Capsular polysaccharides of encapsulated bacterial pathogens such as Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenza, and Salmonella enterica serovar Typhi are the primary antigenic components involved in protective immunity against bacterial pathogens. Purified polysaccharides of these bacteria, however, are T-independent antigens, that elicit poor antibody responses in children under the age of 2 and do not elicit immune ‘memory’, or an anamnestic response. However, by covalently linking (conjugating) the polysaccharide antigens to a protein carrier they are converted to a T-dependent antigens, capable of eliciting robust, anamnestic immune responses in children. Unfortunately, the manufacture of polysaccharide-protein conjugate vaccines is a complex and expensive process requiring each polysaccharide to be conjugated to a carrier protein in individual chemical reactions. The manufacture process for conjugate vaccines is further complicated by the diversity of capsule composition and structure, which often necessitates different conjugation chemistries, and the need to produce multivalent vaccines that contain many different capsular polysaccharides.
Protein Capsular Matrix Vaccine (PCMV) technology, is an alternative to conjugate vaccine technology where the capsular antigens are entrapped in a matrix of crosslinked carrier protein rather than direct covalent linkage to a carrier protein. PCMV technology will allow polysaccharide based vaccines to be produced more efficiently and less expensively due to the potential to produce vaccines containing multiple polysaccharides in single reactions using a single chemistry.
Matrivax is actively developing streamlined processes for polysaccharide purification and PCMV entrapment reactions that could reduce the number of GMP manufacturing steps of a multivalent pneumococcal vaccine by half or more. The simplified PCMV manufacturing process will be significantly less expensive than conventional conjugation and will more easily enable the inclusion of additional pneumococcal serotypes in the vaccine, therefore providing a higher level of vaccine protective efficacy.