Evaluation of Diphtheria-Tetanus-Acellular pertussis (DTaP) vaccine combination model at Institute of Vaccines and Medical Biologicals

This study aimed to evaluate a combined formulation model of diphtheria and tetanus antigens (Institute of Vaccines and Medical Biologicals) adsorbed on aluminium hydroxide with individually adsorbed acellular pertussis antigens (rPT, FHA) from Bionet (Thailand) to develop a diphtheria-tetanus-acellular pertussis (DTaP) vaccine.The DTaP vaccine combination model was assessed based on the characterisation of physical properties, adsorption rate and adsorption capacity of the diphtheria, tetanus antigens either individually or simultaneously adsorbed and of the final DTaP vaccine by using a Nano Particle Analyser SZ-100, flow cytometer and transmission electron microscope (TEM).The study identified alhydrogel 1.3% (Croda, Denmark) as optimal adjuvant with adsorption conditions optimised at pH 6.2 and a 120-minute incubation time for diphtheria and tetanus antigens.Following the combination, the DTaP vaccine remained physically stable and retained its antigen adsorption characteristics when stored at 2-8 o C over an observation period.The research results provide a foundation for establishing combination vaccine technology involving multiple antigens in Vietnam, paving the way for the development of pentavalent and hexavalent vaccines based on the DTaP vaccine platform.