Genetic diversity and relatedness of feline parvovirus in Vietnam and its potential implications for canine-feline transmission

Feline panleukopenia, caused by feline parvovirus (FPV), has been studied worldwide, but there have been very few studies conducted in Vietnam. In this study, 19 rectal swab samples were collected from northern Vietnam in 2018-2019 and screened for the presence of FPV using PCR. Through sequence analysis of the full-length VP2 gene, it was found that the FPV strains detected in Vietnam were closely related to those obtained from dogs in Vietnam, Asia, Europe, and America. Moreover, the FPV strains found in Vietnam may constitute a distinct group, related to viruses sampled in China. Interestingly, most of the nucleotide changes identified were T-C substitutions.

The XVIII International Parvovirus Workshop Rimini, Italy, 14-17 June 2022

The XVIII International Parvovirus Workshop took place in Rimini, Italy, from 14 to 17 June 2022 as an on-site event, continuing the series of meetings started in 1985 and continuously held every two years. The communications dealt with all aspects of research in the field, from evolution and structure to receptors, from replication to trafficking, from virus-host interactions to clinical and veterinarian virology, including translational issues related to viral vectors, gene therapy and oncolytic parvoviruses. The oral communications were complemented by a poster exhibition available for view and discussion during the whole meeting. The XVIII International Parvovirus Workshop was dedicated to the memory of our dearest colleague Mavis Agbandje-McKenna (1963-2021).

Outbreak of densovirus with high mortality in a commercial mealworm (Tenebrio molitor) farm: A molecular, bright-field, and electron microscopic characterization

Mealworms are one of the most economically important insects in large-scale production for human and animal nutrition. Densoviruses are highly pathogenic for invertebrates and exhibit an extraordinary level of diversity which rivals that of their hosts. Molecular, clinical, histological, and electron microscopic characterization of novel densovirus infections is of utmost economic and ecological importance. Here, we describe an outbreak of densovirus with high mortality in a commercial mealworm (Tenebrio molitor) farm. Clinical signs included inability to prehend food, asymmetric locomotion evolving to nonambulation, dehydration, dark discoloration, and death. Upon gross examination, infected mealworms displayed underdevelopment, dark discoloration, larvae body curvature, and organ/tissue softness. Histologically, there was massive epithelial cell death, and cytomegaly and karyomegaly with intranuclear inclusion (InI) bodies in the epidermis, pharynx, esophagus, rectum, tracheae, and tracheoles. Ultrastructurally, these InIs represented a densovirus replication and assembly complex composed of virus particles ranging from 23.79 to 26.99 nm in diameter, as detected on transmission electron microscopy. Whole-genome sequencing identified a 5579-nucleotide-long densovirus containing 5 open reading frames. A phylogenetic analysis of the mealworm densovirus showed it to be closely related to several bird- and bat-associated densoviruses, sharing 97% to 98% identity. Meanwhile, the nucleotide similarity to a mosquito, cockroach, and cricket densovirus was 55%, 52%, and 41%, respectively. As this is the first described whole-genome characterization of a mealworm densovirus, we propose the name Tenebrio molitor densovirus (TmDNV). In contrast to polytropic densoviruses, this TmDNV is epitheliotropic, primarily affecting cuticle-producing cells.

Does Aleutian Disease Occur among Domestic Ferrets in Poland? Results of Preliminary Studies Conducted in Two Regions of Poland

Although ferrets are becoming increasingly popular as companion animals, their population in households is still far lower compared to cats or dogs. This results in a much smaller number of ferret specialists, and thus poorer diagnosis of various diseases, including the Aleutian disease. Aleutian disease is a slowly progressing viral disease which can cause different symptoms in these animals. The virus can also cause symptoms in different species of animals, but in the case of ferrets, there is relatively less information on about both the prevalence and symptoms of this disease. Therefore, the aim of this study was to determine the presence of antibodies and the virus itself in ferrets from two regions of Poland. Blood samples and rectal swabs were obtained from 61 domestic ferrets from Mazowieckie and Dolnośląskie voivodships. The presence of antibodies was determined using serological methods and real-time PCR analysis was performed to determine presence of viral DNA. Serological analyses demonstrated that 49% (n = 30) of the ferrets had antibodies against Aleutian disease virus (ADV). No relationship was observed between the prevalence of antibodies and age, sex, habitual residence or origin of ferrets. The real-time PCR did not confirm DNA of the ADV in any of the blood and rectal swab samples. Obtained results suggest that ADV circulates in the analyzed population of ferrets, therefore further studies in this direction should be carried out.

