Dynamics of antiretroviral restriction factor expression in sheep naturally infected with Small Ruminant Lentivirus (SRLV).

Small Ruminant Lentiviruses (SRLV) cause persistent, slowly progressive infections in sheep and goats, characterized by high genetic variability and a fluctuating immune response that hinders accurate diagnosis and, consequently, effective control. In this study, we monitored the dynamics of SRLV infection and the expression of antiretroviral restriction factors in a flock of 47 ewes over a 16-month period. Six serial samplings were conducted to assess antibodies detection, cell-associated viral load, proviral load, and gene expression of the APOBEC3 Z1, Z3, and tetherin proteins using absolute quantification qPCR. Tetherin expression was consistently observed across most animals and sampling points, whereas APOBEC3 Z1 and Z3 showed intermittent patterns. Statistical analyses revealed significant correlations between gene expression levels and both viral and proviral loads, highlighting distinct role of each factor in the SRLV infection dynamics. Notably, viral RNA was frequently detected, even when provirus or antibodies were absent. These results underscore the involvement of the innate immune response and highlight the potential role of restriction factors as modulators of SRLV infection under natural conditions.