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Virus Families (virus + family)
Selected AbstractsViral appropriation of apoptotic and NF-,B signaling pathwaysJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2004Andrew G. Bowie Abstract Viruses utilize a variety of strategies to evade the host immune response and replicate in the cells they infect. The comparatively large genomes of the Orthopoxviruses and gammaherpesviruses encode several immunomodulatory proteins that are homologous to component of the innate immune system of host cells, which are reviewed here. However, the viral mechanisms used to survive host responses are quite distinct between these two virus families. Poxviruses undergo continuous lytic replication in the host cytoplasm while expressing many genes that inhibit innate immune responses. In contrast, herpesviruses persist in a latent state during much of their lifecycle while expressing only a limited number of relatively non-immunogenic viral proteins, thereby avoiding the adaptive immune response. Poxviruses suppress, whereas latent gammaherpesviruses activate, signaling by NF-,B, yet both viruses target similar host signaling pathways to suppress the apoptotic response. Here, modulation of apoptotic and NF-,B signal transduction pathways are examined as examples of common pathways appropriated in contrasting ways by herpesviruses and poxviruses. © 2004 Wiley-Liss, Inc. [source] Mycoviruses of filamentous fungi and their relevance to plant pathologyMOLECULAR PLANT PATHOLOGY, Issue 1 2009MICHAEL N. PEARSON SUMMARY Mycoviruses (fungal viruses) are reviewed with emphasis on plant pathogenic fungi. Based on the presence of virus-like particles and unencapsidated dsRNAs, mycoviruses are common in all major fungal groups. Over 80 mycovirus species have been officially recognized from ten virus families, but a paucity of nucleic acid sequence data makes assignment of many reported mycoviruses difficult. Although most of the particle types recognized to date are isometric, a variety of morphologies have been found and, additionally, many apparently unencapsidated dsRNAs have been reported. Until recently, most characterized mycoviruses have dsRNA genomes, but ssRNA mycoviruses now constitute about one-third of the total. Two hypotheses for the origin of mycoviruses of plant pathogens are discussed: the first that they are of unknown but ancient origin and have coevolved along with their hosts, the second that they have relatively recently moved from a fungal plant host into the fungus. Although mycoviruses are typically readily transmitted through asexual spores, transmission through sexual spores varies with the host fungus. Evidence for natural horizontal transmission has been found. Typically, mycoviruses are apparently symptomless (cryptic) but beneficial effects on the host fungus have been reported. Of more practical interest to plant pathologists are those viruses that confer a hypovirulent phenotype, and the scope for using such viruses as biocontrol agents is reviewed. New tools are being developed based on host genome studies that will help to address the intellectual challenge of understanding the fungal,virus interactions and the practical challenge of manipulating this relationship to develop novel biocontrol agents for important plant pathogens. [source] Plant virus infection-induced persistent host gene downregulation in systemically infected leavesTHE PLANT JOURNAL, Issue 2 2008Zoltán Havelda Summary Understanding of virus infection-induced alterations in host plant gene expression and metabolism leading to the development of virus disease symptoms is both scientifically and economically important. Here, we show that viruses belonging to various RNA virus families are able to induce efficient host gene mRNA downregulation (shut-off) in systemically infected leaves. We demonstrate that the host gene mRNA shut-off overlaps spatially with virus-occupied sectors, indicating the direct role of virus accumulation in this phenomenon. The establishment of shut-off was not directly connected to active viral replication or the RNA-silencing machinery. Importantly, the induced shut-off phenomenon persisted for several weeks, resulting in severe deficiency of mRNA for important housekeeping genes in the infected plants. Interestingly, we found that some other RNA viruses do not induce or only slightly induce the shut-off phenomenon for the same set of genes, implicating genetic determination in this process. Nuclear run-on experiments suggest that plant viruses, similarly to animal viruses, mediate suppression of host mRNA synthesis in the nucleus. By investigating various host,virus interactions, we revealed a correlation between the intensity of the shut-off phenomenon and the severity of disease symptoms. Our data suggest that efficient and persistent downregulation of host genes may be an important component of symptom development in certain host,virus interactions. [source] Structural analyses of Phycodnaviridae and IridoviridaeACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2003Alan A. Simpson The Phycodnaviridae, Iridoviridae and related viruses, with diameters of 1500,2000,Ĺ, are formed from large trigonal arrays of hexagonally close-packed capsomers forming the faces of icosahedra [Yan et al. (2000), Nature