The immunogenicity of a vaccine is estimated in terms of its capacity to induce an antibody and/or cell-mediated immune response in recipients. Studies have shown that antibodies against viral haemagglutinin are important correlates of protection.
Traditionally, the assessment of immunogenicity is based on two serological assays, the haemagglutination inhibition assay and single radial haemolysis. A haemagglutination inhibition titer of 40 is considered to be an immunological correlate of protection and is regarded as the best available parameter of protection against infection.
Author : Claudia Maria Trombetta
Title : Correlates of Protection for Influenza Vaccines
Volume/Issue : 1;1
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Pneumonia represents considerable infection rates in young children. In 2015, this disease was responsible for 15% of the total deaths in children worldwide. The vaccines available contain 10 to 23 of the more than 90 pathogen’s serotypes, and it’s obtained through fermentations and purifications of the capsular polysaccharides of each serotype. This work proposes a process optimization of only one recombinant protein antigen, the PsaA (pneumococcal surface adhesion A), potentially capable to act against most of all prevalent serotypes of Streptococcus pneumoniae and suggests a formulation for intranasal administration. Based on protein expression in prokaryotic system and purification, this process reached high purity levels and satisfactory yield. Studies of expression level verified that fermentation time could be initially reduced from 16 to 10 hours. Purification steps showed good resolution using anion exchange chromatography (DEAE SepharoseTM FF). For desalting, comparative studies observed that gel filtration technique should be replaced for tangential cross flow filtration, which is better to scale-up using 10 kDa membranes. The developed process resulted in overall yield of 29%, based on BCA analysis. SDS-PAGE analysis after purification showed a PsaA band corresponding to 99% of identified proteins. It was also efficient in DNA and endotoxin clearance. As formulation proposal, chitosan was used to prepare the antigen capsules, using different polymer concentration, which can be considered as an intranasal delivery system. This data show that this process could be promising to obtain recombinant vaccines
Keywords : Pneumococcal vaccine; PsaA; Protein vaccine; Chitosan
Author : Ana Maria Pereira dos Santos
Title : Process Development for Obtaining a Recombinant Protein Pneumococcal Intranasal Vaccine Candidate