Many applications involve coupling between prestressed solids and fluids (possibly flowing). Typical problems might be given by vibroacoustics of fluid-filled pressurized cavities, wave propagation, dynamics and stability of pipes conveying fluids... The goal of this work is to investigate jump conditions that hold for small linear perturbations at any impermeable interfaces, slip or bonded, plane or not, between fluids and structures in the presence of initial flow and prestress. First, the concept of generalized functions in distribution theory and its applications to interface conditions is briefly recalled. One also gives a review about the mixed Eulerian-Lagrangian description, that yields an interesting unification between existing formulations for inviscid fluids (Galbrun's equation) and solids (updated Lagrangian formulation). Based on conservative equations obtained from this description, interface conditions are then derived in an elegant manner thanks to the concept of generalized functions. Interface conditions for displacement and stress are obtained and agree with results found in the literature. As an example, these conditions are applied to the analysis of vibroacoustic wave propagation inside an inviscid fluid-filled pressurized duct. The combined effects of prestress, initial flow and acoustic coupling are briefly discussed.