Investigation of Carnivore protoparvovirus 1 and Amdoparvovirus infections in red fox populations of the Italian Dolomites

Members of the family Parvoviridae are well recognized infectious agents of companion, livestock and wild animals as well, whose relevance on production, health, welfare and conservation is often high. Nevertheless, the knowledge of their epidemiology in wild populations is scarce or fragmentary. In this study, the presence and features of two parvoviruses, Carnivore protoparvovirus 1 and Amdoparvovirus, were evaluated in the red fox population resident in the Dolomites area, Northern Italy, and compared with the scenario of other countries and Italian regions. Six out of 117 spleen samples (5.13%: 95CI: 1.91-10.83%) tested positive to Carnivore protoparvovirus 1 and were molecularly characterized as Canine parvovirus (CPV). Infection frequency was comparable with that observed in wild carnivore populations present in Southern Italian regions, although in that case, Feline parvovirus (FPV) was predominant. No evidence of infection-related clinical signs was reported and viral loads were invariably low, suggesting the subclinical nature of the infection, the persistent carrier status or the detection of traces of viral DNA. No samples tested positive to Amdoparvovirus genus-specific PCR. The present study provides the first evidence of CPV circulation in the Northern Italy fox population. Unfortunately, the inevitable convenience nature of the sampling prevents definitive conclusions. Therefore, a more coordinated and standardized approach should be applied, at least in neighbouring geographic areas, to study these viral infections and their relevance in wildlife.

Genomic characterization and the prevalence of a novel copiparvovirus in wild sika deer (Cervus nippon) in Japan

A preliminary metagenomic analysis of the virome of wild sika deer (Cervus nippon) blood in Japan resulted in the identification of a novel parvovirus. The virus was closest, but only 44.7-60.7% identical to 17 reported strains belonging to the genus Copiparvovirus within the subfamily Parvovirinae, over the near-entire genomic sequence. The sika deer copiparvovirus DNA was detected in 15% (31/206) of sika deer captured in 7 prefectures of Japan, and a region-dependent prevalence of 0-66.7% was noted, with a biased distribution in the southern part of Japan. The observed biased distribution of sika deer copiparvovirus may be due to the habitat density of deer and the number of ticks, which might play a role in the transmission of the virus.

Seroprevalence and Molecular Epidemiology of Aleutian Disease in Various Countries during 1972-2021: A Review and Meta-Analysis

Simple Summary

Aleutian disease is caused by the Aleutian mink disease virus and is one of the most serious infectious diseases that affect the family Mustelidae, including the American mink, wild European mink, weasels, badgers and other animal species, such as skunks, raccoons, dogs, cats and mice, as well as humans. Effective treatments and vaccines against Aleutian disease have not been developed to date. Prophylactic programs that focus on the identification and elimination of infected mink are one of the methods of controlling the negative outcomes of Aleutian disease. This article analyses the seroprevalence of Aleutian mink disease virus infections in American and European mink and other species around the world, and reviews recent knowledge relating to the molecular epidemiology of the Aleutian mink disease virus.

Abstract

Aleutian disease (AD) poses a serious threat to both free-ranging and farmed mink around the world. The disease is caused by the Aleutian mink disease virus (AMDV), which also poses a health risk for other members of the family Mustelidae, including wild mink, weasels, badgers and other animal species. This article analyses the seroprevalence of AMDV infections in mink and other species around the world, and reviews recent knowledge relating to the molecular epidemiology of the AMDV. Depending on the applied diagnostic technique and the country, the prevalence of anti-AMDV antibodies or AMDV DNA was established at 21.60–100.00% in farmed American mink, 0.00–93.30% in free-ranging American mink and 0.00–25.00% in European mink. Anti-AMDV antibodies or AMDV DNA were also detected in other free-living fur-bearing animals in Europe and Canada, where their prevalence was determined at 0.00–32.00% and 0.00–70.50%, respectively. This may indicate a potential threat to various animal species. AMDV strains are not clustered into genotypes based on the geographic origin, year of isolation or pathogenicity. The isolates that were identified on mink farms around the world originated from North America because American mink were introduced to Europe and Asia for breeding purposes and to restock natural populations.

Investigation of Bufavirus and Parvovirus 4 in Patients with Gastro-Enteritis from the South-East of France

Bufavirus (BuV) and human parvovirus 4 (PARV4) belong to the Parvoviridae family. We assessed BuV and PARV4 DNA presence by real-time PCR analysis in stool, blood and respiratory samples collected in patients from Marseille and Nice, two large cities in the South-East of France. Bu-V DNA was detected in diarrheic stool samples from 92 patients (3.6% of 2583 patients), particularly men and adults, and patients from the nephrology and the infectious disease departments. Among the patients with a BuV-positive stool sample and for whom at least one blood sample was available (n = 30 patients), BuV DNA was detected also in 3 blood samples. In contrast, BuV DNA was not detected in any of the respiratory samples from 23 patients with BuV-positive stool. BuV detection rate was comparable in stool samples from patients with and without diarrhea. We did not detect PARV4 DNA in any of the stool specimens (n = 2583 patients). Our results suggest that PARV4 fecal–oral transmission is rare or non-existent in the South-East of France while BuV circulates with a relatively high rate in this area.

