Search results for "DNA VIRUS"

Alix regulates egress of hepatitis B virus naked capsid particles in an ESCRT-independent manner

2010

Hepatitis B virus (HBV) is an enveloped DNA virus that exploits the endosomal sorting complexes required for transport (ESCRT) pathway for budding. In addition to infectious particles, HBV-replicating cells release non-enveloped (nucleo)capsids, but their functional implication and pathways of release are unclear. Here, we focused on the molecular mechanisms and found that the sole expression of the HBV core protein is sufficient for capsid release. Unexpectedly, released capsids are devoid of a detectable membrane bilayer, implicating a non-vesicular exocytosis process. Unlike virions, naked capsid budding does not require the ESCRT machinery. Rather, we identified Alix, a multifunctional …

The discovery, distribution, and diversity of DNA viruses associated with Drosophila melanogaster in Europe

2021

Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here, we report fourteen DNA viruses detected in a metagenomic analysis of 6668 pool-sequenced Drosophila, sampled from forty-seven European locations between 2014 and 2016. These include three new nudiviruses, a new and divergent entomopoxvirus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy viru…

High Diversity of the Viral Community from an Antarctic Lake

2009

Viruses are the most abundant biological entities and can control microbial communities, but their identity in terrestrial and freshwater Antarctic ecosystems is unknown. The genetic structure of an Antarctic lake viral community revealed unexpected genetic richness distributed across the highest number of viral families that have been found to date in aquatic viral metagenomes. In contrast to other known aquatic viromes, which are dominated by bacteriophage sequences, this Antarctic virus assemblage had a large proportion of sequences related to eukaryotic viruses, including phycodnaviruses and single-stranded DNA (ssDNA) viruses not previously identified in aquatic environments. We also o…

Mutational fitness effects in RNA and single-stranded DNA viruses: common patterns revealed by site-directed mutagenesis studies

2010

The fitness effects of mutations are central to evolution, yet have begun to be characterized in detail only recently. Site-directed mutagenesis is a powerful tool for achieving this goal, which is particularly suited for viruses because of their small genomes. Here, I discuss the evolutionary relevance of mutational fitness effects and critically review previous site-directed mutagenesis studies. The effects of single-nucleotide substitutions are standardized and compared for five RNA or single-stranded DNA viruses infecting bacteria, plants or animals. All viruses examined show very low tolerance to mutation when compared with cellular organisms. Moreover, for non-lethal mutations, the me…

2014

The hepatitis B virus (HBV) is an enveloped DNA virus that replicates via reverse transcription of its pregenomic RNA (pgRNA). Budding of HBV is supposed to occur at intracellular membranes and requires scission functions of the endosomal sorting complex required for transport (ESCRT) provided by ESCRT-III and VPS4. Here, we have investigated the impact of the upstream-acting ESCRT-I and ESCRT-II complexes in HBV morphogenesis. RNA interference knockdown of the ESCRT-I subunits TSG101 and VPS28 did not block, but rather stimulate virus release. In contrast, RNAi-mediated depletion of the ESCRT-II components EAP20, EAP30 and EAP45 greatly reduced virus egress. By analyzing different steps of…

Hepatitis B virus maturation is sensitive to functional inhibition of ESCRT-III, Vps4, and gamma 2-adaptin.

2007

ABSTRACT Hepatitis B virus (HBV) is an enveloped DNA virus that presumably buds at intracellular membranes of infected cells. HBV budding involves two endocytic host proteins, the ubiquitin-interacting adaptor γ2-adaptin and the Nedd4 ubiquitin ligase. Here, we demonstrate that HBV release also requires the cellular machinery that generates internal vesicles of multivesicular bodies (MVBs). In order to perturb the MVB machinery in HBV-replicating liver cells, we used ectopic expression of dominant-negative mutants of different MVB components, like the ESCRT-III complex-forming CHMP proteins and the Vps4 ATPases. Upon coexpression of mutated CHMP3, CHMP4B, or CHMP4C forms, as well as of ATPa…

γ2-Adaptin, a Novel Ubiquitin-interacting Adaptor, and Nedd4 Ubiquitin Ligase Control Hepatitis B Virus Maturation

2006

Hepatitis B virus (HBV) budding from infected cells is a tightly regulated process that requires both core and envelope structures. Here we report that HBV uses cellular γ2-adaptin and Nedd4, possibly in conjunction with ubiquitin, to coordinate its assembly and release. In search of interaction partners of the viral L envelope protein, we previously discovered γ2-adaptin, a putative endosomal sorting and trafficking adaptor of the adaptor protein complex family. We now demonstrate that the viral core interacts with the same γ2-adaptor and that disruption of the HBV/γ2-adaptin interactions inhibits virus production. Mutational analyses revealed a hitherto unknown ubiquitin-binding activity …

Impact of infectious burden on extent and long-term prognosis of atherosclerosis.

2002

Background — Recent findings suggest a causative role of infections in the pathogenesis of atherosclerosis. In hypothesizing an association between infectious agents and the development of atherosclerosis, we would expect a correlation to the extent of atherosclerosis. Moreover, this effect could be multiplied by the number of pathogens to which an individual had been exposed. Methods and Results — In 572 patients, IgG or IgA antibodies to herpes simplex virus 1 and 2, cytomegalovirus, Epstein-Barr virus, Hemophilus influenzae , Chlamydia pneumoniae , Mycoplasma pneumoniae , and Helicobacter pylori were measured. The extent of atherosclerosis was determined by coronary angiography, carotid…

Brushing of Oral Mucosa for Diagnosis of HPV Infection in Patients with Potentially Malignant and Malignant Oral Lesions

2006

Introduction: Adequate brushing of oral mucosa is important for accurate human papillomavirus (HPV) detection in potentially malignant (oral leukoplakia [OL], oral lichen planus [OLP]) and malignant (oral squamous cell carcinoma [OSCC]) lesions. Since various factors may limit the adequacy of oral brushing and, consequently, the accuracy of HPV detection, modified sampling procedures should be evaluated for their effect on HPV frequency and/or types detected. Aim: To compare the HPV frequency in samples obtained by brushing the lesion site with the frequency in samples obtained by brushing an apparently normal adjacent site. The correlation between HPV frequency and keratinization of the si…

Presence of viruses in wild eels Anguilla anguilla L, from the Albufera Lake (Spain)

2014

A virological analysis was conducted on wild eels from the Albufera Lake (Spain). A total of 179 individuals at different growth stages were collected in two different surveys (2004 and 2008). Presence of anguillid herpesvirus (AngHV-1), aquabirnavirus and betanodavirus was confirmed by PCR procedures in both surveys, although the number of detections was clearly higher in 2008 (83% of the eels analysed resulted positive for virus presence). AngHV-1 was the viral agent most frequently detected, followed by aquabirnaviruses. Betanodaviruses were detected by the first time in wild eels, and although the detections were only made by nested PCR, high percentage of positives were achieved. In ad…