title: Titration of poliovaccines: improvement of end-point microassays by means of dose-response curves.
abstract: The W.H.O.'s titration method for attenuated poliovaccines, using two-fold dilution steps, was assayed concurrently with an alternative method, using four-fold dilution steps. For the two-fold dilution method, the dispersion of the observed proportions of response was very wide, inducing biased estimations for titers and their standard-error by means of simple usual calculation procedures. On the other hand, the use of the four-fold dilution method constantly provides more accurate estimates for the titers and their confidence limits and thus increases the reliability of the titration results. In addition, replicate poliovirus titrations were performed in three cell lines (HEp-2, LLC-MK2 and Vero), applying a restricted experimental design, in order to characterize statistically their sensitivity for poliovaccine titrations, and their consistency for infectivity titers. Means of improving the reliability of live poliovaccine potency estimates are suggested.
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001681:Biological Assay / Q000379:methods*; D002460:Cell Line; D011054:Poliovirus Vaccine, Inactivated / Q000032:analysis*; D012044:Regression Analysis; D014779:Virus Replication
chemical_list: D011054:Poliovirus Vaccine, Inactivated