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At least 19 recordsLinked to original sources

[Role of stabilizing and splitting selection in evolution of of viruses from the Parvoviridae and Astroviridae families].

We had previously collected and analyzed, by phylogenetic methods, all genetic data available now for the Parvoviridae and Astroviridae families, which made it possible to define the evolutionary relations between the viruses as well as to depict a variety of events in the evolutionary history of the two families. The offered case study is dedicated to investigating the stabilizing and splitting selection types in the evolution of the discussed viral families. We analyzed the number of synonymous and non-synonymous nucleotide substitutions in the coding genomes' regions of the viruses. Finally, the stabilizing selection was shown to be a key factor in the evolution of parvoviruses and astroviruses.

Animals↗

Rapid and sensitive heterologous enzyme immunoassays for densonucleosis virus (Parvoviridae).

There exists a serious lack of rapid and sensitive methods to identify densonucleosis viruses and to discriminate among them. Two different enzyme-linked immunosorbent assays (ELISA) were adapted for this purpose, which were both significantly faster and more sensitive than currently used ELISA procedures. This increase in sensitivity was due to an improvement in the conjugation procedure of peroxidase to antibody, the establishment of the optimum conditions for the various incubations, an optimisation of the substrate (H2O2) concentration, and the use of a new H-donor. The speed of the assay could be considerably shortened by the use of polyethylene glycol-6000 (i.e. the total time of the assay needed for maximum sensitivity of the indirect assay was only 2 hours). The assays using peroxidase conjugates were found considerably more sensitive than those using alkaline phosphatase, which is very probably due to a more efficient and better controlled conjugation procedure for peroxidase. The virus could be detected in the pg to ng range in a large excess of nonspecific antigens and titers for the antisera usually exceeded 10(6). Small differences in the viruses could be detected. Several factors, which may influence the sensitivity and specificity of these densonucleosis virus assays, were further investigated.

Alkaline Phosphatase↗

Parvoviridae.

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Parvoviridae↗

Characterization of hepatopancreatic parvo-like virus, a second unusual parvovirus pathogenic for penaeid shrimps.

The hepatopancreatic parvo-like virus (HPV) of penaeid shrimp was extracted from infected shrimp tissues, purified and subsequently characterized. The viral particles, icosahedral in shape, are 22 nm in diameter and possess a buoyant density of 1.41 g/ml. They contain ssDNA, of approximately 5 kb in size which encodes a single polypeptide of 54 kDa. On the basis of its general characteristics this pathogenic agent belongs to the Parvoviridae family, but because of two unusual characteristics (capsid protein formed with a single polypeptide and genome structure more closely related to the autonomous parvoviruses rather than the densoviruses), it seems to constitute a novel group in the Parvoviridae family.

Animals↗

Parvovirus variation for disease: a difference with RNA viruses?

The Parvoviridae, a family of viruses with single-stranded DNA genomes widely spread from invertebrates to mammal and human hosts, display a remarkable evolutionary capacity uncommon in DNA genomes. Parvovirus populations show high genetic heterogeneity and large population sizes resembling the quasispecies found in RNA viruses. These viruses multiply in proliferating cells, causing acute, persistent or latent infections relying in the immunocompetence and developmental stage of the hosts. Some parvovirus populations in natural settings, such as carnivore autonomous parvoviruses or primate adeno associated virus, show a high degree of genetic heterogeneity. However, other parvoviruses such as the pathogenic B19 human erythrovirus or the porcine parvovirus, show little genetic variation, indicating different virus-host relationships. The Parvoviridae evolutionary potential in mammal infections has been modeled in the experimental system formed by the immunodeficient scid mouse infected by the minute virus of mice (MVM) under distinct immune and adaptive pressures. The sequence of viral genomes (close to 10(5) nucleotides) in emerging MVM pathogenic populations present in the organs of 26 mice showed consensus sequences not representing the complex distribution of viral clones and a high genetic heterogeneity (average mutation frequency 8.3 x 10(-4) substitutions/nt accumulated over 2-3 months). Specific amino acid changes, selected at a rate up to 1% in the capsid and in the NS2 nonstructural protein, endowed these viruses with new tropism and increased fitness. Further molecular analysis supported the notion that, in addition to immune pressures, the affinity of molecular interactions with cellular targets, as the Crml nuclear export receptor or the primary capsid receptor, as well as the adaptation to tissues enriched in proliferating cells, are major selective factors in the rapid parvovirus evolutionary dynamics.

