MVA-BN: A safe and efficacious smallpox vaccine option
Known cases of anthrax infection have recenly brought into sharp focus the acute danger from bioterrorism. Remaining stocks of smallpox (Variola) pose a dangerous threat to mankind. Accordingly, there remains an unmet need for a safe smallpox vaccine.
Scientists Bernd Schlereth, Luis Mateo, Lynette King, Kristiane Wetzel and Paul Chaplin, at the Bavarian Nordic Research Institute in Denmark, have developed a ’highly safe and efficacious smallpox vaccine’ (MVA-BN) which is based on the modified vaccinia virus ankara. MVA-BN is a well-characterised, highly attenuated plaque purified MVA clone.
In contrast to some MVA strains tested in vitro, MVA-BN fails to replicate in mammalian cell lines (monkey and human). In immune-compromised animals, MVA-BN is well tolerated, whereas other MVA strains kill animals within 20-60 days.
Although MVA-BN is highly attenuated it appears to show better efficacy. Vaccination with MVA-BN significantly enhances the speed and magnitude of the antibody response while MVA-BN induces protection in a lethal orthopox mouse challenge model at lower doses than other MVA strains.
When comparing MVA-BN with past smallpox vaccines, such as Elstree or NYCBH-Wyeth that were used in the effort to eradicate smallpox, MVA-BN induces a slightly superior humoral and cell mediated immune response.
Overall MVA-BN is safer and more immunogenic than other MVA strains and is at least as efficacious as earlier vaccines. This makes MVA-BN a promising vaccine against smallpox, especially for immunisation of those most at high risk from developing complications, for example immune-compromised individuals.
Keywords : Bavarian Nordic Research Institute Germany Bioterrorism Anthrax Smallpox Vaccine Safety Efficacy MVA-BN Modified Vaccinia virus Ankara In vitro replication Mammalian cell lines Immune response
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