Occurrence and distribution of compound microsatellites in the genomes of three economically important virus families

Microsatellites are nonrandom hypervariable iterations of one to six nucleotides, existing across the coding as well as noncoding regions of virtually all known genomes, arising primarily due to polymerase slippage and unequal crossing over during replication events. Two or more perfect microsatellites located in close proximity form compound microsatellites. We studied the distribution of compound microsatellites in 118 ssDNA virus genomes belonging to three economically important virus families, namely Anelloviridae, Circoviridae, and Parvoviridae, known to predominantly infect livestock and humans. Among these virus families, 0-58.49% of perfect microsatellites were involved in the formation of compound microsatellites, the majority being located in the coding regions. No clear relationship existed between the genomic features (genome size and GC%) and compound microsatellite characteristics (relative abundance and relative density). The majority of the compound microsatellites resulted from di-SSR couples. A strong positive relationship was observed between the maximum distance value and length of compound microsatellite, percentage of microsatellites involved in the compound microsatellite formation, and relative microsatellite density. The degree of variability among microsatellite characteristics studied was largely a species-specific phenomenon. A major proportion of compound microsatellites was represented by similar motif combinations. The findings of the present study will help in better understanding of the structural, functional, and evolutionary role of compound microsatellites prevailing in the smaller genomes.

A plate of viruses: Viral metagenomics of supermarket chicken, pork and beef from Brazil

A viral metagenomics study was conducted in beef, pork, and chicken sold in supermarkets from Southern Brazil. From chicken, six distinct gyroviruses (GyV) were detected, including GyV3 and GyV6, which for the first time were detected in samples from avian species, plus a novel smacovirus species and two highly divergent circular Rep-encoding ssDNA (CRESS-DNA) viruses. From pork, genomes of numerous anelloviruses, porcine parvovirus 5 (PPV5) and 6 (PPV6), two new genomoviruses and two new CRESS-DNA viruses were found. Finally, two new CRESS-DNA genomes were recovered from beef. Although none of these viruses have history of transmission to humans, the findings reported here reveal that such agents are inevitably consumed in diets that include these types of meat.

Molecular detection and characterization of Carnivore chaphamaparvovirus 1 in dogs

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Canine chaphamaparvovirus (CaChPV) is a novel parvovirus recently discovered in dogs;

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Herein, stool samples from dogs with or without enteric signs were screened for CaChPV;

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CaChPV DNA was found either in diarrhoeic (1.9 %) or asymptomatic (1.6 %) dogs;

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The nearly complete genome sequences were determined for two strains;

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The Italian CaChPV strains tightly clustered with the American reference viruses.

Canine chaphamaparvovirus (CaChPV) is a newly recognised parvovirus discovered by metagenomic analysis during an outbreak of diarrhoea in dogs in Colorado, USA, in 2017 and more recently detected in diarrhoeic dogs in China. Whether the virus plays a role as canine pathogen and whether it is distributed elsewhere, in other geographical areas, is not known. We performed a case-control study to investigate the possible association of CaChPV with enteritis in dogs. CaChPV DNA was detected both in the stools of diarrhoeic dogs (1.9 %, 3/155) and of healthy animals (1.6 %, 2/120). All the CaChPV-infected dogs with diarrhea were mixed infected with other enteric viruses such as canine parvovirus (formerly CPV-2), canine bufavirus (CBuV) and canine coronavirus (CCoV), whilst none of the asymptomatic CaChPV positive animals resulted co-infected. The nearly full-length genome and the partial capsid protein (VP) gene of three canine strains, Te/36OVUD/19/ITA, Te/37OVUD/19/ITA and Te/70OVUD/19/ITA, were reconstructed. Upon phylogenetic analyses based on the NS1 and VP aa sequences, the Italian CaChPV strains tightly clustered with the American reference viruses. Distinctive residues could be mapped to the deduced variable regions of the VP of canine and feline chaphamaparvoviruses, considered as important markers of host range and pathogenicity for parvoviruses.

Molecular biology and structure of a novel penaeid shrimp densovirus elucidate convergent parvoviral host capsid evolution

The giant tiger prawn (Penaeus monodon) is a decapod crustacean widely reared for human consumption. Currently, viruses of two distinct lineages of parvoviruses (PVs, family Parvoviridae; subfamily Hamaparvovirinae) infect penaeid shrimp. Here, a PV was isolated and cloned from Vietnamese P. monodon specimens, designated Penaeus monodon metallodensovirus (PmMDV). This is the first member of a third divergent lineage shown to infect penaeid decapods. PmMDV has a transcription strategy unique among invertebrate PVs, using extensive alternative splicing and incorporating transcription elements characteristic of vertebrate-infecting PVs. The PmMDV proteins have no significant sequence similarity with other PVs, except for an SF3 helicase domain in its nonstructural protein. Its capsid structure, determined by cryoelectron microscopy to 3-Å resolution, has a similar surface morphology to Penaeus stylirostris densovirus, despite the lack of significant capsid viral protein (VP) sequence similarity. Unlike other PVs, PmMDV folds its VP without incorporating a βA strand and displayed unique multimer interactions, including the incorporation of a Ca²⁺ cation, attaching the N termini under the icosahedral fivefold symmetry axis, and forming a basket-like pentamer helix bundle. While the PmMDV VP sequence lacks a canonical phospholipase A2 domain, the structure of an EDTA-treated capsid, determined to 2.8-Å resolution, suggests an alternative membrane-penetrating cation-dependent mechanism in its N-terminal region. PmMDV is an observed example of convergent evolution among invertebrate PVs with respect to host-driven capsid structure and unique as a PV showing a cation-sensitive/dependent basket structure for an alternative endosomal egress.