Animals↗

Characterization of a new densovirus infecting the German cockroach, Blattella germanica.

A new DNA virus (Parvoviridae: Densovirinae, Densovirus) was isolated and purified from descendants of field-collected German cockroaches, Blattella germanica. Viral DNA and cockroach tissues infected with B. germanica densovirus (BgDNV) were examined by electron microscopy. Virus particles, about 20 nm in diameter, were observed both in the nucleus and in the cytoplasm of infected cells. Virus DNA proved to be a linear molecule of about 1.2 microm in length. BgDNV isolated from infected cockroaches infected successfully and could be maintained in BGE-2, a B. germanica cell line. The complete BgDNV genome was sequenced and analysed. Five open reading frames (ORFs) were detected in the 5335 nt sequence: two ORFS that were on one DNA strand encoded structural capsid proteins (69.7 and 24.8 kDa) and three ORFs that were on the other strand encoded non-structural proteins (60.2, 30.3 and 25.9 kDa). Three putative promoters and polyadenylation signals were identified. Structural analysis of the inverted terminal repeats revealed the presence of extended palindromes. The genome structure of BgDNV was compared with that of other members of the family Parvoviridae; the predicted amino acid sequences were aligned and subjected to phylogenetic analyses.

Animals↗

[Detection of TTV DNA in hepatocellular carcinoma].

A new hepatitis agent, TTV has been cloned from post-transfusion hepatitis patient sera. This virus has a single stranded DNA as genome, surrounded by viral capsid antigen without envelope. It might be a member of parvoviridae. But genome organization is far from the known parvoviridae such as B19 and adeno-associated virus. Although this virus could be a new causative agent for nonA-nonG hepatitis, high healthy carrier rate, no relation with hepatocellular carcinoma and no evidence of amplification in parencymal hepatocyte might lead to less importance in liver disease. It is necessary to accumulate further knowledge about this new agent for the coming transplantation medicine.

Base Sequence↗

[A densovirus of German cockroach Blatella germanica: detection, nucleotide sequence and genome organization].

A new Blattella germanica densovirus (BgDNV, Parvoviridae: Densovirinae, Densovirus) was found. Virus DNA and cockroach tissues infected with BgDNV were examined by electron microscopy. Virus particles about 20 nm in diameter were observed both in the nucleus and in the cytoplasm of infected cells. Virus DNA proved to be a linear molecule sized about 1.2 microns. The complete BgDNV genome was sequenced and analyzed. Five ORF were detected: two coded for structural capsid proteins and were on one DNA strand, and three coded for regulatory proteins and were on the other strand. Potential promoters and polyadenylation signals were identified. Structural analysis was performed for terminal inverted repeats containing extended palindromes. The genome structure of BgDNV was compared with that of other Parvoviridae.

Amino Acid Sequence↗

Analysis of the kinetic hairpin transfer model for parvoviral DNA replication.

