RESUMEN
72 clinical strains of Klebsiella spp. isolated from samples obtained from humans in Novosibirsk, Russia, were analyzed. Species identification of strains was performed using 16S rRNA and rpoB gene sequences. It was revealed that Klebsiella pneumoniae strains were dominant in the population (57 strains), while the remaining 15 strains were K. grimontii, K. aerogenes, K. oxytoca and K. quasipneumoniae. By molecular serotyping using the wzi gene sequence, K. pneumoniae strains were assigned to twenty-one K-serotypes with a high proportion of virulent K1- and K2-serotypes. It was found that K. pneumoniae strains isolated from the hospitalized patients had a higher resistance to antibiotics compared to the other Klebsiella species. Real-time PCR revealed that the population contained genes of the blaSHV, blaTEM, blaCTX families and the blaOXA-48 gene, which are the genetic determinants of beta-lactam resistance. It has been shown that the presence of the blaCTX sequence correlated with the production of extended-spectrum beta-lactamases, and phenotypic resistance to carbapenems is due to the presence of the blaOXA-48 gene. At the same time, the carbapenemase genes vim, ndm, kpc, imp were not detected. Among the aminoglycoside resistance genes studied, the aph(6)-Id and aadA genes were found, but their presence did not always coincide with phenotypic resistance. Resistance to fluoroquinolones in the vast majority of strains was accompanied by the presence of the aac(6')-IB-cr, oqxA, oqxB, qnrB, and qnrS genes in various combinations, while the presence of the oqxA and/or oqxB genes alone did not correlate with resistance to fluoroquinolones. Thus, the detection of blaCTX and blaOXA-48 can be used to quickly predict the production of extended-spectrum beta-lactamases and to determine the resistance of Klebsiella to carbapenems. The detection of the aac(6')-Ib-cr and/or qnrB/qnrS genes can be used to quickly determine resistance to fluoroquinolones.
RESUMEN
To date, the association of an imbalance of the intestinal microbiota with various human diseases, including both diseases of the gastrointestinal tract and disorders of the immune system, has been shown. However, despite the huge amount of accumulated data, many key questions still remain unanswered. Given limited data on the composition of the gut microbiota in patients with ulcerative colitis (UC) and irritable bowel syndrome (IBS) from different parts of Siberia, as well as the lack of data on the gut microbiota of patients with bronchial asthma (BA), the aim of the study was to assess the biodiversity of the gut microbiota of patients with IBS, UC and BA in comparison with those of healthy volunteers (HV). In this study, a comparative assessment of the biodiversity and taxonomic structure of gut microbiome was conducted based on the sequencing of 16S rRNA genes obtained from fecal samples of patients with IBS, UC, BA and volunteers. Sequences of the Firmicutes and Bacteroidetes types dominated in all samples studied. The third most common in all samples were sequences of the Proteobacteria type, which contains pathogenic and opportunistic bacteria. Sequences of the Actinobacteria type were, on average, the fourth most common. The results showed the presence of dysbiosis in the samples from patients compared to the sample from HVs. The ratio of Firmicutes/Bacteroidetes was lower in the IBS and UC samples than in HV and higher the BA samples. In the samples from patients with intestinal diseases (IBS and UC), an increase in the proportion of sequences of the Bacteroidetes type and a decrease in the proportion of sequences of the Clostridia class, as well as the Ruminococcaceae, but not Erysipelotrichaceae family, were found. The IBS, UC, and BA samples had signif icantly more Proteobacteria sequences, including Methylobacterium, Sphingomonas, Parasutterella, Halomonas, Vibrio, as well as Escherichia spp. and Shigella spp. In the gut microbiota of adults with BA, a decrease in the proportion of Roseburia, Lachnospira, Veillonella sequences was detected, but the share of Faecalibacterium and Lactobacillus sequences was the same as in healthy individuals. A signif icant increase in the proportion of Halomonas and Vibrio sequences in the gut microbiota in patients with BA has been described for the f irst time.
