RESUMO
Sixty eight nucleotide sequences encoding protein E of the West Nile virus (WNV) were used for the phylogenetic analysis and estimation of the evolution rate of the WNV. Nucleotide substitution accumulation rate was evaluated as 2.5 x 10(-4) substitutions per site per year. Phylogenetic analysis and divergence time estimation carried out using the molecular clocks methodology showed that genotypes 1, 2, and 4 of the WNV circulated in the area of the European Russia with estimated divergence times from a common ancestor of approximately 2360, 2800, and 5950 years ago, respectively. The non-synonymous (dN) to the synonymous (dS) substitution values were found between 0.022-0.275 for the different WNV strains that were grouped by geographical and/or filogenetic characteristics. The highest dN/dS values were found in the group of WNV isolates coming from Russia and North America that have disseminated in these new regions over the past 14 years. Estimation of dN/dS for WNV shows that the dN/ dS value can be used as an indicator of the intraspecies variability and for evaluation of evolution rate for new isolates of WNV. This confirms the hypothesis about of the favorable conditions for the wide dissemination and rapid evolution of different' genotypes of WNV occurring from 2 up to 6 thousand years ago in modern geographical and climatic conditions.
Assuntos
Evolução Molecular , Vírus do Nilo Ocidental/genética , DNA Viral/química , DNA Viral/genética , Genótipo , Filogenia , Polimorfismo de Nucleotídeo Único , Vírus do Nilo Ocidental/classificaçãoRESUMO
The problem of emerging viruses, their genetic diversity and viral evolution in nature are attracting more attention. The phylogenetic analysis and evaluationary rate estimation were made for pathogenic flaviviruses such as tick-borne encephalitis virus (TBEV) and Powassan (PV) circulated in natural foci in Russia. 47 nucleotide sequences of encoded protein E of the TBEV and 17 sequences of NS5 genome region of the PV have been used. It was found that the rate of accumulation of nucleotide substitutions for E genome region of TBEV was approximately 1.4 x 10(-4) and 5.4 x 10(-5) substitutions per site per year for NS5 genome region of PV. The ratio of non-synonymous nucleotide substitutions to synonymous substitution (dN/dS) for viral sequences were estimated of 0.049 for TBEV and 0.098 for PV. Maximum value dN/dS was 0.201-0.220 for sub-cluster of Russian and Canadian strains of PV and the minimum - 0.024 for cluster of Russian and Chinese strains of Far Eastern genotype TBEV. Evaluation of time intervals of evolutionary events associated with these viruses showed that European subtype TBEV are diverged from all-TBEV ancestor within approximately 2750 years and the Siberian and Far Eastern subtypes are emerged about 2250 years ago. The PV was introduced into natural foci of the Primorsky Krai of Russia only about 70 years ago and PV is a very close to Canadian strains of PV. Evolutionary picture for PV in North America is similar to evolution of Siberian and Far Eastern subtypes TBEV in Asia. The divergence time for main genetic groups of TBEV and PV are correlated with historical periods of warming and cooling. These allow to propose a hypothesis that climate changes were essential to the evolution of the flaviviruses in the past millenniums.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos/genética , Encefalite Transmitida por Carrapatos/genética , Encefalite Transmitida por Carrapatos/virologia , Evolução Molecular , Proteínas do Envelope Viral/genética , Substituição de Aminoácidos/genética , Canadá , Europa (Continente) , Ásia Oriental , Variação Genética , Genótipo , Humanos , Filogenia , Federação Russa , SibériaRESUMO
The review presents recent data on the molecular mechanisms of the stages of an Ebola virus replication cycle, on the interaction of viral and cellular components at each stage, as well as on the mechanisms responsible for he realization of viral genetic information in the infected cell.
Assuntos
Ebolavirus/fisiologia , Animais , Citoplasma/metabolismo , Citoplasma/virologia , Ebolavirus/química , Genes Virais/genética , Genoma Viral , Humanos , Nucleocapsídeo/metabolismo , Biossíntese de Proteínas , RNA Viral/biossíntese , RNA Viral/genética , Proteínas Virais/genética , Vírion/química , Vírion/genética , Replicação ViralRESUMO
The trend in hematological and immunological parameters during Ebola virus passages in guinea-pigs indicated that pathophysiological changes occurred just during the second passage and further became stronger. The increase of some parameters and their correlation with the occurrence of fatal outcomes allowed the authors to reveal the most significant changes as increased juvenile platelets, whole blood virus appearance, higher echinocytes, a rise in the pro mil of blast cells and megakaryocytes in the bone marrow, and decreased neutrophilic phagocytic activity. Viral acquisition of the properties of lethality to guinea-pigs depends on the fine mechanisms responsible for viral interaction with host cells, which may lead to viral genetic changes during passages.
Assuntos
Ebolavirus/patogenicidade , Doença pelo Vírus Ebola/imunologia , Animais , Células da Medula Óssea/imunologia , Modelos Animais de Doenças , Ebolavirus/crescimento & desenvolvimento , Cobaias , Doença pelo Vírus Ebola/sangue , Doença pelo Vírus Ebola/virologia , Ativação Linfocitária , Megacariócitos , Neutrófilos/imunologia , Fagocitose , Inoculações Seriadas , Trombocitose/sangue , Carga Viral , VirulênciaRESUMO
The paper describes the structure and functions of Ebola virus properties. It also presents information on the role of structural (NP, VP40, VP35, GP, VP30, VP24, and L) and secreted (sGP, delta-peptide, GP1, GP(1,2delta), ssGP) proteins in the viral replication cycle and in the pathogenesis of Ebola hemorrhagic fever.