A simplified ATP method for the rapid control of cell viability in a freeze-dried BCG vaccine

• Simplified ATP assay for specific activity in a freeze-dried BCG vaccine is proposed.
• Conditions for cell rehydration, reactivation, and lysis are optimized.
• Correlation between the specific activity and intracellular ATP content is linear.
• The method was successfully tested under production conditions.

We propose a simple and cost-effective ATP method for controlling the specific activity of a freeze-dried BCG vaccine. A freeze-dried BCG vaccine is reconstituted with 1 ml saline and incubated for 15 min at room temperature and then for 1 h at 37 °C. The vaccine is then treated with apyrase to remove extracellular ATP. After that, the cells are lysed with DMSO and the ATP content in the lysate is measured by the bioluminescence method. To implement the method, we developed a kit that requires no time-consuming preparation before the analysis. We demonstrated the linear relationship between the experimental values of the specific activity (106 CFU/mg) and intracellular ATP content (ATP, pmol/mg) for different batches of the studied BCG vaccines; the proportionality coefficient was К = 0.36 ± 0.02. We proposed a formula for calculating the specific activity from the measured content of intracellular ATP (ATP, pmol/mg). The comparison of the measured and calculated values of the specific activity (106 CFU/mg) shows that these values are similar; their differences fall within the allowable range of deviations for the specific activity values of the BCG vaccine.

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