RESUMEN
Haemophilus 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. The separations of solid and liquid phases are based on continuous centrifugation in explosion proof installations. The lipopolysaccharides are separated by ultracentrifugation. A simple and efficient method that can easily be scaled-up was developed for purification of polysaccharides. The ethanol precipitation was reduced to only two steps. The phenol treatment was substituted by ultrafiltration and enzymatic digestion. Lipopolysaccharide was removed by ultrafiltration together with addition of detergent and chelating agent.
Asunto(s)
Centrifugación/métodos , Haemophilus influenzae tipo b/química , Polisacáridos Bacterianos/aislamiento & purificación , Ultrafiltración/métodos , Reactores Biológicos/microbiología , Precipitación Química , Etanol/química , Haemophilus influenzae tipo b/metabolismo , Lipopolisacáridos/química , Lipopolisacáridos/aislamiento & purificación , Polisacáridos Bacterianos/químicaAsunto(s)
Vacunas contra Haemophilus , Haemophilus influenzae tipo b , Vacunas Conjugadas , Bromuro de Cianógeno/química , Infecciones por Haemophilus/prevención & control , Haemophilus influenzae tipo b/química , Haemophilus influenzae tipo b/inmunología , Humanos , Estructura Molecular , Polisacáridos Bacterianos/química , Polisacáridos Bacterianos/inmunologíaRESUMEN
AIMS: To assess the effectiveness of a Hib vaccination program against X-ray defined bacterial pneumonia in children <2 years in Colombia. METHODS: 389 cases of radiologically confirmed pneumonia were recruited from hospitals in Bogota and Medellin, Colombia. Two controls per case, matched on age, sex, and socio-economic level, were selected from children attending child health services at the hospitals where pneumonia cases were admitted. RESULTS: The risk of having X-ray confirmed pneumonia decreased with each Hib dose received; the vaccine effectiveness was 47% (2-72%) among those receiving one dose; 52% for two doses received, and 55% for three doses. These effectiveness levels remained after adjusting for other factors associated with risk of pneumonia. CONCLUSIONS: This study indicates that trials may have underestimated the proportion of radiological pneumonia in the under 2s that is due to Hib. This suggests that the impact of the vaccination will be greater than expected if it can be extended to reach the poorest children, who are at the greatest risk.