RESUMO
Circovirids have a circular single-stranded DNA genome packed into a small icosahedral capsid. They are classified within two genera, Circovirus and Cyclovirus, in the family Circoviridae (phylum Cressdnaviricota, class Arfiviricetes, order Cirlivirales). Over the last five years, a number of new circovirids have been identified, and, as a result, 54 new species have been created for their classification based on the previously established species demarcation criterion, namely, that viruses classified into different species share less than 80% genome-wide pairwise sequence identity. Of note, one of the newly created species includes a circovirus that was identified in human hepatocytes and suspected of causing liver damage. Furthermore, to comply with binomial species nomenclature, all new and previously recognized species have been (re)named in binomial format with a freeform epithet. Here, we provide a summary of the properties of circovirid genomes and their classification as of June 2024 (65 species in the genus Circovirus and 90 species in the genus Cyclovirus). Finally, we provide reference datasets of the nucleotide and amino acid sequences representing each of the officially recognized circovirid species to facilitate further classification of newly discovered members of the Circoviridae.
Assuntos
Circoviridae , Genoma Viral , Filogenia , Circoviridae/genética , Circoviridae/classificação , Circoviridae/isolamento & purificação , Humanos , DNA Viral/genética , AnimaisRESUMO
Several bat-associated circoviruses and circular rep-encoding single-stranded DNA (CRESS DNA) viruses have been described, but the exact diversity and host species of these viruses are often unknown. Our goal was to describe the diversity of bat-associated circoviruses and cirliviruses, thus, 424 bat samples from more than 80 species were collected on four continents. The samples were screened for circoviruses using PCR and the resulting amino acid sequences were subjected to phylogenetic analysis. The majority of bat strains were classified in the genus Circovirus and some strains in the genus Cyclovirus and the clades CRESS1 and CRESS3. Some strains, however, could only be classified at the taxonomic level of the order and were not classified in any of the accepted or proposed clades. In the family Circoviridae, 71 new species have been predicted. This screening of bat samples revealed a great diversity of circoviruses and cirliviruses. These studies underline the importance of the discovery and description of new cirliviruses and the need to establish new species and families in the order Cirlivirales.
Assuntos
Quirópteros , Infecções por Circoviridae , Circoviridae , Circovirus , Animais , Circovirus/genética , Filogenia , Circoviridae/genética , Sequência de Aminoácidos , Genoma Viral , Infecções por Circoviridae/genética , Infecções por Circoviridae/veterináriaRESUMO
Viruses in the family Circoviridae have small circular single-stranded DNA (ssDNA) genomes. Circoviruses are known to infect a wide variety of animals, with notable disease pathology in psittacine (psittacine beak and feather disease) and porcine (postweaning multisystemic wasting syndrome) species. There is still a dearth of research investigating circoviruses associated with felid species. In six fecal samples collected from bobcats (Lynx rufus) in California from 2010 to 2011, we identified six viruses belonging to the genera Circovirus (n = 1) and Cyclovirus (n = 5), using a high-throughput-sequencing-based approach. Of these, the virus in the genus Circovirus represents a new species, as it shares only 54-60% genome-wide sequence identity with the other members of this genus. The five viruses in the genus Cyclovirus represent three new species, sharing <73% genome-wide sequence identity with all other cycloviruses. Three of the cycloviruses belong to a single putative species and were obtained from the feces of three individual bobcats, sharing 95.7-99.9% sequence identity, whereas the other two unique cycloviruses were identified in a single fecal sample. At present, it is unknown whether the identified viruses infect bobcats, their prey, or their gut parasites.
