[The smallpox vaccination strain MVA: marker, genetic structure, experience gained with the parenteral vaccination and behavior in organisms with a debilitated defence mechanism (author's transl)].

The MVA virus is a lab virus ideally suited for vaccination of both man and animal which can be differentiated from the known Vaccinia strains by the use of numerous biological markers. Its reduced virulence for the chick embryo, for experimental animals and for man is a particularly characteristic feature. With the exception of chick embryo fibroblasts, the MVA virus grows in cell cultures only abortively. This applies particularly to cells of human origin in which the cytopathic effect and plaque formation are completely missing. The restriction analysis of the DNS of the MVA virus demonstrates that its genetic structure differs from that of the CVA basic virus and other orthopox viruses. In contrast to the WHO reference strain Elstree, the MVA virus has a genome shortened by about 9 per cent. The use of the MVA virus for human vaccination is particularly indicated in persons to be vaccinated for the first time and likely to entail a risk (on account of allergies etc.) because it brings about a state of revaccination without complications. The MVA virus can be administered in intracutaneous, subcutaneous or intramuscular injections. Innocuoursness and successful vaccination have been demonstrated in more than 120000 persons. While other Vaccinia strains, such as the Elstree virus, experience a drastic increase of virulence in the immunosuppressed organism (subjected to whole-body irradiation), the MVA virus cannot be activated not even in this situation.