Hazard Characterization of Modified Vaccinia Virus Ankara Vector: What Are the Knowledge Gaps?

Okeke, Malachy I.; Okoli, Arinze S.; Diaz, Diana; Offor, Collins; Oludotun, Taiwo G.; Tryland, Morten; Bøhn, Thomas; Moens, Ugo

MVA was developed from CVA by over 570 passages in CEF. This resulted in the loss of about 15% (approximately 30 kbp) of the parental CVA genome [45, 46] and several genes coding for host range factors and immunomodulators are either lost or fragmented [46, 57] . MVA is highly host restricted and undergoes abortive infection in all human and other mammalian cells tested so far, except in Baby Hamster Kidney (BHK-21) cells [51] , rat small intestinal epithelial cells 6 (IEC6) [52] and cell lines derived from Egyptian fruit bat [58] . However, there is a significant variability in the susceptibility of MVA strains to mammalian cell lines (Table 1) . MVA-1721 productively infects some human cell lines while MVA-BN undergoes abortive infection in mammalian cell lines (Table 1) . Even in some non-permissive cells as determined by fold increase in virus titer [50] , there is limited production of mature MVA virions [52] .