RESUMEN
The tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is currently subdivided into three main subtypes-the European (TBEV-Eu), the Far-Eastern (TBEV-FE), and the Siberian (TBEV-Sib). The TBEV-Sib is the most common subtype and found in all regions where TBEV was detected, except for Central and Western Europe. Currently, four genetic lineages have been described within TBEV-Sib. In this study, detailed analysis of TBEV-Sib genetic diversity, geographic distribution, phylogeography and divergence time of different TBEV-Sib genetic lineages based on E gene fragments, complete genome sequences, and all currently available data in the GenBank database was performed. As a result, a novel Bosnia lineage within the TBEV-Sib was identified. It was demonstrated that the Zausaev lineage is the most widely distributed among the TBEV-Sib lineages, and was detected in all studied regions except the Far East. The Vasilchenko lineage was found from Western Siberia to the Far East. The Baltic lineage is presented from Europe to Western Siberia. The Obskaya lineage was found only in Western Siberia. TBEV strains from a newly described Bosnia lineage were detected in Bosnia, the Crimean peninsula, Kyrgyzstan and Kazakhstan. The greatest divergence of the TBEV-Sib genetic variants was observed in Western Siberia. Within the TBEV-Sib, the Obskaya lineage diverged from the common ancestor the earliest, after that the Bosnia lineage was separated, then the Baltic lineage, and the Zausaev and Vasilchenko lineages diverged most recently.
Asunto(s)
Virus de la Encefalitis Transmitidos por Garrapatas/genética , Variación Genética , Asia Central , Virus de la Encefalitis Transmitidos por Garrapatas/clasificación , Europa (Continente) , Asia Oriental , Filogenia , Filogeografía , SiberiaRESUMEN
Genetic evidence of the Tula virus (TULV) in Crimea region of Russia is presented. Based on the reverse transcription PCR and subsequent sequence analysis, a total of 4 RNA isolates of the TULV were identified from the tissue samples of the Altai voles Microtus obscurus captured in the Bakhchisaray district of the Republic Crimea. Phylogenetic analysis of the S-, M-, and L-segment sequences of the Crimean TULV strains showed that they formed distinct genetic lineage, Russia IV, in the TULV variant. New sequences were most closely related to the lineage Russia I sequences obtained from common vole (M. arvalis) captured in the Tula region in Central Russia
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Orthohantavirus/genética , Animales , Arvicolinae/virología , Orthohantavirus/aislamiento & purificación , Filogenia , Filogeografía , Federación de RusiaRESUMEN
Expression of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) gene under the control of the 5'-regulatory sequence of the goat alpha-S1-casein gene with and without a matrix attachment region (MAR) element from the Drosophila histone 1 gene was studied in four and eight transgenic mouse lines, respectively. Of the four transgenic lines carrying the transgene without MAR, three had correct tissues-specific expression of the hGM-CSF gene in the mammary gland only and no signs of cell mosaicism. The concentration of hGM-CSF in the milk of transgenic females varied from 1.9 to 14 µg/ml. One line presented hGM-CSF in the blood serum, indicating ectopic expression. The values of secretion of hGM-CSF in milk of 6 transgenic lines carrying the transgene with MAR varied from 0.05 to 0.7 µg/ml, and two of these did not express hGM-CSF. Three of the four examined animals from lines of this group showed ectopic expression of the hGM-CSF gene, as determined by RT-PCR and immunofluorescence analyses, as well as the presence of hGM-CSF in the blood serum. Mosaic expression of the hGM-CSF gene in mammary epithelial cells was specific to all examined transgenic mice carrying the transgene with MAR but was never observed in the transgenic mice without MAR. The mosaic expression was not dependent on transgene copy number. Thus, the expected "protective or enhancer effect" from the MAR element on the hGM-CSF gene expression was not observed.
