The increasing prevalence of CPV-2c in domestic dogs in China

Molecular epidemiology of canine parvovirus type 2 in Sicily, southern Italy: A geographical island, an epidemiological continuum

Since it emerged as a major dog pathogen, canine parvovirus type 2 (CPV-2) has featured a remarkable genetic and phenotypic heterogeneity, whose biological, epidemiological, and clinical impact is still debated. The continuous monitoring of this pathogen is thus of pivotal importance. In the present study, the molecular epidemiology of CPV-2 in Sicily, southern Italy, has been updated by analysing 215 nearly complete sequences of the capsid protein VP2, obtained from rectal swabs/faeces or tissue samples collected between 2019 and 2022 from 346 dogs with suspected infectious gastrointestinal disease. The presence of the original CPV-2 type (4%) and CPV-2a (9%), CPV-2b (18%), or CPV-2c (69%) variants was documented. Over the years, we observed a decrease in the frequency of CPV-2a/-2b and a rapid increase of CPV-2c frequency, with a progressive replacement of the European lineage of CPV-2c by the Asian lineage. The observed scenario, besides confirming epidemiological relevance of CPV-2, highlights the occurrence of antigenic variant shifts over time, with a trend toward the replacement of CPV-2a, CPV-2b, and the European lineage of CPV-2c by the emerging Asian CPV-2c lineage. The comparison with other Italian and international sequences suggests the occurrence of viral exchange with other Italian regions and different countries, although the directionality of such viral flows could not be often established with confidence. In several instances, potential CPV-2 introductions led to epidemiological dead ends. However, major, long-lasting clades were also identified, supporting successful infection establishment, local spreading, and evolution. These results, besides demonstrating the need for implementing more effective control measures to prevent viral introductions and minimize circulation, stress the relevance of routine monitoring activities as the only tool to effectively understand CPV-2 epidemiology and evolution, and develop adequate countermeasures.

Transcriptional Differential Analysis of Nitazoxanide-Mediated Anticanine Parvovirus Effect in F81 Cells

Canine parvovirus (CPV) is a single-stranded DNA virus that can cause typical hemorrhagic enteritis, and it is one of the common canine lethal viruses. In previous studies, we screened the Food and Drug Administration (FDA)'s drug library and identified nitazoxanide (NTZ), which has anti-CPV capabilities. To investigate the potential antiviral mechanisms, we first reconfirmed the inhibitory effect of NTZ on the CPV by inoculating with different doses and treating for different lengths of time. Then, the differences in the transcription levels between the 0.1%-DMSO-treated virus group and the NTZ-treated virus group were detected using RNA-seq, and a total of 758 differential expression genes (DEGs) were finally identified. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs revealed that these genes are involved in a variety of biological processes and/or signaling pathways, such as cell cycle, mitosis and cell proliferation and differentiation. A protein-protein interaction (PPI) analysis further identified hub genes associated with cell cycle and division among the DEGs. In addition, the expression levels of some of the enriched genes were detected, which were consistent with the high-throughput sequencing results. Moreover, when the cell cycle was regulated with cell cycle checkpoint kinase 1 (Chk1) inhibitor MK-8776 or Prexasertib HCl, both inhibitors inhibited the CPV. In summary, the transcriptome differential analysis results presented in this paper lay the foundation for further research on the molecular mechanism and potential targets of NTZ anti-CPV.

Investigation of circulating infectious agents in experimental Beagle dogs of a production colony and three research facilities in China from June 2021 to May 2022

To understand the epizootiologic characteristics of pathogens and opportunistic infections in one Beagle dog production colony and three research facilities, viruses and mycoplasma were detected in 1777 samples collected from Beagle dogs in China by polymerase chain reaction/reverse transcription polymerase chain reaction, and bacteria were isolated and identified by 16S rRNA sequence analysis. In addition, genotyping of the major circulating viruses was carried out by amplification of gene fragments and homology analysis. Canine coronavirus (CCoV), Escherichia coli, canine parvovirus (CPV), Bordetella bronchiseptica, Clostridium perfringens, Mycoplasma cynos, Klebsiella pneumoniae, Streptococcus canis, canine astrovirus (CaAstV), canine kobuvirus (CaKV), Pseudomonas aeruginosa, Proteus mirabilis, Macrococcus canis, Pasteurella canis, canine bocavirus (CBoV) and canine adenovirus (CAdV) were detected in the samples. Single, double, triple and quadruple infections accounted for 6.6%, 1.4%, 1.2% and 0.96% of samples, respectively. CCoV strains in 81 samples included three genotypes, CCoV-I, CCoV-IIa and CCoV-IIb, by analysis of S gene. The rate of single infection of CCoV-I, CCoV-IIa or CCoV-IIb was 19%, 38% or 7.4% respectively. The double and triple infection rates of CCoV were 32.8% and 2.5% respectively. All CPV strains in 36 samples belonged to CPV-2c. There were three amino acid differences in the Fiber protein of CAdV-positive sample QD2022, compared with the reference strain Toronto A26/61 and the vaccine strain YCA-18. These results suggest that CCoV and CPV are primary infectious agents, and that these two viruses were often identified in mixed infections, or coinfections alongside mycoplasma or other bacteria. These results will provide the basis for improvements in prevention and control of naturally occurring infectious diseases in Beagle dog production colonies and research facilities.

