Membrane-Based Clarification of Polysaccharide Vaccines
Polysaccharide vaccines are essential for protection against infectious diseases, which remain an alarming cause of mortality. The first glycoconjugate vaccine for use in humans was licensed in the year 1987 for prevention of Haemophilus influenzae type b (Hib) infection. This vaccine successfully reduced the incidence of invasive Hib disease in childhood and led to the further development of conjugate vaccines designed to prevent infection by other encapsulated bacteria, i.e., Streptococcus pneumoniae, Neisseria meningitidis, Salmonella typhi, etc.
Polysaccharide vaccines are derived mainly from bacterial source. Production of polysaccharide vaccines is a complex process involving many different steps and processes, starting with bacterial fermentation. Clarification is a critical step in purification of polysaccharide (PS) vaccines. There are several technologies that can be applied for PS vaccine clarification. Typical clarification techniques include membrane filtration (microfiltration, tangential-flow filtration), centrifugation, and depth filtration (normal flow filtration). Historically conjugate polysaccharide vaccine harvest clarification was usually achieved by centrifugation followed by depth filtration. Recently membrane based technologies gained prominence in vaccine clarification.
Clarification of polysaccharide vaccines presents several challenges due to high cell mass at harvest stage (primary clarification) and unique particle size distribution and colloidal load (secondary clarification). Centrifugation or microfiltration devices had been preferred for primary clarification. Of late, charged depth filters have shown promise for primary clarification, and membrane filters are proving to be better options for secondary clarification. Improvement in clarification steps can result in higher final yields and purity in vaccine processes. As new clarification products, tools, and solutions are being made available, vaccine developers and producers will continue to be better prepared for efficient and effective clarification processes.
We published an article that offers a comprehensive view on different filter based technologies and their application in clarification of polysaccharide vaccines.
To view the paper click here.