First molecular detection of small ruminant lentivirus in a roe deer (Capreolus capreolus) in Italy

Small Ruminant lentiviruses (SRLVs) infect sheep and goats worldwide, representing one of the most insidious viral infections in this species. Presence of antibodies against SRLVs was reported in wild ruminants in the USA and Europe and detection of virus was reported from wild ibex (Capra ibex) and red deer (Cervus elaphus) in Europe. This evidence suggests the potential role of wild ruminants as SRLVs reservoirs. A passive surveillance program was conducted in roe deer (Capreolus capreolus) from 2023 to 2025 in Central Italy, to investigate the presence and circulation of SRLVs. In 2025, one female roe deer was detected positive for SRLVs by PCR; sequencing and phylogenetic analysis indicated the virus belonged to the A23 sub-genotype, clustering with SRLVs previously identified in domestic species in Southern Italy. Even though this is an isolated case, this first-ever detection of SRLV in a roe deer suggests the possibility of spillover to/from domestic small ruminants and highlights the importance of long-term wildlife monitoring to clarify the extent and dynamics of SRLV circulation in wild cervid populations.