RESUMO
Quimi-Hib is a conjugate vaccine against Haemophilus influenza type b (Hib) where the Hib antigen is the only one produced by chemical synthesis. NMR has become the alternative of choice for the identity of intermediates during the chemical synthesis of Hib antigen. We explore a rapid quantitative proton magnetic resonance (qHNMR) assay for the determination of N,N-dimethylformamide (DMF) as a residual in one of the critical intermediates. The proposed assay has been shown to be accurate, precise for intermediate precision conditions (relative standard deviation <3% for spectrometer-to-spectrometer variations), specific (no detected interferences), and rugged (percentage difference <3% for day-to-day and spectrometer-to-spectrometer variations). The quantitative NMR assay can replace the common chromatographic methods for monitoring the DMF contents in one crucial step of the synthetic scheme.
Assuntos
Dimetilformamida/análise , Vacinas Anti-Haemophilus/química , Espectroscopia de Ressonância Magnética , Conformação Molecular , Prótons , Vacinas Conjugadas/químicaRESUMO
Capsular polysaccharides are important virulence factors of Streptococcus pneumoniae. The polysaccharide has been used as a component of vaccines against pneumococcal diseases either as plain polysaccharide or better conjugated to a protein. The last one is the vaccine of choice to target child protection. The immune responses depend on several polysaccharide physicochemical properties that can be affected during either purification or modification in the case of conjugate vaccines. In serotype 18C, the repeating unit has a complex structure having a branched pentasaccharide with two apparently labile subtituents: glycerol-phosphate and O-acetyl group. The loss of these groups may potentially reduce the ability of the 18C polysaccharide to induce the desired immune response. Therefore, the relationship of both groups with the antigenicity and immunogenicity of 18C capsular polysaccharide is explored. It is shown that glycerol-phosphate must be preserved for conserving adequate antigenicity of the 18C capsular polysaccharide. At the same time, it was proved that O-acetyl groups do not play any role for the antigenicity and immunogenicity.
Assuntos
Antígenos de Bactérias/química , Antígenos de Bactérias/imunologia , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/imunologia , Streptococcus pneumoniae/química , Streptococcus pneumoniae/imunologia , Animais , Humanos , Éteres Fosfolipídicos/química , Éteres Fosfolipídicos/imunologia , CoelhosAssuntos
Vacinas Anti-Haemophilus , Haemophilus influenzae tipo b , Vacinas Conjugadas , Brometo de Cianogênio/química , Infecções por Haemophilus/prevenção & controle , Haemophilus influenzae tipo b/química , Haemophilus influenzae tipo b/imunologia , Humanos , Estrutura Molecular , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/imunologiaRESUMO
Since 1989, we have been involved in the development of a vaccine against Haemophilus influenzae type b. The new vaccine is based on the conjugation of synthetic oligosaccharides to tetanus toxoid. Our main goals have been (i) to verify the feasibility of using the synthetic antigen and (ii) to search for new production alternatives for this important infant vaccine. Overall, eight trials have already been conducted with adults, children (4 to 5 years old), and infants. We have described herein the details from the first two phase I clinical trials conducted with human adult volunteers under double blind, randomized conditions. The participants each received a single intramuscular injection to evaluate safety and initial immunogenicity. We have found an excellent safety profile and an antibody response similar to the one observed for the control vaccine.