Encapsulation of immunoreactive protective antigen within a nanofibrous membrane for use as a transdermal anthrax vaccine

Bacillus anthracis, the bacterium which causes anthrax, has been a source of major concern since the deadly series of contaminated postal letters back in 2001. The three main proteins secreted by the bacterium are protective antigen (PA), lethal factor (LF), and edema factor (EF), and are the cause of its virulent effect. With the impeding threat of bioterrorist attacks, studies have been undertaken to develop an effective anthrax vaccine. The currently proposed technologies suffer from immunity conferred only in a small percentage of subjects, but most importantly the unrealistic method of delivery during a pandemic situation. Our group has proposed to construct a transdermal patch composed of a nonwoven nanofibrous membrane of PA as a self administrable anthrax vaccine prepared by the cost efficient technique of electrospinning. The fabricated water-soluble membrane with a high surface area-to-volume and mass ratios is expected to allow antigen penetration into the human skin layers, where antigen presenting cells will enable cutaneous immunity. This study utilized a novel immunoblotting assay to investigate the effect of electrospinning process on the protein's immunoreactivity. The developed method allowed for accurate quantification of the immobilized PA deposited on 4 mm times 4 mm silicon wafers proposed as delivery vehicles.