Virome of a Feline Outbreak of Diarrhea and Vomiting Includes Bocaviruses and a Novel Chapparvovirus

An unexplained outbreak of feline diarrhea and vomiting, negative for common enteric viral and bacterial pathogens, was subjected to viral metagenomics and PCR. We characterized from fecal samples the genome of a novel chapparvovirus we named fechavirus that was shed by 8/17 affected cats and identified three different feline bocaviruses shed by 9/17 cats. Also detected were nucleic acids from attenuated vaccine viruses, members of the normal feline virome, viruses found in only one or two cases, and viruses likely derived from ingested food products. Epidemiological investigation of disease signs, time of onset, and transfers of affected cats between three facilities support a possible role for this new chapparvovirus in a highly contagious feline diarrhea and vomiting disease.

The First Detection of Human Bocavirus Species 2 and 3 in Raw Sewage and Mussels in South Africa

Human bocavirus (HBoV) has a global distribution and is associated with respiratory and enteric infections, particularly in the paediatric population. In this study, raw sewage and mussel samples were analysed for the presence of HBoV using nested PCR with primers targeting the VP1/VP2 junction. Amplification and sequencing of the 382 bp region followed by phylogenetic analysis indicated the presence of HBoV 2 in mussel samples and HBoV 3 in sewage samples. This is the first report describing the presence of enteric-associated HBoV in environmental samples from South Africa and in mussel samples from the African continent. The results signify the need for further studies examining the potential risk of foodborne transmission of HBoV and highlight the importance of continued screening to determine the prevalence and epidemiology of HBoV in South Africa.

Liver virome of healthy pigs reveals diverse small ssDNA viral genomes

Brazil is a major exporter of pork meat worldwide. Swine liver is a common ingredient in food consumed by humans, thus emphasizing the importance of evaluating the presence of associated pathogens in swine liver. To obtain knowledge, this study aimed to provide insights into the viral communities of livers collected from slaughtered pigs from southern Brazil. The 46 livers were processed and submitted for high-throughput sequencing (HTS). The sequences were most closely related to Anelloviridae, Circoviridae and Parvoviridae families. The present work also describes the first Brazilian PCV1 and the first PPV6 and PPV7 from South America. Virus frequencies revelead 63% of samples positive for TTSuV1, 71% for TTSuVk2, 10.8% for PCV, 13% for PPV and 6% for PBov. This report addresses the diversity of the liver virome of healthy pigs and expands the number of viruses detected, further characterizing their genomes to assist future studies.

Identification of a Novel Ichthyic Parvovirus in Marine Species in Hainan Island, China

Parvoviruses are a diverse group of viruses that are capable of infecting a wide range of animals. In this study, we report the discovery of a novel parvovirus, tilapia parvovirus HMU-HKU, in the fecal samples of crocodiles and intestines of tilapia in Hainan Province, China. The novel parvovirus was firstly identified from crocodiles fed with tilapia using next-generation sequencing (NGS). Screening studies revealed that the prevalence of the novel parvovirus in crocodile feces samples fed on tilapia (75–86%) was apparently higher than that in crocodiles fed with chicken (4%). Further studies revealed that the prevalence of the novel parvovirus in tilapia feces samples collected at four areas in Hainan Province was between 40 and 90%. Four stains of the novel parvovirus were identified in this study based on sequence analyses of NS1 and all the four strains were found in tilapia in contrast only two of them were detected in crocodile feces. The nearly full-length genome sequence of the tilapia parvovirus HMU-HKU-1 was determined and showed less than 45.50 and 40.38% amino acid identity with other members of Parvoviridae in NS1 and VP1 genes, respectively. Phylogenetic analysis based on the complete helicase domain amino acid sequences showed that the tilapia parvovirus HMU-HKU-1 formed a relatively independent branch in the newly proposed genus Chaphamaparvovirus in the subfamily Hamaparvovirinae according to the ICTV’s most recent taxonomic criteria for Parvoviridae classification. Tilapia parvovirus HMU-HKU-1 likely represented a new species within the new genus Chaphamaparvovirus. The identification of tilapia parvovirus HMU-HKU provides further insight into the viral and genetic diversity of parvoviruses and its infections in tilapia populations need to be evaluated in terms of pathogenicity and production losses in tilapia farming.

