Polysaccharide conjugation with detoxified E. COLI heat labile enterotoxin (LT) used as vaccine

Abstract

A detoxified recombinant E. coli heat-labile enterotoxin mutant, LTS61K, is employed as a carrier protein to conjugate polysaccharide. The LTS61K contains a mutated mature sub-unit A (LTA) that includes lysine at amino acid position 61 and a wild-type mature sub-unit B (LTB). Various types of bacterial capsular polysaccharide antigens were chemically conjugated with the LTS61K protein by a reductive amination reaction. The conjugated polysaccharide-LTS61K products were physically, chemically and biochemically identified as soluble form. Rabbits were immunized intramuscularly to determine the immunogenicity of conjugated vaccines by ELISA to detect anti- polysaccharide antigen IgG titers and serum bactericidal assay thereby determining the functional activity of the antibodies.; Study results show that conjugated polysaccharide-LTS61K vaccines induce higher polysaccharide-specific IgG titers and greater bactericidal activity in sera than that of polysaccharide alone or polysaccharide mixed with LTS61K. The presence of anti-LTS61K serum IgG antibody alleviates travel diarrhea caused by E. coli (ETEC enterotoxigenic E. coli).

Description

[0001] Related Application Cross Reference [0002] This application claims priority to US Provisional Patent Application No. 61 / 330,650, filed May 3, 2010, the disclosure of which is incorporated herein by reference in its entirety. technical field Background technique [0003] Polysaccharide vaccines lack immune memory responses when prepared without the use of carrier proteins. Currently known conjugate vaccines include capsular polysaccharides from bacteria such as Haemophilus influenzae type b, Neisseria meningitidis group C, and Streptococcus pneumoniae serotypes 1, 3, 4 , 5, 6B, 7F, 9V, 14, 19F, 23F. The vaccine is covalently coupled to a carrier protein such as tetanus toxoid, diphtheria toxoid, CRM197, mutant avirulent diphtheria toxin, or N. meningitidis outer membrane protein. These polysaccharide-conjugated vaccines induce T-cell-dependent responses especially in infants younger than two years of age; and they promote long-term immune memory, produce high-affi...

AI Technical Summary

Problems solved by technology

TT and DT, these two toxoid proteins are legal vaccines for infants / children; high frequency of TT and DT in the short term may affect immunogenicity and safety

Images