Assuntos
Circoviridae , Circovirus , Lynx , Animais , Suínos , Circoviridae/genética , Circovirus/genética , California , Fezes , DNA de Cadeia Simples , Filogenia , Genoma ViralRESUMO
Replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA viruses comprise viruses with covalently closed, circular, single-stranded DNA (ssDNA) genomes, and are considered the smallest known autonomously replicating, capsid-encoding animal pathogens. CRESS DNA viruses (phylum Cressdnaviricota) encompass several viral families including Circoviridae. Circoviruses are classified into two genera, Circovirus and Cyclovirus, and they are known to cause fatal diseases in birds and pigs. Circoviruses have also been identified in human stools, blood, and cerebrospinal fluid (CSF), as well as in various wild and domestic vertebrates, including reptiles. The synanthropic presence of Squamata reptiles has increased in the last century due to the anthropic pressure, which has shifted forested animal behavior to an urban and peri-urban adaptation. In this paper, we explored the diversity of CRESS DNA viruses in Squamata reptiles from different Italian areas representative of the Mediterranean basin. CRESS DNA viruses were detected in 31.7% (33/104) of sampled lizards and geckoes. Different CRESS DNA viruses likely reflected dietary composition or environmental contamination and included avian-like (n = 3), dog (n = 4), bat-like (n = 1), goat-like (n = 1), rodent-like (n = 4), and insect-like (n = 2) viruses. Rep sequences of at least two types of human-associated cycloviruses (CyV) were identified consistently, regardless of geographic location, namely, TN9-like (n = 11) and TN12-like (n = 6). A third human-associated CyV, TN25-like, was detected in a single sample. The complete genome of human-like CyVs, of a rodent-like, insect-like, and of a bat-like virus were generated. Collectively, the results recapitulate hosts dietary and environmental sources of exposure and may suggest unexpected ecological niches for some CRESS DNA viruses. IMPORTANCE CRESS DNA viruses are significant pathogens of birds and pigs and have been detected repeatedly in human samples (stools, serum, and cerebrospinal fluid), both from healthy individuals and from patients with neurological disease, eliciting in 2013 a risk assessment by the European Centre for Disease Prevention and Control (ECDC). Sequences of CRESS DNA viruses previously reported in humans (TN9, TN12, and TN25), and detected in different animal species (e.g., birds, dogs, and bats) were herein detected in fecal samples of synanthropic squamates (geckos and lizards). The complete genome sequence of six viruses was generated. This study extends the information on the genetic diversity and ecology of CRESS DNA viruses. Because geckos and lizards are synanthropic animals, a role in sustaining CRESS DNA virus circulation and increasing viral pressure in the environment is postulated.
Assuntos
Brassicaceae , Circoviridae , Animais , Aves/genética , Brassicaceae/genética , Circoviridae/genética , Vírus de DNA/genética , DNA de Cadeia Simples , DNA Viral/genética , Cães , Genoma Viral , Filogenia , SuínosRESUMO
The first representative of a seemingly novel virus family has been found during the metagenomic examination of a diseased and dead horse in the USA [Li et al. in J Gen Virol 96:2721-2733, 2015]. These authors have suggested the need for the establishment of a new family with the tentative name Kirkoviridae; however, the suggested name is not official yet. Soon after the discovery, similar, relatively large CRESS-DNA viruses have been detected in various animals in China and elsewhere. Besides the two main genes (rep and cap), characteristic for members of the family Circoviridae, the tentative kirkoviruses have considerably larger genomes of approximately 4000 nucleotides. Accordingly, these viruses possess three four additional ORFs coding for proteins of unknown function. This has been described previously. In the present manuscript, the authors report the sequence of kirkovirus-like viruses, detected by PCR in donkey excretes in China. From 73 samples, 8 were found positive. From three of these newly detected viruses, the full genomic sequence was determined, whereas from the other five only one gene, namely the replication-associated (Rep) protein was sequenced.