Struct. Biol.7, 101,103; Nandhagopal et al. (2002), Proc. Natl Acad. Sci. USA, 99, 14758,14763]. Caspar and Klug predicted that such structures could be assembled from hexameric capsomers [Caspar & Klug (1962), Cold Spring Harbor. Symp. Quant. Biol.27, 1,24], as was subsequently found in numerous icosahedral viruses. During the course of evolution, some viruses, including the virus families mentioned above, replaced hexameric capsomers with pseudo-hexameric trimers by gene duplication. In large dsDNA icosahedral viruses, the capsomers are organized into `pentasymmetrons' and `trisymmetrons'. The interactions between the trimeric capsomers can be divided into three groups, one between similarly oriented trimers and two between oppositely oriented trimers (trimers related by an approximately sixfold rotation). The interactions within a trisymmetron belong to the first class, whereas those between trisymmetrons and within the pentasymmetron are of the other two types. Knowledge of these distances permits a more accurate fitting of the atomic structure of the capsomer into the cryo-electron microscopy (cryoEM) reconstruction of the whole virus. The adoption of pseudo-hexagonal capsomers places these viruses into a subset of the Caspar and Klug surface lattices. [source] Immune responses to gene therapy vectors in the context of corneal transplantationACTA OPHTHALMOLOGICA, Issue 2009T RITTER Purpose The genetic engineering of grafts or cells prior to transplantation is an attractive approach to protect the graft from allogeneic rejection. Virus vector-based gene therapy is a promising method for successful ex-vivo gene transfer however, the induction of an immune response against gene-modified tissues raises concern. Methods Different virus families (Adenovirus, Retrovirus, Adeno-associated virus, Herpesvirus) have been studied as gene therapy vehicles for the delivery of therapeutic molecules. Moreover, different serotypes or envelope proteins have been used to modulate transduction efficiencies of target cells or to evade pre-existing immunity. Results Here we review gene therapeutic applications using viral vectors in the context of cornea transplantation. Both local and systemic expression of immunomodulatory molecules have led to the prevention of corneal graft rejection. However, different results have been obtained with regard to the induction of immune responses after local or systemic expression of the gene therapy vector. Not surprisingly over-expression of anti-inflammatory molecules not only modulated allograft rejection but also influenced the immune response against the viral vector and virally transduced cells. Conclusion Recent clinical trials indicate that the application of viral vectors in ophthalmology is promising however, the generation of immune responses against the viral vector or virally transduced cells are still a serious obstacle for a broader application of gene therapy. Supported by Deutsche Forschungsgemeinschaft (DFG Pl 150/14-1 and Ri 764/10-1) and Science Foundation of Ireland (SFI 06/RFP/BIC056 and SFI 07/IN.1/B925) [source] Evaluation of coexistence of the Human Herpesvirus type 8 (HHV-8) infection and pemphigusINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2010Naser Tayyebi Meibodi Associate Professor Background, Human Herpesvirus type 8 (HHV-8) is a new member of the herpes virus family, first found in the tissue of acquired immune deficiency syndrome (AIDS)-related Kaposi's sarcoma. Environmental factors including viral infection may play a role in the onset and/or development of pemphigus. Some studies based on polymerase chain reaction findings suggest an association between HHV-8 and pemphigus. The aim of this study is investigation of the association of pemphigus with HHV-8 and the relationship between inflammatory and acantholytic cells with HHV-8 infection. Methods, Tissue-extracted DNA from 41 paraffin-embedded skin tissues from patients first presenting with pemphigus was tested using nested PCR for the presence of HHV-8. A total of 37 cases had pemphigus vulgaris (PV) and 4 patients had pemphigus foliaceus (PF). For our control group, normal skin of 21 cosmetic surgery patients were included. Furthermore, microscopic slides with H&E staining were evaluated for the number of inflammatory and acantholytic cells per microscopic field. Results, Skin lesions from 13 of 37 patients (35.1%) with PV and 2 of 4 cases (50%) with PF were positive for HHV-8 DNA. All specimens in our control group were negative for this virus. Conclusion, HHV-8 infection might be a contributing factor in the initiation or development of pemphigus. [source] Cytomegalovirus Infection: Perinatal ImplicationsJOURNAL OF OBSTETRIC, GYNECOLOGIC & NEONATAL NURSING, Issue 1 2002Elizabeth G. Damato RN Cytomegalovirus (CMV), a member of the herpes virus family, is the most common cause of congenital infection in humans, affecting 0.5,3% of all newborns worldwide. Congenital cytomegalovirus infection is the leading infectious cause of deafness, learning disabilities, and mental retardation in children. The high prevalence of cytomegalovirus in the general population, unpredictability of transmission, and asymptomatic nature of the disease in otherwise healthy women challenge prevention and treatment efforts. [source] | |||||||||||||