First detection and full genomic analysis of Canine Circovirus in CPV-2 infected dogs in Colombia, South America

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.

Characterization, Quantification, and Molecular Identification of Co-Infection of Canine Parvovirus (CPV-2) Variants in Dogs Affected by Gastroenteritis in Ecuador During 2022-2023

Canine parvovirus (CPV-2) is a highly contagious virus in canines, and it is mostly spread by touching infected feces. Dogs of all ages can catch it, but puppies are more likely to suffer from it. Severe signs include vomiting, diarrhea with blood, feeling tired, and not drinking enough water. There are three different types of the original CPV-2 that have been found so far, which are CPV-2a, 2b, and 2c. The genome of CPV-2 is about 5.2 kb long and has two open reading frames (ORFs), namely the VP region and the NS region. Based on changes in amino acids at position 426, the VP2 protein distinguishes the gene apart in the VP region. Using a molecular method, this study contemplated the presence of CPV-2 and its variants in dogs that had gastroenteritis, as well as other infections. There were 511 samples tested, and 401 (78.47%) of them were positive for CPV-2. Of these, 144 (25.91%) were positive for the original genotype, 258 (64.34%) for genotype 2a, 343 (85.54%) for genotype 2b, and 167 (41.65%) for genotype 2c. Using the multiplex qPCR for genotyping, CPV-2a and CPV-2b were determined as the most frequent co-infections (16.45%). The three genotypes (2a, 2b, and 2c) were found in the samples examined based on the amino acids at position 426 of the VP2 protein, as demonstrated by the VP2 gene sequencing. Furthermore, it was discovered that in certain samples, a genetic modification at position 297 was connected to the virus's pathogenicity.

Epidemiological and evolutionary analysis of canine circovirus from 1996 to 2023

BACKGROUND

Canine circovirus (CanineCV), a non-enveloped virus with a circular DNA genome, has been identified in various avian and mammalian species, including domestic and wild canids. This study aimed to comprehensively analyze the prevalence of CanineCV across diverse animal species in 11 provinces of China.

RESULTS

A total of 1,666 serum samples were collected, revealing a 5.82% prevalence of CanineCV in dogs, with the highest rates being observed in southern and eastern China. Phylogenetic analysis of 266 global CanineCV genomes sourced from the NCBI identified six distinct genotypes, elucidating the complex dynamics of their evolution. Evidence suggested a potential bat origin for CanineCV, with positive selection and high rates of evolution being observed. Recombination analysis revealed dynamic genetic exchange, highlighting the intricate nature of CanineCV evolution. Mutational analysis identified key amino acid substitutions likely to influence the virus's adaptation. Additionally, glycosylation, palmitoylation, and SUMOylation sites were predicted, shedding light on crucial functional properties of the virus.

CONCLUSIONS

This study provides a global perspective on the origin, genetic diversity, and evolutionary dynamics of CanineCV. Understanding these factors is crucial for elucidating its epidemiology and potential health risks.

Molecular characterization of canine circovirus based on the Capsid gene in Thailand

BACKGROUND

Canine circovirus (CanineCV) is a single-stranded circular DNA virus that infects domestic and wild canids in many countries. CanineCV is associated with gastroenteritis and diarrhea, respiratory disease, and generalized vasculitis leading to a fatal event. The Capsid protein (Cap) is a structural protein of the virus which has high genetic variability and plays a role in the canine immune response. In this study, we cloned the full-length CanineCV Capsid gene (Cap). In-silico analyses were used to explore the genomic and amino acid variability and natural selection acting on the Cap gene. The immune relevance for T-cell and B-cell epitopes was predicted by the immunoinformatic approach.

RESULTS

According to the Cap gene, our results showed that CanineCV was separated into five phylogenetic groups. The obtained CanineCV strain from this study was grouped with the previously discovered Thai strain (MG737385), as supported by a haplotype network. Entropy analyses revealed high nucleotide and amino acid variability of the Capsid region. Selection pressure analysis revealed four codons at positions 24, 50, 103, and 111 in the Cap protein evolved under diversifying selection. Prediction of B-cell epitopes exhibited four consensus sequences based on physiochemical properties, and eleven peptide sequences were predicted as T-cell epitopes. In addition, the positive selection sites were located within T-cell and B-cell epitopes, suggesting the role of the host immune system as a driving force in virus evolution.

CONCLUSIONS

Our study provides knowledge of CanineCV genetic diversity, virus evolution, and potential epitopes for host cell immune response.