Assuntos
Circoviridae , Genoma Viral , Animais , Circoviridae/genética , Equidae/genética , Variação Genética , Genoma Viral/genética , FilogeniaRESUMO
Nested PCRs with circovirus/cyclovirus pan-rep (replicase gene) primers detected eukaryotic circular Rep-encoding single-stranded DNA (CRESS DNA) viruses in three (samples CN9E, CN16E and CN34) of 18 canine parvovirus-2-positive fecal samples from household dogs with hemorrhagic gastroenteritis on the Caribbean island of Nevis. The complete genomes of CRESS DNA virus CN9E, CN16E and CN34 were determined by inverse nested PCRs. Based on (i) genome organization, (ii) location of the putative origin of replication, (iii) pairwise genome-wide sequence identities, (iv) the presence of conserved motifs in the putative replication-associated protein (Rep) and the arginine-rich region in the amino terminus of the putative capsid protein (Cp) and (v) a phylogenetic analysis, CN9E, CN16E and CN34 were classified as cycloviruses. Canine-associated cycloviruses CN16E and CN34 were closely related to each other and shared low genome-wide nucleotide (59.642-59.704%), deduced Rep (35.018-35.379%) and Cp (26.601%) amino acid sequence identities with CN9E. All the three canine-associated cycloviruses shared < 80% genome-wide pairwise nucleotide sequence identities with cycloviruses from other animals/environmental samples, constituting two novel species (CN9E and CN16E/34) within the genus Cyclovirus. Considering the feeding habits of dogs, we could not determine whether the cycloviruses were of dietary origin or infected the host. Interestingly, the CN9E putative Rep-encoding open reading frame was found to use the invertebrate mitochondrial genetic code with an alternative initiation codon (ATA) for translation, corroborating the hypothesis that cycloviruses are actually arthropod-infecting viruses. To our knowledge, this is the first report on the detection and complete genome analysis of cycloviruses from domestic dogs.
Assuntos
Circoviridae/classificação , Circoviridae/isolamento & purificação , Doenças do Cão/virologia , Gastroenterite/virologia , Filogenia , Sequência de Aminoácidos , Animais , Proteínas do Capsídeo/genética , Circoviridae/genética , Vírus de DNA/genética , DNA Viral/genética , Cães , Fezes/virologia , Genoma Viral , Sequenciamento de Nucleotídeos em Larga Escala , Fases de Leitura Aberta , Parvovirus Canino/classificação , Parvovirus Canino/genética , Parvovirus Canino/isolamento & purificação , São Cristóvão e Névis , Análise de Sequência de DNA , Sequenciamento Completo do GenomaRESUMO
Members of the family Circoviridae are known to infect several avian species, with the ability to cause severe disease outcomes in some species. Using a high-throughput sequencing-informed approach, we identified two novel lineages of circoviruses, referred to as wigfec circovirus 1 and 2, in faecal matter of American wigeons (Mareca americana) collected in Arizona, USA. Wigfec circovirus 1 was identified in eight samples and is most closely related to the other waterfowl circoviruses, sharing ~64% genome-wide sequence identity with duck circoviruses. On the other hand, wigfec circovirus 2 was identified in two samples and is most closely related to two circoviruses identified in bat samples, sharing ~71% genome-wide pairwise identity. Both novel circoviruses were recovered from samples collected at the same location two months apart. Furthermore, in one sample, both of these viruses were identified, indicating these viruses are likely common amongst these birds and/or their environment.