Viruses in Horses with Neurologic and Respiratory Diseases

Metagenomics was used to identify viral sequences in the plasma and CSF (cerobrospinal fluid) of 13 horses with unexplained neurological signs and in the plasma and respiratory swabs of 14 horses with unexplained respiratory signs. Equine hepacivirus and two copiparvoviruses (horse parvovirus-CSF and a novel parvovirus) were detected in plasma from neurological cases. Plasma from horses with respiratory signs contained the same two copiparvoviruses plus equine pegivirus D and respiratory swabs contained equine herpes virus 2 and 5. Based on genetic distances the novel copiparvovirus qualified as a member of a new parvovirus species we named Eqcopivirus. These samples plus another 41 plasma samples from healthy horses were tested by real-time PCRs for multiple equine parvoviruses and hepacivirus. Over half the samples tested were positive for one to three viruses with eqcopivirus DNA detected in 20.5%, equine hepacivirus RNA and equine parvovirus-H DNA in 16% each, and horse parvovirus-CSF DNA in 12% of horses. Comparing viral prevalence in plasma none of the now three genetically characterized equine parvoviruses (all in the copiparvovirus genus) was significantly associated with neurological and respiratory signs in this limited sampling.

An Ancient Lineage of Highly Divergent Parvoviruses Infects both Vertebrate and Invertebrate Hosts

Chapparvoviruses (ChPVs) comprise a divergent, recently identified group of parvoviruses (family Parvoviridae), associated with nephropathy in immunocompromised laboratory mice and with prevalence in deep sequencing results of livestock showing diarrhea. Here, we investigate the biological and evolutionary characteristics of ChPVs via comparative in silico analyses, incorporating sequences derived from endogenous parvoviral elements (EPVs) as well as exogenous parvoviruses. We show that ChPVs are an ancient lineage within the Parvoviridae, clustering separately from members of both currently established subfamilies. Consistent with this, they exhibit a number of characteristic features, including several putative auxiliary protein-encoding genes, and capsid proteins with no sequence-level homology to those of other parvoviruses. Homology modeling indicates the absence of a β-A strand, normally part of the luminal side of the parvoviral capsid protein core. Our findings demonstrate that the ChPV lineage infects an exceptionally broad range of host species, including both vertebrates and invertebrates. Furthermore, we observe that ChPVs found in fish are more closely related to those from invertebrates than they are to those of amniote vertebrates. This suggests that transmission between distantly related host species may have occurred in the past and that the Parvoviridae family can no longer be divided based on host affiliation.

ICTV Virus Taxonomy Profile: Parvoviridae

Members of the family Parvoviridae are small, resilient, non-enveloped viruses with linear, single-stranded DNA genomes of 4-6 kb. Viruses in two subfamilies, the Parvovirinae and Densovirinae, are distinguished primarily by their respective ability to infect vertebrates (including humans) versus invertebrates. Being genetically limited, most parvoviruses require actively dividing host cells and are host and/or tissue specific. Some cause diseases, which range from subclinical to lethal. A few require co-infection with helper viruses from other families. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the Parvoviridae, which is available at www.ictv.global/report/parvoviridae.

Methylation Status of the Adeno-Associated Virus Type 2 (AAV2)

To analyze the methylation status of wild-type adeno-associated virus type 2 (AAV2), bisulfite PCR sequencing (BPS) of the packaged viral genome and its integrated form was performed and 262 of the total 266 CG dinucleotides (CpG) were mapped. In virion-packaged DNA, the ratio of the methylated cytosines ranged between 0⁻1.7%. In contrast, the chromosomally integrated AAV2 genome was hypermethylated with an average of 76% methylation per CpG site. The methylation level showed local minimums around the four known AAV2 promoters. To study the effect of methylation on viral rescue and replication, the replication initiation capability of CpG methylated and non-CpG methylated AAV DNA was compared. The in vitro hypermethylation of the viral genome does not inhibit its rescue and replication from a plasmid transfected into cells. This insensitivity of the viral replicative machinery to methylation may permit the rescue of the integrated heavily methylated AAV genome from the host's chromosomes.

An Atypical Parvovirus Drives Chronic Tubulointerstitial Nephropathy and Kidney Fibrosis

The occurrence of a spontaneous nephropathy with intranuclear inclusions in laboratory mice has puzzled pathologists for over 4 decades, because its etiology remains elusive. The condition is more severe in immunodeficient animals, suggesting an infectious cause. Using metagenomics, we identify the causative agent as an atypical virus, termed "mouse kidney parvovirus" (MKPV), belonging to a divergent genus of Parvoviridae. MKPV was identified in animal facilities in Australia and North America, is transmitted via a fecal-oral or urinary-oral route, and is controlled by the adaptive immune system. Detailed analysis of the clinical course and histopathological features demonstrated a stepwise progression of pathology ranging from sporadic tubular inclusions to tubular degeneration and interstitial fibrosis and culminating in renal failure. In summary, we identify a widely distributed pathogen in laboratory mice and establish MKPV-induced nephropathy as a new tool for elucidating mechanisms of tubulointerstitial fibrosis that shares molecular features with chronic kidney disease in humans.