Identification and characterization of a novel canine circovirus with truncated replicate protein in Sichuan, China

Canine circovirus (CanineCV) is a recently identified member of the Circoviridae family. Since its discovery in 2011, CanineCV has been detected in different countries worldwide, infecting both domestic and wild canids. The virus is potentially associated with gastrointestinal and respiratory illnesses. In 2016, CanineCV was reported in the southwestern region of Guangxi, China. However, its prevalence in other provinces in the Southwest region remained unknown. This study collected a total of 208 serum samples from domestic dogs in Sichuan, China in 2022 to investigate the prevalence of CanineCV. Among these samples, 26 tested positive for CanineCV, resulting in a positivity rate of 12.5%. Additionally, 12 strains were sequenced, 9 of which had a sequence length of 2,063 nucleotides (nt), 2 of the other threes had a length of 2,062 nts and another was 2,064 nt. Notably, a frameshift mutation was identified, resulting in a truncated ORF1 and the occurrence of a novel sequence comprised of 13 amino acids at the end of the replicate protein (Rep). This mutation could affect the replication cycle of the virus. Phylogenetic and evolutionary analyses revealed that the isolates belonged to the CanineCV-3 genotype and were prevalent in the Southeast and the Southwest regions of China, as well as in the neighboring countries alongside other strains of the same genotype. Collectively, this epidemiological investigation widens our understanding of the genetic diversity of CanineCV in Southwest China and provides insights into viral evolution.

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.

Canine circovirus genomic characterization in dogs with and without diarrheal syndrome in Medellín, Colombia

Canine circovirus (CanineCV) is an emerging agent described for the first time in 2011, it infects domestic and wild canids, mainly associated with gastrointestinal signs; however, it has also been reported in samples obtained from animals without clinical signs, so its pathogenesis and epidemiology are still poorly understood. In Colombia, the CanineCV was first reported in 2020 from CPV-2 positive dogs. In the present work, CanineCV was detected in 30% of fecal samples obtained from dogs with or without diarrhea, in the city of Medellín, Colombia. No coinfection with CPV-2 was found. The highest number of positive samples was found in the subgroup of animals with diarrhea. Phylogenetic and evolutionary analyses confirmed the separation of the CanineCV genomes into five different clades with a European origin of the Colombian viruses and at least two different introductions of the CanineCV into the country. Our results highlight the importance of the CanineCV in Colombian dog populations and the need for continue surveillance of emerging pathogens in canine populations.

Molecular epidemiology of Canine circovirus in domestic dogs and wildlife in Namibia, Africa

Canine circovirus (CanineCV) is a DNA virus affecting domestic dogs and other wild carnivore species. Despite the potential implications for dogs' health and wildlife conservation, data on CanineCV presence, epidemiology and genetic features from Africa is still poor. In the present study, biological specimens collected between 2020 and 2022 from a total of 32 jackals and 575 domestic dogs were tested for the presence of CanineCV DNA to evaluate its frequency. Furthermore, sequencing was conducted on positive samples to characterize the strains and compare them with publicly available sequences through phylogenetic analysis. A high CanineCV prevalence was observed both in jackals (43.75%; 95 CI: 28.17% - 60.67%) and domestic dogs (27.13%; 95 CI: 23.66% - 30.91%). All aside from one Namibian strain formed an independent clade, suggestive of extremely rare introduction events, followed by local persistence, circulation, and evolution. Remarkably, different recombination events were observed involving strains from both jackals and domestic dogs, which testify to the likely strain exchange between these populations. Distinctive amino acid residues were also observed in jackals. The limitations of the considered host populations however prevent a definitive conclusion on host adaptation, biological, and clinical features. Further studies should be performed to expand our current knowledge of the CanineCV disease scenario in Namibia, other African regions, and associated host species in Africa.

Detection of Selected Canine Viruses in Nigerian Free-Ranging Dogs Traded for Meat Consumption

Animal trade favors the spreading of emerging and re-emerging pathogens. Concerns have been previously expressed regarding the risks of dog trade in spreading zoonotic pathogens in Nigeria. However, the role of these dogs in disseminating highly pathogenic canine viruses has not yet been explored. The present study aimed to identify selected canine viruses in dogs traded for meat consumption in Nigeria. A total of 100 blood samples were screened for carnivore protoparvovirus-1 (CPPV-1), canine adenovirus 1/2 (CAdV-1/2), canine circovirus (CaCV), and canine distemper virus (CDV) by using real-time PCR and conventional PCR and/or sequencing. CPPV-1 DNA was identified in 83% of canine samples while CaCV DNA and CDV RNA were detected in 14% and 17% of the dog samples, respectively. None of the dogs tested positive for CAdV-1/2. The CaCVs identified in this study clustered along with other European, Asian, and American strains. Moreover, CDV strains identified in Nigeria clustered in a separate lineage with the closest genetic relatedness to the Europe-South America-1 clade. Further surveys prior to and after arrival of dogs at the slaughtering points are required to clarify the real virus burden in these animals.