Assuntos
Infecções por Circoviridae , Circoviridae , Circovirus , Animais , Circoviridae/genética , Infecções por Circoviridae/veterinária , Circovirus/genética , Patos , Genoma Viral , FilogeniaRESUMO
Fecal samples from 76 of 83 apparently healthy small Indian mongooses (Urva auropunctata) were PCR positive with circovirus/cyclovirus pan-rep (replicase gene) primers. In this case, 30 samples yielded high quality partial rep sequences (~400 bp), of which 26 sequences shared maximum homology with cycloviruses from an arthropod, bats, humans or a sheep. Three sequences exhibited maximum identities with a bat circovirus, whilst a single sequence could not be assigned to either genus. Using inverse nested PCRs, the complete genomes of mongoose associated circoviruses (Mon-1, -29 and -66) and cycloviruses (Mon-20, -24, -32, -58, -60 and -62) were determined. Mon-1, -20, -24, -29, -32 and -66 shared <80% maximum genome-wide pairwise nucleotide sequence identities with circoviruses/cycloviruses from other animals/sources, and were assigned to novel circovirus, or cyclovirus species. Mon-58, -60 and -62 shared maximum pairwise identities of 79.90-80.20% with human and bat cycloviruses, which were borderline to the cut-off identity value for assigning novel cycloviral species. Despite high genetic diversity, the mongoose associated circoviruses/cycloviruses retained the various features that are conserved among members of the family Circoviridae, such as presence of the putative origin of replication (ori) in the 5'-intergenic region, conserved motifs in the putative replication-associated protein and an arginine rich region in the amino terminus of the putative capsid protein. Since only fecal samples were tested, and mongooses are polyphagous predators, we could not determine whether the mongoose associated circoviruses/cycloviruses were of dietary origin, or actually infected the host. To our knowledge, this is the first report on detection and complete genome analysis of circoviruses/cycloviruses in the small Indian mongoose, warranting further studies in other species of mongooses.
Assuntos
Infecções por Circoviridae/veterinária , Circoviridae/genética , Circoviridae/isolamento & purificação , Circovirus/genética , Circovirus/isolamento & purificação , Genoma Viral , Herpestidae/virologia , Animais , Circoviridae/classificação , Circovirus/classificação , DNA Viral/genética , Fezes/virologia , Sequenciamento de Nucleotídeos em Larga Escala , Índia , Filogenia , Análise de Sequência de DNARESUMO
Circoviridae is a family of circular single-stranded DNA viruses whose members infect a wide variety of hosts. While well characterized in avian and mammalian hosts, little is known about circoviruses associated with Antarctic animals. From 48 Weddell seal (Leptonychotes weddellii) fecal samples collected on the sea ice in McMurdo between Nov 2014 and Dec 2014, we identified and determined the genomes of novel viruses that fall within two genera of the family Circoviridae, i.e. Circovirus (n = 7) and Cyclovirus (n = 45). We named these viruses as werosea circovirus (WerCV) and werosea cyclovirus (WerCyV). The genomes of WerCV and WerCyV share ~63-64% genome-wide pairwise identity with classified circoviruses and cycloviruses, respectively. Based on the species demarcation threshold of 80% for members of the Circoviridae, the genomes of WerCV and WerCyV represent new species in their respective genera. Evidence indicated recombination in five of the 45 WerCyV genomes identified in this study. These are the first circoviruses found associated with Antarctic pinnipeds, adding to those recently identified associated with Adélie (Pygoscelis adeliae) and chinstrap penguins (P. antarcticus).
Assuntos
Infecções por Circoviridae/veterinária , Circoviridae/isolamento & purificação , Genoma Viral , Animais , Circoviridae/classificação , Circoviridae/genética , Infecções por Circoviridae/virologia , Circovirus/classificação , Circovirus/genética , Circovirus/isolamento & purificação , Focas VerdadeirasRESUMO
Cycloviruses (CyV) (genus Cyclovirus, family Circoviridae) are nonenveloped DNA viruses. The first report in humans was in 2010 and research has focused only on disease-associated human sample detection. The only HuACyV (CyCV-ChileNPA1, HuACyV10) reported in the Chilean population was in children (3.3%) with an acute respiratory infection. Its detection in respiratory samples from adults, with/without respiratory disease remains unknown. The aim of this study was to detect HuACyV10 in adults with and without respiratory disease. HuACyV10 was studied in nasopharyngeal swabs from 105 hospitalized adults with community-acquired pneumonia (CAP) and 104 adults without respiratory symptoms. Total nucleic acids were extracted, and viral rep and cp gene fragments were amplified by real-time polymerase chain reaction. HuACyV10 was detected in 19.05% adults with CAP and in 0.96% asymptomatic adults, being significantly higher in adult CAP than asymptomatic (n = 1) ones (p = 0.0001). C t values were between 26.7 and 39.6, and the median was 34.1 for rep and 33.8 for the CAP in adults CAP (p = 0.68), and 35.7 and 36.0, respectively, in the asymptomatic case. HuACyV10 detection in CAP adults concentrated in the Autumn-Winter season of the Southern hemisphere. The only asymptomatic adult with HuACyV10 was detected in the Spring-Summer period. In this first report of HuACyV10 in respiratory samples from adults, detection was significantly higher in CAP than in asymptomatic adults. As the sensitivity of both rep and cp genes was similar, both can be applied for detecting HuACyV10. It would be advisable to investigate the pathogenic role of HuACyV10 in adult respiratory infections. â.
