1,721,035 research outputs found
Vaccini a base di particelle simil virali, nuove opportunità nella profilassi immunizzante della bluetongue e delle altre infezioni da Orbivirus.
No full textEpizootic haemorrhagic disease, malattia esotica da prendere in considerazione nella diagnosi differenziale di bluetongue.
No full textA capsid protein of nonenveloped Bluetongue virus exhibits membrane fusion activity.
No full textThe outer capsid layer of Bluetongue virus, a member of the nonenveloped Reoviridae family, is composed of two proteins, a receptor-binding protein, VP2, and a second protein, VP5, which shares structural features with class I fusion proteins of enveloped viruses. In the replication cycle of Bluetongue virus VP5 acts as a membrane permeabilization protein that mediates release of viral particles from endosomal compartments into the cytoplasm. Here, we show that VP5 can also act as a fusion protein and induce syncytium formation when it is fused to a transmembrane anchor and expressed on the cell surface. Fusion activity is strictly pH-dependent and is triggered by short exposure to low pH. No cell-cell fusion is observed at neutral pH. Deletion of the first 40 amino acids, which can fold into two amphipathic helices, abolishes fusion activity. Syncytium formation by VP5 is inhibited in the presence of VP2 when it is expressed in a membrane-anchored form. The data indicate an interaction between the outer capsid protein VP2 and VP5 and show that VP5 undergoes pH-dependent conformational changes that render it capable of interacting with cellular membranes. More importantly, our data show that a membrane permeabilization protein of a nonenveloped virus can evolve into a fusion protein by the addition of an appropriate transmembrane anchor. The results strongly suggest that the mechanism of membrane permeabilization by VP5 and membrane fusion by viral fusion proteins require similar structural features and conformational changes
Bluetongue virus entry into cells.
No full textBluetongue virus (BTV) is a member of the Orbivirus genus within the Reoviridae family. Like those of other members of the family, BTV particles are nonenveloped and contain two distinct capsids, namely, an outer capsid and an inner capsid or core. The two outer capsid proteins, VP2 and VP5, are involved in BTV entry into cells and in the delivery of the transcriptionally active core to the target cell cytoplasm. However, very little is known about the precise mechanism of BTV entry. In this report, using RNA interference, we demonstrate that inhibition of the clathrin-dependent endocytic pathway correlates with reduced BTV internalization and subsequent replication. Furthermore, by using the ATPase inhibitor bafilomycin A1, we show that exposure of the virus to acidic pH is required for productive infection. Moreover, microscopic analysis of cells incubated with BTV indicated that the virus is internalized into early endosomes, where separation of the outer capsid and inner core occurs. Together, our data indicate that BTV undergoes low-pH-induced penetration in early endosomes following clathrin-mediated endocytosis from the plasma membrane, supporting a stepwise model for BTV entry and penetration
Detection of deformed wing virus in Vespa crabro
Full text linkSpecimens of Vespa crabro L. queen were found to be infected by deformed wing virus (DWV). The abdomen and the thorax of asymptomatic and symptomatic wasps were positive for the virus by strand specific RT-PCR, indicating active replication. This finding confirms the ability of the virus to infect not only bees (Apoidea) but also wasps (Vespoidea) suggesting a possible transmission route by ingestion of infected honey bees by waspâs larva. This is the first report concerning the detection of DWV in V. crabro. In the view of this finding the possibility of using naturally infected bees as a tool for the biological control of its predators is discussed
Hepatitis E virus-related liver alterations and viral antigen localization in European wild boar (Sus scrofa)
No full textSixty-four sera and faecal samples from hunted wild boar were submitted to indirect ELISA and RT-PCR to detect hepatitis E virus (HEV) infection. Liver samples were used to characterize liver alterations associated with HEV infection. Thirty-six (56.2 %) sera scored positive for HEV antibodies while six (9.4 %) faecal samples were viruspositive. A higher seroprevalence was found in adults with no differences between genders. Histological lesions were subclinical and characterized by mild multifocal and periportal lymphoplasmacytic infiltration of mainly CD3+ lymphocytes. All six liver samples from HEV RT-PCR-positive subjects showed immunohistochemical cytoplasmic positivity for viral antigen in inflammatory foci. HEV infection had no apparent effect on wild boar body condition and biometric parameters.
However, HEV infection in wild boar constitutes a threat for
hunters, forest workers and consumers of undercooked wild
boar meat or liver
Expression and functional characterization of bluetongue virus VP5 protein: role in cellular permeabilization.
No full textSegment 5 of bluetongue virus (BTV) serotype 10, which encodes the outer capsid protein VP5, was tagged with glutathione S-transferase and expressed by a recombinant baculovirus. The recombinant protein was subsequently purified to homogeneity, and its possible biological role in virus infection was investigated. Purified VP5 was able to bind mammalian cells but was not internalized, which indicates it is not involved in receptor-mediated endocytosis. The purified VP5 protein was shown to be able to permeabilize mammalian and Culicoides insect cells, inducing cytotoxicity. Sequence analysis revealed that VP5 possesses characteristic structural features (including two amino-terminal amphipathic helices) compatible with virus penetration activity. To assess the role of each feature in the observed cytotoxicity, a series of deleted VP5 molecules were generated, and their expression and biological activity was compared with the parental molecule. VP5 derivatives that included the two amphipathic helices exhibited cytotoxicity, while those that omitted these sequences did not. To confirm their role in membrane destabilization two synthetic peptides (amino acids [aa] 1 to 20 and aa 22 to 41) encompassing the two helices and an additional peptide representing the adjacent downstream sequences were also assessed for their effect on the cell membrane. Both helices, but not the downstream VP5 sequence, exhibited cytotoxicity with the most-amino-terminal helix (aa 1 to 20) showing a higher activity than the adjacent peptide (aa 22 to 41). Purified VP5 was shown to readily form trimers in solution, a feature of many proteins involved in membrane penetration. Taken together, these data support a role for VP5 in virus-cell penetration consistent with its revelation in the entry vesicle subsequent to cell binding and endocytosis
Hepatitis E Virus RNA Presence in Wild Boar Carcasses at Slaughterhouses in Italy
Full text linkHepatitis E virus (HEV) is a waterborne and foodborne pathogen largely spread around the world. HEV is responsible for acute hepatitis in humans and it is also diffused in domestic and wild animals. In particular, domestic pigs represent the main reservoir of the infection and particular attention should be paid to the consumption of raw and undercooked meat as a possible zoonotic vehicle of the pathogen. Several studies have reported the presence of HEV in wild boar circulating in European countries with similar prevalence rates. In this study, we evaluated the occurrence of HEV in wild boar hunted in specific areas of Tuscany. Sampling was performed by collecting liver samples and also by swabbing the carcasses at the slaughterhouses following hunting activities. Our data indicated that 8/67 (12%) of liver samples and 4/67 (6%) of swabs were positive for HEV RNA. The presence of HEV genome on swabs indicates the possible cross-contamination of carcass surfaces during slaughtering procedures. Altogether, our data indicated that it is essential to promote health education programmes for hunters and consumers to limit the diffusion of the pathogen to humans
Complete genome sequence of deformed wing virus isolated from Vespa crabro in Italy
Full text linkIn this article, we document the first isolation of a replication-competent deformed wing virus from Vespa crabro in Italy. Although the virus has never been isolated from this insect, the sequence of this virus shows a strong sequence homology with isolates obtained from Apis mellifera, which is considered its natural host
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