Bluetongue virus: current perspectives on characterisation and the need to formalise nomenclature in an era of rapidly evolving technology.

Bluetongue virus (BTV) is a complex, transboundary arboviral pathogen that circulates globally in ruminant populations. Bluetongue disease is a World Organisation for Animal Health listed disease affecting economically important farmed ruminants. BTV is a dsRNA virus from the Sedoreoviridae family that has a segmented genome. Classification of BTV traditionally focussed on antigenic characteristics. More recently, however, Sanger sequencing methods have been adopted for typing based on specific genome segment analysis and targeted whole-genome sequencing (WGS) is being more widely applied. Despite these advances, standardised approaches for analysing genomic sequencing data to better define individual BTV strains are lacking. New perspectives are needed to update and unify the current array of approaches surrounding BTV genetic characterisation nomenclature. A transition from single-segment-based serotyping and genotype descriptors to adopting WGS-derived descriptors that better describe a detected virus rather than an individual segment is required. This change will improve the ability of researchers to understand and communicate virus movement pathways with improved granularity. This review paper aims to condense the extensive literature on BTV characterisation, genomic sequencing and virus transmission from an Australian perspective. Recommendations are made to assist with clarity and uniformity around virus characterisation, including genomic definitions and more standardised BTV nomenclature.