Highly attenuated modified vaccinia virus Ankara replicates in baby hamster kidney cells, a potential host for virus propagation, but not in various human transformed and primary cells.

Although desirable for safety reasons, the host range restrictions of modified vaccinia virus Ankara (MVA) make it less applicable for general use. Propagation in primary chicken embryo fibroblasts (CEF) requires particular cell culture experience and has no pre-established record of tissue culture reproducibility. We investigated a variety of established cell lines for productive virus growth and recombinant gene expression. Baby hamster kidney cells (BHK), a well-characterized, easily maintained cell line, supported MVA growth and as proficient expression of the E. coli lacZ reporter gene as the highly efficient CEF, whereas other cell lines were non-permissive or allowed only very limited MVA replication. Importantly, no virus production occurred in patient-derived infected primary human cells. These results emphasize the safety and now improved accessibility of MVA for the development of expression vectors and live recombinant vaccines.