M. H. Motedayen - Department of Immunization and Plasma Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
G. Nikbakht Brujeni - Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
M. J. Rasaee - Department of Medical Biotechnology, School of Medicine, Tarbiat Modares University, Tehran, Iran
A. Zare Mirakabadi - Department of Venomous Animals, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
A. Khorasani - Department of Foot and Mouth Disease, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
H. Eizadi - Department of Foot and Mouth Disease, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
M. M. Ranjbar - Department of Virology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
S.M. Azimi - Department of Foot and Mouth Disease, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
M. Esmaelizad - Department of Biotechnology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran

Venomous snakebite is a life-threatening injury in many tropical and subtropical areas including Iran. The gold standard treatment option for human envenomation is the use of antivenoms. Despite the unique effects of horse-derived antivenoms on the treatment of snakebite, they are not fully perfect and need improvements. In this study, human recombinant Fab fragment antivenom was produced in Rosetta-g bacterium using a gene library constructed in the previous study. The prepared Fab was purified in several steps, desalted, and lipopolysaccharide-depleted using ammonium sulfate solution and dialysis against phosphate buffer and Triton X-۱۱۴ solution, respectively. Subsequently, the product was initially confirmed by the sodium dodecyl sulfate polyacrylamide gel electrophoresis and enzyme-linked immunosorbent assay (ELISA), respectively. Finally, the neutralization potency of the product was investigated in laboratory Syrian Mice. The obtained results showed corresponding reduced bands to Fab fragment with the molecular weight of about ۲۸ kDa at a concentration of ۳.۱ mg/ml. There was a significant difference between the groups in terms of ELISA test (P<۰.۰۵). The neutralization potency of the product against the venom of Echis carinatus (E. carinatus) was about ۷ LD۵۰/ml (۵۴.۶ µg/ml) when tested on mice. Based on the results, the Fab fragment antivenom had the ability to neutralize the in vivo biological activity of the venom of Iranian E. carinatus. However, further studies are recommended to reach a suitable concentration of antivenom fragment.

Echis carinatus, Fab fragment, Gene library, Antivenom, Polyclonal