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Encephalitis Virus (encephalitis + virus)
Kinds of Encephalitis Virus Selected AbstractsEffects of crowding on populations of Aedes albifasciatus larvae under laboratory conditionsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2000Raquel M. Gleiser Abstract Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) is a neotropical flood water mosquito, incriminated as the main vector of the western equine encephalitis virus, and which affects beef and milk production in central Argentina. The short time required to hatch and develop from egg to adult, usually in temporary pools, suggests a strategy which allows for exploitation of transient pools, thus evading predation and interspecific competition. Under these conditions intra specific competition could represent a major density-dependent source of larval mortality, but the relative importance of density-dependent regulation of mosquito populations has generated controversy. Therefore we examined the effects of larval density on basic population characteristics of Ae. albifasciatus in the laboratory. Larvae were obtained by synchronous hatching of eggs laid by field-trapped females. Emerging larvae (L1) were used to build cohorts of different initial densities, kept in plastic trays with 400 ml of distilled water, and food supplied daily during the first 10 days (0.1 g per larvae day,1). Age-specific development time and specific and relative mortality were estimated, and their relation to initial larval density was assessed through linear and non-linear regressions and correlation analysis. First hatching was registered 3 h after flooding the eggs. Higher levels of pre-adult mortality were detected in groups with higher densities. Specific mortality and average time to enter a stage of L1 to L3 could directly be related to initial larval density, but no significant relations were found for L4 and pupae. Results suggest that crowding could be a factor capable of regulating the density of natural populations of Ae. albifasciatus. [source] Altered effector functions of virus-specific and virus cross-reactive CD8+ T cells in mice immunized with related flavivirusesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2010Derek W. Trobaugh Abstract Memory cross-reactive CD8+ T-cell responses may induce protection or immunopathology upon secondary viral challenge. To elucidate the potential role of T cells in sequential flavivirus infection, we characterized cross-reactive CD4+ and CD8+ T-cell responses between attenuated and pathogenic Japanese encephalitis virus (JEV) and pathogenic West Nile virus (WNV). A previously reported WNV NS4b CD8+ T-cell epitope and its JEV variant elicited CD8+ T-cell responses in both JEV- and WNV-infected mice. The peptide variant homologous to the immunizing virus induced greater cytokine secretion and activated higher frequencies of epitope-specific CD8+ T cells. However, there was a virus-dependent, peptide variant-independent pattern of cytokine secretion; the IFN,+ -to-IFN,+TNF,+ CD8+ T-cell ratio was greater in JEV- than in WNV-infected mice. Despite similarities in viral burden for pathogenic WNV and JEV viruses, CD8+ T cells from pathogenic JEV-immunized mice exhibited functional and phenotypic profiles similar to those seen for the attenuated JEV strain. Patterns of killer cell lectin-like receptor G1 (KLRG1) and CD127 expression differed by virus type, with a rapid expansion and contraction of short-lived effector cells in JEV infection and persistence of high levels of short-lived effector cells in WNV infection. Such cross-reactive T-cell responses to primary infection may affect the outcomes of sequential flavivirus infections. [source] Immunomodulatory cytokines determine the outcome of Japanese encephalitis virus infection in miceJOURNAL OF MEDICAL VIROLOGY, Issue 2 2010S.M. Biswas Abstract Japanese encephalitis virus (JEV) induces an acute infection of the central nervous system, the pathogenic mechanism of which is not fully understood. To investigate host response to JEV infection, 14-day-old mice were infected via the extraneural route, which resulted in encephalitis and death. Mice that received JEV immune splenocyte transfer were protected from extraneural JEV infection. Pathology and gene expression profiles were then compared in brains of mice that either succumbed to JEV infection or were protected from infection by JEV immune cell transfer. Mice undergoing progressive JEV infection had increased expression of proinflammatory cytokines, chemokines, and signal transducers associated with the interferon (IFN) pathway. In contrast, mice receiving immune cell transfer had increased production of the Th2 cytokine IL-4, and of IL-10, with subdued expression of IFN-,. We observed IL-10 to be an important factor in determining clinical outcome in JEV infection. Data obtained by microarray analysis were further confirmed by quantitative RT-PCR. Together, these data suggest that JEV infection causes an unregulated inflammatory response that can be countered by the expression of immunomodulatory cytokines in mice that survive lethal infection. J. Med. Virol. 