Canine parvovirology - A brief updated review on structural biology, occurrence, pathogenesis, clinical diagnosis, treatment and prevention

Structures and functions of the limited natural polyclonal antibody response to parvovirus infection

Host antibody responses are key components in the protection of animals against pathogens, yet the defining properties of viral antigens and induction of B cell responses that result in varied protection are still poorly understood. Parvoviruses are simple molecular structures that display 60 repeated motifs on their capsid surface, and rapidly induce strong antibody responses that protect animals from infection. We recently showed that following canine parvovirus infection of its natural host, the polyclonal response in the sera contained only two or three dominant antibodies that bound two epitopes on the capsid. Here, we characterize key antibodies present in that immune response, identifying their sequences, defining their binding properties on the capsid by cryoelectron microscopic (cryoEM) analysis, and testing their effects on viral infectivity. Two antibodies sharing the same heavy chain bound to the side of the capsid threefold spike (B-site), while another distinct antibody bound close to the threefold axis (A-site). The epitopes of these antibodies overlapped the binding site of the host receptor, the transferrin receptor type-1, but to varying degrees. The antibodies varied widely in their neutralization efficiencies as either immunoglobulins (IgGs) or monomeric antigen-binding fragments (Fabs), which was consistent with their ability to compete for the receptor. The monoclonal antibodies characterized here matched the structures from the cryoEM analysis of polyclonal sera, including those present in a different dog than the monoclonal source. This shows that after infection, a focused response to the viral antigen is produced that protects against infection.

Identification of Host-Protein Interaction Network of Canine Parvovirus Capsid Protein VP2 in F81 Cells

Canine Parvovirus (CPV) is a highly contagious virus that causes severe hemorrhagic enteritis and myocarditis, posing a major threat to the life and health of dogs. The molecular mechanism by which VP2, the major capsid protein of CPV, infects host cells and utilizes host cell proteins for self-replication remains poorly understood. In this study, 140 host proteins specifically binding to CPV VP2 protein were identified by immunoprecipitation combined with liquid chromatography-mass spectrometry (LC-MS/MS). Subsequently, the protein Interaction Network (PPI), the annotation of gene ontology (GO) and the database of Kyoto Encyclopedia of Genes and Genomes (KEGG) were constructed for in-depth analysis. The results showed that CPV VP2 protein participated mainly in cell metabolism, cell biosynthesis, protein folding and various signal transduction processes. According to the results of proteomics analysis, we randomly selected seven proteins for co-immunoprecipitation verification, and the experimental results were consistent with the LC-MS/MS data. In addition, our study found that the expression level of the VP2-interacting protein FHL2 mediated CPV replication. Preliminary studies have shown that knockdown of FHL2 promotes CPV replication by decreasing the expression of interferon β (IFN-β) and interferon-stimulated genes (ISGs), while overexpression of FHL2 can inhibit the replication of CPV by up-regulating the expression of IFN-β and related ISGs. This study lays the foundation for elucidating the potential function of CPV VP2 protein in the process of viral infection and proliferation which provides a theoretical basis for the design of antiviral agents and vaccines.

Overview of Recent Advances in Canine Parvovirus Research: Current Status and Future Perspectives

Canine parvovirus (CPV-2) was first identified in the late 1970s and has since become one of the most significant infectious agents affecting dogs. CPV-2 causes severe diseases such as hemorrhagic gastroenteritis and myocarditis, posing a major threat to canine health, particularly with a high mortality rate in puppies. It is globally recognized as a highly contagious and lethal pathogen. CPV is prone to rapid mutation, leading to the emergence of new variants. Despite widespread vaccination efforts, CPV remains one of the primary causes of acute gastroenteritis and death in young and juvenile dogs. Furthermore, the detection of CPV in swine populations has introduced additional challenges to its control. This review summarizes the current epidemiological status of CPV, highlighting recent advancements in diagnostic techniques and vaccine development. Additionally, it discusses the latest research on the pathogenesis of the virus and the development of antiviral agent research and proposes prevention and control suggestions for CPV under the One Health concept. In particular, there is a need to enhance surveillance of viral dynamics, accelerate the development of novel vaccines, and deepen the exploration of the underlying pathogenic mechanisms. This review aims to provide a scientific foundation for effective control of CPV and to guide future research directions.