Asunto(s)
Caseínas/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Regiones de Fijación a la Matriz/genética , Animales , Clonación Molecular , Cartilla de ADN/genética , Drosophila/genética , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Cabras/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/sangre , Histonas/genética , Humanos , Masculino , Glándulas Mamarias Animales/metabolismo , Ratones , Ratones Transgénicos , Plásmidos/genética , Reacción en Cadena de la Polimerasa , Secuencias Reguladoras de Ácidos Nucleicos/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Chicken anemia virus gene encoding apoptin, a selective killer of cancer cells was synthesized and inserted into vaccinia virus (strain L-IVP) genome. The insertion has replaced major part of the viral C11R gene encoding viral growth factor (VGF), which is important for the virulence. The recombinant virus VVdGF-ApoS24/2 was obtained through the transient dominant selection technique with the use of puromycin resistance gene as the selective marker. The expression apoptin gene from a synthetic early-late promoter of vaccinia virus effectively provides accumulation of the protein in the cells infected with the VVdGF-ApoS24/2 virus. Despite the presence of virus growth factor signal peptide at apoptin N-terminal secretion of the recombinant protein into culture medium did not occur. The recombinant virus VVdGF-ApoS24/2 was found to have a significantly greater selective lyticactivity on human cancer cell lines (A549, A431, U87MG, RD and MCF7) as compared with the parent strain L-IVP and its variant VVdGF2/6 with the deletion of the C11R gene. The results suggest that the use of apoptin represents a promising approach for improving the natural anticancer activities of vaccinia virus.
Asunto(s)
Vacunas contra el Cáncer/genética , Proteínas de la Cápside/genética , Neoplasias/genética , Virus Oncolíticos/genética , Virus Vaccinia/genética , Animales , Proteínas de la Cápside/uso terapéutico , Virus de la Anemia del Pollo/genética , Pollos/genética , Pollos/virología , Vectores Genéticos , Genoma Viral , Humanos , Células MCF-7 , Neoplasias/terapia , Neoplasias/virología , Viroterapia Oncolítica/métodos , Replicación Viral/genéticaRESUMEN
Increasing information concerning molecular biology of viruses and virus-cell interactions makes it possible to use viruses as a tool in effort to treat cancer diseases. As a rule, tumor cells are highly sensitive to viruses that may be used in cancer therapy. Therewith, applications of viral oncolysis in treatment of cancer diseases assume maximum possible safety of used viruses for patient and environment. Human enteroviruses are one of the most convenient sources to generate oncolytic viruses. Many of enteroviruses are non-pathogenic for humans or cause mild disease. Progress in genetic engineering permits to develop attenuated enterovirus variants with high safety and selectivity. This review focuses on the main members of Enterovirus genus, such as Coxsackieviruses, and vaccine strains as promising source for development of oncolytic agents, applicable for cancer therapy. It reviews data concerning recently developed and tested oncolytic variants of enteroviruses and discusses perspectives of their application in cancer therapy and problems, concerning their improvement and practical use.
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Vacunas contra el Cáncer/genética , Enterovirus/inmunología , Genoma Viral , Neoplasias/tratamiento farmacológico , Neoplasias/prevención & control , Virus Oncolíticos/inmunología , Vacunas Virales/genética , Antineoplásicos/administración & dosificación , Antineoplásicos/inmunología , Vacunas contra el Cáncer/inmunología , Enterovirus/genética , Ingeniería Genética , Humanos , Neoplasias/inmunología , Viroterapia Oncolítica/métodos , Virus Oncolíticos/genética , Vacunas Virales/inmunología , Replicación ViralRESUMEN
The latest data on selection and construction of poxviruses capable of specifically lysing tumor cells of different genesis, inducing antitumor immunity and apoptosis of malignant cells are discussed. The review concerns several directions: virus attenuation, insertion of immunomodulatory protein genes, and anti-tumor protein genes. Thymidine kinase and viral growth factor genes make the greatest contribution to the virus attenuation as their inactivation results in the virus inability to replicate in non-dividing cells, thereby contributing to increased selectivity with respect to tumor cells. Among the immunomodulatory proteins, interleukins 2, 12, and granulocyte-macrophage colony-stimulating factor proved to be most promising for oncolytic virotherapy. An attempt to use p53 protein gene expressed by vaccinia virus for addressed apoptosis of tumor cells was reported. The use of the double and triple viral recombinants carrying genes of multidirectional action seems to be most promising. Encouraging results were obtained using vaccinia virus in the oncotherapy with prodrugs and angiogenesis inhibitors. At present, two poxviral strains are undergoing Phase III clinical trials as anti-tumor preparations in the USA.