82:304,310, 2010. © 2009 Wiley-Liss, Inc. [source] Development of a consensus microarray method for identification of some highly pathogenic virusesJOURNAL OF MEDICAL VIROLOGY, Issue 11 2009Kang Xiao-Ping Abstract Some highly pathogenic viruses, such as Chikungunya virus, Japanese encephalitis virus, Yellow fever virus, Dengue virus, Hanta virus, SARS-CoV, and H5N1 avian influenza virus can cause severe infectious diseases. However, the consensus method for detecting these viruses has not been well established. A rapid and sensitive microarray approach for detection of these viruses and a panel of specific probes covering nine genera and 16 virus species were designed. 70-mer oligonucleotides were used at the genus level and 50-mer oligonucleotides were at the species level, respectively. To decrease the interference of the host genome in hybridization, the consensus genus primers were designed and used to reverse transcribe only virus genome. The synthesis of the second strand was carried out with a random primer sequence (5,-GTTTCCCAGTAGGTCTCNNNNNNNN-3,). The amplified products were labeled and processed for microarray analyses. This microarray-based method used the highly conserved consensus primers to synthesize specifically the virus cDNA and could identify effectively Chikungunya virus, Japanese encephalitis virus, Yellow fever virus, Dengue virus, Tick borne encephalitis virus, and H5N1 avian influenza virus. Using this method, one unknown virus isolated from pig brain in Shanxi Province, China was identified. This method may have an important potential application for the diagnosis of virus infection. J. Med. Virol. 81:1945,1950, 2009. © 2009 Wiley-Liss, Inc. [source] Humoral immunity in natural infection by tick-borne encephalitis virusJOURNAL OF MEDICAL VIROLOGY, Issue 4 2009Giulietta Venturi Abstract Tick-borne encephalitis (TBE) virus is one of the most important flaviviruses associated with neurological disease in Europe. Cross-reactive antibodies elicited by different flaviviruses can make difficult the interpretation of ELISA and hemagglutination-inhibition (HI) tests for the diagnosis of TBE. Neutralization tests, which are more specific, are not in common use because they are difficult to perform and standardize. A plaque reduction neutralization test (PRNT), optimized previously in vaccinated children, was evaluated in sera from acute cases of TBE, collected for diagnostic purposes, and from healthy human population and wild ruminants, collected for serosurvey purposes. The PRNT results were compared with the results of ELISA and HI tests. In acute TBE disease, most sera were positive for IgM antibodies by ELISA and with high HI antibody titers; neutralizing antibodies were detected in 71.4% of patients, at a very low titer (1:10 NT50) in almost all cases. Seroprevalences of 8% and 6.5% for anti-TBE ELISA antibodies were found in healthy subjects and wild ruminants, respectively. Among anti-TBE positive healthy subjects, a very low 1:10 NT50 titer was detected in 17.4% of cases, while NT80 titers ranging from 1:10 to 1:80 were detected in 65.2% of cases. Among wild ruminants, 90.9% of ELISA and HI positive samples showed a positive, ,1:10 NT80 titer. In conclusion, neutralization assays can be useful for the diagnosis and serosurveys of TBE. J. Med. Virol. 81:665,671, 2009 © 2009 Wiley-Liss, Inc. [source] Prevalence of tick-borne encephalitis virus in Ixodes Ricinus from a novel endemic area of North Eastern ItalyJOURNAL OF MEDICAL VIROLOGY, Issue 2 2009P. D'Agaro Abstract In Alpine area of extreme North Eastern Italy the first autochthonous case of TBE was reported in 1998 and was followed by 45 cases during the period 2001,2007, thus defining this area as definitely endemic. An ecological survey evaluated the tick density and the Tick-borne encephalitis virus (TBEV) infection prevalence in tick collected in selected sites. In addition, TBE strains were characterized by sequencing and phylogenetic analysis. Overall, 2,361 ticks (2,198 nymphs and 163 adults) of the Ixodes ricinus L. species collected during 2005 and 2006 were examined. Five samples were positive for TBEV, corresponding to an overall prevalence rate of 0.21%. When analyzed by place, TBEV was discovered in three sites where the highest tick density was found. The difference of prevalence between high and low density areas tested to be statistically significant (P,=,0.028). Phylogenetic analysis showed that four sequences clustered with the Neudoerfl prototype, while the other clustered with the Isosaari 17 strain and with a number of Slovenian isolates. In addition, a sequence detected in archival samples from one human case segregated with another variant, namely the Swedish Torö strain. J. Med. Virol. 