Abstract: A system in which vRNP purified from influenza virus particles is introduced into yeast (Saccharomyces cerevisiae) and the transcription and replication from the viral RNA genome are supported by the yeast. The virus genome replication, the virus gene transcription and the virus protein expression occurring in yeast cells in which a great amount of genetic information is accumulated will permit identifying specific host cell factors that are involved in influenza virus infection, influenza virus growth in host and pathogenicity thus providing a tool and a technique that are essential for the development of anti-influenza virus agents.