Jaagsiekte sheep retrovirus (JSRV) is the aetiological agent of ovine pulmonary adenocarcinoma (OPA). No JSRV-specific immunological responses have been detected in clinical cases of OPA or in experimentally infected lambs. The aim of the present study was to induce immune responses in sheep against JSRV proteins using several immunisation strategies. The vaccines were administered subcutaneously and intradermally, or intranasally, in adjuvant. Antibodies were measured by ELISA and immunoblotting, and T cell responses by lymphoproliferation assay. Antibodies specific for JSRV-capsid protein were induced by inoculation of recombinant proteins in adjuvant, and transient JSRV-specific T cell responses by intranasal inoculation with inactivated virus. These results will help in the design of a protective vaccine against JSRV infection and the development of OPA.