This Small Business Innovation Research Phase I project will develop a biological method for control of mammalian pests that attack agricultural crops. Annual economic losses in excess of $5 billion result from nuisance mammalian pests (USDA estimates). An ideal method to control these pests would: (a) specifically target and depress the population in a nonlethal, reversible manner; (b) use a safe biological method that is environmentally friendly; (c) be inexpensive and easy to use. This project will attempt to develop a biological control method that meets all of these criteria. An immunocontraceptive product, using a rodent specific zona pellucida antigen previously shown to immunize mice will be developed. The antigen will be expressed in alfalfa linked to the immunoadjuvant protein cholera toxin. Preliminary studies demonstrate that mice fed spinach infected with tobacco mosaic virus carrying the ZP3 antigen fused to the TMV coat protein developed ZP3 specific antibodies and became infertile. Because the conceptual basis of this idea has been reduced to practice and a patent has been submitted, the next step and the primary objective of this proposal is to develop a commercially viable means to deliver the immunocontraceptive vaccine. The overall objective of phase I is to demonstrate that transgenic alfalfa plants expressing ZP3 epitopes are immunogenic in mice and that these mice have reduced fecundity. To this end a plant expression vector will be constructed comprised of the cholera toxin A and B chains with a selected ZP3 epitope fused to the cholera A chain and a selectable marker between the CTA and CTB chains. The expression of the CTB chain will be augmented by fusion of a KDEL sequence to the C terminus. Transgenic alfalfa plants will be generated and antigen expression demonstrated. Mice will be immunized with transgenic alfalfa to demonstrate immunogenicity of the fusion protein and feeding experiments to demonstrate oral vaccination will be initiated. The goal is to demonstrate feasibility of using transgenic alfalfa as a means to deliver contraceptive epitopes for oral immunization as a means of pest control and preliminary work suggests that the probability of success is high. This work will result in the generation of a novel, safe and effective means to control nuisance pests. Nuisance pests cost billions of dollars worth of economic loss and endanger human lives. An effective means of control will generate a commercially viable business opportunity in excess of $100 million annually.