Canine circovirus: An emerging or an endemic undiagnosed enteritis virus?

Canine Circovirus (CanineCV) belongs to the family Circoviridae. It is an emerging virus described for the first time in 2011; since then, it has been detected in different countries and can be defined as worldwide distribution virus. CanineCV infects domestic and wild canids and is mainly related to hemorrhagic enteritis in canines. However, it has been identified in fecal samples from apparently healthy animals, where in most cases it is found in coinfection with other viral agents such as the canine parvovirus type-2 (CPV). The estimated prevalence/frequency of CanineCV has been variable in the populations and countries where it has been evaluated, reaching from 1 to 30%, and there are still many concepts to define the epidemiological characteristics of the virus. The molecular characterization and phylo-evolutive analyses that allow to postulate the wild origin and intercontinental distribution of the virus. This review focuses on the importance on continuing research and establish surveillance systems for this emerging virus.

Epidemiology, genetic diversity, and association of canine circovirus infection in dogs with respiratory disease

Although canine circovirus (CanineCV)-associated with gastroenteritis has been well documented, the virus is also detectable in the respiratory discharge of dogs with respiratory disease. In this study, an epidemiological approach was used to explore the association between the presence of CanineCV and respiratory symptoms in dogs. Respiratory swabs were collected from 76 healthy dogs and 114 dogs with respiratory illness and tested for CanineCV using conventional PCR (cPCR). Furthermore, lung tissues collected from 15 necropsied dogs showing pneumonia were tested using the real-time PCR (qPCR) and in situ hybridization (ISH) technique. A total of 8.95% (17/190) of dogs were CanineCV positive, with a significant association (p = 0.013) in dogs with respiratory signs. Four necropsied dogs were qPCR positive with the CanineCV-DNA labeling localized in tracheobronchial lymphoid cells (3/4), pulmonary parenchyma, capillary endothelia, and mononuclear cells harboring in alveoli (2/4). Full-length genome sequences of seven CanineCV strains were analyzed, indicating that the detected CanineCV genome clustered in the CanineCV-4 genotype. Genetic recombination was also evident in the replicase (Rep) gene. Although the role of CanineCV primarily affecting lung lesions could not be determined from this study, the presence of CanineCV DNA in pulmonary-associated cells indicated the potential association of the virus with canine respiratory disease; thus, linking causality must be examined in further studies.

Detection of canine circovirus in dogs infected with canine parvovirus

Since the first detection of canine circovirus (CanineCV), several reports have been published over the last decade about the worldwide distribution of this emerging virus of dogs. In order to investigate the prevalence and genomic features of CanineCV in Iranian dogs, a total of 203 dog faecal samples was collected between February and November 2018 from five different geographical regions and screened by real-time PCR (qPCR). Thirteen dogs (6.4%) tested positive for CanineCV DNA, all being detected in co-infections with the highly virulent canine parvovirus (CPV). Three partial replicase nucleotide sequences of the detected CanineCV strains were obtained and compared with the reference sequences deposited in the GenBank database. The Iranian CanineCV sequences had a nucleotide identity of 96.4-98.2% each to other and of 88.3-98.2% with other sequences available on the GenBank. Phylogenetic analysis showed that the Iranian sequences are more closely related to Turkish strains than to strains reported from other countries. The present study provides new insights into the CanineCV molecular epidemiology and its possible role as a co-infectious pathogen.

Canine Circovirus Suppresses the Type I Interferon Response and Protein Expression but Promotes CPV-2 Replication

Canine circovirus (CanineCV) is an emerging virus in canines. Since the first strain of CanineCV was reported in 2012, CanineCV infection has shown a trend toward becoming a global epidemic. CanineCV infection often occurs with coinfection with other pathogens that may aggravate the symptoms of disease in affected dogs. Currently, CanineCV has not been successfully isolated by laboratories, resulting in a lack of clarity regarding its physicochemical properties, replication process, and pathogenic characteristics. To address this knowledge gap, the following results were obtained in this study. First, a CanineCV strain was rescued in F81 cells using infectious clone plasmids. Second, the Rep protein produced by the viral packaging rescue process was found to be associated with cytopathic effects. Additionally, the Rep protein and CanineCV inhibited the activation of the type I interferon (IFN-I) promoter, blocking subsequent expression of interferon-stimulated genes (ISGs). Furthermore, Rep was found to broadly inhibit host protein expression. We speculate that in CanineCV and canine parvovirus type 2 (CPV-2) coinfection cases, CanineCV promotes CPV-2 replication by inducing immunosuppression, which may increase the severity of clinical symptoms.

