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1.
Vet Microbiol ; 167(1-2): 168-80, 2013 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-24035480

RESUMO

West Nile virus (WNV) is a flavivirus transmitted between certain species of birds and mosquito vectors. Tangential infections of equids and subsequent equine epizootics have occurred historically. Although the attack rate has been estimated to be below 10%, mortality rates can approach 50% in horses that present clinical disease. Symptoms are most commonly presenting in the form of encephalitis with ataxia as well as limb weakness, recumbency and muscle fasciculation. The most effective strategy for prevention of equine disease is proper vaccination with one of the numerous commercially available vaccines available in North America or the European Union. Recently, WNV has been increasingly associated with equine epizootics resulting from novel non-lineage-1a viruses in expanding geographic areas. However, specific experimental data on the virulence of these novel virus strains is lacking and questions remain as to the etiology of the expanded epizootics: whether it be a function of inherent virulence or ecological and/or climactic factors that could precipitate the altered epidemiological patterns observed.


Assuntos
Doenças dos Cavalos/virologia , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/fisiologia , Animais , Doenças dos Cavalos/diagnóstico , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/patologia , Doenças dos Cavalos/prevenção & controle , Cavalos , Filogenia , Febre do Nilo Ocidental/diagnóstico , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/patologia , Febre do Nilo Ocidental/prevenção & controle , Vírus do Nilo Ocidental/classificação , Vírus do Nilo Ocidental/genética
2.
Mol Ecol Resour ; 12(2): 238-46, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22136215

RESUMO

For vectorborne infections, host selection by bloodfeeding arthropods dictates the interaction between host and pathogen. Because Culex mosquitoes that transmit West Nile virus (WNV) feed both on mammalian and avian hosts with varying competence, understanding the bloodfeeding patterns of these mosquitoes is important for understanding the transmission dynamics of WNV. Herein, we describe a new microsphere-based assay using Luminex xMAP® technology to rapidly identify 15 common hosts of Culex mosquitoes at our California study sites. The assay was verified with over 100 known vertebrate species samples and was used in conjunction with DNA sequencing to identify over 125 avian and mammalian host species from unknown Culex bloodmeals, more quickly and with less expense than sequencing alone. In addition, with multiplexed labelled probes, this microsphere array identified mixed bloodmeals that were difficult to discern with traditional sequencing. The microsphere set was easily expanded or reduced according to host range in a specific area, and this assay has made it possible to rapidly screen thousands of Culex spp. bloodmeals to extend our understanding of WNV transmission patterns.


Assuntos
Aves/genética , Culex/fisiologia , Ensaios de Triagem em Larga Escala/métodos , Insetos Vetores/fisiologia , Mamíferos/genética , Reação em Cadeia da Polimerase/métodos , Animais , Aves/classificação , Sangue , Culex/virologia , Comportamento Alimentar , Ensaios de Triagem em Larga Escala/instrumentação , Especificidade de Hospedeiro , Humanos , Insetos Vetores/virologia , Mamíferos/classificação , Mamíferos/virologia , Reação em Cadeia da Polimerase/instrumentação
3.
Int J Obes (Lond) ; 33(10): 1166-73, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19687792

RESUMO

AIM: Biotransformation of blueberry juice by the Serratia vaccinii bacterium gave rise to adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and glucose uptake in muscle cells and adipocytes, but inhibited adipogenesis. This study investigated the antiobesity and antidiabetic potential of biotransformed blueberry juice (BJ) in KKA(y) mice, rodent model of leptin resistance. METHODS: BJ was incorporated in drinking water of KKA(y) mice. Parameters of body weight, food intake, plasma glucose, insulin, leptin, and adiponectin were measured. Before and after therapy, animals were subjected to an oral glucose tolerance test. At the end of treatment, liver, muscle, kidney, epididymal fat pad, abdominal fat pad, and dorsal fat pad were collected and weighed. RESULTS: Incorporating BJ in drinking water protected young KKA(y) mice from hyperphagia and significantly reduced their weight gain. Moreover, BJ protected young KKA(y) mice against the development of glucose intolerance and diabetes mellitus. Chronic BJ administration in obese and diabetic KKA(y) mice reduced food intake and body weight. This effect could not fully explain the associated antidiabetic effect because BJ-treated mice still showed lower blood glucose level when compared with pair-fed controls. The adipokines pathway also seems to be involved because BJ significantly increased adiponectin levels in obese mice. CONCLUSIONS: This study shows that BJ decreases hyperglycemia in diabetic mice, at least in part by reversing adiponectin levels. BJ also protects young pre-diabetic mice from developing obesity and diabetes. Thus, BJ may represent a novel complementary therapy and a source of novel therapeutic agents against diabetes mellitus.