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Genes p53 , Interleucinas/genética , Neoplasias/terapia , Viroterapia Oncolítica , Virus Oncolíticos/genética , Virus Vaccinia/genética , Inhibidores de la Angiogénesis/genética , Vectores Genéticos , Humanos , Timidina Quinasa/genética , Virus Vaccinia/ultraestructuraRESUMEN
Molecular epidemiological study of novel strain of Rubella virus isolated during the outbreak in Western Siberia in 2004 was described. Detailed phylogenetic analysis performed based upon entire SP-region, which encodes all three Rubella structural proteins (C, E2, and E1), was implemented. This analysis provides characterization of this strain and classifies it as 1H genotype, thereby correcting previous classification of this strain based upon shorter nucleotide sequence, only encoding E1 protein. Therefore, this study identified the genotype of the Rubella virus not previously detected in Western Siberia (and even entire Russian Federation), which highlights the importance of more extensive characterization of genetic variability of the Rubella virus, especially with regard to potential influence of vaccination on the Rubella virus mutagenesis.
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Virus de la Rubéola/clasificación , Virus de la Rubéola/genética , Rubéola (Sarampión Alemán)/virología , Genotipo , Técnicas de Genotipaje , Humanos , Mutación , Filogenia , Rubéola (Sarampión Alemán)/epidemiología , Virus de la Rubéola/aislamiento & purificación , Siberia/epidemiología , Proteínas del Envoltorio Viral/clasificación , Proteínas del Envoltorio Viral/genética , Proteínas Estructurales Virales/clasificación , Proteínas Estructurales Virales/genéticaRESUMEN
Potential ORFs were sought in the extended segments of terminal variable regions in the variola virus genome. These ORFs underwent a detailed structural and functional analysis and were compared both between themselves and with homologous ORFs of various orthopoxviruses. The most conservative and heterogeneous ORFs of 70 VARV strains were detected. The unique for VARV ORF (111 a.a) was revealed for Helder and Mary strains of the Russian collection. In addition, only in the Helder strain, ORF D14L was disintegrated into two separate ORFs. A number of ambiguities were found in the current databases for VARV ORF. The dominating type of evolution was ascertained to be stabilizing selection for analyzed ORF. It has been established that VARV ORF C3L, unlike other poxviral orthologs, undergoes an adaptive selection. These findings suggest that this gene plays an important role in human VARV adaptation.
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Orden Génico , Código Genético , Genoma Viral/genética , Sistemas de Lectura Abierta/genética , Virus de la Viruela/genética , Adaptación Fisiológica/genética , Evolución Molecular , Humanos , Filogenia , Análisis de Secuencia de ADN , Virus de la Viruela/clasificaciónRESUMEN
Comparative analysis of amino acid and nucleotides sequences of ORFs located in extended segments of the terminal variable regions in variola virus genome detected a promising locus for viral genotyping according to the geographic origin. This is ORF O1L of VARV. The primers were calculated for synthesis of this ORF fragment by PCR, which makes it possible to distinguish South America-Western Africa genotype from other VARV strains. Subsequent RFLP analysis reliably differentiated Asian strains from African strains (except Western Africa isolates). This method has been tested using 16 VARV strains from various geographic regions. The developed approach is simple, fast and reliable.
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Reacción en Cadena de la Polimerasa/métodos , Viruela/virología , Virus de la Viruela/clasificación , Virus de la Viruela/aislamiento & purificación , África , Secuencia de Aminoácidos , Repetición de Anquirina/genética , Asia , Cartilla de ADN/genética , Variación Genética , Genoma Viral/genética , Humanos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta/genética , Polimorfismo de Longitud del Fragmento de Restricción , Sensibilidad y Especificidad , Alineación de Secuencia , América del Sur , Virus de la Viruela/genéticaRESUMEN
Previous restriction fragment length polymorphism analysis divided variola virus (VARV) strains into two subtypes, one of which included West African and South American isolates. This allowed a dating to be introduced for the first time in estimation of the VARV evolution rate. The results were used to analyze the molecular evolution of the total family Poxviridae. Comparisons of the known nucleotide sequences were performed for the extended conserved central genome region in 42 orthopoxvirus strains and for the eight genes of multisubunit RNA polymerase in 65 viruses belonging to various genera of the family Poxviridae. Using the Bayesian dating method, the mutation accumulation rate of poxviruses was estimated at (1.7-8.8) x 10(-6) nucleotide substitutions per site per year. Computations showed that the modem poxvirus genera started diverging from an ancestral virus more than 200 thousand years ago and that an ancestor of the genus Orthopoxvirus emerged 131 +/- 45 thousand years ago. The other genera of mammalian poxviruses with a low GC content diverged approximately 110-90 thousand years ago. The independent evolution of VARV started 3.4 +/- 0.8 thousand years ago. It was shown with the example of VARV and the monkeypox virus (MPXV) that divergent evolution of these orthopoxviruses started and the West African subtypes of VARV and MPXV were formed as geographical conditions changed to allow isolation of West African animals from other African regions.