The first evidence of Asian-like CPV-2b in Slovakia in a vaccinated dog with an acute fatal course of parvovirus infection: a case report

This study provides a comprehensive description of the clinical course of a fatal parvovirus infection in a vaccinated dachshund puppy, along with the first identification of a new CPV-2 variant in Slovakia, elucidated through molecular amino acid analysis of the VP2 gene. The dog exhibited clinical signs such as apathy, vomiting, and bloody diarrhea. After confirming CPV-2 infection with a commercial snap test, intensive therapy was initiated. The dog succumbed within 48 h of admission. A rectal swab sample was collected, CPV-2 was examined using the PCR method, and sequenced. The virus detected in the patient was related to strains of CPV-2c of Asian origin and unrelated to European CPV-2b strains. The sequence had genetic signatures typical of Asian strains (VP2: 5Gly, 267Tyr, 324Ile, 370Arg, and 440Thr). Phylogenetic analysis classified this strain as similar to Asian strains of CPV-2c. It is believed to be derived from an Asian strain similar to CPV-2c that acquired the 426Asp mutation. With this finding, we present the first evidence of an Asian-like CPV-2b strain in the territory of Slovakia.

Prevalence and significance of a canine bocavirus-2 outbreak in a cohort of military dogs in Austria

Introduction

Bocaviruses are single-stranded DNA viruses from the Parvoviridae family, which have been minimally discussed in veterinary literature and are considered potentially pathogenic. Due to the recurring illness among young dogs in a closed cohort of military dogs in Austria, we assessed the prevalence, possible disease manifestation and outcome of CBoV-2 infection in this cohort.

Materials and methods

This led to a comprehensive study that not only analyzed past cases but also performed prospective screening PCR tests to identify CBoV-2 positive dogs within this specific dog population. Pharyngeal and rectal swabs were taken. In addition, a control group (n = 20) of clinically healthy client-owned dogs was sampled. A total of 190 samples were taken and tested for the presence of CBoV-2 specific nucleic acid using screening PCR. In addition to the primers used for routine diagnostics, two other primer pairs were used to verify questionable results. The retrospective part of the study includes a total of 13 military dogs that had previously shown suspected clinical signs.

Results

At the time of the first examination within the prospective part of the study, CBoV-2 was detected in 31% (12/39) of the dogs. During the second examination, 2% (1/47) tested positive, while all PCR testing in the control group (n = 20) was negative in all cases. The retrospective evaluation of the 13 cases revealed a total of six animals tested positive for CBoV-2 via screening PCR. All puppies suffered from skin lesions (papules, vesicles, or pustules). Other clinical signs included diarrhea (83%), vomiting (77%), respiratory (15%), and neurological (8%) signs.

Discussion

According to the study there are certain indications that CBoV-2 shares similarities with CPV-2 infection but also exhibits critical differences, making their differentiation essential for patient management, outcomes, and prevention strategies.

Identification of a Novel Parvovirus in the Arctic Wolf (Canis lupus arctos)

A novel virus, temporarily named "Arctic wolf parvovirus" (AWPV), was discovered in a pharyngeal metagenomic library derived from an Arctic wolf (Canis lupus arctos) in China. The genome sequence was assigned GenBase accession number C_AA071902.1. AWPV has a genome comprised of 4,920 base pairs with a nucleotide composition of 36.4% A, 23.4% T, 18.2% G, and 22.0% C, with a GC content of 40.2%. Its structure resembles parvoviruses, containing two open reading frames: the nonstructural (NS) region encoding replication enzymes and the structural (VP) region encoding capsid protein. Pairwise sequence comparison and phylogenetic analysis suggest AWPV may represent a novel species within the genus Protoparvovirus. This discovery enhances our understanding of mammalian virus ecology and potential future infectious diseases.

Sensitivity of lateral flow technique for diagnosis of canine parvovirus

In this study, we devised a nanogold lateral flow immunoassay (LFA-CPV antigen test) for detecting canine parvovirus (CPV) in living attenuated CPV vaccines. We conducted instrumental characterization of the prepared nanogold particles and the developed LFA-CPV antigen test was rigorously evaluated for its performance verification including limit of detection, sensitivity, specificity, selectivity and accuracy. The LFA-CPV antigen test demonstrated strong performance when assessed against qPCR using different batches of live attenuated CPV vaccines, indicated a sensitivity of 96.4%, specificity of 88.2%, and an overall accuracy of 95%. These results suggest that the developed LFA-CPV antigen test could serve as a viable alternative for evaluation live attenuated CPV vaccines, and provide it as a point of care test for CPV diagnosis, offering a potential substitute for traditional laboratory methods, particularly qPCR.

