The advantages of using tobacco to manufacture a vaccine are significant. The initial costs for plant growth are much cheaper than design of traditional pharmaceutical facilities. In addition, the material extracted from tobacco leaves can be easily purified, and then might be spray dried or freeze-dried, yielding a highly stable compound, storable at ambient temperatures for extended periods. This will be essential for an Ebola vaccine, since it will primarily be stockpiled to use only if there is a disease outbreak.
Vaccines typically contain adjuvantsimmune modulating factors that improve a vaccine's protective qualities. Most vaccines contain alum (or aluminum hydroxide), which is an FDA approved adjuvant. In the case of the plant-derived Ebola vaccine, alum did not improve the survival rates in mice when it was co-administered with EIC. Instead, the group found that a Toll-like receptor (TLR) agonist known as PIC, when delivered in tandem with EIC, dramatically improved survival.
Toll-like receptors are part of the body's innate immune systeminvolved in processes of inflammation, where defensive cells like macrophages and dendritic cells are attracted to the site of infection. Arntzen explains that the TLR agonist PIC acts to mimic a site of inflammation, amplifying the immune response, without causing tissue damage. In experiments using a combination of PIC and EIC, mice achieved an 80 percent survival rate against a lethal challenge of Ebolacommensurate with the best existing vaccine candidates.
The road ahead
In their companion PNAS paper, Arnzen's collaborators at Mapp Biopharmaceuticals outline the process for creating the monoclonal antibodies used for this research. Treatment for an Ebola infection, Arntzen says, would likely involve the injection of fast act
|Contact: Joseph Caspermeyer|
Arizona State University