Neutralization of venom-induced hemorrhage by equine antibodies raised by immunization with a plasmid encoding a novel P-II metalloproteinase from the lancehead pitviper Bothrops asper.

In this work, the cDNA encoding a novel P-II type metalloproteinase from Bothrops asper venom glands was cloned, sequenced and used for DNA immunization of animals with accelerated DNA-coated tungsten microparticles and the helius Gene Gun system. Specific antibodies against B. asper venom antigens were induced in mice co-immunized with the plasmid encoding the P-II metalloproteinase together with an expression plasmid encoding the murine IL-2. Similarly, specific antibodies against B. asper venom antigens were also induced in a horse co-immunized with the plasmid encoding the P-II metalloproteinase, together with a plasmid encoding the equine IL-6. The equine antibodies induced by immunization with the P-II metalloproteinase encoding plasmid cross react with several proteins of B. asper, Crotalus durissus durissus, and Lachesis stenophrys venoms in western blot, demonstrating antigenic similarity between the cloned metalloproteinase and other metalloproteinases present in these venoms. Furthermore, the equine antibodies induced by immunization with the P-II metalloproteinase encoding plasmid completely neutralized the hemorrhagic activity of the whole B. asper venom and partially the hemorrhagic activity of C. durissus durissus venom. The neutralizing ability of the produced antibodies raises, for the first time, the possibility of developing therapeutic antivenoms in horses by DNA immunization using tungsten microparticles.