A new in-vitro agglutination technique for potency estimation of antisnake venom serum (ASVS)

Traditionally the potency of ASVS is assayed quantitatively by in-vivo neutralization test for lethality in mice. A sensitive and simple in-vitro agglutination assay for the quantitative determination of Antisnake Venom Serum (ASVS) potency is reported. The method is rapid, cheap, simple, economical and above all does not require the use of experimental animals for potency assay of in process, unpurified and purified sera batches. Among in-vitro procedures, agglutination assay was favored in comparison to flocculation as the later was found to give variable results and also time consuming (high Kf value). Before application, the method was standardized and validated for choice and concentration of particulate material (latex vs. bentonite), temperature and optimum antiserum concentration. It is well known fact that venoms lose toxicity on dilution however this study demonstrated that the bentonite adsorbed venoms of the entire four snake species viz., Cobra, Krait, Russell's viper and Echis are stable even up to 30 days of storage. Among five lots each of unpurified serum, unprocessed plasma and purified sera tested, the results were found comparable with universally accepted in-vivo biological assay. The coefficient of correlation was found to be near 1.0 within 95% fiducial limits of acceptance and also significantly less variation was observed in the mean potency values and standard deviations. For all results p value was observed to be <0.01. Results indicate that in-vitro agglutination assay is suitable and can be used for potency estimation of in process as well as unpurified and purified ASVS batches.