Recent advances in knowledge of BTV-host-vector interaction

Bluetongue virus (BTV) has since 1998 extended its distribution further North than where it has previously been encountered. Changes in the epidemiology of Bluetongue (BT), as well as novel features of recent outbreaks of BTV in Europe, have stimulated research on BTV-vector-host interaction. The outbreak of BTV-8 in Northern Europe from 2006-2008 is particular noteworthy in this regard, as the European strain of BTV-8 demonstrated novel properties, including high virulence - especially for cattle - and the capability to cross the ruminant placenta. The virus was in addition transmitted by indigenous European Culicoides species that had not previously been implicated in the widespread transmission of BTV. Recent advances in the scientific understanding of BTV-vector-host interaction include increased knowledge of the virus' replication cycle, the role of biotic factors in influencing viral infection of the insect vector, increased knowledge of BTV immunology and pathogenesis in the mammalian host, and increased knowledge of virulence and pathogenicity features of newly discovered serotypes/strains of the virus. New research on aspects of BTV-vector-host interaction has been driven in part by developments in molecular biology and experimental infection biology, of which next generation sequencing, the expression of individual viral proteins in cell culture, the establishment of a reverse genetics system for the virus, the development of novel in vitro and in vivo infection models, and refinement of existing BTV experimental infection methodologies have proven instrumental. Moreover, these developments have also provided the opportunity for the development of novel vaccine strategies. This article provides a synopsis of selected recent advances that have been made in the understanding of BTV-vector-host interaction, with a particular focus on research that has been conducted in Europe over the last 5 years