Virus research
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The idea of using viruses as gene vehicles to combat disease is tantalizing for the simplicity of its principle, and for the unlimited perspectives that it raises. Yet the initial enthusiasm gave way to deep skepticism, when the complex challenges became apparent. Issues that hampered clinical successes include the specificity and efficiency of gene delivery; the immune response to viral vectors and targeted cells; standardized and affordable production of vectors; and safety for patients and environment. ⋯ However, limiting these deleterious effects to tumor cells is mandatory for clinical safety. A number of approaches have been taken to improve the specificity and/or efficacy of cancer virotherapy. Recent studies concerning oncolytic adenoviruses exemplify these strategies.
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To identify the hantaviruses causing hemorrhagic fever with renal syndrome (HFRS) in the Far East of Russia, blood samples collected from HFRS patients in 1994-1998, were examined by reverse transcription-polymerase chain reaction. In addition, 36 sera were tested by an immunofluorescence assay for antibodies against Hantaan, Seoul, Puumala, and Khabarovsk viruses, and 54 samples were tested by plaque reduction neutralization test. With both serological assays, the highest antibody titers were to Hantaan and/or Seoul viruses. ⋯ All S segment sequences were from FE lineage, and differed from Hantaan virus by 10.7-12.6%. Thirty of the 36 (83%) analyzed sequences were found to be the FE genotype, which is very similar to that of Hantaan virus, strain 76-118. Of the remaining hantaviruses, 11% were the AMR genotype, and 6% the VDV genotype, which are genetically novel genotypes of Hantaan or Seoul viruses, respectively.
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Comparative Study
Comparison of nucleotide sequences of M genome segments among Seoul virus strains isolated from eastern Asia.
The nucleotide sequences of the M genome segments of three Seoul virus strains (KI strains) which were isolated from urban rats inhabiting the same enzootic focus between 1983 and 1988 were compared. The viral cDNAs were amplified by PCR and were directly sequenced. The nucleotide sequences of KI strains were extremely homologous regardless of isolation year (less than 10 substitutions in 3651 nucleotides, less than 4 substitutions in 1133 amino acids). ⋯ The nucleotide and amino acid sequences of Seoul virus strains were highly conserved although they were isolated from various districts of eastern Asia. These results indicate the genetic stability of Seoul virus strains maintained under a natural environment and the homology of Seoul viruses isolated from various districts of eastern Asia. The relationship among Seoul virus strains isolated from eastern Asia was compared by phylogenetic analysis.