All linear DNA molecules face special problems in replicating their 5' ends, as DNA polymerases add nucleotides only to pre-existing strands with free 3'-OH groups. Parvoviruses, a group of small animal viruses with a linear single-stranded DNA genome, cope with this problem by having palindromic terminal sequences that can fold back on themselves to form hairpin structures essential in priming DNA replication. The 3' terminal sequence that initiates replication becomes reversed in orientation during the process, and if the palindrome is imperfect, two different, reverse-complementary terminal sequences are generated. The relative abundances of the terminal sequence orientations at each end of the DNA molecules can be measured and give information about the replication process. From such clues, we developed a "kinetic hairpin transfer model" based on differential rates of hairpin formation and inversion processes depending on the conformations of the 3' termini. Numerical studies showed that this simple idea can account for the diverse pattern of DNA distributions observed in the family Parvoviridae. In this paper, we simplify the model to a set of coupled linear first-order ordinary differential equations in order to delineate its essential properties by Perron-Frobenius theory. Secondly, we examine our assumption of linear kinetics by modeling enzyme catalysis of the component steps of the hairpin transfer process. We show that the rate-determining step of the process is the binding of initiation complex to the self-priming hairpin structures. Furthermore, we find that if the replication machinery is saturated by DNA substrate late in an infection, the differential equations become non-linear but the steady-state DNA distribution is still given by the solution of our original linear equations.

Computer Simulation↗

Human bocavirus: prevalence and clinical spectrum at a children's hospital.

BACKGROUND: Molecular methods of pathogen discovery have recently led to the description of several new respiratory viruses. Human bocavirus (HBoV), a proposed member of the family Parvoviridae, is one of the most recently described respiratory viruses. Initial reports indicate that HBoV is a common cause of respiratory tract infection in children. METHODS: A total of 1474 nasal scraping specimens collected over a 20-month period were screened by polymerase chain reaction for the presence of HBoV nucleic acid. Positive results were confirmed with a second polymerase chain reaction assay from a different genomic region. The medical records of patients with positive results were reviewed for demographic and clinical data. RESULTS: HBoV DNA was identified in 82 samples (5.6%). The peak rate of HBoV infection occurred during the period of March through May in both 2004 and 2005. Sixty-three percent of infected patients were <12 months of age. The most common symptoms were cough, rhinorrhea, and fever. Other symptoms of interest included diarrhea and a "paroxysmal" cough that was clinically suspected to be caused by Bordetella pertussis. CONCLUSIONS: HBoV DNA is commonly present in children with upper and lower respiratory tract infections. The presence of a pertussis-like cough and diarrhea in association with HBoV infection merits further investigation.

Adolescent↗

Characterization of a parvovirus isolated from a pig fetus.

A small hemagglutinating virus belonging to the Parvoviridae Family was isolated from a 70 day-old pig fetus in a breeding herd in which infertility, metritis and abortions were reported. The virus, named 85/193L, was isolated either in primary pig kidney (PK) cells or in a continuous cell line of minipig kidney origin (MPK), both cell cultures actively growing. It produced a typical cytopathic effect (CPE) starting from the 3rd passage and intranuclear inclusions surrounded by a halo were observed in stained preparations. The isolate was completely resistant to ether, chloroform and to pH 3; it was not inactivated after treatment at 56 degrees C for 4 h and at 70 degrees C for 2 h, while it was completely inhibited by the 80 degrees C/30 min temperature. It contained deoxyribonucleic acid (DNA). The highest infectious titer was reached at 96 h post infection. The infectivity and the hemagglutinating activity of the isolated strain were both inhibited by the reference immune serum against NADL-2 pig parvovirus. This further confirmed that the 85/193L isolate belongs to the parvovirus genus.

Abortion, Veterinary↗

Rhesus and pig-tailed macaque parvoviruses: identification of two new members of the erythrovirus genus in monkeys.

We have previously reported the identification of a novel simian parvovirus in cynomolgus monkeys, which causes severe anemia in immunosuppressed cynomolgus monkeys and is currently being studied as an animal model for human B19 infection. We now report two similar outbreaks of anemia in rhesus and pig-tailed macaques associated with two distinct but similar simian parvoviruses (pig-tailed macaque and rhesus parvovirus). Both viruses have been cloned and over 5000 nucleotides sequenced from each virus. The viruses show marked similarities to other members of the Erythrovirus genus in the Parvoviridae family.

