FOCUSING IMMUNITY vs BOTULINUM TOXIN WITH CYTOKINE DNA

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DESCRIPTION (provided by applicant): The toxin of Clostridium botulinum, particularly administered by inhalation, is a potential weapon of bioterrorism and germ warfare, and protecting people from the potentially devastating effects of its use is a high priority. At the same time, botulinum toxin (BT) has very important medicinal uses as an antispasmotic agent. We propose a collaborative project to use gene delivery of cDNAs encoding BT, serotype A (BT/A), antigens, to be given in tandem with cDNAs encoding cytokines that preferentially stimulate secretory IgA antibody (SIgA) responses. The goal of these studies is develop immunization regimens that protect from inhalational BT without precluding the important therapeutic uses of this agent. We will use both plasmid and recombinant adenoviral gene delivery vehicles to deliver both the heavy chain of BT (HC). Antibody elicited by HC protects from challenge with the complete toxin. These vectors will also deliver DNAs encoding cytokines that preferentially weight immune responses in favor of SIgA, at the expense of serum IgG antibody: transforming growth factor-beta1 and interleukins-4 and -5 (IL-4, IL-5). Our main hypothesis is: Immunizing regimens using cytokines that favor SIgA can elicit protective mucosal immunity to BT without system antibody. To test this hypothesis we propose four aims. We will: 1. Produce plasmid and adenovirus expression constructs to deliver BT/A-HC and cvtokine cDNAs. 2. Define parameters of local and svstemic immunity to BT, elicited by plasmid and rAd vectors. 3. Add cytokine-carrying vectors, individually and then in combinations, to these immunization regimens. 4. Modify expression constructs and administration regimens to optimize selectivity, protection, and safety. Thus, we will apply current understanding of the signaling mechanisms that occur during the activation of the secretory immune system to the need to protect people from the potential weaponization of botulinum toxin without limiting its important therapeutic applications.