Female C57BL/6 (B6) mice were obtained from Centre d'Elevage Janvier (Le Genest Saint Isle, France). Mice were all between 7 and 10 weeks of age at beginning of experiments. For transduction with rAAV vectors, mice back legs were shaved under general anesthesia and titrated 1 × 10 11 vector genomes (vg) rAAV2/1-Ova or rAAV2/8-Ova were injected (50 μl in PBS) in the gastrocnemius muscles. Where indicated, 10 11 vg rAAV2/1-PD-L1 or rAAV2/1-PD-L2 were mixed with 10 11 vg rAAV-Ova and co-injected using the same procedure. For costimulation blockade experiments, mice were injected i.p. with 200 μg CTLA-4/Ig (Chimerigen laboratories, MF-110A4) diluted in 200 μl of PBS.