The present invention relates to the use of a Saccharomyces cerevisiae mitochondrial nucleic acids fraction and an antigen for the preparation of a pharmaceutical composition intended to orient the immune response toward a Th1 type response directed against said antigen, more particularly for the prevention and/or the treatment of cancer, infectious disease and allergy. Adjuvant compositions with synergic effect, vaccine compositions with synergic effect, and kits of part are also provided. Methods of treatment of individuals thereof are also provided.