Assuntos
Adiponectina/sangue , Mirtilos Azuis (Planta) , Diabetes Mellitus/sangue , Hiperglicemia/prevenção & controle , Hipoglicemiantes/farmacologia , Leptina/sangue , Obesidade/prevenção & controle , Animais , Bebidas , Peso Corporal , Diabetes Mellitus/prevenção & controle , Hiperglicemia/sangue , Hiperfagia/prevenção & controle , Masculino , Camundongos , Obesidade/sangue
5.
J Ethnopharmacol ; 115(3): 507-14, 2008 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-18061382

RESUMO

AIM OF THE STUDY: Silybum marianum (milk thistle) is a Mediterranean plant that has been used since Greco-Roman times to treat liver ailments. Silibinin, the most active hepatoprotective constituent of the plant's seed, possesses antioxidant and anti-inflammatory properties. We thus assessed its protective potential in liver transplantation injury. MATERIALS AND METHODS: Rat livers were isolated and preserved during 24h at 4 degrees C in University of Wisconsin (UW) solution alone (control), UW containing 100 microM silibinin or UW containing vehicle (ethanol). Livers were then reperfused at 37 degrees C for 1h with Krebs-Henseleit solution supplemented with 20% erythrocytes. RESULTS: Compared to control, cold preservation and warm reperfusion promoted lipid peroxidation (+40%) and superoxide anion generation (+147%), while attenuating reduced glutathione (-23%), mitochondrial ATP content (-57%) and respiratory control ratio (RCR; -37%). Preservation done in presence of silibinin improved parameters affected by preservation and reperfusion. In fact, silibinin promoted an increase of ATP and RCR by, respectively, 39 and 16% and decreased oxidative stress to values observed in livers never preserved nor perfused. CONCLUSIONS: In conclusion, silibinin shows promise in protecting the liver from cold preservation/warm reperfusion damages. Moreover our study suggests that concepts of traditional medicine have the potential to be transposed successfully in the context of modern medical interventions such as liver transplantation surgery.


Assuntos
Antioxidantes/farmacologia , Transplante de Fígado/efeitos adversos , Traumatismo por Reperfusão/prevenção & controle , Silybum marianum/química , Trifosfato de Adenosina/metabolismo , Animais , Antioxidantes/isolamento & purificação , Modelos Animais de Doenças , Glucose , Glutationa/efeitos dos fármacos , Glutationa/metabolismo , Técnicas In Vitro , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/patologia , Masculino , Medicina Tradicional , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Traumatismo por Reperfusão/etiologia , Sementes , Silibina , Silimarina/isolamento & purificação , Silimarina/farmacologia , Superóxidos/metabolismo , Trometamina
6.
J Med Entomol ; 44(2): 320-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17427704

RESUMO

The hypothesis that Ixodes pacificus Cooley & Kohls (Acari: Ixodidae) may serve as a reservoir and vector of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in California was tested by determining the ability of this tick species to become infected with the NY99 strain of WNV while feeding on viremic song sparrows, to maintain the infection transstadially, and then to transmit WNV to recipient naive song sparrows and western fence lizards during the nymphal stage. The percentage of ticks testing positive by reverse transcription-polymerase chain reaction (RT-PCR) decreased from 77% of 35 larvae at day 6 after ticks were transferred to donor song sparrows (day of detachment) to 23% of 35 nymphs at 59 d postinfestation (approximately 19 d after molting to the nymphal stage). However, the percentage of ticks positive by RT-PCR from which infectious virus was recovered by Vero cell assay decreased from 59% on day 6 to 12% on day 59, even though there was no statistically significant decrease in the quantity of RNA within positive ticks. Attempts to improve the sensitivity of plaque assays by blind passage through C6/36 cell cultures were unsuccessful. These data indicated that ticks maintained viral RNA but not necessarily infectious virus over time. Nymphs from larvae that fed on song sparrows with peak viremias ranging from 7.2 to 8.5 log10 plaque-forming units (PFU) per ml were used in transmission attempts. From one to seven RNA-positive nymphal ticks engorged and detached from each of four recipient song sparrows or western fence lizards. Blood samples from sparrows and lizards remained negative, indicating that transmission did not occur. An additional four lizards inoculated with 1,500 PFU of WNV developed moderate viremias, ranging from 4.2 to 5.6 log10 PFU/ml. Our data and data from previous studies collectively indicated that ixodid ticks were not able to experimentally transmit WNV and therefore most likely would not be important vectors in WNV transmission cycles.


