Haemophilus influenzae type b (Hib), a Gram-negative capsulated bacterium, is a causative agent of meningitis worldwide. The capsular polysaccharide, a high molecular mass polymer consisting of the repeated units of the polyribosyl-ribitol-phosphate, is considered the main virulence factor and it is used as an antigen to vaccines, conjugated to a carrier protein. The industrial production of the polysaccharide requires the cultivation of Hib in rich medium, which impacts process costs and product recovery.
View Article and Find Full Text PDFConjugate vaccines are being widely used since their introduction. Nowadays the interest in these vaccines is still growing and new antigens and conjugate chemistry are being studied and developed. Pneumococcal surface protein A (PspA) is one of the most studied pneumococcal antigens and is an important vaccine candidate.
View Article and Find Full Text PDFPneumococcal surface protein A (PspA) is essential for Streptococcus pneumoniae virulence and its use either as a novel pneumococcal vaccine or as carrier in a conjugate vaccine would improve the protection and the coverage of the vaccine. Within this context, the development of scalable production and purification processes of His-tagged recombinant fragment of PspA from clade 3 (rfPspA3) in Escherichia coli BL21(DE3) was proposed. Fed-batch production was performed using chemically defined medium with glucose or glycerol as carbon source.
View Article and Find Full Text PDFHaemophilus influenzae type b, an encapsulated bacterium, causes meningitis in infants worldwide. The capsular polysaccharide conjugated to a carrier protein is effective in the prevention of such infections. The traditional purification process of polysaccharide from bacterial cultures for vaccine production is based on several selective precipitations with solvents such as: ethanol, phenol, and cationic detergents.
View Article and Find Full Text PDFHaemophilus influenzae type b (Hib) causes invasive infections in infants and young children. Vaccines consisting of Hib capsular polysaccharide (polymer of ribosylribitol phosphate [PRP]) conjugated to a protein are effective in the prevention of such infections. The production of capsular polysaccharide type b was studied in three cultivation conditions: single, glucose pulse, and repeated batch.
View Article and Find Full Text PDFThe modern vaccinology encompasses the recombinant DNA technology, protein and carbohydrate chemistry to obtain safe molecularly defined vaccines. Nevertheless most of the vaccines are poorly immunogenic because a large number of antigens are membrane proteins and consequently they are not present in their active conformation in the vaccine. Others are not as potent because they contain only B epitopes and therefore, cannot stimulate cellular memory.
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