RESUMO
In order to gain insight into the genetic variability of dengue virus type 3 (DENV-3) genotype III isolated in the Latin American region, phylogenetic analysis were carried out using envelope (E) gene sequences from 57 DENV-3 genotype III strains isolated in 11 Latin American countries. At least six different genotype III clades were observed. Amino acids substitutions were found in domain III E protein neutralization epitopes and in surface-exposed domain II and III E protein amino acid sequences.
Assuntos
Vírus da Dengue/classificação , Vírus da Dengue/genética , Variação Genética , RNA Viral/genética , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Vírus da Dengue/isolamento & purificação , Epitopos/genética , Genótipo , Humanos , América Latina , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Estrutura Terciária de Proteína , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência , Proteínas do Envelope Viral/genéticaRESUMO
Dengue virus (DENV) is a member of the genus Flavivirus of the family Flaviviridae. DENV-3 re-emerged in Central America in 1994, and continues to expand into the South American region. Little is known about the evolutionary rates, viral spread and population dynamics of this genotype in the Latin American region. In order to gain insight into these matters, we used a Bayesian Markov chain Monte Carlo (MCMC) approach, to analyze envelope (E) gene sequences of the DENV-3 genotype III of strains included in a monophyletic cluster composed by Ecuadorian as well as strains from Cuba, Puerto Rico and Peru. The results of these studies revealed that the expansion population growth model was the best fit to the data. The most common recent ancestor (MRCA) was placed around 1989, in agreement with the first reports of the emergence of this new DENV-3 type. A mean rate 1.033 x 10(-3) nucleotide substitution per site per year was obtained. This rate is comparatively higher than the ones obtained for DENV-2 and DENV-4 in the same region. Faster population growth and greater population dispersal may have contributed to the vigorous initial transmission dynamics of this genotype in the Latin American region.
Assuntos
Vírus da Dengue/genética , Dengue/virologia , Evolução Molecular , Vírus da Dengue/classificação , Vírus da Dengue/isolamento & purificação , Equador , Modelos Genéticos , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNARESUMO
Dengue virus (DENV) is a member of the genus Flavivirus of the family Flaviviridae. DENV causes a wide range of diseases in humans, from the acute febrile illness dengue fever (DF) to life-threatening dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). There is not knowledge of the genetic relations among DENV circulating in Ecuador. Given the emerging behaviour of DENV, a single tube RT-PCR assay using a pair of consensus primers to target the NS5 coding region has been recently validated for rapid detection of flaviviruses. In order to gain insight into the degree of genetic variation of DENV strains isolated in Ecuador, DENV NS5 sequences from 23 patients were obtained by direct sequencing of PCR fragments using the mentioned one step RT-PCR assay. Phylogenetic analysis carried out using the 23 Ecuadorian DENV NS5 sequences, as well as 56 comparable sequences from DENV strains isolated elsewhere, revealed a close genetic relation among Ecuadorian strains and DENV isolates of Caribbean origin. The use of partial NS5 gene sequences may represent a useful alternative for a rapid phylogenetic analysis of DENV outbreaks.
Assuntos
Vírus da Dengue/genética , Dengue/virologia , Filogenia , Proteínas não Estruturais Virais/genética , Vírus da Dengue/classificação , Vírus da Dengue/isolamento & purificação , Equador , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , América do SulRESUMO
Hepatitis C virus genotyping was assessed for 257 chronic hepatitis C patients with viral loads above 1,000 IU/ml. Twelve patients were coinfected with more than one genotype. Their median viral loads did not differ significantly from those observed for monoinfected patients, which in turn did not vary significantly among different genotypes.
Assuntos
Hepacivirus/genética , Hepatite C Crônica/virologia , Carga Viral , Adulto , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , RNA Viral/análiseRESUMO
An enzyme-linked immunosorbent assay to diagnose Chagas' disease by a serological test was performed with Trypanosoma cruzi recombinant antigens (JL8, MAP, and TcPo). High sensitivity (99.4%) and specificity (99.3%) were obtained when JL8 was combined with MAP (JM) and tested with 150 serum samples from chagasic and 142 nonchagasic individuals. Moreover, JM also diagnosed 84.2% of patients in the acute phase of T. cruzi infection.
Assuntos
Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Doença de Chagas/diagnóstico , Trypanosoma cruzi/imunologia , Doença Aguda , Animais , Doença Crônica , Ensaio de Imunoadsorção Enzimática , Humanos , Imunoglobulina G/sangue , Proteínas Recombinantes/imunologia , Sensibilidade e Especificidade , Testes SorológicosRESUMO
Hepatitis C virus (HCV) has high genomic variability and, since its discovery, at least six different types and an increasing number of subtypes have been reported. Genotype 1 is the most prevalent genotype found in South America. In the present study, three different genomic regions (5'UTR, core and NS5B) of four HCV strains isolated from Peruvian patients were sequenced in order to investigate the congruence of HCV genotyping for these three genomic regions. Phylogenetic analysis using 5'UTR-core sequences found strain PE22 to be related to subtype 1b. However, the same analysis using the NS5B region found it to be related to subtype 1a. To test the possibility of genetic recombination, phylogenetic studies were carried out, revealing that a crossover event had taken place in the NS5B protein. We discuss the consequences of this observation on HCV genotype classification, laboratory diagnosis and treatment of HCV infection.