Hyalomma marginatum ticks (449 pools, 4787 ticks in total) collected in European Russia and Dermacentor niveus ticks (100 pools, 1100 ticks in total) collected in Kazakhstan were screened by ELISA for the presence of Crimean-Congo haemorrhagic fever virus (CCHFV). Virus antigen was found in 10?2 and 3?0 % of the pools, respectively. RT-PCR was used to recover partial sequences of the CCHFV small (S) genome segment from seven pools of antigen-positive H. marginatum ticks, one pool of D. niveus ticks, four CCFH cases and four laboratory virus strains. Additionally, the entire S genome segments of the CCHFV strains STV/HU29223 (isolated from a patient in European Russia) and TI10145 (isolated from H. asiaticum in Uzbekistan) were amplified, cloned and sequenced. Phylogenetic analysis placed all CCHFV sequences from Russia in a single, well-supported clade (nucleotide sequence diversity up to 3?2 %). Virus sequences from H. marginatum were closely related or identical to those recovered from patients in the same regions of southern Russia. Newly described CCHFV strains from Central Asian countries fell into two genetic lineages. The first lineage was novel and included closely related virus sequences from Kazakhstan and Tajikistan (nucleotide sequence diversity up to 3?2 %). In contrast, a newly described CCHFV strain from Uzbekistan, strain TI10145, clustered on the phylogenetic trees with strains from China.
Genetic analysis of wild-type Crimean-Congo hemorrhagic fever (CCHF) virus strains recovered in the European part of Russia was performed. Reverse transcriptase PCR followed by direct sequencing was used to recover partial sequences of the CCHF virus medium (M) genome segment (M segment) from four pools of Hyalomma marginatum ticks and six human patients. Phylogenetic analysis of the M-segment sequences from Russian strains revealed a close relatedness of the strains (nucleotide sequence diversity, <5.0%). The strains differed significantly from CCHF viruses from other regions of the world (nucleotide sequence diversity, 10.3 to 20.4%), suggesting that CCHF virus strains recovered in the European part of Russia form a distinct group.
Crimean-Congo hemorrhagic fever (CCHF) is a severe zoonosis with a high fatality rate. In Russia, local CCHF outbreaks have occurred in the Stavropol Territory, and the Volgograd and Astrakhan Regions during 2000 and 2001. Seven strains of CCHF virus (CCHFV) were isolated from infected patients and collected ticks. Two fragments of the CCHF virus M genome segment were PCR amplified and their nucleotide sequences were determined. All these virus strains appear to be closely related (up to 5.8% nucleotide sequence differences) and form a distinct clade on the CCHFV phylogenetic tree. Within this clade, CCHFV strains from Stavropol and Astrakhan cluster together, whereas those from Volgograd form a separate subgroup.
The data on the structure of the M genome segment of CCHF virus strains from Russia and Central Asia (Tajikistan) are presented. Data obtained have been compared with other available published sequences of the middle segment of strains from China, Nigeria, and Pakistan. It has been found that all the known strains can be divided into four genetic groups, based on the nucleotide sequence of the M genome segment and an amino acid sequence of the glycoprotein precursor it encodes, whereas VLG/TI29414 and STV/HU29223 strains from Russia form a separate group. The CCHF virus strain from Tajikistan, TADJ/HU8966, was genetically related to strains 7803 and 75024 from China, and together with these and the Nigerian IbAr 10200 strain, it forms another group.
Nearly all lethal viral outbreaks in the past two decades were caused by newly emerging viruses. Viruses are often studied by electron microscopy (EM), which provides new high-resolution data on the structure of viral particles relevant to both fundamental virology and practical pharmaceutical nanobiotechnology. Electron microscopy is also applied to ecological studies to detect viruses in the environment, to analysis of technological processes in the production of vaccines and other biotechnological components, and to diagnostics. Despite the advances in more sensitive methods, electron microscopy is still in active use for diagnostics. The main advantage of EM is the lack of specificity to any group of viruses, which allows working with unknown materials. However, the main limitation of the method is the relatively high detection limit (107 particles/mL), requiring viral material to be concentrated. There is no most effective universal method to concentrate viruses. Various combinations of methods and approaches are used depending on the virus and the goal. A modern virus concentration protocol involves precipitation, centrifugation, filtration, and chromatography. Here we describe the main concentrating techniques exemplified for different viruses. Effective elution techniques are required to disrupt the bonds between filter media and viruses in order to increase recovery. The paper reviews studies on unique traps, magnetic beads, and composite polyaniline and carbon nanotubes, including those of changeable size to concentrate viral particles. It also describes centrifugal concentrators to concentrate viruses on a polyethersulfone membrane. Our review suggests that the method to concentrate viruses and other nanoparticles should be chosen with regard to objectives of the study and the equipment status of the laboratory.
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