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Virus Sequences (virus + sequence)
Selected AbstractsBarley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grassesJOURNAL OF ECOLOGY, Issue 6 2007CAROLYN M. MALMSTROM Summary 1In plant invasion ecology, viruses and other pathogens are often considered in terms of the enemy release hypothesis, which predicts that plants become invasive in new ranges if they escape pathogens from their home range. However, pathogens may sometimes facilitate host spread rather than hinder it. 2Previously, we hypothesized that apparent competition mediated by barley and cereal yellow dwarf viruses (Luteoviridae: BYDVs, CYDVs) may have facilitated historical grassland invasion in California, USA, where Eurasian grasses displaced native grasses in the 18th and 19th centuries (the disease facilitation hypotheses). However, this could have happened only if the viruses were present during the invasion, which is unknown. 3To investigate the historical ecology of BYDVs in California grasses, we analysed preserved virus infections in herbarium specimens and used the historical virus sequences to determine rough time estimates of relevant phylogenetic events. 4The historical viral RNA sequences we identified in invasive and native grasses date from 1917 and are among the oldest recovered from plants thus far and the oldest from North America. 5Herbarium evidence and phylogenetic analysis suggest that BYDVs were likely to have been present in wild grasses during the California grassland invasion and to have shared some functional characteristics with present-day isolates, supporting the disease facilitation hypothesis. 6We found evidence of virus spread from California to Australia (or, less likely, from Australia to California) in the late 19th century, when much horticultural exchange occurred, as well as potential correspondence in the timing of virus diversification events and the beginning of extensive human exchange between the Old and New Worlds. 7Synthesis. Increasing evidence indicates that viruses are important in the ecology of grasslands and may, in some cases, mediate apparent competition among species. Historical data provide essential insight into plant virus ecology and suggest the need to examine human influence on plant virus diversification and spread within natural ecosystems. [source] Genetic characterization of the M RNA segment of a Balkan Crimean-Congo hemorrhagic fever virus strain,JOURNAL OF MEDICAL VIROLOGY, Issue 3 2005Anna Papa Abstract Crimean-Congo hemorrhagic fever (CCHF) virus causes one of the most severe diseases in humans, with a mortality rate of up to 30%. It is transmitted to humans by the bite of hard ticks or by contact with blood or tissues from human patients or infected livestock. Balkan Peninsula is an endemic region of the disease, and sporadic cases or even outbreaks are observed every year. The M RNA segment encodes for the glycoprotein precursor of two surface glycoproteins Gn and Gc. Up to now complete M RNA CCHF virus sequences have been published from strains isolated in Nigeria, China, Pakistan, Tajikistan, and Russia. In the present study, the genetic characterization of the complete nucleotide sequence of the M RNA segment of a Balkan CCHF virus strain, Kosovo/9553/2001, isolated in summer of 2001 from a human fatal case in Kosovo is reported. This is the first published complete M nucleotide sequence of a CCHF virus strain isolated in Balkans. It was found that the Balkan strain is similar to the Russian strain, both strains differing from all other completely sequenced CCHF virus strains by approximately 22% at the nucleotide level forming an independent clade in the phylogenetic tree. J. Med. Virol. 75:466,469, 2005. © 2005 Wiley-Liss, Inc. [source] Fulminant liver failure from acute autochthonous hepatitis E in France: description of seven patients with acute hepatitis E and encephalopathyJOURNAL OF VIRAL HEPATITIS, Issue 5 2007J. M. Péron Summary., Fulminant hepatitis E has not been well characterized in industrialized countries. The aim of this study was to prospectively describe patients with acute hepatitis E presenting as fulminant hepatic failure, i.e. with encephalopathy and prothrombin index <50%. Between February 1997 and April 2005, seven patients with encephalopathy were diagnosed with acute hepatitis E using viral RNA detection. These patients were compared with 33 patients diagnosed with a mild form (absence of encephalopathy) of acute hepatitis E during the same time period. Patients were 65 ± 11 years old. Five were active drinkers and six had chronic liver disease. All hepatitis E virus sequences evaluated (5/7) were of genotype 3. All patients but two died (71%). Four patients had no travel history. When compared with patients with a mild form of acute hepatitis E, active alcohol abuse and chronic liver disease were more frequent in patients with the severe form. Duration of hospitalization was longer. Aspartate transferase and bilirubin levels were significantly higher. Prothrombin index and accelerin levels were lower and death was more frequent. Acute nontravel-associated hepatitis E can appear as fulminant hepatitis with encephalopathy and coagulation disorders. Prognosis is severe and this may be due to the age at which it occurs and frequent underlying chronic liver disease. [source] Gene expression kinetics of the yellow head virus in experimentally infected Litopenaeus vannameiAQUACULTURE RESEARCH, Issue 10 2010Yenelli Cedano-Thomas Abstract The yellow head virus (YHV) has been reported to be one of most pathogenic viruses for cultivated shrimp; however, serious problems have only been reported in farms in south and southeastern Asian. Recently, a YHV strain was detected in Litopenaeus vannamei cultivated in Mexican farms that lacked virus-associated mortalities or epizooties, and the animals were apparently healthy. The identity of the virus was confirmed by sequencing replicative and structural protein-encoding regions and comparing with homologous virus sequences. Phylogenic relationships and genetic distances were also determined and, although some differences were observed, an influence on virulence was uncertain. In addition, the expression levels of several transcripts (3CLPRO, POL, GP64 and GP116) were evaluated by quantitative real-time polymerase chain reaction during an experimental infection. Although the transcript showed varying kinetics, viral genes were expressed in infected L. vannamei, demonstrating the replicative capability of this YHV strain. [source] | ||||||||||