The present invention relates to a method for producing and purifying a wild type, an attenuated and/or a recombinant Orthopoxvirus. The present invention relates to a purified wild type, attenuated and/or recombinant Orthopoxvirus obtained by the method of the invention and to a pharmaceutical composition, preferably a vaccine, comprising said purified Orthopoxvirus for the treatment and/or the prevention a cancer, an infectious disease and/or an autoimmune disorder, and uses thereof. The present invention also relates to the use of an immortalized avian cell line obtained from an avian cell belonging to the Anatidae family, in particular Cairina moschata immortalized avian cell lines comprising a nucleic acid sequence coding a telomerase reverse transcriptase (TERT) and optionally an E1A nucleic acid sequence, for the production of a wild type, attenuated and/or recombinant Orthopoxvirus according to the process of the invention.