Assuntos
Infecções por Circoviridae/epidemiologia , Circoviridae/genética , Infecções Comunitárias Adquiridas/epidemiologia , Infecções Comunitárias Adquiridas/virologia , Pneumonia Viral/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Chile/epidemiologia , Circoviridae/isolamento & purificação , DNA Viral/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nasofaringe/virologia , Adulto JovemRESUMO
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.
Assuntos
Anelloviridae/genética , Circoviridae/genética , Vírus de DNA/genética , Genoma Viral/genética , Repetições de Microssatélites/genética , Parvoviridae/genética , DNA Viral/genética , Tamanho do Genoma/genética , Genômica/métodosRESUMO
Viral infections were investigated in American black bears (Ursus americanus) from Nevada and northern California with and without idiopathic encephalitis. Metagenomics analyses of tissue pools revealed novel viruses in the genera Circoviridae, Parvoviridae, Anelloviridae, Polyomaviridae, and Papillomaviridae. The circovirus and parvovirus were of particular interest due to their potential importance as pathogens. We characterized the genomes of these viruses and subsequently screened bears by PCR to determine their prevalence. The circovirus (Ursus americanus circovirus, UaCV) was detected at a high prevalence (10/16, 67%), and the chaphamaparvovirus (Ursus americanus parvovirus, UaPV) was found in a single bear. We showed that UaCV is present in liver, spleen/lymph node, and brain tissue of selected cases by in situ hybridization (ISH) and PCR. Infections were detected in cases of idiopathic encephalitis and in cases without inflammatory brain lesions. Infection status was not clearly correlated with disease, and the significance of these infections remains unclear. Given the known pathogenicity of a closely related mammalian circovirus, and the complex manifestations of circovirus-associated diseases, we suggest that UaCV warrants further study as a possible cause or contributor to disease in American black bears.
Assuntos
Doenças dos Animais/virologia , Circoviridae/patogenicidade , Encefalite Viral/virologia , Parvoviridae/patogenicidade , Ursidae/virologia , Doenças dos Animais/epidemiologia , Animais , Encéfalo/virologia , Circoviridae/genética , Circoviridae/isolamento & purificação , Código de Barras de DNA Taxonômico , Encefalite Viral/epidemiologia , Fígado/virologia , Metagenoma , Parvoviridae/genética , Parvoviridae/isolamento & purificação , Baço/virologia , Estados UnidosRESUMO
Wild birds are major natural reservoirs and potential dispersers of a variety of infectious diseases. As such, it is important to determine the diversity of viruses they carry and use this information to help understand the potential risks of spillover to humans, domestic animals, and other wildlife. We investigated the potential viral causes of paresis in long-standing, but undiagnosed, disease syndromes in wild Australian birds. RNA from diseased birds was extracted and pooled based on tissue type, host species, and clinical manifestation for metagenomic sequencing. Using a bulk and unbiased metatranscriptomic approach, combined with clinical investigation and histopathology, we identified a number of novel viruses from the families Astroviridae, Adenoviridae, Picornaviridae, Polyomaviridae, Paramyxoviridae, Parvoviridae, and Circoviridae in common urban wild birds, including Australian magpies, magpie larks, pied currawongs, Australian ravens, and rainbow lorikeets. In each case, the presence of the virus was confirmed by reverse transcription (RT)-PCR. These data revealed a number of candidate viral pathogens that may contribute to coronary, skeletal muscle, vascular, and neuropathology in birds of the Corvidae and Artamidae families and neuropathology in members of the Psittaculidae The existence of such a diverse virome in urban avian species highlights the importance and challenges in elucidating the etiology and ecology of wildlife pathogens in urban environments. This information will be increasingly important for managing disease risks and conducting surveillance for potential viral threats to wildlife, livestock, and human health.IMPORTANCE Wildlife naturally harbor a diverse array of infectious microorganisms and can be a source of novel diseases in domestic animals and human populations. Using unbiased RNA sequencing, we identified highly diverse viruses in native birds from Australian urban environments presenting with paresis. This research included the clinical investigation and description of poorly understood recurring syndromes of unknown etiology: clenched claw syndrome and black and white bird disease. As well as identifying a range of potentially disease-causing viral pathogens, this study describes methods that can effectively and efficiently characterize emergent disease syndromes in free-ranging wildlife and promotes further surveillance for specific pathogens of potential conservation and zoonotic concern.
