Canine Adenovirus (CAdV-1), but vaccination protocols should be tailored to dog lifestyles. Vaccination guidelines suggest vaccinating adult dogs no more frequently than every 3 years using modified live (attenuated) vaccines (MLV), thus obtaining a long-lasting (sometimes throughout life) specific protection in many but not all animals. The aim of this study was to determine the actual levels of seroprotection against CPV-2, CDV and CAdV-1 in a cohort of Italian dogs by using the in-practice test VacciCheck. A total of 1,027 dogs (951 vaccinated and 76 unvaccinated) were analyzed for Protective Antibody Titers (PATs) against CPV-2, CDV, and CAdV-1. Differences related to sex, age, breed size, health status, and time elapsed since last vaccination were evaluated. Half of the entire canine cohort (50.6%) had PATs for all three viruses (68.5% considering only vaccinated dogs). In particular, 90.8% of dogs were protected against CPV-2, 68.6% against CDV, and 79.8% against CAdV-1. Most dogs remained protected for 3 years after vaccination or longer. Revaccination on a 3-year basis can then be recommended for core MLV vaccines without altering individual's seroprotection or even herd immunity.

Coinfection with canine distemper virus and canine circovirus in a dog in Brazil

Canine distemper virus (CDV) and canine circovirus (CanineCV) have been described worldwide in multi-systemic disease in dogs. Both agents may be occasionally associated with other viral pathogens, but reports of coinfection by CDV and CanineCV associated with disease are rare. In this article, we report a coinfection between CDV and CanineCV detected during an investigation of viral agents involved in multisystemic disease in dogs in Southern Brazil. Molecular testing by PCR in lungs and intestines of 77 dogs necropsied in pathology services (2015-2020) revealed several single and mixed viral infections, including a CDV/CanineCV coinfection. In the case reported here, gross and histological findings were compatible with CDV pathology (bronchointerstitial pneumonia and viral intracytoplasmatic inclusions in pneumocytes and transitional epithelial cells of urinary bladder). CanineCV DNA and CDV antigens were detected in lung and intestine fragments by PCR and immunohistochemistry, respectively. CanineCV PCR amplicons subjected to nucleotide sequencing showed > 98.6% nucleotide identity with CanineCV sequences from GenBank. Although the role of CanineCV in the pathogenesis of the reported case could not be determined, our results show that CanineCV may be associated with other viral infections in cases of multisystemic disease in dogs. These results reinforce the circulation of CanineCV in dogs in Brazil and highlight the importance of including this virus in the list of differential diagnoses of respiratory and gastroenteric infectious diseases in dogs.

Concomitant Infections With Canine Parvovirus Type 2 and Intracellular Tick-Borne Pathogens in Two Puppy Dogs

In this report the concomitant infection with canine parvovirus type 2 (CPV-2), Hepatozoon canis and Ehrlichia canis in two puppy dogs from Southern Italy is described. Dogs were referred to a veterinary university hospital for the acute onset of lethargy and gastrointestinal signs. A complete clinical and clinicopathological evaluation was carried out and the multiple infection was confirmed by microscopic detection of inclusion bodies in peripheral blood smear, rapid immunoenzymatic tests, indirect fluorescent antibody tests, and molecular assays. Sequence analysis revealed that the CPV-2 identified belonged to the 2c variant and had amino acid residues in the predicted VP2 protein typical of “Asian-like” strains widespread in Asia and occasionally reported in Romania, Nigeria and Italy, particularly in the region of Sicily. Numerous monocytes were infected by both H. canis gamonts and E. canis morulae, suggesting that this co-infection is not accidental and that E. canis preferably infects those cells parasitized by H. canis. The clinical presentation of these animals was severe but supportive cares associated with early etiological therapy allowed a good prognosis. Movement of puppies from geographic areas where vector-borne pathogens are endemic must be carefully evaluated and core vaccinations and ectoparasite prevention treatments must be rigorously adopted.

Canine Adenovirus 1 Isolation Bioinformatics Analysis of the Fiber

Canine adenovirus type 1 (CAdV-1) is a double-stranded DNA virus, which is the causative agent of fox encephalitis. The Fiber protein is one of the structural proteins in CAdV-1, which mediates virion binding to the coxsackievirus and adenovirus receptor on host cells. The suspected virus was cultured in the MDCK cells, and it was determined through the cytopathic effects, sequencing and electron microscopy. The informatics analysis of the Fiber was done using online bioinformatics servers. The CAdV-1-JL2021 strain was isolated successfully, and were most similar to the CAdV-1 strain circulating in Italy. The occurrence of negative selection and recombination were found in the CAdV-1-JL2021 and CAdV-2-AC_000020.1. Host cell membrane was its subcellular localization. The CAdV-1-JL2021 Fiber (ON164651) had 6 glycosylation sites and 107 phosphorylation sites, exerted adhesion receptor-mediated virion attachment to host cell, which was the same as CAdV-2-AC_000020.1 Fiber. The Fiber tertiary structure of the CAdV-1-JL2021 and CAdV-2-AC_000020.1 was different, but they had the same coxsackievirus and adenovirus receptor. “VATTSPTLTFAYPLIKNNNH” were predicted to be the potential CAdV-1 B cell linear epitope. The MHC-I binding peptide “KLGVKPTTY” were both presented in the CAdV-1-JL2021 and CAdV-2-AC_000020.1 Fiber and it is useful to design the canine adenovirus vaccine.