Intracellular Localization of Blattella germanica Densovirus (BgDV1) Capsid Proteins

Densovirus genome replication and capsid assembly take place in the nucleus of the infected cells. However, the mechanisms underlying such processes as the delivery of virus proteins to the nucleus and the export of progeny virus from the nucleus remain elusive. It is evident that nuclear transport signals should be involved in these processes. We performed an in silico search for the putative nuclear localization signal (NLS) and nuclear export signal (NES) motifs in the capsid proteins of the Blattella germanica Densovirus 1 (BgDV1) densovirus. A high probability NLS motif was found in the common C-terminal of capsid proteins together with a NES motif in the unique N-terminal of VP2. We also performed a global search for the nuclear traffic signals in the densoviruses belonging to five Densovirinae genera, which revealed high diversity in the patterns of NLSs and NESs. Using a heterologous system, the HeLa mammalian cell line expressing GFP-fused BgDV1 capsid proteins, we demonstrated that both signals are functionally active. We suggest that the NLS shared by all three BgDV1 capsid proteins drives the trafficking of the newly-synthesized proteins into the nucleus, while the NES may play a role in the export of the newly-assembled BgDV1 particles into the cytoplasm through nuclear pore complexes.

Novel Parvoviruses from Wild and Domestic Animals in Brazil Provide New Insights into Parvovirus Distribution and Diversity

Parvoviruses (family Parvoviridae) are small, single-stranded DNA viruses. Many parvoviral pathogens of medical, veterinary and ecological importance have been identified. In this study, we used high-throughput sequencing (HTS) to investigate the diversity of parvoviruses infecting wild and domestic animals in Brazil. We identified 21 parvovirus sequences (including twelve nearly complete genomes and nine partial genomes) in samples derived from rodents, bats, opossums, birds and cattle in Pernambuco, São Paulo, Paraná and Rio Grande do Sul states. These sequences were investigated using phylogenetic and distance-based approaches and were thereby classified into eight parvovirus species (six of which have not been described previously), representing six distinct genera in the subfamily Parvovirinae. Our findings extend the known biogeographic range of previously characterized parvovirus species and the known host range of three parvovirus genera (Dependovirus, Aveparvovirus and Tetraparvovirus). Moreover, our investigation provides a window into the ecological dynamics of parvovirus infections in vertebrates, revealing that many parvovirus genera contain well-defined sub-lineages that circulate widely throughout the world within particular taxonomic groups of hosts.

Atomic Resolution Structure of the Oncolytic Parvovirus LuIII by Electron Microscopy and 3D Image Reconstruction

LuIII, a protoparvovirus pathogenic to rodents, replicates in human mitotic cells, making it applicable for use to kill cancer cells. This virus group includes H-1 parvovirus (H-1PV) and minute virus of mice (MVM). However, LuIII displays enhanced oncolysis compared to H-1PV and MVM, a phenotype mapped to the major capsid viral protein 2 (VP2). This suggests that within LuIII VP2 are determinants for improved tumor lysis. To investigate this, the structure of the LuIII virus-like-particle was determined using single particle cryo-electron microscopy and image reconstruction to 3.17 Å resolution, and compared to the H-1PV and MVM structures. The LuIII VP2 structure, ordered from residue 37 to 587 (C-terminal), had the conserved VP topology and capsid morphology previously reported for other protoparvoviruses. This includes a core β-barrel and α-helix A, a depression at the icosahedral 2-fold and surrounding the 5-fold axes, and a single protrusion at the 3-fold axes. Comparative analysis identified surface loop differences among LuIII, H-1PV, and MVM at or close to the capsid 2- and 5-fold symmetry axes, and the shoulder of the 3-fold protrusions. The 2-fold differences cluster near the previously identified MVM sialic acid receptor binding pocket, and revealed potential determinants of protoparvovirus tumor tropism.

Frequency of human parvovirus 4 (PARV4) viremia among HBV-infected patients and healthy donors in Shiraz, Iran

BACKGROUND/AIM

PARV4, a small DNA virus belonging to the family Parvoviridae, was first isolated in an HBV injecting drug user. Several studies have investigated PARV4 co-infection with HBV and HCV and its effect on the progression of liver disease. The aim of this study was to determine the frequency of PARV4 among HBV-infected patients and healthy individuals.

MATERIALS AND METHODS

A group of 90 HBV patients and a group of 90 healthy subjects were included in this study. Samples were selected after screening tests such as HBsAg ELISA, anti-HCV ELISA, and anti-HIV ELISA. Nested-PCRs were conducted to detect the PARV4 genome. Positive samples were then subjected to DNA sequencing.

RESULTS

PARV4 DNA was detected in 4.4% of HBV patients in comparison with 1.1% of healthy individuals (P-value: 0.36). DNA sequencing results revealed that PARV4 in all five positive samples was genotype I.Conclusions: Although this pilot study showed no significant difference between the frequency of PARV4 among HBV patients and healthy donors, further studies with a larger sample size are suggested to determine the association of PARV4 with HBV co-infection and the impact of this virus on the progression of liver disease in patients with hepatitis B.

