Molecular characterization of the first Australian isolate of Japanese encephalitis virus, the FU strain.

The complete genomic and predicted amino acid sequence of the Japanese encephalitis virus (JEV) FU strain, a human isolate recovered from the first outbreak of Japanese encephalitis in Australian territory, was determined. Comparison of the FU genome with 15 fully sequenced JEV genomes revealed high levels of sequence identity, ranging from 88.7% (GP78) to 89.7% (K94P05) for nucleotides and 96.8% (K94P05) to 98.0% (JaGAr01) for amino acid sequences. A total of 39 unique amino acid differences were found in the FU strain polyprotein. Phylogenetic analyses were performed on all available full-length JEV genomes and a selection of 64 E gene sequences from temporally and geographically diverse JEV strains. For comparison with the E gene phylogeny, phylogenetic analysis using cognate prM gene sequences was also carried out. The FU strain was found to be most closely related to Korean isolate K94P05 in the full-length analysis and to Southeast Asian strains in the E and prM gene analyses. The E gene analysis corresponded well with the prM gene analysis and with previous genotyping studies using the prM gene. The epidemiological implications of this investigation are discussed.