Evaluating the Immunological cross-reactivity of Indian polyvalent antivenoms towards the venom of Hypnale hypnale (hump-nosed pit viper) from the Western Ghats

Hypnale hypnale (hump-nosed pit viper) is a venomous pit viper species found in the Western Ghats of India and Sri Lanka. Due to the severe life-threatening envenomation effects induced by its venom components, Hypnale hypnale has been classified under category 1 of medically important snake species by the World Health Organization. Since there are no specific antivenoms available to combat its envenomation in India, the only option available is to administer Indian polyvalent antivenoms. However, the cross-neutralization potential of the commercially available polyvalent antivenoms on Indian Hypnale hypnale venom has not been explored so far. In the current study, in vitro immunological cross-reactivity of Hypnale hypnale venom towards various Indian polyvalent antivenoms were assessed using end point titration ELISA and Western blotting. A three to four-fold increase in EC50 values were obtained for Hypnale hypnale venom towards all the antivenoms tested. Observation of minimal binding specificities towards low and high molecular mass venom proteins are suggestive of the fact that commercially available polyvalent antivenoms failed to detect and bind to the antigenic epitopes of considerable number of proteins present in Hypnale hypnale venom. This highlights the importance of including Hypnale hypnale venom in the immunization mixture while raising antivenoms.