Assuntos
Vetores Artrópodes/virologia , Doenças das Aves/transmissão , Ixodes/virologia , Lagartos , Pardais , Febre do Nilo Ocidental/veterinária , Animais , Doenças das Aves/virologia , Larva , Lagartos/virologia , Ninfa , RNA Viral/isolamento & purificação , Pardais/virologia , Fatores de Tempo , Viremia/veterinária , Febre do Nilo Ocidental/transmissão , Vírus do Nilo Ocidental
7.
Protein Eng Des Sel ; 19(2): 77-84, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16368720

RESUMO

Laccases are oxidizing enzymes of interest because of their potential environmental and industrial applications. We performed site-directed mutagenesis of a laccase produced by Trametes versicolor in order to improve its catalytic properties. Considering a strong interaction of the Asp residue in position 206 with the substrate xylidine, we replaced it with Glu, Ala or Asn, expressed the mutant enzymes in the yeast Yarrowia lipolytica and assayed the transformation of phenolic and non-phenolic substrates. The transformation rates remain within the same range whatever the mutation of the laccase and the type of substrate: at most a 3-fold factor increase was obtained for k(cat) between the wild-type and the most efficient mutant Asp206Ala with 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic) acid as a substrate. Nevertheless, the Asn mutation led to a significant shift of the pH (DeltapH = 1.4) for optimal activity against 2,6-dimethoxyphenol. This study also provides a new insight into the binding of the reducing substrate into the active T1 site and induced modifications in catalytic properties of the enzyme.


Assuntos
Lacase/genética , Lacase/metabolismo , Polyporales/enzimologia , Polyporales/genética , Sequência de Aminoácidos , Compostos de Anilina/metabolismo , Sequência de Bases , Domínio Catalítico , DNA Fúngico/genética , Concentração de Íons de Hidrogênio , Cinética , Lacase/química , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Engenharia de Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Yarrowia/enzimologia , Yarrowia/genética
8.
Insect Mol Biol ; 13(6): 625-35, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15606811

RESUMO

Arthropod-borne alphaviruses transmitted by mosquitoes almost exclusively use culicines; however, the alphavirus o'nyong-nyong (ONNV) has the unusual characteristic of being transmitted primarily by anopheline mosquitoes. This unusual attribute makes ONNV a valuable tool in the characterization of mosquito determinants of infection as well as a useful expression system in Anopheles species. We developed a series of recombinant alphaviruses, based upon the genome of ONNV, designed for the expression of heterologous genes. The backbone genome is a full-length infectious cDNA clone of ONNV from which wild-type virus can be rescued. Additional constructs are variants of the primary clone and contain the complete genome plus a duplicated subgenomic promoter element with a multiple cloning site for insertion of heterologous genes. We inserted a green fluorescent protein (GFP) gene downstream of this promoter and used it to characterize infection and dissemination patterns of ONNV within An. gambiae mosquitoes. These experiments allowed us to identify atypical sites of initial infection and dissemination patterns in this mosquito species not frequently observed in comparable culicine infections. The utility of these ONNVs for studies in anopheline mosquitoes includes the potential for identification of vector infection determinants and to serve as tools for antimalaria studies. Viruses that can express a heterologous gene in a vector and rapidly and efficiently infect numerous tissues in An. gambiae mosquitoes will be a valuable asset in parasite-mosquito interaction and interference research.


