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 t he same enzootic focus between 1983 and 1988 were compared. The viral cDNAs were amplified by PCR and were directly sequenced. The nucleotid e sequences of KI strains were extremely homologous regardless of isol ation year (less than 10 substitutions in 3651 nucleotides, less than 4 substitutions in 1133 amino acids). In addition, the nucleotide sequ ence of the KI strain isolated in 1983 (KI-83-262) was also quite simi lar to that of other Seoul viruses, which were isolated from laborator y rats in Japan (strain SR-11, 98.1% and B-1 strain, 96.5%), from an u rban rat in Korea (Seoul 80-39, 96.5%) and from an urban rat in China (R22 strain, 93.4%). All possible N-glycosylation sites in the deduced amino acid sequences were conserved among all Seoul viruses examined. The nucleotide and amino acid sequences of Seoul virus strains were h ighly conserved although they were isolated from various districts of eastern Asia. These results indicate the genetic stability of Seoul vi rus strains maintained under a natural environment and the homology of Seoul viruses isolated from various districts of eastern Asia. The re lationship among Seoul virus strains isolated from eastern Asia was co mpared by phylogenetic analysis.