Interfering effect of diphtheria-tetanus-acellular pertussis combined (DTaP) vaccines on the bacterial endotoxin test

Area of Science:

• Microbiology
• Immunology
• Vaccinology

Background:

• The Limulus amebocyte lysate (LAL) assay is a standard method for endotoxin detection.
• Diphtheria, tetanus, and acellular pertussis (DTaP) vaccines are widely used globally.
• Ensuring the safety and efficacy of vaccines requires accurate detection of residual endotoxins.

Purpose of the Study:

• To evaluate the applicability of the LAL endotoxin test for DTaP vaccines.
• To investigate potential interference between DTaP vaccine components and endotoxin detection.
• To assess the impact of observed interference on vaccine safety indicators.

Main Methods:

• DTaP vaccine batches were spiked with endotoxin.
• Limulus amebocyte lysate (LAL) assay was used to measure endotoxin activity over time.
• In vitro tumor necrosis factor-alpha (TNF-α) induction in RAW264.7 cells was assessed.
• In vivo pyrogenicity in rabbits was evaluated.

Main Results:

• No immediate interference was observed in the LAL assay.
• Some DTaP batches exhibited time-dependent interference with LAL activity.
• The observed interference did not affect in vitro TNF-α induction or in vivo pyrogenicity.
• Aluminium hydroxide gel was identified as a potential cause of interference.

Conclusions:

• The LAL test can be applied to DTaP vaccines, but potential time-dependent interference must be considered.
• Interference in the LAL assay does not necessarily correlate with reduced vaccine safety.
• Thorough evaluation of interference effects is essential for reliable endotoxin testing in DTaP vaccines.