Assuntos
Alphavirus/genética , Anopheles/virologia , Vetores Genéticos/genética , Animais , Células Cultivadas , DNA Complementar/genética , Técnicas de Transferência de Genes , Proteínas de Fluorescência Verde/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa
9.
Arch Virol Suppl ; (18): 43-64, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15119762

RESUMO

Following a period of inactivity from 1973-1991, Venezuelan equine encephalitis (VEE) reemerged during the past decade in South America and Mexico. Experimental studies of VEE virus (VEEV) infection of horses with virus strains isolated during these outbreaks have revealed considerable variation in the ability of equine-virulent, epizootic strains to exploit horses as efficient amplification hosts. Subtype IC strains from recent outbreaks in Venezuela and Colombia amplify efficiently in equines, with a correlation between maximum viremia titers and the extent of the outbreak from which the virus strain was isolated. Studies of enzootic VEEV strains that are believed to represent progenitors of the epizootic subtypes support the hypothesis that adaptation to efficient replication in equines is a major determinant of emergence and the ability of VEEV to spread geographically. Correlations between the ability of enzootic and epizootic VEEV strains to infect abundant, equiphilic mosquitoes, and the location and extent of these outbreaks, also suggest that specific adaptation to Ochlerotatus taeniorhynchus mosquitoes is a determinant of some but not all emergence events. Genetic studies imply that mutations in the E2 envelope glycoprotein gene are major determinants of adaptation to both equines and mosquito vectors.


Assuntos
Encefalomielite Equina Venezuelana/transmissão , Animais , Modelos Animais de Doenças , Vetores de Doenças , Vírus da Encefalite Equina Venezuelana/classificação , Vírus da Encefalite Equina Venezuelana/genética , Vírus da Encefalite Equina Venezuelana/patogenicidade , Cavalos , Humanos , Zoonoses
10.
Virology ; 315(2): 381-8, 2003 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-14585341

RESUMO

Little is known about the genetic relationships between European and other Old-World strains of West Nile virus (WNV) and persistence of WNV North of Mediterranean. We characterized the complete genomes of three WNV strains from France (horse-2000), Tunisia (human-1997) and Kenya (mosquito-1998), and the envelope, NS3 and NS5 genes of the Koutango virus. Phylogenetic analyses including all available full-length sequences showed that: (1) Koutango virus is a distant variant of WNV; (2) the three characterized strains belong to lineage 1, clade 1a; (3) the Tunisian strain roots the lineage of viruses introduced in North America. We established that currently available partial envelope sequences do not generate reliable phylogenies. Accordingly, establishing a large WNV sequence database is pivotal for the understanding of spatial and temporal epidemiology of this virus. For rapid completion of that purpose, colinearized E-NS3-NS5 gene sequences were shown to constitute a valuable surrogate for complete sequences.


Assuntos
Vírus do Nilo Ocidental/classificação , África , Sequência de Bases , Evolução Biológica , Europa (Continente) , Genes Virais , Oriente Médio , RNA Helicases , Serina Endopeptidases , Proteínas do Envelope Viral/genética , Proteínas não Estruturais Virais/genética
11.
J Virol ; 75(21): 10118-31, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11581380

RESUMO

Partial E1 envelope glycoprotein gene sequences and complete structural polyprotein sequences were used to compare divergence and construct phylogenetic trees for the genus Alphavirus. Tree topologies indicated that the mosquito-borne alphaviruses could have arisen in either the Old or the New World, with at least two transoceanic introductions to account for their current distribution. The time frame for alphavirus diversification could not be estimated because maximum-likelihood analyses indicated that the nucleotide substitution rate varies considerably across sites within the genome. While most trees showed evolutionary relationships consistent with current antigenic complexes and species, several changes to the current classification are proposed. The recently identified fish alphaviruses salmon pancreas disease virus and sleeping disease virus appear to be variants or subtypes of a new alphavirus species. Southern elephant seal virus is also a new alphavirus distantly related to all of the others analyzed. Tonate virus and Venezuelan equine encephalitis virus strain 78V3531 also appear to be distinct alphavirus species based on genetic, antigenic, and ecological criteria. Trocara virus, isolated from mosquitoes in Brazil and Peru, also represents a new species and probably a new alphavirus complex.


