The present invention relates to a chimeric poxvirus with improved anticancer activity (higher cancer cell killing capacities and better tumor selectivity), as well as variant version thereof with one or more altered viral genes, recombinant versions thereof comprise one or more nucleic acid(s) of interest and recombinant variant versions thereof, all of which may be included in a composition and used for the treatment of a disease, in particular proliferative disease, notably cancers.