Bluetongue virus (BTV) is an arbovirus responsible for bluetongue (BT), a non-contagious disease that affects a wide range of wild and domestic ruminants. It is transmitted by blood-feeding midges belonging to the Culicoides genus. BTV induces a large panel of clinical manifestations ranging from asymptomatic infection to lethal hemorrhagic fever. This variability is due to several factors related both to the infected host and the viral serotypes and strains. Despite the fact that BTV has been studied extensively, we still have little understanding of the molecular determinants of BTV virulence. We took advantage of functional proteomic approaches such as high-throughput yeast two-hybrid (Y2H) to map interactions between BTV and cellular proteins. As a starting point, this approach has been applied on two serotypes of BTV (BTV-8 and 27). These serotypes have been chosen for their recent (re)-emergence and differences in term of pathogenicity/interspecies transmission: only BTV-8 induces clinical signs in cattle whereas BTV-27 infects exclusively goats without causing any symptoms. All viral proteins encoded by BTV were used as baits to screen two cDNA libraries originating from cattle and Culicoides. Therefore, 43 Y2H screens were performed and 1,478 positive yeast colonies were analyzed, allowing us to identify a hundred of new virus-host interactions (Figure 1). A preliminary global analysis of these interactions has uncovered many signal transduction factors involved in the modulation of autophagy, apoptosis and the ubiquitin-proteasome system. Moreover, most of the BTV-host interactions identified by Y2H seem to be specific to either viral serotype and/or infected host. These cellular interactors are currently re-tested by several protein-protein interaction methods such as GPCA (Gaussia princeps protein complementation assay) and at functional level with the viral proteins encoded by BTV-8, BTV-27 and also other serotypes like BTV-1 and 4. Conserved protein interactions will be instrumental to design generic drugs against multiple serotypes. On the other hand, interactions that are highly specific of a particular virus would shed light on the molecular mechanisms responsible for its virulence/pathogenicity and transgression of cross-species barriers.