Molecular typing of canine parvovirus type 2 by VP2 gene sequencing and restriction fragment length polymorphism in affected dogs from Egypt

Introduction

Canine parvovirus-2 (CPV-2) is one of the most common infectious diseases in dogs characterized by severe gastroenteritis, vomiting, and bloody diarrhea. Little information is available about this topic in Egypt, particularly in the Delta region. This study reports the prevalence and molecular analysis of CPV-2 variants collected from El-Gharbia and Kafrelsheikh governorates in the Delta of Egypt.

Methods

In this study, 320 rectal swabs were collected from infected domestic dogs from two districts in delta Egypt. The samples were investigated by rapid immunochromatographic test and polymerase chain reaction for detection the prevalence of CPV-2 variants. The genetic characterization was performed using restriction fragment length polymorphism (RFLP) analysis and partial VP2 gene sequence.

Results and discussion

The viral antigen was detected in (264/320, 82.5%) of samples by IC test, while PCR was found more sensitive by detecting (272/320, 85%) positive samples. The RFLP technique using MboII restriction enzyme was successfully used for the differentiation of CPV-2c antigenic variants from CPV-2a/2b strains. Interestingly, the molecular and phylogenetic analysis revealed that both CPV-2a and CPV-2c are circulating in the study area. Deduced amino acid sequence analysis showed changes at residue (N426E) and residue (T440A).: Our results indicated that CPV-2 is prevalent among dogs in Egypt, and therefore further molecular and epidemiological studies of CPV-2 are warranted.

Not Asian Anymore: Reconstruction of the History, Evolution, and Dispersal of the "Asian" Lineage of CPV-2c

Variability has been one of the hallmarks of canine parvovirus type 2 (CPV-2) since its discovery, and several lineages and antigenic variants have emerged. Among these, a group of viruses commonly called Asian CPV-2c has recently been reported with increasing frequency in different regions. Currently, its global epidemiology and evolution are essentially unknown. The present work deals with this information gap by evaluating, via sequence, phylodynamic, and phylogeographic analyses, all the complete coding sequences of strains classified as Asian CPV-2c based on a combination of amino acid markers and phylogenetic analysis. After its estimated origin around 2008, this lineage circulated undetected in Asia until approximately 2012, when an expansion in viral population size and geographical distribution occurred, involving Africa, Europe, and North America. Asia was predicted to be the main nucleus of viral dispersal, leading to multiple introduction events in other continents/countries, where infection establishment, persistence, and rapid evolution occurred. Although the dog is the main host, other non-canine species were also involved, demonstrating the host plasticity of this lineage. Finally, although most of the strains showed an amino acid motif considered characteristic of this lineage, several exceptions were observed, potentially due to convergent evolution or reversion phenomena.

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.

Prevalence and Characteristics of Canine Parvovirus Type 2 in Henan Province, China

