Immune Responses to O-Specific Polysaccharide and Lipopolysaccharide of Vibrio cholerae O1 Ogawa in Adult Bangladeshi Recipients of an Oral Killed Cholera Vaccine and Comparison to Responses in Patients with Cholera

Abstract

Abstract. Protective immunity to cholera is serogroup specific, and serogrouping is defined by the O-specific polysaccharide (OSP) of lipopolysaccharide (LPS). We characterized OSP-specific immune responses in adult recipients of an oral killed cholera vaccine (OCV WC-rBS) and compared these with responses in patients with cholera caused by Vibrio cholerae O1 Ogawa. Although vaccinees developed plasma immunoglobulin G (IgG), IgM, IgA antibody and antibody secreting cell (ASC, marker of mucosal response) to Ogawa OSP and LPS 7 days after vaccination, responses were significantly lower than that which occurred after cholera. Similarly, patients recovering from cholera had detectable IgA, IgM, and IgG memory B cell (MBC) responses against OSP and LPS on Day 30 and Day 90, whereas vaccinees only developed IgG responses to OSP 30 days after the second immunization. The markedly lower ASC and MBC responses to OSP and LPS observed among vaccinees might explain, in part, the lower protection of an OCV compared with natural infection.

O-Specific Polysaccharide-Specific Memory B Cell Responses in Young Children, Older Children, and Adults Infected with Vibrio cholerae O1 Ogawa in Bangladesh

“…We have also found that OSP serum responses are much more prominent following naturally acquired disease than following vaccination with oral killed cholera vaccine, especially in young children (30,31). This may in part be due to the fact that OSP is a polysaccharide and as such is a T cell-independent antigen.…”

“…Unfortunately, protection afforded by oral killed cholera vaccines is of lower magnitude and of shorter duration in children under 5 years of age than that in older children and adults and than that afforded by naturally acquired disease in children 5 years of age and younger (22,23,31,43). We have also previously shown that vaccination with an oral killed cholera vaccine (Dukoral; whole-cell oral cholera vaccine supplemented with 1 mg/dose of recombinant nontoxic cholera toxin B subunit [CtxB]; WCrBS; Crucell, Sweden) in the youngest children is associated with a proregulatory (interleukin-10 [IL-10]) response, versus a proinflammatory (IL-17, interferon gamma, and IL-13) response seen in young children with naturally acquired cholera (47), and that OSP-specific memory B cell responses following oral killed cholera vaccination of adults are markedly blunted following vaccination compared to what occurs following naturally acquired disease (30). Whether OSP-specific How memory B cell responses targeting OSP, a T cell-independent antigen, develop in young children following naturally acquired cholera is unclear.…”

“…We added 100 l of plasma (diluted 1:50 for OSP and LPS and 1:100 for CtxB in 0.1% bovine serum albumin in phosphate-buffered saline-0.05% Tween) per well and detected responses using horseradish peroxidase-conjugated secondary antibodies to human IgG, IgA, or IgM (Jackson ImmunoResearch, West Grove, PA; 1:1,000 dilution). After incubation at 37°C and washing, we developed the plates with orthophenylene diamine (Sigma, St. Louis, MO) in 0.1 M sodium citrate buffer (pH 4.5) and 0.012% hydrogen peroxide followed by reading the plates kinetically at 450 nm for 5 min (30,39). We normalized the maximal rate of change in optical density in milli-absorbance units per minute across plates by calculating the ratio of the test sample to a standard of pooled convalescent-phase sera from previously infected cholera patients that was included on each plate.…”

“…We have also previously shown that baseline plasma IgA antibody levels and circulating IgG memory B cell (MBC) responses to V. cholerae O1 LPS correlate with protection against cholera in household contacts of cholera patients (21,29). We have recently developed the technology to isolate V. cholerae O1 OSP, and since serogroup specificity is determined by OSP, we have begun evaluating OSP responses in cholera patients (30)(31)(32)(33). We have found that OSP serum and mucosal responses occur in patients with cholera, that the OSP response correlates with vibriocidal and LPS responses, and that the vibriocidal response can be largely adsorbed away by OSP (30)(31)(32).…”

Biomarkers of Environmental Enteropathy are Positively Associated with Immune Responses to an Oral Cholera Vaccine in Bangladeshi Children

“…We quantified LPS- (prepared in house) [16] and cholera toxin B subunit- (CTB, gifts of A. M Svennerholm, Göteborg University) specific IgA, IgG and IgM antibody responses in plasma using a previously described kinetic enzyme-linked immunosorbent assay (ELISA) [14,17,18,19]. …”