Exposure to organophosphates (OPs), in the form of nerve gas and insecticides poses an ever increasing military and civilian threat. In recent years exogenous administration of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) have been successfully used as safe and efficacious prophylactic treatments due to their capacity to scavenge OPs in the blood before inhibition of the targeted endogenous AChE can occur. However, the 1:1 stoichiometry between enzyme activity and OP dose required for protection may not be obtainable if the enzyme is rapidly cleared by antibody induced following single or repeated administration/s . To date, immune responses to non-self ChE have varied widely and the critical role of antibody in enzyme clearance is still unclear. The aim of this proposal is to assess, for the first time in primates, the immunogenicity and safety of injecting homologous macaque-derived BChE (MaBChE) into macaques to provide the preclinical data for the potential use of HuBChE. as an OP scavenger in humans. This involves three specific aims: (i) To purify MaBChE from monkey blood sufficient to inject macaques with levels approximating those known to protect from OP toxicity (ii) To compare the macaque immune response, both humoral and cell mediated, following a single i.v. injections and if more plasma is available, another two months later. IgM, IgG and IgA production will be measured in serum by ELISA and in lymph nodes by ELISPOT. IgE-mediated hypersensitivity testing will be done. Specific T cell proliferative responses and intracellular cytokine responses will also be monitored (iii) To determine the role of anti-BChE antibody in clearance of exogenous BChE using B cell deficient recombinase activating gene 2(RAG 2) knock out mice injected with various forms of HuBChE with or without anti-HuBChE antibody. In phase II, through collaborative efforts or partnerships, delivery by intranasal spray or powder will be assessed for immunogenicity and efficacy and kinetics of protection.
Benefits: Commercial applications include situations where nasal and pulmonary delivery of `self" protein based drugs are life saving e.g. 1) for the rapid treatment of inhaled toxins resulting from inhalation/exposure of toxic materials including nerve gas 2) for increased quality of life for patients requiring chronic i.m. or i.v. administration of protein/peptides (i.e. diabetics) , 3) alleviating life threatening condition(s) e.g. apnea resulting from the succinylcholine.injection in BchE atypical people 4) for delivery safer and more efficacious vaccines human studies.