To investigate the epidemic profile and genetic diversity of canine parvovirus type 2 (CPV-2), a total of 111 clinical samples collected from dogs suspected of CPV-2 infection in 10 cities of Henan province of China during 2020 to 2021 were screened by PCR. The results showed a CPV-2-positive rate of 88.29% (98/111). Nearly full-length genomes of 98 CPV-2 strains were sequenced and analyzed. CPV-2c strains (91.84%, 90/98) were significantly higher than that of new CPV-2a strains (8.16%, 8/98) in Henan province without detecting other CPV genotypes, indicating that CPV-2c has become the dominant genotype in Henan province. A phylogenetic analysis of NS1 and VP2 amino acids grouped the strains in this study with Asian strains, which clustered into an identical branch. Based on the CPV-2 VP2 sequences in this study and available in the NCBI database, the adaptation analyses showed that 17 positive selection sites and 10 parallel evolution sites were identified in the VP2 protein of CPV-2, of which three sites (sites 5, 370, and 426) were both under positive selection pressure and parallel evolution. Interestingly, two amino acid mutations (A5G and Q370R) were also observed in the VP2 proteins of 82 CPV-2c strains in this study, which differed from the earlier CPV-2c strain (GU380303) in China. In addition, a unique mutation (I447M) was observed in the VP2 protein of five CPV-2c strains, which was first reported in China. This study provides powerful insight to further our understanding of the epidemic status and evolution of CPV-2 in China. IMPORTANCE CPV-2 was the original virus strain identified in dogs, which cause an acute and lethal disease in dogs. Subsequently, the original CPV-2 was replaced throughout the world by novel antigenic variants (e.g., CPV-2a, CPV-2b, new CPV-2a, new CPV-2b, and CPV-2c). Currently, the epidemiological characteristics of CPV-2 in Henan province of China is still unclear. In our study, a total of 98 nearly full-length genomes of CPV-2 strains were obtained to explore prevalence and genetic evolution of CPV-2 in Henan Province. Moreover, the epidemiological and genetic evolution of CPV-2 in China since its discovery was also investigated. The results of this study will provide valuable information regarding the evolution of CPV-2 strains in China.

Molecular characterization and antiviral effects of canine interferon regulatory factor 1 (CaIRF1)

BACKGROUND

Interferon regulatory factor 1 (IRF1) is an important transcription factor that activates the type I interferon (IFN-I) response and plays a vital role in the antiviral immune response. Although IRF1 has been identified in several mammals, little information related to its function in canines has been described.

RESULTS

In this study, canine IRF1 (CaIRF1) was cloned. After a series of bioinformatics analyses, we found that the CaIRF1 protein structure was similar to that of other animal IRF1 proteins, including a conserved DNA-binding domain (DBD), an IRF-association domain 2 (IAD2) domain and two nuclear localization signals (NLSs). An indirect immunofluorescence assay (IFA) revealed that CaIRF1 was mainly distributed in the nucleus. Overexpression of CaIRF1 in Madin-Darby canine kidney cells (MDCK) induced high levels of interferon β (IFNβ) and IFN-stimulated response element (ISRE) promoter activation and induced interferon-stimulated gene (ISG) expression. Subsequently, we assayed the antiviral activity of CaIRF1 against vesicular stomatitis virus (VSV) and canine parvovirus type-2 (CPV-2) in MDCK cells. Overexpression of CaIRF1 effectively inhibited the viral yields of VSV and CPV-2, while knocking down of CaIRF1 expression mildly increased viral gene copies.

CONCLUSIONS

CaIRF1 is involved in the cellular IFN-I signaling pathway and plays an important role in the antiviral response.

Source apportionment based on lead isotope ratios: Could domestic dog's blood lead be used to identify the level and sources of lead pollution in children?

Domestic dogs have been proved to be used as "sentinel organisms" to monitor human lead exposure. However, whether dogs' blood can be used to identify the levels and pollution source of children's lead exposure still needs evidence. To evaluate the potential use of domestic dogs' blood lead as an indicator of lead exposure levels and pollution source of children, accompanying with potential environmental media samples, lead concentrations and isotope ratios (expressed as ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb) in blood were investigated and compared between children and dogs, who came from a Pb-Zn smelter area, a coal fired area and a control area without industrial activity. The results showed that there were significant correlations in blood lead levels (BLLs) between children and dogs in the study areas (p < 0.01). The lead isotope ratios (LIRs) in blood of children and dogs were disparate among the three areas, however, the LIRs of dogs were quite correlated with those of children in each area (p < 0.01). With the comparison of LIRs between potential pollution sources (slag, ore, coal, paint) and blood samples, the identified lead sources based on dogs' blood were found to be coincident with those based on children's blood. Ore smelting and coal combustion were the main sources of lead exposure for the dogs and children in the smelting area, and coal combustion was the predominant source for the children and dogs living in the coal burning area and control area. The results showed that dogs' BLLs might be used to estimate children's BLLs, and blood LIRs measurements of dogs' could be used as an alternative for identifying the sources of children's lead exposure. This study further provided relevant evidence for dogs to be sentinels exposed to human lead exposure and an alternative method for source apportionment of children's lead exposure.

