Identification and characterization of two atypical strains of bluetongue virus in sheep, Tunisia

• Detection of two atypical BTV strains in the Governorate of Gafsa, in the southwest region of Tunisia. • The combination of serological and genomic analysis allowed us to characterize these two novel strains. • We recognised the recurrence of an atypical BTV strain (BTV-Y TUN2022) and a novel putative BTV-W TUN2022. • Further investigations are needed to understand the role of these atypical BTV serotypes in vivo and in BTV evolution and eco-epidemiology. Bluetongue virus (BTV) is the causative agent of the bluetongue disease (BT), an infectious disease of domestic and wild ruminants that is primarily transmitted by Culicoides biting midges. In recent years, several novel BTV serotypes (often referred to as “atypical” BTVs) have been documented. These strains are usually asymptomatic in animals and seem to be unable to replicate efficiently in the arthropod vector. Here we report the detection of two putative atypical BTV strains in the Governorate of Gafsa, in the southwest region of Tunisia. Specifically, we recognised the recurrence of an atypical BTV strain (BTV-Y TUN2022) and a novel BTV-W TUN2022.