Sequence determination and phylogenetic analysis of the Akabane bunyavirus S RNA genome segment.

Abstract

The nucleotide sequence of the small (S) RNA segment of Akabane (AKA) bunyavirus was determined. The segment is 858 nucleotides long and contains two overlapping open reading frames (ORFs), which encode the nucleocapsid (N) and nonstructural (NSs) proteins, consistent with other bunyaviruses. Comparisons with the Aino virus S RNA sequence indicated that there is 73n5 % identity in nucleotide sequence. However, the sequence identity of the 5h non-coding region of the genomic RNA between these two viruses is only 55 %. The N ORFs from 20 Japanese and 2 Australian isolates of AKA virus were sequenced and subjected to phylogenetic analysis. This suggested that AKA virus has evolved in multiple lineages. Twenty-three isolates were grouped into three major clusters, and 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.Bunyaviruses have been divided into 18 serogroups on the basis of neutralization and complement-fixation (CF) tests. The viruses are characterized by a genome consisting of three unique species of single-stranded negative-sense RNA, designated L (large), M (medium) and S (small). Genetic studies have shown that the S RNA encodes the nucleocapsid (N) protein, which acts as a CF antigen, and a nonstructural protein (NSs). The M RNA encodes the two envelope glycoproteins, G1 and G2, and a second nonstructural protein (NSm). The L RNA encodes the large virion protein, L, which has replicase and transcriptase activities (Bishop, 1990 ;Elliott, 1990 ;

Generation of a Recombinant Akabane Virus Expressing Enhanced Green Fluorescent Protein

“…NSs acts as a type I interferon antagonist and contributes to the regulation of host protein synthesis (3). Orthobunyavirus N and NSs proteins are encoded by overlapping open reading frames (ORFs) on a single mRNA (4)(5)(6)(7). However, phleboviruses, such as Rift Valley fever virus (RVFV), utilize an ambisense strand strategy to express N and NSs (8).…”

Genomic and phylogenetic characterization of Shuni virus

“…In particular, for the N ORF, the values of 97.9 % (nt) and 100 % (aa) were very high for isolates from different geographic locations and isolated decades apart but reflected what has been seen in other bunyaviruses such as RVF. However, for Aino and Akabane viruses, the identity between Australian and Japanese strains can result in differences up to 7-8.9 % [36,37]. The highest variation existed in the NSm and Gc proteins, Gc is exposed on the outer surface of the virion and is thus a principal target of neutralizing antibodies.…”

A sensitive nested real-time RT-PCR for the detection of Shuni virus

“…The sensitivity of the assay was demonstrated by amplification in both a tissue (brain) and a blood sample, both samples were from horses that had displayed which is largely due to the high level of sequence conservation in the N gene of the orthobunyaviruses (Akashi et al, 1997;Saeed et al, 2000).…”