Demographic, clinical and microbiological characteristics of patients.

<p>Demographic, clinical and microbiological characteristics of patients.</p

Avidity indices of LTB (A and D), CFA/I (B and E) and CS6 (C and F) specific IgA and IgG antibodies in plasma in Bangladeshi adults infected with ETEC.

<p>Columns indicate mean avidity indices, and error bars represent standard errors of the mean (SEM). An asterisk denotes a statistically significant difference (<i>P</i><0.05) from the acute stage of infection (day 2).</p

Correlation analyses^* of antibody avidity index (AI) and memory B cell (MBC) responses in patients infected with ETEC.

<p>*Spearman's test was used for correlation analyses.</p

Anti-LTB (A and D), CFA/I (B and E) and CS6 (C and F) specific IgA and IgG antibody responses in plasma in Bangladeshi adults infected with ETEC.

<p>The columns indicate mean responses and the error bars represent standard errors of the mean (SEM). An asterisk denotes a statistically significant difference (<i>P</i><0.05) from the acute stage of infection (day 2). Mean fold changes and responder frequencies compared to day 2 levels are also indicated.</p

CD38⁺CD161^loVα7.2⁺ cells are inversely associated with age and changes in MAIT cells.

<p>A) Spearman correlation of day 2 to day 7 fold changes in %MAIT cells with fold changes across the same days in i) CD161^loVα7.2⁺, and ii) CD38⁺CD161^loVα7.2⁺ cells. B) Spearman correlation of CD38⁺CD161^loVα7.2⁺ cells with age for i) healthy controls and ii) cholera patients on day 7 after presentation.</p

Class-switched antibody responses against LPS are correlated with MAIT cell responses.

<p>Antibody responses against A) LPS, and B) CtxB, of cholera patients at days 2, 7, and 30 after hospitalization, displayed as mean with standard errors. Compared with day 2, * P<0.05; ** P<0.01; *** P<0.001. Correlation of fold changes in %MAIT cells and fold changes in antibody response against C) LPS, and D) CtxB, of cholera patients.</p

Plasma and memory B cell responses targeting O-specific polysaccharide (OSP) are associated with protection against <i>Vibrio cholerae</i> O1 infection among household contacts of cholera patients in Bangladesh

<div><p>Background</p><p>The mediators of protection against cholera, a severe dehydrating illness of humans caused by <i>Vibrio cholerae</i>, are unknown. We have previously shown that plasma IgA as well as memory B IgG cells targeting lipopolysaccharide (LPS) of <i>Vibrio cholerae</i> O1 correlate with protection against <i>V</i>. <i>cholerae</i> O1 infection among household contacts of cholera patients. Protection against cholera is serogroup specific, and serogroup specificity is defined by the O-specific polysaccharide (OSP) component of LPS. Therefore, we prospectively followed household contacts of cholera patients to determine whether OSP-specific immune responses present at the time of enrollment are associated with protection against <i>V</i>. <i>cholerae</i> infection.</p><p>Methodology</p><p>In this study, we enrolled two hundred forty two household contacts of one hundred fifty index patients who were infected with <i>Vibrio cholerae</i>. We determined OSP-specific memory B cells and plasma IgA, IgG and IgM antibody responses on study entry (day 2).</p><p>Principle findings</p><p>The presence of OSP-specific plasma IgA, IgM, and IgG antibody responses on study entry were associated with a decrease in the risk of infection in household contacts (IgA, p = 0.015; IgM, p = 0.01, and IgG, p = 0.024). In addition, the presence of OSP-specific IgG memory B cell responses in peripheral blood on study entry was also associated with a decreased risk of infection (44% reduction; 95% CI: 31.1 to 99.8) in contacts. No protection was associated with cholera toxin B subunit (CtxB)-specific memory B cell responses.</p><p>Conclusion</p><p>These results suggest that immune responses that target OSP, both in plasma and memory responses, may be important in mediating protection against infection with <i>V</i>. <i>cholerae</i> O1.</p></div

Risk of infection for contacts with detectable LPS- and OSP-specific memory B cell (MBC) responses relative to those without detectable MBC.

<p>Risk of infection for contacts with detectable LPS- and OSP-specific memory B cell (MBC) responses relative to those without detectable MBC.</p

Plasma vibriocidal antibody titers upon enrollment.

<p>Bars represent geometric mean responses. <i>P</i> values for statistical significant differences between groups determined by Mann-Whitney U test.</p

Plasma and memory B cell responses targeting O-specific polysaccharide (OSP) are associated with protection against <i>Vibrio cholerae</i> O1 infection among household contacts of cholera patients in Bangladesh - Fig 3

<p><b>Plasma OSP-specific IgA, IgG and IgM antibody values (A, B and C, respectively) upon enrollment (day 2).</b> Bars represent median responses. <i>P</i> values for statistical significant differences between groups determined by Mann-Whitney U test.</p