Assuntos
Alphavirus/classificação , Regiões 3' não Traduzidas/química , Regiões 3' não Traduzidas/genética , Alphavirus/genética , Sequência de Bases , Genes Virais , Filogenia , Reação em Cadeia da Polimerase , Proteínas do Envelope Viral/genética , Proteínas Estruturais Virais/genética
12.
J Virol ; 75(13): 5823-32, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11390583

RESUMO

Venezuelan equine encephalitis viruses (VEEV) belonging to subtype IC have caused three (1962-1964, 1992-1993 and 1995) major equine epizootics and epidemics. Previous sequence analyses of a portion of the envelope glycoprotein gene demonstrated a high degree of conservation among isolates from the 1962-1964 and the 1995 outbreaks, as well as a 1983 interepizootic mosquito isolate from Panaquire, Venezuela. However, unlike subtype IAB VEEV that were used to prepare inactivated vaccines that probably initiated several outbreaks, subtype IC viruses have not been used for vaccine production and their conservation cannot be explained in this way. To characterize further subtype IC VEEV conservation and to evaluate potential sources of the 1995 outbreak, we sequenced the complete genomes of three isolates from the 1962-1964 outbreak, the 1983 Panaquire interepizootic isolate, and two isolates from 1995. The sequence of the Panaquire isolate, and that of virus isolated from a mouse brain antigen prepared from subtype IC strain P676 and used in the same laboratory, suggested that the Panaquire isolate represents a laboratory contaminant. Some authentic epizootic IC strains isolated 32 years apart showed a greater degree of sequence identity than did isolates from the same (1962-1964 or 1995) outbreak. If these viruses were circulating and replicating between 1964 and 1995, their rate of sequence evolution was at least 10-fold lower than that estimated during outbreaks or that of closely related enzootic VEEV strains that circulate continuously. Current understanding of alphavirus evolution is inconsistent with this conservation. This subtype IC VEEV conservation, combined with phylogenetic relationships, suggests the possibility that the 1995 outbreak was initiated by a laboratory strain.


Assuntos
Surtos de Doenças , Vírus da Encefalite Equina Venezuelana/classificação , Encefalomielite Equina Venezuelana/epidemiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Encefalomielite Equina Venezuelana/virologia , Humanos , Dados de Sequência Molecular , Filogenia , Fatores de Tempo , Venezuela
13.
Am J Trop Med Hyg ; 64(1-2): 93-7, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11425170

RESUMO

This report describes Trocara virus, a newly recognized member of the genus Alphavirus, that has been isolated from Aedes serratus mosquitoes collected at two widely separated sites in the Amazon Basin. Biological, antigenic and genetic characteristics of the new virus are given. Results of these studies indicate that Trocara virus is the first member of a newly discovered antigenic complex within the family Togaviridae genus Alphavirus. The public health and veterinary importance of Trocara virus is still unknown.


Assuntos
Aedes/virologia , Alphavirus/genética , Alphavirus/isolamento & purificação , Alphavirus/ultraestrutura , Animais , Brasil , Testes de Fixação de Complemento , Cricetinae , Primers do DNA , Testes de Hemaglutinação , Camundongos , Microscopia Eletrônica , Peru , Reação em Cadeia da Polimerase , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa
14.
Am J Trop Med Hyg ; 65(6): 738-46, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11791968

RESUMO

During field studies of enzootic Venezuelan equine encephalitis (VEE) viruses associated with epizootic emergence, a large number of virus isolates were made in sylvatic foci of Venezuela and Colombia. To rapidly characterize these isolates, antigenic subtypes were determined by means of immunofluorescence and by single-strand conformational polymorphism (SSCP) analysis by use of an 856-bp fragment from the P62 gene, which we used to distinguish genetic variants. Representative isolates were sequenced to assess the sensitivity of SSCP to detect genetic differences. The SSCP analysis distinguished isolates differing by as little as 1 nucleotide; overall, differences of > or = 1 nucleotide were recognized 89% of the time, and the sensitivity to distinguish strains that differed by only 1 or 4 nucleotides was 17 and 57%, respectively. Phylogenetic analyses of representative sequences showed that all recent isolates from the Catatumbo region of western Venezuela and the middle Magdalena Valley of Colombia were closely related to epizootic subtype IAB and IC strains; strains from Yaracuy and Miranda States were more distantly related. Cocirculation of the same virus genotype in both Colombian and Venezuelan foci indicated that these viruses are readily transported between enzootic regions separated by > 300 km. The SSCP analysis appears to be a simple, fast, and relatively efficient method of screening VEE virus isolates to identify meaningful genetic variants.