Assuntos
Animais Selvagens/virologia , Doenças das Aves/epidemiologia , Aves/virologia , Infecções por Vírus de DNA/veterinária , Metagenoma , Infecções por Vírus de RNA/veterinária , Transcriptoma , Adenoviridae/classificação , Adenoviridae/genética , Adenoviridae/isolamento & purificação , Animais , Astroviridae/classificação , Astroviridae/genética , Astroviridae/isolamento & purificação , Austrália/epidemiologia , Doenças das Aves/virologia , Circoviridae/classificação , Circoviridae/genética , Circoviridae/isolamento & purificação , Cidades , Infecções por Vírus de DNA/epidemiologia , Infecções por Vírus de DNA/virologia , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Paramyxoviridae/classificação , Paramyxoviridae/genética , Paramyxoviridae/isolamento & purificação , Parvoviridae/classificação , Parvoviridae/genética , Parvoviridae/isolamento & purificação , Filogenia , Picornaviridae/classificação , Picornaviridae/genética , Picornaviridae/isolamento & purificação , Polyomaviridae/classificação , Polyomaviridae/genética , Polyomaviridae/isolamento & purificação , Infecções por Vírus de RNA/epidemiologia , Infecções por Vírus de RNA/virologiaRESUMO
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.
Assuntos
Vírus de DNA/genética , DNA de Cadeia Simples/genética , Genoma Viral/genética , Fígado/virologia , Suínos/virologia , Viroma/genética , Anelloviridae/genética , Animais , Brasil , Circoviridae/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Parvoviridae/genética , Doenças dos Suínos/virologiaRESUMO
The capsid protein (Cap) is the sole structural protein and the main antigen of porcine circovirus type 2 (PCV2). Structural loops of the Cap play crucial roles in viral genome packaging, capsid assembly, and virus-host interactions. Although the molecular mechanisms are yet unknown, the carboxyl terminus (CT) of the PCV2 Cap is known to play critical roles in the evolution, pathogenesis, and proliferation of this virus. In this study, we investigated functions of CT. Removal of this loop leads to abrogation of the in vitro Cap self-assembly into virus-like particles (VLPs). Likewise, the mutated virus resists rescue from PK15 cell culture. A conserved PXXP motif in the CT is dispensable for VLP assembly and subsequent cell entry. However, its removal leads to the subsequent failure of virus rescued from PK15 cells. Furthermore, substituting either the PCV1 counterpart or an AXXA for the PXXP motif still supports virus rescue from cell culture but results in a dramatic decrease in viral titers compared with wild type. In particular, a strictly conserved residue (227K) in the CT is essential for VLP entry into PK15 cells, and its mutation to alanine greatly attenuates cell entry of the VLPs, supporting a mechanism for the failure to rescue a mutated PCV2 infectious DNA clone (K227A) from PK15 cell culture. These results suggest the CT of the PCV2 Cap plays critical roles in virus assembly, viral-host cell interaction(s), and virus propagation in vitroIMPORTANCE The carboxyl terminus (CT) of porcine circovirus type 2 (PCV2) capsid protein (Cap) was previously reported to be associated with immunorecognition, alterations of viral titer in swine sera, and pathogenicity. However, the molecular mechanisms underlying these effects remain unknown. In this study, roles of the critical residues and motifs of the CT are investigated with respect to virus-like particle (VLP) assembly, cell entry, and viral proliferation. The results revealed that the positively charged 227K of the CT is essential for both cell entry of PCV2 VLPs and virus proliferation. Our findings, therefore, suggest that the CT should be considered one of the key epitopes, recognized by neutralizing antibodies, for vaccine design and a target for drug development to prevent PCV2-associated diseases (PCVADs). Furthermore, it is important to respect the function of 227K for its role in cell entry if using either PCV2 VLPs for nanoscale DNA/drug cell delivery or using PCV2 VLPs to display a variety of foreign epitopes for immunization.