Virotherapy of digestive tumors with rodent parvovirus: overview and perspectives

INTRODUCTION

Toolan's H-1 parvovirus (H-1PV) exerts a cytotoxic/oncolytic effect, predominantly mediated by its non-structural protein (NS1). This rat parvovirus is harmless, unlike other parvoviruses, and its antitumor potential may be useful to clinicians as its oncolytic action appears to be true in numerous non-digestive and digestive cancers.

AREAS COVERED

After a brief review of parvovirus genus and biology, we summarize the proposed mechanisms to explain the cytotoxicity of H-1PV to tumors which results in dysregulation of cell transcription, cell-cycle arrest, termination of cell replication, activation of cellular stress response and induction of cell death. Viral oncolysis induces a strong tumor-specific immune response leading to the recognition and elimination of minimal residual disease. As the action of H-1PV is not limited to the digestive tract, we initially analyse studies performed in non-digestive cancers such as glioma (as the virus is able to cross the blood brain barrier), and then focused more particularly on the results in digestive cancers.

EXPERT OPINION

Based on the results of studies showing little H-1PV toxicity to living bodies, we advocate for the use of the parvovirus in cancers such as melanoma, glioma and pancreatic ductal adenocarcinoma in addition to conventional chemotherapy.

Discovery of a novel Parvovirinae virus, porcine parvovirus 7, by metagenomic sequencing of porcine rectal swabs

Parvoviruses are a diverse group of viruses containing some of the smallest known species that are capable of infecting a wide range of animals. Metagenomic sequencing of pooled rectal swabs from adult pigs identified a 4103-bp contig consisting of two major open reading frames encoding proteins of 672 and 469 amino acids (aa) in length. BLASTP analysis of the 672-aa protein found 42.4 % identity to fruit bat (Eidolon helvum) parvovirus 2 (EhPV2) and 37.9 % to turkey parvovirus (TuPV) TP1-2012/HUN NS1 proteins. The 469-aa protein had no significant similarity to known proteins. Genetic and phylogenetic analyses suggest that PPV7, EhPV2, and TuPV represent a novel genus in the family Parvoviridae. Quantitative PCR screening of 182 porcine diagnostic samples found a total of 16 positives (8.6 %). Together, these data suggest that PPV7 is a highly divergent novel parvovirus prevalent within the US swine.

Comparative paleovirological analysis of crustaceans identifies multiple widespread viral groups

Background

The discovery of many fragments of viral genomes integrated in the genome of their eukaryotic host (endogenous viral elements; EVEs) has recently opened new avenues to further our understanding of viral evolution and of host-virus interactions. Here, we report the results of a comprehensive screen for EVEs in crustaceans. Following up on the recent discovery of EVEs in the terrestrial isopod, Armadillidium vulgare, we scanned the genomes of six crustacean species: a terrestrial isopod (Armadillidium nasatum), two water fleas (Daphnia pulex and D. pulicaria), two copepods (the salmon louse, Lepeophtheirus salmonis and Eurytemora affinis), and a freshwater amphipod (Hyalella azteca).

Results

In total, we found 210 EVEs representing 14 different lineages belonging to five different viral groups that are present in two to five species: Bunyaviridae (−ssRNA), Circoviridae (ssDNA), Mononegavirales (−ssRNA), Parvoviridae (ssDNA) and Totiviridae (dsRNA). The identification of shared orthologous insertions between A. nasatum and A. vulgare indicates that EVEs have been maintained over several millions of years, although we did not find any evidence supporting exaptation. Overall, the different degrees of EVE degradation (from none to >10 nonsense mutations) suggest that endogenization has been recurrent during the evolution of the various crustacean taxa. Our study is the first to report EVEs in D. pulicaria, E. affinis and H. azteca, many of which are likely to result from recent endogenization of currently circulating viruses.

Conclusions

In conclusion, we have unearthed a large diversity of EVEs from crustacean genomes, and shown that four of the five viral groups we uncovered (Bunyaviridae, Circoviridae, Mononegavirales, Parvoviridae) were and may still be present in three to four highly divergent crustacean taxa. In addition, the discovery of recent EVEs offers an interesting opportunity to characterize new exogenous viruses currently circulating in economically or ecologically important copepod species.

Electronic supplementary material

The online version of this article (doi:10.1186/s13100-015-0047-3) contains supplementary material, which is available to authorized users.

Novel bocaparvoviruses in rabbits

Bocaparvovirus is a newly established genus within the family Parvoviridae and has been identified as a possible cause of enteric, respiratory, reproductive/neonatal and neurological disease in humans and several animal species. In this study, metagenomic analysis was used to identify and characterise a novel bocaparvovirus in the faeces of rabbits with enteric disease. To assess the prevalence of the novel virus, rectal swabs and faecal samples obtained from rabbits with and without diarrhoea were screened with a specific PCR assay. The complete genome sequence of the novel parvovirus was reconstructed. The virus was distantly related to other bocaparvoviruses; the three ORFs shared 53%, 53% and 50% nucleotide identity, respectively, to homologous genes of porcine bocaparvoviruses. The virus was detected in 8/29 (28%) and 16/95 (17%) samples of rabbits with and without diarrhoea, respectively. Sequencing of the capsid protein fragment targeted by the diagnostic PCR identified two distinct bocaparvovirus populations/sub-types, with 91.7-94.5% nucleotide identity to each other. Including these novel parvoviruses in diagnostic algorithms of rabbit diseases might help inform their potential pathogenic role and impact on rabbit production and the virological profiles of laboratory rabbits.