Assuntos
Vírus da Encefalite Equina Venezuelana/genética , Encefalomielite Equina Venezuelana/epidemiologia , Polimorfismo Conformacional de Fita Simples , Aedes , Animais , Colômbia/epidemiologia , Cricetinae , Culex , Primers do DNA , Vírus da Encefalite Equina Venezuelana/classificação , Imunofluorescência , Humanos , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade , Venezuela/epidemiologia
15.
J Gen Virol ; 81(Pt 2): 471-9, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10644846

RESUMO

Chikungunya (CHIK) virus is a member of the genus Alphavirus in the family TOGAVIRIDAE: Serologically, it is most closely related to o'nyong-nyong (ONN) virus and is a member of the Semliki Forest antigenic complex. CHIK virus is believed to be enzootic throughout much of Africa and historical evidence indicates that it spread to other parts of the world from this origin. Strains from Africa and Asia are reported to differ biologically, indicating that distinct lineages may exist. To examine the relatedness of CHIK and ONN viruses using genetic data, we conducted phylogenetic studies on isolates obtained throughout Africa and Southeast Asia. Analyses revealed that ONN virus is indeed distinct from CHIK viruses, and these viruses probably diverged thousands of years ago. Two distinct CHIK virus lineages were delineated, one containing all isolates from western Africa and the second comprising all southern and East African strains, as well as isolates from Asia. Phylogenetic trees corroborated historical evidence that CHIK virus originated in Africa and subsequently was introduced into Asia. Within the eastern Africa and southern Africa/Asia lineage, Asian strains grouped together in a genotype distinct from the African groups. These different geographical genotypes exhibit differences in their transmission cycles: in Asia, the virus appears to be maintained in an urban cycle with Aedes aegypti mosquito vectors, while CHIK virus transmission in Africa involves a sylvatic cycle, primarily with AE: furcifer and AE: africanus mosquitoes.


Assuntos
Alphavirus/genética , Vírus Chikungunya/genética , Evolução Molecular , Aedes/virologia , África , Alphavirus/classificação , Alphavirus/isolamento & purificação , Infecções por Alphavirus/transmissão , Infecções por Alphavirus/virologia , Animais , Anticorpos Antivirais , Antígenos Virais/genética , Sudeste Asiático , Sequência de Bases , Vírus Chikungunya/classificação , Vírus Chikungunya/isolamento & purificação , Cricetinae , Primers do DNA/genética , Humanos , Insetos Vetores/virologia , Camundongos , Dados de Sequência Molecular , Filogenia , Sorotipagem , Fatores de Tempo
16.
J Virol ; 74(9): 4258-63, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10756040

RESUMO

Venezuelan equine encephalitis (VEE) virus antigenic subtypes and varieties are considered either epidemic/epizootic or enzootic. In addition to epidemiological differences between the epidemic and enzootic viruses, several in vitro and in vivo laboratory markers distinguishing the viruses have been identified, including differential plaque size, sensitivity to interferon (IFN), and virulence for guinea pigs. These observations have been shown to be useful predictors of natural, equine virulence and epizootic potential. Chimeric viruses containing variety IAB (epizootic) nonstructural genes with variety IE (enzootic) structural genes (VE/IAB-IE) or IE nonstructural genes and IAB structural genes (IE/IAB) were constructed to systematically analyze and map viral phenotype and virulence determinants. Plaque size analysis showed that both chimeric viruses produced a mean plaque diameter that was intermediate between those of the parental strains. Additionally, both chimeric viruses showed intermediate levels of virus replication and virulence for guinea pigs compared to the parental strains. However, IE/IAB produced a slightly higher viremia and an average survival time 2 days shorter than the VE/IAB-IE virus. Finally, IFN sensitivity assays revealed that only one chimera, VE/IAB-IE, was intermediate between the two parental types. The second chimera, containing the IE nonstructural genes, was at least five times more sensitive to IFN than the IE parental virus and greater than 50 times more sensitive than the IAB parent. These results implicate viral components in both the structural and nonstructural portions of the genome in contributing to the epizootic phenotype and indicate the potential for epidemic emergence from the IE enzootic VEE viruses.


