Functional F11L and K1L genes in modified vaccinia virus Ankara restore virus-induced cell motility but not growth in human and murine cells.

Modified vaccinia virus Ankara (MVA) was generated by serial passaging in chicken embryo fibroblasts. During this attenuation, MVA lost the capacity to productively grow in human and most other mammalian cell lines, as well as acquiring a multitude of deletions and mutations in the MVA genome. This means that the precise molecular basis for the MVA host-range restriction is still unknown.

Viral host-range factor C7 or K1 is essential for modified vaccinia virus Ankara late gene expression in human and murine cells, irrespective of their capacity to inhibit protein kinase R-mediated phosphorylation of eukaryotic translation initiation factor 2alpha.

Vaccinia virus (VACV) infection induces phosphorylation of eukaryotic translation initiation factor 2alpha (eIF2alpha), which inhibits cellular and viral protein synthesis. In turn, VACV has evolved the capacity to antagonize this antiviral response by expressing the viral host-range proteins K3 and E3. This study revealed that the host-range genes K1L and C7L also prevent eIF2alpha phosphorylation in modified VACV Ankara (MVA) infection of several human and murine cell lines.