[Experimental study of controlled release microencapsulated Salmonella typhi capsular polysaccharide vaccines...

Salmonella Typhi capsular polysaccharide vaccines were encapsulated in the Micro-particles made from polyethylene glycol-poly-DL-lactide (PELA). BALB/c mouse were divided into three groups with 20 mice in each. Mouse were immunized respectively with controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines and Salmonella Typhi capsular polysaccharide vaccines by oral and subcutaneous administration. The mice blood and salvia were collected at the 2nd, 4th and 8th weeks respectively for the titrating of IgG and sIgA antibodies by RIA. At the 8th week, live typhoid bacteria were injected into the immunized mice for the calculation of the rate of immunization protection. The IgG titers of the controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines group were higher than those of the other groups(P < 0.05). The IgA titers of the low groups of controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines (oral and subcutaneous) were higher than those of the group of Salmonella Typhi capsular polysaccharide vaccines (P < 0.05). The immunization protection rates of the three groups were 40%, 100% and 60% respectively. The controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines possess the advantages of releasing slowly in vivo and persisting long time immunogenicity.