Assuntos
Vírus da Encefalite Equina Venezuelana/genética , Vírus da Encefalite Equina Venezuelana/patogenicidade , Animais , Antivirais/farmacologia , Linhagem Celular , Cricetinae , Vírus da Encefalite Equina Venezuelana/efeitos dos fármacos , Vírus da Encefalite Equina Venezuelana/crescimento & desenvolvimento , Cobaias , Interferon-alfa/farmacologia , Interferon beta/farmacologia , Recombinação Genética , Ensaio de Placa Viral , Virulência
17.
Transpl Int ; 13(6): 420-7, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11140240

RESUMO

Applying the orthotopic rat liver transplantation (ORLT) model, postoperative survival has been shown to be mainly dependent on the portal vein clamping time (PVCT). It was hypothesized that prolonged intestinal congestion was responsible for the activation of Kupffer cells (KC) with overproduction of TNF, secondary to splanchnic endotoxin accumulation and release on reperfusion. The role of KCs was directly investigated in the context of long PVCTs by eliminating them (using liposome-encapsulated dichloromethylene diphosphonate), by preventing their activation (using a calcium channel blocker, nisoldipine) and by inhibiting TNF production (using thalidomide). Livers from different groups of rats were transplanted following 24-h cold preservation in the UW solution with long PVCTs (from 18-21 min). KCs depletion, preservation with nisoldipine and pretreatment with thalidomide significantly improved survival in conditions using long PVCTs. KC depletion and nisoldipine preservation had no effect on liver enzymes or pathological findings while lung injury was significantly improved. The present data confirm that, in the context of ORLT with long PVCTs, KCs are directly responsible for the systemic endotoxin-like shock syndrome and their effect is mediated through overproduction of TNF.


Assuntos
Hepatectomia/métodos , Células de Kupffer/fisiologia , Transplante de Fígado/métodos , Soluções para Preservação de Órgãos , Veia Porta , Complicações Pós-Operatórias/prevenção & controle , Choque/prevenção & controle , Obtenção de Tecidos e Órgãos/métodos , Fator de Necrose Tumoral alfa/biossíntese , Adenosina , Adenosina-5'-(N-etilcarboxamida) , Alopurinol , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Contagem de Células , Ácido Clodrônico/administração & dosagem , Ácido Clodrônico/farmacologia , Temperatura Baixa , Constrição , Glutationa , Sobrevivência de Enxerto , Imunossupressores/farmacologia , Insulina , Isquemia , Células de Kupffer/efeitos dos fármacos , Lipossomos , Fígado/irrigação sanguínea , Fígado/patologia , Transplante de Fígado/patologia , Pulmão/patologia , Ativação de Macrófagos/efeitos dos fármacos , Masculino , Nisoldipino/farmacologia , Complicações Pós-Operatórias/etiologia , Rafinose , Ratos , Ratos Endogâmicos Lew , Espécies Reativas de Oxigênio , Choque/etiologia , Talidomida/farmacologia , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismo
18.
Am J Trop Med Hyg ; 61(4): 579-86, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10548292

RESUMO

Eastern equine encephalitis virus (EEEV), the sole species in the EEE antigenic complex, is divided into North and South American antigenic varieties based on hemagglutination inhibition tests. Here we describe serologic and phylogenetic analyses of representatives of these varieties, spanning the entire temporal and geographic range available. Nucleotide sequencing and phylogenetic analyses revealed additional genetic diversity within the South American variety; 3 major South/Central American lineages were identified including one represented by a single isolate from eastern Brazil, and 2 lineages with more widespread distributions in Central and South America. All North American isolates comprised a single, highly conserved lineage with strains grouped by the time of isolation and to some extent by location. An EEEV strain isolated during a 1996 equine outbreak in Tamaulipas State, Mexico was closely related to recent Texas isolates, suggesting southward EEEV transportation beyond the presumed enzootic range. Plaque reduction neutralization tests with representatives from the 4 major lineages indicated that each represents a distinct antigenic subtype. A taxonomic revision of the EEE complex is proposed.