Fatal canine parvovirus type 2a and 2c infections in wild Chinese pangolins (Manis pentadactyla) in southern China

The Chinese pangolin (Manis pentadactyla) is a critically endangered scale-covered mammal belonging to the order Pholidota. Wild pangolins are notably susceptible to pathogen infection and are typically characterized by impoverished health. However, little is currently known regarding the viruses prevalent among pangolins. In this study, we report the detection of two subtypes of canine parvovirus type 2 (CPV-2), namely CPV-2a and CPV-2c, both of which caused severe diarrheal disease in two post-rescue pangolins with fatal consequences. As in CPV-2-infected dogs, intensive lesion of the mucosal layer of the small intestines is a prominent feature in infected pangolins. Moreover, the immunochemistry results demonstrated that CPV-2 antigens were distributed in the crypts of small intestine. Additionally, typical parvovirus-associated CPV-2 were detected after four passages in F81 cells, and typical parvovirus-like particles, approximately 20 nm in diameter, were observed in the cell supernatants. Phylogenetic analysis revealed that the VP2 viral protein sequences (GenBank accession number OP208805) isolated from one pangolin (termed P1) were classified as CPV-2c, with 99.8% identity to a CPV-2c strain (MN832850) isolated from a Taiwanese pangolin found in Taiwan Province. In contrast, VP2 sequences (#OP208806) obtained from the second pangolin (P2) were classified as CPV-2a, with 99.8% identity to a CPV-2a strain (KY386858) isolated from southern China. In this study, we thus confirmed the infection of pangolins with CPV-2c in mainland China and demonstrated that CPV-2a also can infect pangolins. Based on these findings, we recommend that further investigations should be conducted to establish the interspecies transmission of these viruses among wild pangolins, wild carnivores, and stray dogs.

Isolation and identification of a novel canine parvovirus type 2c strain in domestic cats in Dalian, China

Canine parvovirus (CPV) and feline panleukopenia virus (FPV) are highly contagious and cause severe enteric diseases, with high mortality rates in dogs and cats. In the present study, we isolated and identified a novel CPV-2c strain (FPV-DL04 strain) from 18 cats with gastroenteritis symptoms and a positive parvovirus PCR test result in Dalian, China. Molecular characterization, sequence analysis, and phylogeny determination were performed on the VP2 gene of this strain. The results showed that the FPV-DL04 strain had 99.4% homology with the CPV-2c CN/HN1708 strain, and both strains had S297A and A300G key mutation sites. Interestingly, we also found that the DL04 strain has a A5G mutation site, but no F267Y and Y324I mutation sites. This study provided new important findings regarding the evolution of parvovirus infection in domestic cats in China.

Cross-Neutralization of Vanguard C4 Vaccine Against Australian Isolates of Canine Parvovirus Variants CPV-2a, CPV-2b, and CPV-2c

Canine parvovirus type 2 (CPV-2) remains one of the most significant viral pathogens in dogs in Australia and worldwide despite the availability of safe and effective CPV vaccines. At least three different variants of CPV-2 have emerged and spread all around the world, namely CPV-2a, CPV-2b, and CPV-2c. The ability of the current vaccines containing either original CPV-2 type or CPV-2b variant to cross protect the heterologous variants has been well demonstrated in laboratory studies, despite some concerns regarding the vaccine efficacy against the emerging variants. Vanguard^®, a series of multivalent vaccines, has been in the market for a considerable period of time and demonstrated to provide efficacy against all three types of CPV variants CPV-2a, CPV-2b, and CPV-2c. The purpose of this study was to evaluate the ability of the recently registered Vanguard C4 vaccine to induce cross-neutralizing antibodies against the Australian isolates of CPV-2a, CPV-2b, and CPV-2c variants. Blood samples collected from dogs vaccinated with Vanguard C4 were analyzed by virus neutralizing assays developed for each of three CPV variants. The results of the study demonstrated that Vanguard vaccine induced cross-neutralizing antibodies against the Australian isolates of CPV-2a, CPV-2b, and CPV-2c, thus offering cross protection against all three Australian CPV variants.

Molecular characterization of carnivore protoparvovirus 1 circulating in domestic carnivores in Egypt

Canine parvovirus (CPV) and feline panleukopenia virus (FPV), now included in the unique species Carnivore protoparvovirus 1 (CPPV1), have been circulating in dogs and cats for several decades and are considered the causes of clinically important diseases, especially in young animals. While genetic evidence of the circulation of parvoviruses in Egyptian domestic carnivores has been provided since 2016, to date, all available data are based on partial fragments of the VP2 gene. This study reports the molecular characterization of CPPV strains from Egypt based on the full VP2 gene. Overall, 196 blood samples were collected from dogs and cats presented at veterinary clinics for routine medical assessment in 2019 in Egypt. DNA extracts were screened and characterized by real-time PCR. Positive samples were amplified by conventional PCR and then were sequenced. Nucleotide and amino acid changes in the sequences were investigated and phylogeny was inferred. Carnivore protoparvovirus DNA was detected in 18 out of 96 dogs (18.8%) and 7 of 100 cats (7%). Phylogenetic analyses based on the full VP2 gene revealed that 9 sequenced strains clustered with different CPV clades (5 with 2c, 2 with 2a, 1 with 2b, and 1 with 2) and 1 strain with the FPV clade. All three CPV variants were detected in dog and cat populations with a predominance of CPV-2c strains (7 of 18, 38.9%) in dog samples, thus mirroring the circulation of this variant in African, European, and Asian countries. Deduced amino acid sequence alignment revealed the presence of the previously unreported unique mutations S542L, H543Q, Q549H, and N557T in the Egyptian CPV-2c strains.

