Emergence of multireassortant bluetongue virus serotype 4 in Hungary

The genome sequence and the phylogenetic relationships of a serotype 4 bluetongue virus (BTV-4) emerged during 2014 in Hungary are described in this study. Genome segment 2 encoding the major neutralization antigen, VP2, shared moderate sequence similarity (nt, ⩽ 94.3%) with the corresponding gene of contemporary and historic homotypic bluetongue viruses, whereas genome segments S1, S4, S5, S7-S10 were typically more closely related to the cognate genes of heterotypic isolates. Importantly, in many gene phylogenies the Hungarian BTV-4 strain showed genetic relationship to BTV strains identified in outbreaks in the western Mediterranean basin. Our results indicate the identified Hungarian bluetongue virus strain evolved through reassortment involving multiple genome segments from various heterotypic bluetongue viruses.