Suitability of Alternative ATP Potency Assay for Lot Release of Tokyo BCG- 172-1 Vaccines in Thailand

Abstract

The potency assay of the BCG vaccine is routinely performed by a conventional viable count on a solid medium. This assay method is not only time-consuming, but can give variable results because of the tendency to clump of mycobacterium. The intracellular ATP was used as an alternative method that gave more rapid and reproducible results than the conventional viable count. The ATP assay kits included extraction reagents from three commercial kits that showed different ATP activity of the BCG vaccine; the cell viability kit and extraction reagent from the Biothema found a higher amount of ATP activity than the other two commercial kits. In order to reduce the cost of the assay, three lots of in-house extraction reagents were separately prepared and assessed along with the cell viability kit for the detection of ATP activity of the BCG vaccines. Using a commercial kit that was a combination of the Biothema and in-house extraction reagent, it was proven effective for determining the viability of mycobacterium from the BCG vaccines. No difference in ATP activity was found when the in-house extraction reagent was used instead of commercial reagents. From this study, the feasibility of an alternative ATP potency assay was routinely used for the lot release of the BCG vaccine in Thailand by using an in-house extraction reagent since it was easy to utilise and took only two days to produce the estimate of the viable cell content compared with four weeks for the conventional method.