A novel genotype of MVA that efficiently replicates in single cell suspensions

Background Vectored vaccines based on modified vaccinia Ankara (MVA) may lead to new treatment options against infectious diseases and certain cancers. MVA is highly attenuated and requires avian cells for production. We established avian continuous cell lines (including CR and related CR.pIX) and adapted these cells to proliferation in single-cell suspension in a chemically defined medium [1,2]. Replication of several viruses was efficient in CR suspension cultures [3,4] but yields for MVA were low. We suspected that cell-to-cell spread may be an important mechanism for MVA replication in agitated suspension cultures and developed a production medium that is added at the time of infection to induce cell aggregates [2]. MVA (and other host-restricted poxviruses) replicate to very high titers with this robust and fully scalable cultivation protocol but further improvement may facilitate production for large vaccine programs. We now describe a novel genotype of MVA that replicates with high efficiency in single-cell suspensions without aggregate induction.