ABSTRACT
Encapsulated bacterial diseases are the most prevalent and serious infections in humans, particularly in young children. There is increasing interest in study of the chemical basis of immunogenicity to capsular polysaccharides and prevention of bacterial infections through immunization. Development of the polysaccharide (PS)-protein conjugate vaccines for encapsulated pathogens will enhance the antibody response to PS. Maternal immunization with the PS or PS-protein conjugate vaccine during gestation could help in solving problems of poor immunogenicity of PS vaccine in young children. The immune system of infants differs from that of adults in both its relative lack of previous antigenic exposure and its functional immaturity. Although the immunogenicity to PS antigens is enhanced by conjugation of PS with a protein carrier, differences in antibody responses have been observed among the conjugate immunogens from different encapsulated bacteria. Current meningococcal PS vaccines are effective and safe in prevention of infection caused by serogroups A, C, Y, and W135 organisms.