Aleutian Disease: An Emerging Disease in Free-Ranging Striped Skunks (Mephitis mephitis) From California

Aleutian disease virus (ADV, Amdovirus, Parvoviridae) primarily infects farmed mustelids (mink and ferrets) but also other fur-bearing animals and humans. Three Aleutian disease (AD) cases have been described in captive striped skunks; however, little is known about the relevance of AD in free-ranging carnivores. This work describes the pathological findings and temporospatial distribution in 7 cases of AD in free-ranging striped skunks. All cases showed neurologic disease and were found in a 46-month period (2010-2013) within a localized geographical region in California. Lesions included multisystemic plasmacytic and lymphocytic inflammation (ie, interstitial nephritis, myocarditis, hepatitis, meningoencephalitis, pneumonia, and splenitis), glomerulonephritis, arteritis with or without fibrinoid necrosis in several organs (ie, kidney, heart, brain, and spleen), splenomegaly, ascites/hydrothorax, and/or encephalomalacia with cerebral microangiopathy. ADV infection was confirmed in all cases by specific polymerase chain reaction and/or in situ hybridization. The results suggest that AD is an emerging disease in free-ranging striped skunks in California.

What is for dinner? Viral metagenomics of US store bought beef, pork, and chicken

We describe here the metagenomics-derived viral sequences detected in beef, pork, and chicken purchased from stores in San Francisco. In beef we detected four previously reported viruses (two parvoviruses belonging to different genera, an anellovirus, and one circovirus-like virus) and one novel bovine polyomavirus species (BPyV2-SF) whose closest relatives infect primates. Detection of porcine hokovirus in beef indicated that this parvovirus can infect both ungulate species. In pork we detected four known parvoviruses from three genera, an anellovirus, and pig circovirus 2. Chicken meat contained numerous gyrovirus sequences including those of chicken anemia virus and of a novel gyrovirus species (GyV7-SF). Our results provide an initial characterization of some of the viruses commonly found in US store-bought meats which included a diverse group of parvoviruses and viral families with small circular DNA genomes. Whether any of these viruses can infect humans will require testing human sera for specific antibodies.

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Eukaryotic viral genomes in store-bought beef, pork, and chicken are identified.

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A novel bovine polyomavirus genome, closest to a group of viruses from primates, is sequenced.

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Porcine hokovirus is detected in beef samples.

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A small circovirus-like circular DNA genome in beef is genetically characterized.

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Several species of gyrovirus including a novel species are detected in chicken meat.

[Bocavirus: a new human parvovirus]

A new virus was recently discovered by molecular techniques in respiratory samples collected from young children with respiratory disease. This virus, which represents a new member of the Parvoviridae family is genetically related to the bovine parvovirus and the canine minute virus that belong to the Bocavirus genus. It has been classified in the Bocavirus genus and named human bocavirus (HBoV). Recent studies conducted in different countries have shown that HBoV is found in 3 to 18 %of children with respiratory disease worldwide. Genetic analysis indicate that this virus shows low genetic variability. The clinical signs observed in patients infected with HBoV are not different from those caused by other respiratory viruses.A frequent association of HBoV with other respiratory pathogens may be observed. Therefore, the exact role played by this virus in human diseases still remains unclear. Further studies including control populations are needed to ascertain the pathogenic potential of this virus.

Le bocavirus humain (HboV) un nouveau pathogene respiratoire?

Un nouveau virus a été très récemment identifié par biologie moléculaire dans des prélèvements respiratoires chez de jeunes enfants. Ce virus est un nouveau représentant de la famille des Parvoviridae et a été classé dans le genre Bocavirus aux côtés du parvovirus bovin (BPV) et du virus minute canin (MCV). Quelques études ont depuis été conduites sur ce virus qui est désormais appelé le bocavirus humain (HboV). Les premières conclusions sur l'épidémiologie de ce nouveau virus révèlent une prévalence assez importante, comprise entre 3 à 10 % des infections respiratoires de l'enfant, une association fréquente avec d'autres virus respiratoires, une répartition mondiale et l'absence de réelle distribution saisonnière. Un seul type viral semble circuler dans la population cible qui apparaît être essentiellement les jeunes enfants. Les données cliniques disponibles ne permettent pas la mise en évidence de spécificité par rapport aux autres viroses respiratoires. A ce jour, les liens de causalité entre la présence de ce nouveau virus découvert par génie moléculaire et une pathologie respiratoire sont loin d'être établis. Le rôle exact du HBoV en pathologie humaine reste donc à confirmer.