Genetic characterization and evolutionary analysis of canine parvovirus in Tangshan, China

Canine parvovirus (CPV) is a major enteric virus of carnivores worldwide that poses a considerable threat to dogs. In this study, we investigated the genetic variation of CPV in Tangshan, China, and the relationships between CPV disease and the vaccination status, age, and gender of dogs. Seventy-seven fecal samples from dogs in Tangshan that tested positive for CPV were obtained for analysis. Twenty-two full-length VP2 gene sequences were successfully amplified. The 22 strains included 17 CPV-2c variants, four new CPV-2a variants, and one new CPV-2b variant. Phylogenetic analysis showed that all of the CPV-2c strains clustered together and were closely related to CPV-2c strains from Asia but distantly related to CPV-2c strains from Europe. Further amino acid sequence analysis showed that, relative to CPV-2c strains from Europe, most of the CPV-2c stains in this study had A5G, F267Y, Y324I, and Q370R mutations. These findings provide a more comprehensive understanding of the variants of CPV circulating in China.

Phylogenetic Characteristics of Canine Parvovirus Type 2c Variant Endemic in Shanghai, China

Canine parvovirus type 2 (CPV-2) has spread and mutated globally over the past 40 years. In the present study, 206 samples from dogs suspected of CPV-2 infection were collected from five veterinary clinics in Shanghai city, China. The average positive rate for CPV-2 was detected to be 40.78% using the PCR method. Using an F81 cell (feline kidney cell) culture, the isolates of three CPV-2c strains were obtained. The near full-length genome sequences of the isolates were determined and submitted to GenBank: CPV-SH2001 (MW650830), CPV-SH2002 (MW811188), and CPV-SH2003 (MW811189). By comparing the amino acid sequences of 12 CPV strains with those of 48 related strains retrieved from GenBank, all of the CPV strains from Shanghai were typed as belonging to a relatively new CPV-2c variant spreading in Asia, with typical amino acid residues (5Gly, 267Tyr, 324Ile, and 370Arg) in the VP2 protein. The divergence time of this new CPV-2c clade was estimated by the phylogenetic tree using the maximum likelihood and RelTime with Dated Tips (RTDT) approaches. Our results indicate that the 426 and 324 VP2 amino acid residues are under strong selection pressure with a posterior probability of 0.966 and 0.943, respectively. Therefore, this study provides insight into the phylogenetic characteristics of the current CPV-2c variant in Shanghai city, China.

Detection and molecular epidemiology of canine parvovirus type 2 (CPV-2) circulating in Jilin Province, Northeast China

Canine parvovirus (CPV) is highly contagious and can cause haemorrhagic enteritis and myocarditis in dogs. To understand the current epidemic situation of CPV in Jilin Province, China, a total of 44 fecal or intestinal tissue samples of pet dogs suspected of being infected with CPV from February 2018 to November 2019 in Changchun and Liaoyuan City, Jilin Province were collected.All of the 44 collected samples were tested positive to CPV-2 by a PCR assay. The sequencing and analyzing of complete VP2 genes showed that CPV-2c was the most prevalent variant (n = 31;70.4 %), followed by new-CPV-2a (n = 8;18.2 %), new-CPV-2b (n = 4; 9.1 %) and CPV-2 (n = 1; 2.3 %). Phylogenetic analysis revealed that the 31 CPV-2c strains in our study are closely related to local CPV-2c isolates in cluster I. The VP2 protein of the acquired CPV 2c strains all possessed the substitutions Ala5Gly, Phe267Tyr, Tyr324Ile, and Gln370Arg only one with a novel Arg481Lys mutation. These findings demonstrate that CPV-2c was the most prominent type of CPV circulating in Jilin in 2018-2019, clustered in a separate group that is far from the vaccine strains and suggest that further and extensive epidemiological investigation among pet dogs are warranted to provide information for usage and research of current vaccines.