ABSTRACT
Objective To determine Haemophilus influenzae type b strains in molecular level using PCR,and to study the immunogenicity of capsular polysaccharide conjugates in mice.Methods Extracting genomes using bacterial DNA extract kit from Hoemophilus influenzae type b strains,and PCR for determining the strains through serotyping-specific and capsular genotyping primers respectively.Various capsular polysaccharides conjugated TT respectively,and the conjugates were administered subcutaneously to mice through dilution.After vaccination with two doses,blood samples were collected for the detection of antibody levels to polyribosylribitol phosphate ( PRP),the capsular polysaccharide of Hib.Results All five Haemophilus influenzae type b strains contain type-specific(482 bp) and capsular type (343 bp)DNA fragment through PCR detecting.The DNA fragments were sequenced.BLAST show that these sequences are 100％ homology comparing the above strains respectively,and are 99％ and 100％ homology comparing the GenBank X78559.1 and M19995.1 respectively.The immunogenicity of mice from various capsular polysaccharide conjugates (PRP-TT) was not significantly different by ELISA detecting.Conclusion Through PCR,Haemophilus influenzae type b strain can be determined in molecular level.The immunogenicity of mice from purified capsular polysaccharide conjugates was not different.The study provides a detection means for the features and heredity stability of Haemophilus influenzae type b strain and reference data for the immunogenicity of different polysaccharide conjugates in vaccine research and development and production.
ABSTRACT
Objective To investigate the immunogenicity of group A plus group C meningococeal glycoconjugate vaccine,namely dosage,immune memory and compatibility. Methods The mice were injected with group A plus group C meningococcal glycoconjugate vaccine with different dosages. Blood samples were taken on the 14th day after the last injection for testing the antibodies against polysaccharide A and C. After the optimal immunization dosage had been decided,the mice were inoculated separately with the monovalent group A and the monovalent group C and the bivalent group A plus group C glycoconjugate vaccine with one,two or three injections for observation of the effectiveness of different injections and the compatibilities. Results The dosage of 1.25 μg of each polysaccharide of group A and group C in bivalent glycoconjugate vaccine appears to be immunologically optimal to vaccinate the mice. Immunological memory could be induced in mice inoculated with the glycoconjugate vaccine,and the antigenic immunogenicity of the group A component and group C component in the formulation of group A plus group C meningococcal glycoconjugate vaccine was not affected. Conclusion Group A plus group C meningococcal glycoconjugate vaccine have good immunogenicity,immune memory and compatibility.