Assuntos
Variação Antigênica/genética , Vírus da Encefalite Equina do Leste/genética , Encefalomielite Equina/epidemiologia , Variação Genética , Filogenia , Sequência de Aminoácidos , Animais , Sequência de Bases , Aves , América Central/epidemiologia , Primers do DNA/química , DNA Viral/química , Surtos de Doenças/veterinária , Vírus da Encefalite Equina do Leste/imunologia , Cavalos , Humanos , Testes de Neutralização/veterinária , América do Norte/epidemiologia , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Alinhamento de Sequência , Análise de Sequência de RNA , Sigmodontinae/virologia , América do Sul/epidemiologia
19.
Am J Physiol ; 276(5): R1258-64, 1999 05.
Artigo em Inglês | MEDLINE | ID: mdl-10233015

RESUMO

The goal of the present experiment was to measure the volume of the different compartments in liver of exercised rats and to get some insights into the appropriate working of the hepatic function following exercise. Hence, livers from male rats were isolated and perfused after treadmill exercise or rest. This procedure was performed on rats that were overnight semifasted (50% food restriction) or well fed. To evaluate the hepatocyte cell volume, the multiple-indicator dilution curve technique was used after 40 min of perfusion. Radioactive tracers for red blood cells, sucrose, and water were used to measure liver vascular space, liver interstitial space, and water cellular space, respectively. The hepatocyte function was assessed by taurocholate and propanolol clearance. Oxygen consumption, intrahepatic resistance, bile secretion, and lactate dehydrogenase release estimated liver viability. Liver viability and hepatocyte function were not changed following exercise either in the fed or in the semifasted animals. As expected, liver glycogen levels were significantly (P < 0.01) reduced in the food-restricted rats. Consequently, liver glycogen levels following exercise were decreased significantly (P < 0.01) only in the fed rats. Despite this, exercise decreased the hepatocyte water space in both food-restricted and fed groups ( approximately 15%; P < 0.01) without altering the sinusoidal and interstitial space. The present data show that acute exercise decreased the hepatocyte volume and that this volume change is not entirely linked to a decrease in hepatic glycogen level.


Assuntos
Fígado/citologia , Fígado/metabolismo , Esforço Físico/fisiologia , Animais , Bile/metabolismo , Peso Corporal , Sobrevivência Celular/fisiologia , Detergentes/farmacocinética , Jejum/fisiologia , Ácidos Graxos não Esterificados/sangue , Glucagon/sangue , Glicogênio/sangue , Insulina/sangue , L-Lactato Desidrogenase/sangue , L-Lactato Desidrogenase/metabolismo , Masculino , Técnicas de Cultura de Órgãos , Consumo de Oxigênio/fisiologia , Propranolol/farmacocinética , Ratos , Ratos Sprague-Dawley , Ácido Taurocólico/farmacocinética , Vasodilatadores/farmacocinética , Água/metabolismo
20.
J Virol ; 73(5): 4316-26, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10196330

RESUMO

The alternating host cycle and persistent vector infection may constrain the evolution of arboviruses. To test this hypothesis, eastern equine encephalitis virus was passaged in BHK or mosquito cells, as well as in alternating (both) host cell passages. High and low multiplicities were used to examine the effect of defective interfering particles. Clonal BHK and persistent mosquito cell infections were also evaluated. Fitness was measured with one-step growth curves and competition assays, and mutations were evaluated by nucleotide sequencing and RNA fingerprinting. All passages and assays were done at 32 degrees C to eliminate temperature as a selection factor. Viruses passaged in either cell type alone exhibited fitness declines in the bypassed cells, while high-multiplicity and clonal passages caused fitness declines in both types of cells. Bypassed cell fitness losses were mosquito and vertebrate specific and were not restricted to individual cell lines. Fitness increases occurred in the cell line used for single-host-adaptation passages and in both cells for alternately passaged viruses. Surprisingly, single-host-cell passage increased fitness in that cell type no more than alternating passages. However, single-host-cell adaptation resulted in more mutations than alternating cell passages. Mosquito cell adaptation invariably resulted in replacement of the stop codon in nsP3 with arginine or cysteine. In one case, BHK cell adaptation resulted in a 238-nucleotide deletion in the 3' untranslated region. Many nonsynonymous substitutions were shared among more than one BHK or mosquito cell passage series, suggesting positive Darwinian selection. Our results suggest that alternating host transmission cycles constrain the evolutionary rates of arboviruses but not their fitness for either host alone.


Assuntos
Adaptação Biológica/genética , Arbovírus/genética , Vírus da Encefalite Equina do Leste/genética , Aedes/citologia , Sequência de Aminoácidos , Animais , Arbovírus/crescimento & desenvolvimento , Sequência de Bases , Linhagem Celular , Cricetinae , DNA Viral , Vírus Defeituosos , Vírus da Encefalite Equina do Leste/crescimento & desenvolvimento , Cavalos , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Vírion
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