Cross neutralization of the lethal activities of Myanmar and Thai Russell's viper venoms by Thai and Myanmar antivenoms.

The efficacy of homologous neutralization of the lethal activity of Myanmar Russell's viper venom (MRV) and Thai Russell's viper venom (TRV) by Myanmar antivenom (MAV) and Thai antivenom (TAV), respectively, were studied and compared with the heterologous neutralization of the lethal activity of MRV and TRV by TAV and MAV, respectively, in experimental mice. Although MRV and TRV were the same subspecies, their lethal activities and protective efficacy of MAV and TAV were apparently different from each other. However, there was some extent of cross reactivities between MRV and TAV, and TRV and MAV. The findings of this study suggested that it is necessary to administer heterologous antivenom in dosage of 1.7-4 times greater than that of homologous antivenom to achieve an equal potency.