LAUSR

A glycoconjugate (dLPS‐CBSA) from hydrazine‐detoxified lipopolysaccharide (LPS) of Vibrio cholerae O139 and BSA was used for immunization of BALB/c mice. The immunogenicity (concentration of induced IgG antibodies) of the conjugate was determined by enzyme‐linked immunosorbent assay. The highest level of LPS‐specific IgGs was found in sera collected 2 weeks after the third immunization. Both IgM and IgG antibodies present in the anti‐V. cholerae O139‐specific sera showed long‐lasting vibriocidal activity. The glycoconjugate also stimulated production of IL‐4, IL‐6, IFNγ, TNFα and IL‐10. Immunization with the conjugate induced significant production of both Th1 and Th2 cytokine sets, indicating balanced Th1/Th2 immune response polarization. The quantitative analysis of total and LPS‐specific IgM and IgG antibodies production by B lymphocytes (from both the spleen and the bone marrow) was performed by ELISPOT assay. From the analysis of antibodies produced directly by B lymphocytes in the bone marrow (of dLPS‐CBSA immunized mice), we were able to identify the IgM‐IgG switch in the antibodies produced.