FMD is highly infectious. Furthermore, due to the fear of inadvertent spread to farm animals, research with the live virus to test vaccine efficacy is heavily restricted to only a few government laboratories in the US. The investigators therefore developed a new proprietary neutralization assay (using a mock virus unrelated to FMD to assess the ability of the vaccine-induced antibodies to neutralize virus infection). Inovio previously reported the induction of strong cellular and antibody responses in vaccinated pigs after a single vaccination. In a follow-on investigation of the immune responses with the novel neutralization assay against the Asia strain, the vaccinated animals developed neutralizing antibody (NAb) titers averaging 90 after a single vaccination and increasing in magnitude to 191 after two vaccinations. For comparison, commercially available attenuated/killed FMD virus vaccines are able to protect swine with an NAb titer of 32-40. These results are the first report of a DNA vaccine producing high titers of neutralizing antibodies against FMD.
In the second large-animal study, sheep were vaccinated three times at 0, 5, and 10 weeks with a combination vaccine targeting either four subtypes (O, A, C, Asia), three subtypes (O, A, Asia), or a single subtype (Asia). The study investigators observed in the vaccinated animals high levels of seroconversion (production of antibodies specific to a particular antigen) and antibody titers (the actual level of antibody production; in this case, ranging from 1000 – 100,000) to all the vaccine subtypes after only one or two vaccinations. Import
|SOURCE Inovio Pharmaceuticals, Inc.|
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