Chaperonin TRiC/CCT subunit CCT7 is involved in the replication of canine parvovirus in F81 cells

Canine parvovirus (CPV) is one of the most common lethal viruses in canines. The virus disease is prevalent throughout the year, with high morbidity and mortality rate, causing serious harm to dogs and the dog industry. Previously, yeast two hybrid method was used to screen the protein chaperonin containing TCP-1 (CCT7) that interacts with VP2. However, the mechanism of interactions between CCT7 and VP2 on CPV replication remains unclear. In this study, we first verified the interaction between CCT7 and viral VP2 proteins using yeast one-to-one experiment and co-immunoprecipitation (CoIP) experiment. Laser confocal microscopy observation showed that CCT7 and VP2 were able to co-localize and were mostly localized in the cytoplasm. In addition, the study of VP2 truncated mutant found that the interaction region of VP2 with CCT7 was located between amino acids 231 and 320. Cycloheximide (CHX) chase experiments showed that CCT7 can improve the stability of VP2 protein. After further regulation of CCT7 expression in F81 cells, it was found that the expression level of VP2 protein was significantly reduced after knocking down CCT7 expression by RNA interference (RNAi) or HSF1A inhibitor, and increased after overexpressing host CCT7. The study reveals the role of VP2 interacting protein CCT7 in the replication process of CPV, which could provide a potential target for the prevention and control of CPV.

Molecular Characterization of Canine Parvovirus Variants CPV-2a and CPV-2c, Associated with Vaccinated Dogs at Libreville, Gabon

The first detection of canine parvovirus type-2 (CPV-2) was in the early 1970s, when it was known to cause severe gastroenteritis in dogs. However, it has evolved over the years into CPV-2a within 2 years, into CPV-2b after 14 years, into CPV-2c after 16 years and more recently CPV-2a-, 2b- and 2c-like variants reported in 2019, with a global distribution. Reports on the molecular epidemiology of this virus are missing in most African countries. The report of clinical cases among vaccinated dogs in Libreville in Gabon triggered the execution of this study. The objective of this study was to characterize circulating variants from dogs showing clinical signs suggestive of CPV that were examined by a veterinarian. A total of eight (8) fecal swab samples were collected, and all had positive PCR results. Sequencing, Blast analysis and assembly of two whole genomes and eight partial VP2 sequences were performed, and the sequences submitted to GenBank. Genetic characterization revealed the presence of CPV-2a and CPV-2c variants with predominance of the former. Phylogenetically, the Gabonese CPVs formed distinct groups similar to Zambian CPV-2c and Australian CPV-2a sequences. The antigenic variants CPV-2a and CPV-2c have not yet been reported in Central Africa. However, these CPV-2 variants circulate in young, vaccinated dogs in Gabon. These results suggest additional epidemiological and genomic studies are required in order to evaluate the occurrence of different CPV variants in Gabon and effectiveness of the commercial vaccines used against protoparvovirus in the country.

First isolation and molecular characterization of canine parvovirus-type 2b (CPV-2b) from red foxes (Vulpes vulpes) living in the wild habitat of Turkey

BACKGROUND

The canine parvovirus, with its many variants, is responsible for a pivotal and common viral infection affecting millions of dogs and other carnivore species worldwide, particularly the wild ones, which are considered as the main reservoir hosts. To that end, this study investigated the presence of canine parvovirus (CPV) in red foxes (Vulpes vulpes) living in wild habitats of several regions of Turkey.

METHODS

We randomly collected 630 archival fox stool specimens from rural areas of 22 provinces and used real-time PCR to detect CPV.

RESULTS

Two of the 630 (0.3%) stool samples were positive for CPV-DNA, named Tr-Fox/128(Aydın) and Tr-Fox/159(Manisa). We attempted to isolate the virus in a MDCK cell line, and cytopathic effects were observed four days post-inoculation. Three regions corresponding to the CPV capsid protein VP2 gene from extracted DNA of positive samples were amplified by conventional PCR, and the products were visualised, purified, and Sanger sequenced. Three overlapping DNA raw sequence fragments, were read, assembled, and aligned to obtain approximately 1.5 kb-long regions that cover most of the VP2 gene, then deposited in GenBank. After comparing the isolates with parvovirus sequences data of domestic and wild carnivores by BLAST processing, our isolates' similarity rate with each other was 99.40%, with base differences in 9 nucleotide positions. They were classified as 2b variant closely related to isolates from dogs in Turkey, Egypt, Iraq, Italy, Thailand, and China.

CONCLUSION

This study presents evidence of interspecies transmission of CPV, of which there are no reports on prevalence in wildlife carnivores of our country. Identification of CPV in red foxes threatens local and hunting dogs, which may contract the infection or disseminate it to other wild animal species or vice-versa.

Detection at high prevalence of newlavirus (protoparvovirus) in the carcasses of red foxes

Wildlife conservation also relies on the study of animal virome. We identified the DNA of a novel fox protoparvovirus, newlavirus, with high (71%) prevalence in the carcasses of red foxes. On genome sequencing, high genetic diversity and possible recombination was observed, suggesting complex evolutionary dynamics in wildlife.