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ADN Viral/genética , Evolución Molecular , Polimorfismo de Longitud del Fragmento de Restricción , Poxviridae/genética , Análisis de Secuencia de ADN , Animales , Humanos , Análisis de Secuencia de ADN/métodosRESUMEN
Nucleotide sequences of two extended segments of the terminal variable regions in variola virus genome were determined. The size of the left segment was 13.5 kbp and of the right, 10.5 kbp. Totally, over 540 kbp were sequenced for 22 variola virus strains. The conducted phylogenetic analysis and the data published earlier allowed us to find the interrelations between 70 variola virus isolates, the character of their clustering, and the degree of intergroup and intragroup variations of the clusters of variola virus strains. The most polymorphic loci of the genome segments studied were determined. It was demonstrated that that these loci are localized to either noncoding genome regions or to the regions of destroyed open reading frames, characteristic of the ancestor virus. These loci are promising for development of the strategy for genotyping variola virus strains. Analysis of recombination using various methods demonstrated that, with the only exception, no statistically significant recombinational events in the genomes of variola virus strains studied were detectable.
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Genoma Viral/genética , Sistemas de Lectura Abierta/genética , Filogenia , Polimorfismo Genético , Sitios de Carácter Cuantitativo/genética , Virus de la Viruela/genética , Recombinación Genética/genética , Especificidad de la EspecieRESUMEN
A genetic construct of the human interleukin-2 (IL-2) gene within vaccinia virus (L-IVP strain) has been designed. The authors show the capacity of CV-1 cells infected with the recombinant vaccinia virus VV-SIL2 to secrete human IL-2 into the culture medium. Human IL-2 has been detected by immunoblotting. The sera from the animals immunized with the recombinant virus VV-SIL2 exhibited both human IL-2 and its antibodies throughout the observation period. This recombinant virus immunization induced both humoral and cell-mediated immune responses to human IL-2; the observed changes in the concentrations of cytokines are likely to suggest that the response predominantly followed a Th1 pathway. The study construct was nontoxic at the used concentrations and administration routes. The findings point that it is promising to investigate the adjuvant properties of the recombinant VV-SIL2 vaccine-based preparation for immunization in combination with various vaccines and to study this construct in therapy for cancer diseases.
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Anticuerpos Antivirales/sangre , Inmunización , Interleucina-2/genética , Interleucina-2/inmunología , Infecciones por Poxviridae/sangre , Infecciones por Poxviridae/inmunología , Vacuna contra Viruela/inmunología , Virus Vaccinia/genética , Virus Vaccinia/inmunología , Animales , Línea Celular , Citocinas/sangre , Humanos , Técnicas para Inmunoenzimas , Inyecciones Subcutáneas , Interleucina-2/sangre , Activación de Linfocitos , Masculino , Ratones , Ratones Endogámicos BALB C , Vacuna contra Viruela/administración & dosificación , Vacuna contra Viruela/genética , Bazo/inmunología , Células TH1/inmunología , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/inmunologíaRESUMEN
Unlike vertebrates and RNA-containing viruses, the objective estimate of molecular clock for DNA-containing viruses was so far absent. An extended central conservative genomic region of orthopoxviruses (about 102 kbp) and the sequence of DNA polymerase gene (about 3 kbp) of the viruses belonging to various genera from the family Poxviridae were analyzed. During this analysis, the known dating of variola virus (VARV) transfer from West Africa to South America (XVI century) and our own data on close phylogenetic relations between the modem West African and South American VARV isolates were used. As a result of this work, it was calculated for the first time that the rate of mutation accumulation in these DNA-containing viruses amounted to 0.9-1.2 x 10(-6) substitutions per site per year. The poxviruses started separating from the ancestor virus to form the modem genera approximately 500 thousand years ago; the ancestor of the genus Orthopoxvirus separated about 300 thousand years ago; and its division into the modem studied species took place approximately 14 thousand years ago.
