Process development for the production of an E. coli produced clinical grade recombinant malaria vaccine for Plasmodium vivax.

The global eradication of malaria will require the development of vaccines to prevent infection cause by Plasmodium vivax in addition to Plasmodium falciparum. In an attempt to contribute to this effort we have previously reported the cloning and expression of a vaccine based on the circumsporozoite protein of P. vivax. The synthetic vaccine encodes for a full-length molecule encompassing the N-terminal and C-terminal regions flanking a chimeric repeat region representing VK210 and VK247, the two major alleles of P. vivax CSP. The vaccine, designated vivax malaria protein 001 (VMP001), was purified to >95% homogeneity using a three-column purification scheme and had low endotoxin levels and passed the rabbit pyrogenicity assay. The protein is recognized by monoclonal antibodies directed against the two repeat motifs, as well as polyclonal antibodies. Immunization with VMP001 induced high titer antibodies in mice using Montanide ISA 720. We currently have more than 10,000 doses of purified bulk and 1800 vials of formulated bulk vaccine available for clinical testing and VMP001 is currently undergoing further development as a candidate vaccine to prevent malaria in humans.

Effects of physostigmine and human butyrylcholinesterase on acoustic startle reflex and prepulse inhibition in C57BL/6J mice.

The use of exogenously administered cholinesterases as bioscavengers of highly toxic organophosphorus nerve agents is a viable prophylactic against this threat. To use this strategy, cholinesterases must provide protection without disrupting behavior when administered alone. To assess behavioral safety, the acoustic startle reflex and prepulse inhibition (PPI) of C57BL/6J mice were investigated following administration of human plasma-derived butyrylcholinesterase (HuBChE). Two hours before testing, four groups of mice (n=10 per group) were pretreated with saline or HuBChE (2000 U, ip). Fifteen minutes before testing, subjects received either saline or the carbamate physostigmine (0.4 mg/kg, sc). Mice exposed to physostigmine exhibited a significant attenuation of the startle reflex, an increased time to peak startle amplitude, and significantly increased PPI. This effect was partially mitigated in mice pretreated with HuBChE. HuBChE alone did not change startle behavior or PPI significantly compared to saline controls. The circulatory time-course of butyrylcholinesterase was assessed in a separate group of mice and revealed levels approximately 600 times the physiological norm 2-4 h post administration. Thus, HuBChE does not appear to significantly alter startle or PPI behavior at a dose 30-fold higher than that estimated to be necessary for protection against 2LD50 of soman in humans.