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

Similar to biodistribution, multiplication competence of the virus vector is an important consideration in evaluating shedding given that multiplication competent virus vector may persist in the vaccinee for extended periods of time and can increase in amount leading to higher shedding of infectious particles with an associated likelihood of virus transmission. For such multiplication competent virus vectors, it is important to analyze their molecular variants, which can also influence virus shedding. In general, the basic assumptions in the ERA of multiplication competent virus vectors are that there is a likelihood of spread of the viral vector from the vaccinee into the environment [157] . Immune status of the recipient can affect shedding, a hazard which becomes higher when a multiplication competent virus vector is the case under evaluation. If a virus vector is multiplication incompetent, shedding of the virus is unlikely but evidence should be provided that in such a case, the protein(s) encoded by the inserted transgene(s) has not altered the multiplication incompetence of the vector.