Identification of discrete genetic determinants of attenuation was not successful, indicating that multiple mutations were responsible for the attenuated phenotype 8, 9, 10. By repeated passaging (at least 80 times), MeV adapted and became attenuated 6 through accumulation of many mutations throughout its genome 7. This isolated virus was passaged in the laboratory on human and animal primary cells, as well as on immortalized cell lines 3 that retrospectively do not express one of the two physiologically relevant human cellular entry receptors SLAM F1 4 or nectin-4 5. The causative agent, the measles virus (MeV), was isolated in 1954 from a small boy with acute measles, David Edmonston. With its introduction into the human population dating back to the sixth century BCE 2, the death toll over time has been immense. Measles has been known for centuries as a scourge of humanity, killing millions of children in historical times per annum 1. This review aims to present an overview of the versatility of this vaccine vector as platform technology to target various diseases, as well as current research and developmental stages, with one vaccine candidate ready to enter phase III clinical trials to gain marketing authorization, MV-CHIK. Effective humoral and cellular immune responses are induced not only against the MeV vector, but also against the foreign antigen cargo in immunized individuals, which can protect against the associated pathogen. These live-attenuated vaccine constructs can encode and express additional foreign antigens during transient virus replication following immunization. The advent of recombinant DNA technologies, combined with systems to generate infectious negative-strand RNA viruses on the basis of viral genomes encoded on plasmid DNA in the 1990s, paved the way to generate recombinant, vaccine strain-derived MeVs. Live-attenuated measles virus (MeV) has been extraordinarily effective in preventing measles infections and their often deadly sequelae, accompanied by remarkable safety and stability since their first licensing in 1963.
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