Recombinant Russell’s viper venom-factor X activator (RVV-X)-specific antibody: neutralization and crossreactivity with Cryptelytrops albolabris and Calloselasma rhodostoma venoms

Background: Russell’s viper venom-factor X activator (RVV-X) is a major procoagulant in Russell’s viper venom, and is composed of a heavy chain (RVV-XH) and two light chains (RVV-XL). It directly activates factor X in the final common coagulation pathway, which leads to rapid formation of blood clots.

Objective: Produce rabbit anti-recombinant protein antibodies and identify their cross-reactivity with two viperine snake venoms.

Methods: cDNA clones encoding RVV-XH and one of the light chains (RVV-XL; LC1) were recombinantly expressed in E. coli BL21 and used as antigens for rabbit immunization. The cross-reactivity of these anti-recombinant protein antibodies with two viperine snake venoms was determined using Western blot analysis.

Results: rRVV-XH was more immunogenic than rRVV-XL. Rabbit anti-rRVV-XH and rRVV-XL IgG antibodies bind specifically to RVV-X, but they do not neutralize purified RVV-X. In addition, rabbit anti-rRVV-XH IgG antibody also bind to an 18-kDa protein in C. rhodostoma venom, and many proteins in C. albolabris venom. Rabbit antirRVV- XL IgG antibody recognized protein bands of crude venoms of C. rhodostoma and C. albolabris at about 25-kDa and 23-kDa, respectively.

Conclusion: Rabbit anti-rRVV-XH and rRVV-XL IgG antibodies cross-reacted with molecules in other viperine venoms, which could have molecules with similar antigenic determinants. These antibodies could be useful to purify snake venom molecules by affinity chromatography as the first step in purification of factor X activator and other cross reacting molecules.