Comparative analysis reveals the long-term coevolutionary history of parvoviruses and vertebrates

Parvoviruses (family Parvoviridae) are small DNA viruses that cause numerous diseases of medical, veterinary, and agricultural significance and have important applications in gene and anticancer therapy. DNA sequences derived from ancient parvoviruses are common in animal genomes and analysis of these endogenous parvoviral elements (EPVs) has demonstrated that the family, which includes twelve vertebrate-specific genera, arose in the distant evolutionary past. So far, however, such "paleovirological" analysis has only provided glimpses into the biology of ancient parvoviruses and their long-term evolutionary interactions with hosts. Here, we comprehensively map EPV diversity in 752 published vertebrate genomes, revealing defining aspects of ecology and evolution within individual parvovirus genera. We identify 364 distinct EPV sequences and show these represent approximately 200 unique germline incorporation events, involving at least five distinct parvovirus genera, which took place at points throughout the Cenozoic Era. We use the spatiotemporal and host range calibrations provided by these sequences to infer defining aspects of long-term evolution within individual parvovirus genera, including mammalian vicariance for genus Protoparvovirus, and interclass transmission for genus Dependoparvovirus. Moreover, our findings support a model of virus evolution in which the long-term cocirculation of multiple parvovirus genera in vertebrates reflects the adaptation of each viral genus to fill a distinct ecological niche. Our findings show that efforts to develop parvoviruses as therapeutic tools can be approached from a rational foundation based on comparative evolutionary analysis. To support this, we published our data in the form of an open, extensible, and cross-platform database designed to facilitate the wider utilisation of evolution-related domain knowledge in parvovirus research.

Unusual "Asian-origin" 2c to 2b point mutant canine parvovirus (Parvoviridae) and canine astrovirus (Astroviridae) co-infection detected in vaccinated dogs with an outbreak of severe haemorrhagic gastroenteritis with high mortality rate in Hungary

In this study, the aetiological background of an outbreak of severe haemorrhagic gastroenteritis (HGE) in a colony of purebred Jack Russell Terriers vaccinated against CPV-2 in Hungary was investigated. Canine parvovirus 2 (CPV-2, Parvoviridae) and canine astrovirus (CaAstV, Astroviridae) co-infection was identified by viral metagenomics and next-generation sequencing (VM-NGS) methods from a rectal swab of an affected 7-week-old puppy. The complete coding sequence of CPV-2 strain FR1/CPV2-2021-HUN (ON733252) and the complete genome of CaAstV strain FR1/CaAstV-2021-HUN (ON733251) were determined by VM-NGS and PCR methods. Results of sequence and phylogenetic analyses showed that CPV-2 strain FR1/CPV2-2021-HUN was different from the applied vaccine strains and previously identified strains from Hungary but showed high sequence identity (> 99.8%) and close phylogenetic relationship to recently described “Asian-origin” CPV-2c strains from Italy. But, based on the single amino acid difference on position 426 of VP2 (Glu/Asp) between the study strain and the closest relatives, FR1/CPV2-2021-HUN belonged to the 2b antigenic type rather than 2c. The CaAstV strain FR1/CaAstV-2021-HUN showed close relationship with a CaAstV strain identified previously from a diarrhoeic dog in Hungary. Both viruses were continuously detectable by PCR in additional enteric samples, and the CPV-2 could also be detected in several (n = 32) tissue samples from 9 affected deceased puppies. Further comparative studies are necessary to confirm the role of the point mutation causing the change in the antigenic type of this “Asian-origin” CPV-2 and/or the role of CaAstV co-infection in the development and/or severity of (haemorrhagic) gastroenteritis among dogs vaccinated against CPV-2.

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 parvovirus-2: An Emerging Threat to Young Pets

Canine parvovirus-2 (CPV-2) is a highly contagious and key enteropathogen affecting the canine population around the globe by causing canine parvoviral enteritis (CPVE) and vomition. CPVE is one of the the leading causes of morbidity and mortality in puppies and young dogs. Over the years, five distinct antigenic variants of CPV-2, namely CPV-2a, CPV-2b, new CPV-2a, new CPV-2b, and CPV-2c, have emerged throughout the world. CPV-2 infects a diverse range of wild animals, and the newer variants of CPV-2 have expanded their host range to include felines. Despite the availability of highly specific diagnostics and efficacious vaccines, CPV-2 outbreaks have been reported globally due to the emergence of newer antigenic variants, expansion of the viral host range, and vaccination failures. The present chapter describes the latest information pertaining to virus properties and replication, disease manifestations in animals, and an additional recent updates on diagnostic, prevention and control strategies of CPV-2.