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Evolución Molecular , Filogenia , Poxviridae/genética , ADN Viral/genética , ADN Polimerasa Dirigida por ADN/genética , Mutación , Orthopoxvirus/genética , Virus de la Viruela/genéticaRESUMEN
Libraries of hybrid plasmids carrying DNA fragments of complete genomes of 8 variola virus strain from the Russian Collection belonging to 2 epidemical types and isolated in various geographic regions of the world were obtained. Genomic sequences of variola virus can be thus preserved for a long time in a biologically safe form and provide the research work on studying the genetic organization of this unique virus and on developing modern methods for rapid detection of variola virus and other orthopoxviruses.
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Genoma Viral , Virus de la Viruela/genética , ADN Viral/análisis , ADN Viral/genética , Salud Global , Plásmidos/genética , Reacción en Cadena de la Polimerasa , Mapeo RestrictivoRESUMEN
A method for one-stage rapid identification of four orthopoxvirus species pathogenic to humans based on multiplex polymerase chain reaction (MPCR) was developed. Five pairs of oligonucleotide primers--one, genus-specific; and the rest, species-specific for variola, monkeypox, cowpox, and vaccinia viruses, respectively--were used concurrently for MPCR assay of orthopoxvirus DNAs. Specificity and sensitivity of the method developed were evaluated using DNAs of 57 orthopoxvirus strains, including the DNAs isolated from human case clinical materials.
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Orthopoxvirus/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Virus de la Viruela Vacuna/aislamiento & purificación , Cartilla de ADN , ADN Viral/análisis , Humanos , Monkeypox virus/aislamiento & purificación , Orthopoxvirus/genética , Orthopoxvirus/patogenicidad , Sensibilidad y Especificidad , Virus Vaccinia/aislamiento & purificación , Virus de la Viruela/aislamiento & purificaciónAsunto(s)
Mapeo Cromosómico/métodos , Variación Genética/genética , Filogenia , Alineación de Secuencia/métodos , Análisis de Secuencia de ADN/métodos , Virus de la Viruela/genética , Secuencia de Bases , Evolución Molecular , Geografía/métodos , Datos de Secuencia Molecular , Especificidad de la EspecieRESUMEN
Comparative RFLP analysis was for the first time performed for 21 variola virus (VARV) strains of the Russian collection with 20 amplicons covering the total VARV genome. The amplicons were synthesized in the long polymerase chain reaction. A database useful as a reference for identifying VARV strains was generated. VARV strains isolated in different geographical regions were compared and proved to vary mostly in variable genome regions. Each of the dendrograms constructed included three clusters of African, Asian, and VARV-alastrim isolates. The VARV-alastrim isolates differed to the greatest extent from the other strains. VARV strains isolated during an ecdemic variola burst in Moscow (1960) grouped with Asian isolates. Polymorphism of VARV strains was for the first time observed for a single variola burst with a few affected patients.
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Genoma Viral , Virus de la Viruela/genética , Secuencia de Bases , Cartilla de ADN , Electroforesis en Gel de Poliacrilamida , Federación de RusiaRESUMEN
Integrative plasmids p delta C, p delta D, and p delta G were designed to contain a selective marker beyond the region of homology to virus DNA and to allow construction of recombinant cowpox viruses (CPV) that lack C18L, D11L, or G3L coding for kelch-like proteins. CPV mutants lacking one (C18L, D11L, or G3L), two (D11L/G3L or C18L/D11L), or three (D11L/G3L/C18L, that is, all) kelch-like protein genes of the left variable region of the virus genome were obtained. Impaired reproduction was observed for the triple mutant. Pocks produced by the triple mutant and the original virus differed in size and morphology. In addition, the two CPV variants differed in destructive changes caused in the chorioallantoic membrane of chicken embryos.