Preparation of a subcellular conjugate with the lipopolysaccharide from Vibrio cholerae 01 using beta-D-glucan as matrix

Immunological efficacy of glycoconjugates derived from Vibrio cholerae O1 serotype Ogawa detoxified LPS in mice

This study focused on changes in selected parameters of humoral and cellular immunity following vaccination of mice with unique Vibrio cholerae LPS–protein-complexed conjugates. The V. cholerae detoxified LPS (dLPS)-derived antigenic structures O-specific polysaccharide (O-SP) and de-O-acylated LPS (DeOAc-LPS) were used to prepare glycoconjugates by linking both dLPSs to glucan, the immunomodulating matrix, and then to BSA carrier. Animals were given a primary vaccination and boosted at 2-week intervals with a dose of 4.5 μg saccharide antigen. The last boost was given either subcutaneously or intraperitoneally (i.p.) to compare the boosting effect and to optimize the effective immunization route. Both conjugates (O-SP–BSA and DeOAc-LPS–BSA) induced significant levels of antigen-specific Ig isotypes, especially IgG and IgM. The i.p. booster route was more effective. A T helper 1 response was achieved only by immunization with O-SP–BSA conjugate administered i.p. Significant acceleration of phagocytic capacity and respiratory burst of neutrophils was demonstrated by both immunogenic formulations. Activation of T- and B-cell adaptive immunities was exhibited as specific changes in CD3 : CD19 and CD4 : CD8 ratios, B-cell low-affinity Fcγ II and III receptor expression and induction of CD45R antigen.

Immunological properties of complex conjugates based on Vibrio cholerae O1 Ogawa lipopolysaccharide antigen

Host protection by humoral immunity against Vibrio cholerae O1 confers lipopolysaccharide (LPS)-specific vibriocidal antibodies. Levels of relevant specific antibodies are closely related to complement-mediated inactivation of the vibrios inoculum, especially on the mucosal surface of intestine. We have tested complex V. cholerae O1 Ogawa-detoxified lipopolysaccharide (dLPS) conjugates. The first conjugate contained glucan both as the immunomodulator and the matrix; the second conjugate contained immunologically inert amylose as matrix. Both d-LPS conjugates contain multiply attached dLPS antigen. These conjugates elicited a statistically significant increase of antigen-specific IgG levels in mice (P<0.001 and P<0.05, respectively). The specific anti-conjugate IgG and IgA response after the second (booster) dose were significantly higher compared to pre-immune and whole-cell response. The most effective vibriocidal activity was observed in the case of conjugate, with glucan as the matrix. The highest correlation was found between vibriocidal activity and specific IgG2b (r=0.765) and IgA (r=0.887) sera levels. The determination of specific IgG subclasses and IgG2a + 2b/IgG1 ratio revealed a dominant T(H)1 cell response crucial for effective vaccine candidate.