Assuntos
Proteínas do Capsídeo/metabolismo , Circovirus/metabolismo , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/imunologia , Capsídeo/metabolismo , Proteínas do Capsídeo/genética , Circoviridae/genética , Circoviridae/metabolismo , Infecções por Circoviridae/genética , Infecções por Circoviridae/metabolismo , Circovirus/genética , Epitopos/imunologia , Suínos , Doenças dos Suínos/virologia , Vacinas de Partículas Semelhantes a Vírus/imunologia , Montagem de Vírus/genética , Internalização do VírusRESUMO
Cycloviruses, small ssDNA viruses belonging to the Circoviridae family, have been suggested as possible causes of enteric, respiratory and neurological disorders in human patients. One of these species, cyclovirus-Vietnam (CyCV-VN), initially isolated from cerebrospinal fluid samples of patients with unexplained neurological disorders, has since been reported in serum samples from chronically patients infected with HBV, HCV or HIV, in Italy. On the other hand, CyCV-VN was not detected in serum samples from healthy individuals. Here, we report on a high prevalence of 43.4% (40/92) of CyCV-VN in plasma samples from asymptomatic blood donors from Madagascar. Interestingly, this virus was not detected by metagenomics and PCR in six other African countries, suggesting regional differences in CyCV-VN prevalence across Africa. Phylogenetic analysis based on the complete genomes showed that CyCV-VN sequences isolated from blood were most closely related to sequences previously reported from human stool in Madagascar. Further investigations using larger cohorts are required to determine the global epidemiology, the natural history and the pathological significance, if any, of CyCV-VN infection in humans.
Assuntos
Doadores de Sangue , Infecções por Circoviridae/virologia , Circoviridae , Adolescente , Adulto , Circoviridae/classificação , Circoviridae/genética , Infecções por Circoviridae/sangue , DNA Viral , Feminino , Genoma Viral , Humanos , Madagáscar/epidemiologia , Masculino , Metagenômica/métodos , Pessoa de Meia-Idade , Filogenia , Prevalência , Vigilância em Saúde Pública , Adulto JovemRESUMO
Three cycloviruses (genus Cyclovirus, family Circoviridae) were recovered from a dragonfly (Odonata: Anisoptera) captured in Fuzhou, China. The three cycloviruses, named dragonfly associated cyclovirus 9, 10 and 11 (DfCyV-9, -10, -11), respectively, show 56.1-79.6% genome-wide identity to known cycloviruses and 61.6-65.1% among themselves. Thus, according to the current species demarcation criteria, they represent three novel cycloviruses. Notably, DfCyV-10 has a predicted replication-associated protein (Rep) that is most similar to that of bat associated cyclovirus 2 (BatACyV-2), a cyclovirus discovered in China, with 79.4% amino acid sequence identity, but a putative capsid protein (Cp) most similar to that of BatACyV-10, a cyclovirus discovered in Brazil, with 71.7% amino acid sequence identity. These data are useful for understanding the diversity and evolution of cycloviruses, especially those found in insects.
