Reduction of Purification Time of Polyspecific Equine F(ab´)2 Antivenom against Scorpion Envenomation

Background and Aims: In this study we improved the purification of immunoglobulins from equine antiserum raised against the venom of 6 types of scorption species. Caprylic acid (octanoic acid), a fatty acid, was found to have no effect on the activity of the enzymes pepsin, which is used in antivenom purification to digest Fc fragment of immunoglobulins to obtain F(ab acute;)2. Materials and Methods: A new method was developed for the production of F(ab acute;)2 antivenom whereby whole equine antiserum was mixed with equal amount of 0.15 M HCl and pH 3.4 with pepsin 660 mg/L of diluted antivenom and incubated for 4 h at 37 °C. After digestion the pH were brought to 4.8 with sodium hydroxide solution (1.5 M) and then 1.5% caprylic acid and 10% ammonium sulfate was added and mixed for 60 minutes and passed through filter paper. Results: Caprylic acid caused precipitation of albumin, and ammonium sulfate reduced turbidity of solution, resulting in a reduced protein load presented to the digestion enzymes culminating in substantial reductions in processing time. Conclusions: The equine F(ab acute;)2 obtained using these novel caprylic acid methods were comparable in terms of yield, purity and specific activity to those obtained by multistep and time consuming conventional salt fractionation with ammonium sulfate.