Detection and Genomic Characterization of Canine Circovirus in Iran

Simple Summary

During the last decade, canine circovirus (CaCV) has been repeatedly reported in domestic dogs with and without acute enteritis. Here we report the detection and full genome characterization of CaCV strains from non-diarrheic dogs in Iran. The results showed the circulation of the virus in this country, with Iranian strains segregating from the CaCVs detected in other countries.

Abstract

Canine circovirus (CaCV) is a single-stranded DNA virus that globally circulates in dogs and wild carnivores. Although the pathogenic potential of the virus has not been fully understood yet, CaCV has been suggested to exacerbate the clinical course of other canine viral infections but also to circulate in dogs without clinical signs. In this study, we carried out real-time PCR assays to detect enteric pathogens from 156 canine rectal swabs collected from dogs without enteritis in 3 different regions in Iran. A total of 14 samples tested positive for CaCV and full-length genome sequences were obtained from 6 of the detected strains. Sequence and phylogenetic analyses showed that, despite the distance between the different sample collection sites, all Iranian CaCV strains were closely related and formed a separate clade from extant CaCVs. The present study shows that CaCV is circulating in non-diarrheic dogs in Iran, thus highlighting the need for further epidemiological investigations in Iranian domestic and wild carnivores.

Novel Cyclovirus Species in Dogs with Hemorrhagic Gastroenteritis

Nested PCRs with circovirus/cyclovirus pan-rep (replicase gene) primers detected eukaryotic circular Rep-encoding single-stranded DNA (CRESS DNA) viruses in three (samples CN9E, CN16E and CN34) of 18 canine parvovirus-2-positive fecal samples from household dogs with hemorrhagic gastroenteritis on the Caribbean island of Nevis. The complete genomes of CRESS DNA virus CN9E, CN16E and CN34 were determined by inverse nested PCRs. Based on (i) genome organization, (ii) location of the putative origin of replication, (iii) pairwise genome-wide sequence identities, (iv) the presence of conserved motifs in the putative replication-associated protein (Rep) and the arginine-rich region in the amino terminus of the putative capsid protein (Cp) and (v) a phylogenetic analysis, CN9E, CN16E and CN34 were classified as cycloviruses. Canine-associated cycloviruses CN16E and CN34 were closely related to each other and shared low genome-wide nucleotide (59.642–59.704%), deduced Rep (35.018–35.379%) and Cp (26.601%) amino acid sequence identities with CN9E. All the three canine-associated cycloviruses shared < 80% genome-wide pairwise nucleotide sequence identities with cycloviruses from other animals/environmental samples, constituting two novel species (CN9E and CN16E/34) within the genus Cyclovirus. Considering the feeding habits of dogs, we could not determine whether the cycloviruses were of dietary origin or infected the host. Interestingly, the CN9E putative Rep-encoding open reading frame was found to use the invertebrate mitochondrial genetic code with an alternative initiation codon (ATA) for translation, corroborating the hypothesis that cycloviruses are actually arthropod-infecting viruses. To our knowledge, this is the first report on the detection and complete genome analysis of cycloviruses from domestic dogs.

Detection and molecular characterization of two canine circovirus genotypes co-circulating in Vietnam

Background

Canine circovirus is reported in dogs in many countries, including the USA, China and Thailand. It has been detected in healthy dogs and dogs with diarrhea, hemorrhagic gastroenteritis, and vasculitis. It comprises five genotypes and is frequently found as a coinfection with canine parvovirus-2 (CPV-2).

Aim

To characterize canine circovirus genotypes co-circulating with CPV-2 in Vietnam.

Method

PCR assessment of 81 CPV-2-positive fecal samples from Vietnamese diarrheic dogs up to seven months of age for other viral enteric pathogens, including canine bocavirus, canine adenovirus, paramyxovirus, canine coronavirus, porcine circovirus-3 and canine circovirus. In addition, eight selected full genome sequences of Vietnamese canine circovirus were analyzed and used for phylogeny.

Results

In total 19.8% of samples were found to be positive for canine circovirus. Phylogeny revealed that the Vietnamese canine circovirus strains were clustered in two different genotypes (genotype-1 and -3). The genetic diversity among Vietnamese canine circovirus was 86.0–87.2%. The nucleotide discrepancy among both genotypes altered the deduced amino acid sequence in 14 and ten residues of the replicase and capsid proteins, respectively. Genetic recombination analysis revealed that the Vietnamese canine circovirus-6 strain has the American and Chinese canine circovirus as its major and minor parents, respectively. Only a single dog revealed triple detections of CPV-2c, Canine circovirus and canine adenovirus (1.2%).

Conclusion

The co-circulation of two different genotypes of canine circovirus and CPV-2c in dogs in Vietnam has been illustrated.

Clinical relevance

The mortality rate with CPV-2 only (22%) doubled in dogs with canine circovirus and CPV-2 co-infection.