Physico-chemical properties of Salmonella typhi Vi polysaccharide–diphtheria toxoid conjugate vaccines affect immunogenicity

Preparation and testing of a Vi conjugate vaccine using pneumococcal surface protein A (PspA) from Streptococcus pneumoniae as the carrier protein

“…This pattern of boosting is typical of most polysaccharide-protein conjugate vaccines. Anti-Vi responses obtained after 3 doses of the Vi-PspA conjugates were similar to those achieved with Vi-DT conjugates [1,7]. Un-conjugated PspA was poorly immunogenic particularly family 1, conjugation of PspA to Vi significantly increased the anti-PspA response.…”

“…Conjugates were prepared using a two step procedure as described previously [1] with the following changes.…”

“…To combat this problem a number of conjugate vaccines based on Vi capsular polysaccharide are being developed [1]. These conjugates mainly use diphtheria toxoid or the non toxic mutant diphtheria toxin (CRM 197 ) or tetanus toxoid as the carrier protein.…”

Preparation and testing of a Haemophilus influenzae Type b/Hepatitis B surface antigen conjugate vaccine

“…HBsAg and DT were derivatized as previously described [12]. Briefly the HBsAg or DT was derivatized by binding ADH to the protein in the presence of EDC, final concentrations of protein, ADH and EDC were 3.0:10.5:1.2 mg/mL for HBsAg and 10.0:35.0:4.0 mg/mL for DT.…”

A bivalent conjugate vaccine containing PspA families 1 and 2 has the potential to protect against a wide range of Streptococcus pneumoniae strains and Salmonella Typhi

“…Typhoid vaccines are available but are used only sporadically and new Vi-based conjugate vaccines are being developed targeting introduction into routine Extended Programs of Immunization [3]. Serotype specific pneumococcal polysaccharide conjugate vaccines are available, however, they are expensive and there is limited supply.…”