Amino Acid Sequence↗

Biochemical and genomic characterization of muscovy duck parvovirus.

A duck parvovirus (DPV) isolated from muscovy ducks during the epizootic in France in 1989 was purified from inoculated allanto-amniotic fluids by CsCl density gradient centrifugation and characterized. Full and empty non-enveloped icosahedral viral particles were observed banding at densities of 1.39 to 1.42 and 1.38 respectively, with a diameter of 22 to 23 nm. Viral proteins were analyzed by SDS-PAGE and the estimated molecular weights of the 3 major proteins were 91, 78 and 58 kDa. The nucleic acid was shown to be a single-stranded DNA of about 5,300 bases with terminal palindromic hairpins. These results confirm the previous classification of the virus in the family Parvoviridae established by Jestin et al. [14] on morphological and serological bases. The DPV DNA was reannealed indicating that complementary DNA strands were encapsidated. A partial restriction endonuclease map was also established. This work constitutes the first biochemical and genomic description of a muscovy duck parvovirus.

Animals↗

The association of calf serum with the contamination of BHK21 clone 13 suspension cells by a parvovirus serologically related to the minute virus of mice (MVM).

An investigation of persistent cell deaths of BHK21 suspension cells during subculturing resulted in the isolation of a viral agent. The agent was isolated from samples of dead cells, cell growth media and 2 batches of calf serum. It was established that the agent was associated with the use of certain batches of calf serum. The isolated virus was found to replicate effectively only in rapidly growing BHK cell cultures. In monolayers it caused the formation of large intranuclear inclusion bodies. The isolate was a strong haemagglutinin; it was stable to ether, chloroform, pH 3 and heating at 56 degrees C. It was shown to be a DNA-virus and by electron-microscopy it was evident as unenveloped spherical, small particles (21 nm in diameter). In sucrose density gradients the virus sedimented as 2 peaks at approximately 114S and 85-92S, and by caesium chloride equilibrium centrifugation, two main peaks at densities of 1.39 and 1.31 g/ml were evident with a minor peak at 1.35. The capsid of the complete virion consisted of 3 polypeptides. The agent has therefore been provisionally designated a member of the Parvoviridae family, genus parvovirus. Serologically it was found to be related to MVM. The isolated parvovirus was inactivated by 0.05 per cent peracetic acid and 0.05 per cent acetylethyleneimine.

Animals↗

Identification of aviadenovirus and dependoparvovirus in an Ad&#xe9;lie penguin fecal sample from Cape Royds (Ross Island, Antarctica).

Adenoviruses (Adenoviridae) and their associated replication-deficient dependoparvoviruses (Parvoviridae) are recognized as significant components of the avian virome. While well-studied in domestic birds, these viruses remain underexplored in wild Antarctic birds. Information is limited on viruses circulating in penguins, particularly outside of the Antarctic Peninsula Region. Here we leverage a fecal sample collected for diet analyses to identify an aviadenovirus (37,731 nt) and two distinct dependoparvoviruses. The Ad&#xe9;lie penguin (Pygoscelis adeliae) feces-derived adenovirus exhibits a genome organization consistent with members of the genus Aviadenovirus but shares only ~64% amino acid identity in the DNA polymerase protein with its closest known relative and thus represents a new species of aviadenovirus identified in penguins. Additionally, we identified two new dependoparvoviruses, one in length of 4,869 nt and a second of 4,162 nt. These two dependoparvoviruses are diverse, sharing <61% Rep amino acid identity with those of other dependoparvoviruses. Penguin dependoparvovirus 1 represents a new species. The co-detection of these viruses in a single seasonal sample could suggest a potential helper-satellite relationship in Ad&#xe9;lie penguins. This study provides the first evidence of aviadenoviruses in Ad&#xe9;lie penguin feces. These findings highlight the importance of surveillance to understand pathogen dynamics in isolated Antarctic populations.

Animals↗