Botulinum toxin is classified as a category A biothreat due to its high potency and the potential to be used as a bioweapon. Because there is no FDA-approved vaccine, there is a high priority in rapid development of a vaccine that can be used in the event of an attack. The overall goal of our Phase I project is to develop an orally administered multivalent serotype A, B, and E botulinum vaccine. We have discovered that Hc50 of serotypes A and B individually induce immunity against high level challenge when administered orally. The basis for oral vaccination is the inherent property of the carboxyl terminal 50% of the heavy chain of each of the serotypes of the toxin (Hc50 or fragment C) to bind and to cross intestinal epithelial cells and enter blood and lymphatic circulation. Specifically, in aim 1, we will determine the capacity of Hc50 serotype E to act as a mucosal immunogen.
In specific aim 2, we will make the trivalent A, B, and E vaccine and test the vaccine in mice for induction of protective immunity when the vaccine is given mucosally by the intranasal route.
In specific aim 3, we plan to immunize rats orally and determine whether the trivalent vaccine can induce protective immunity, to determine the duration of immunity, and the robustness of the immune response in comparison to injected vaccine given with an adjuvant. The additional component of mucosal immunity, which is expected from the application of the vaccine by the intranasal or oral route will also be addressed. Mucosal immunity in the form of polymeric secretory IgA may provide an additional level of protection against toxin exposure by inactivating a portion of it before it crosses into general circulation. A vaccine for botulinum toxin that can be administered mucosally, especially by the oral route, is expected to have several advantages over an injected counterpart. As the vaccine can be given without trained personnel, it will avoid the use of invasive needles and the associated pain. This is expected to result in greater compliance and convenience for the end user and the possibility of disseminating the vaccine outside of the traditional clinic or doctor's office setting for vaccination, resulting in the possibility of rapid implementation of a preventive vaccination program. The end result of Phase I work will be the identification of an effective mucosal combination vaccine for serotypes A, B, E. In Phase II, the project will involve 1) formulation studies to improve performance, 2) study of the vaccine in additional animal models, and 3) greater characterization of processes for making the trivalent vaccine. At the end of Phase II, we expect to have identified a vaccine to advance to clinical studies. ? ? ?