Assuntos
Proteínas do Capsídeo/genética , Circoviridae/genética , DNA Viral/genética , Genoma Viral , Odonatos/virologia , Filogenia , Sequência de Aminoácidos , Animais , Evolução Biológica , China , Circoviridae/classificação , Circoviridae/isolamento & purificação , Variação Genética , Conformação de Ácido Nucleico , Análise de Sequência de DNA , Sequenciamento Completo do GenomaRESUMO
Circular replication-associated protein encoding single-stranded DNA (CRESS DNA) viruses are increasingly recognized worldwide in a variety of samples. Representative members include well-described veterinary pathogens with worldwide distribution, such as porcine circoviruses or beak and feather disease virus. In addition, numerous novel viruses belonging to the family Circoviridae with unverified pathogenic roles have been discovered in different human samples. Viruses of the family Genomoviridae have also been described as being highly abundant in different faecal and environmental samples, with case reports showing them to be suspected pathogens in human infections. In order to investigate the genetic diversity of these viruses in European bat populations, we tested guano samples from Georgia, Hungary, Romania, Serbia and Ukraine. This resulted in the detection of six novel members of the family Circoviridae and two novel members of the family Genomoviridae. Interestingly, a gemini-like virus, namely niminivirus, which was originally found in raw sewage samples in Nigeria, was also detected in our samples. We analyzed the nucleotide composition of members of the family Circoviridae to determine the possible host origins of these viruses. This study provides the first dataset on CRESS DNA viruses of European bats, and members of several novel viral species were discovered.
Assuntos
Quirópteros/virologia , Circoviridae/genética , Infecções por Vírus de DNA/epidemiologia , Vírus de DNA/genética , DNA de Cadeia Simples/genética , DNA Viral/genética , Genoma Viral , Sequência de Aminoácidos , Animais , Circoviridae/classificação , Circoviridae/isolamento & purificação , Infecções por Vírus de DNA/transmissão , Infecções por Vírus de DNA/virologia , Vírus de DNA/classificação , Vírus de DNA/isolamento & purificação , Europa Oriental/epidemiologia , Fezes/virologia , República da Geórgia/epidemiologia , Humanos , Filogenia , Replicação ViralRESUMO
The genome sequence of a novel avian cyclovirus is described in this study. The genome size and orientation of predicted genes was similar to those described in other vertebrate and insect origin cycloviruses. The greatest genome sequence identity was shared with a dragonfly cyclovirus (nt, 60.6%). Phylogenetic analysis showed marginal relatedness with another avian cyclovirus, the chicken associated cyclovirus 1. In contrast, along a short fragment of the replication-associated protein coding gene (rep) (spanning nt 1240-1710) the duck origin cyclovirus was very similar to human origin and honey bee origin rep sequences (human - TN4, 98%; honey bee - hb10, 100%). Related cyclovirus strains existing amongst various animal species living in diverse ecosystems and separated by large geographic distances show the need for additional studies to better understand the ecology and epidemiology of cycloviruses.
Assuntos
Circoviridae/classificação , Circoviridae/genética , Patos/virologia , Genoma Viral , Análise de Sequência de DNA , Animais , Circoviridae/isolamento & purificação , Ordem dos Genes , Genes Virais , Filogenia , Homologia de SequênciaRESUMO
The family Circoviridae comprises viruses with small, circular, single-stranded DNA (ssDNA) genomes, including the smallest known animal viruses. Members of this family are classified into two genera, Circovirus and Cyclovirus, which are distinguished by the position of the origin of replication relative to the coding regions and the length of the intergenic regions. Within each genus, the species demarcation threshold is 80â% genome-wide nucleotide sequence identity. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Circoviridae, which is available at www.ictv.global/report/circoviridae.