SEQUENCE DETERMINATION AND PHYLOGENETIC ANALYSIS OF THE AKABANE BUNYAVIRUS S-RNA GENOME SEGMENT

The nucleotide sequence of the small (5) RNA segment of Akabane (AKA) bunyavirus was determined. The segment is 858 nucleotides long and con tains two overlapping open reading frames (ORFs), which encode the nuc leocapsid (N) and nonstructural (NSs) proteins, consistent with other bunyaviruses. Comparisons with the Aino virus S RNA sequence indicated that there is 73.5% identity in nucleotide sequence. However, the seq uence identity of the 5' non-coding region of the genomic RNA between these two viruses is only 55%. The N ORFs from 20 Japanese and 2 Austr alian isolates of AKA virus were sequenced and subjected to phylogenet ic analysis. This suggested that AKA virus has evolved in multiple lin eages. Twenty-three isolates were grouped into three major clusters, a nd the cluster which includes recent isolates was subdivided into two branches. Thus, phylogenetic analysis of the AKA virus N protein gene gives a greater insight into bunyavirus evolution.