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

Even when recombinant poxvirus vaccines are released in areas where some knowledge exists on the characteristics and occurrence of naturally circulating relatives, no systematic study has been undertaken post release to monitor the occurrence of potential adverse effect due to the interactions between genetically modified poxvirus vaccines and naturally circulating OPVs. Raboral-VRG, a VACV-vectored rabies vaccine [139] was, alongside the attenuated rabies virus vaccine, successfully used in some regions of Belgium and France during the eradication of fox rabies in western parts of Europe in a campaign that started about three decades ago. Surveillance programs to monitor the efficacy of the vaccination (i.e., prevalence of rabies) have been ongoing [140] , but no report exists on the interaction between VRG and naturally circulating OPVs in foxes and other wildlife in Europe. A comprehensive, genome wide mapping of OPVs in foxes and other animals in the foxes' food chain in the regions where the Raboral-VRG bait vaccine has been used would yield data that would help risk assessors evaluate the potential for recombination, complementation and reversion of the vector back to wild type. Thus, the absence of data on naturally circulating OPVs before and after release of recombinant poxvirus (including MVA) vectored vaccines is a significant knowledge gap in the ERA of MVA-vectored vaccines.