81:309,316, 2009. © 2008 Wiley-Liss, Inc. [source] Characterization of tick-borne encephalitis virus from latvia: Evidence for co-circulation of three distinct subtypesJOURNAL OF MEDICAL VIROLOGY, Issue 4 2001Åke Lundkvist Abstract Viruses of the tick-borne encephalitis (TBE) antigenic complex within the family Flaviviridae cause a variety of diseases, including uncomplicated febrile illness, meningoencephalitis, and hemorrhagic fever. Different domesticated animals or wildlife species often act as reservoir hosts and ixodid ticks serve as vectors. Although TBE is a serious problem in Latvia, the knowledge concerning TBE virus (TBEV) strains circulating in the country is most limited. Only two strains (Latvia-1-96 isolated from a TBE patient, and RK1424 originating from an Ixodes persulcatus tick), which belonged to the Siberian and the Far Eastern subtypes of TBEV, respectively, have previously been characterized. In the present study, we concentrated on the western and central regions of Latvia, with predominantly Ixodes ricinus ticks. Five virus strains were isolated from serum samples of patients with clinical symptoms of an acute TBE infection. Nucleotide sequences encoding the envelope (E) protein of TBEV, which were recovered from the five TBEV isolates, showed the highest level of identity to the corresponding sequences of the prototype strain Neudoerfl and other European strains of the Western TBEV subtype characterized previously. Accordingly, phylogenetic analysis placed the new Latvian isolates within the Western genetic lineage of TBEV. Taken together with earlier observations, the results proved that all three TBEV subtypes are co-circulating in Latvia and indicated that the genetic diversity of TBEV within certain geographical areas is much more complex than previously believed. J. Med. Virol. 65:730,735, 2001. © 2001 Wiley-Liss, Inc. [source] Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks in FinlandJOURNAL OF MEDICAL VIROLOGY, Issue 1 2001Xiuqi Han Abstract Approximately 20 cases of tick-borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Åland islands. Ixodes ricinus panels collected in 1996,1997 from two endemic areas were screened for the presence of RNA. Two distinct RT-PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 ,l. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Åland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000,200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia. J. Med. Virol. 64:21,28, 2001. © 2001 Wiley-Liss, Inc. [source] Emerging viral infections in AustraliaJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 1 2002AJ Daley Abstract: Emerging viruses include known viruses that have increased in incidence or geographic range (such as enteroviruses and Japanese encephalitis virus), new viruses associated with known diseases (Australian bat lyssavirus) and new viruses associated with previously unrecognized diseases (Hendra and Nipah viruses). Some may have a predilection for children (Japanese encephalitis, influenza viruses and enterovirus 71) and vigilance is essential to ensure early recognition of these agents. [source] Identification and characterization of Japanese encephalitis virus envelope protein gene from swineLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2010J.-M. Fan Abstract Aims:, Identification and characterization of Japanese encephalitis virus (JEV) envelope protein gene from swine. Methods and Results:, Genomic RNA was separated from JEV isolated strain Henan-09-03, and used as templates for cDNA synthesis of E gene. The cDNA of E gene was amplified by RT-PCR and cloned into the pMD19-T-Vector and confirmed by sequencing. The cloned gene was then subcloned into the pET-32a and was introduced into Escherichia coli BL21 (DE3) for expression. The E protein was purified by Ni chelating column-based affinity chromatography. The molecular weight of expressed protein was about 50 kDa. Compared with the published sequence of SA14 (AF495589), the homology of the nucleotide sequence was 98% and the seven mutations resulting in amino acid substitutions at Leu 36 Ser, Leu107 Val, Ala167 Thr, Asn 230 Ser, Leu 340 Pro, Asn 430 Ile, Phe 448 Leu. Phylogenetic analysis of the E sequence of isolated strain classified it within genotype III of the JEV. The result of Western blotting indicated that the antigenicity of the protein was specific. Conclusions:, The stable expression of the protein and the analysis of its antigenic specificity provide the foundation for developing the ELISA early stage diagnosis kit. Significance and Impact of the Study:, As coating antigen, the recombinant E protein served a good source in the indirect ELISA method for the detection of JEV antibody. [source] | |||||||||||||