Article ID: JJID.2016.086
Cases of autochthonous dengue virus type 1 (DENV-1) infections were detected in Japan following a 70-year period devoid of dengue outbreaks. We have previously shown that E gene sequences are identical in 11 of 12 DENV-1 strains autochthonous to Japan. However, the E sequence represents only 14% of the genome. In the present study, we sequenced the entire genome of 6 autochthonous DENV-1 strains isolated from patients during the 2014 outbreak. Sequencing of 5 Yoyogi group strains with identical E sequences and 1 Shizuoka strain with a different E sequence revealed that the first Yoyogi group strain identified differed from the Shizuoka strain by 18 amino acid residues and that 2 Yoyogi group strains had different nucleotide sequences whilst the other 3 had identical sequences. Phylogenetic analyses indicated that the Hyogo strain, a Yoyogi group strain, was the first to diverge from the other 4 Yoyogi group strains. The E gene sequence of Yoyogi group strains exhibits the highest homology to those of strains isolated in Malaysia and Singapore during 2013–2014. The patient infected with the Hyogo strain had visited Malaysia before the onset of dengue fever, suggesting that this was an imported case of dengue infection from Malaysia.
