ELECTROPHORETIC PROFILES AND BIOLOGICAL-ACTIVITIES - INTRASPECIFIC VARIATION IN THE VENOM OF THE MALAYAN PIT VIPER (CALLOSELASMA-RHODOSTOMA)

The Malayan pit viper (Calloselasma rhodostoma) is of major clinical s ignificance both as a leading cause of snakebite and as the source of ancrod (Arvin(TM). Although its venom has been extensively studied, th e degree to which venom composition varies between individuals is poor ly known. We individually analysed the venoms of over 100 C. rhodostom a using isoelectric focusing. In all populations, females produced an intense band that was absent from all males, and significant ontogenet ic variation was detected. Principal components analysis of the bandin g profiles also revealed strong geographic variation, which was signif icantly congruent with variation in the biological activities of the v enom (phosphodiesterase, alkalinephosphoesterase, L-amino acid oxidase , arginine ester hydrolase, 5'-nucleotidase, thrombin-like enzyme, hae morrhagic activity). Studies of captive-bred snakes indicate that the intraspecific variation in venom is genetically inherited rather than environmentally induced. The intraspecific variation in venom composit ion and biological activity could be of applied importance to snakebit e therapy, both in correct diagnosis of the source of envenomation and in the development of a more effective antivenom. Greater attention s hould be given to the source of C. rhodostoma venom used in research t o ensure reproducibility of results.