Comparison of O-specific polysaccharide responses in patients following infection with
Vibrio cholerae
O139 versus vaccination with a bivalent (O1/O139) oral killed cholera vaccine in Bangladesh
Authors: Kaisar M. Hasanul , Kelly Meagan , Kamruzzaman Mohammad , Bhuiyan Taufiqur R. , Chowdhury Fahima , Khan Ashraful Islam , LaRocque Regina C. , Calderwood Stephen B. , Harris Jason B. , Charles Richelle C. , Čížová Alžbeta , Mečárová Jana , Korcová Jana , Bystrický Slavomír , Kováč Pavol , Xu Peng , Qadri Firdausi , Ryan Edward T. 
Published: August 2023

Cholera caused by
Vibrio cholerae
O139 emerged in the early 1990s and spread rapidly to 11 Asian countries before receding for unclear reasons. Protection against cholera is serogroup-specific, which is defined by the O-specific polysaccharide (OSP) component of lipopolysaccharide (LPS).
V. cholerae
O139 also expresses the OSP-capsule. We, therefore, assessed antibody responses targeting
V. cholerae
O139 OSP, LPS, capsule, and vibriocidal responses in patients in Bangladesh with cholera caused by
V. cholerae
O139. We compared these responses to those of age-gender-blood group-matched recipients of the bivalent oral cholera vaccine (OCV O1/O139). We found prominent OSP, LPS, and vibriocidal responses in patients, with a high correlation between these responses. OSP responses primarily targeted the terminal tetrasaccharide of OSP. Vaccinees developed OSP, LPS, and vibriocidal antibody responses, but of significantly lower magnitude and responder frequency (RF) than matched patients. We separately analyzed responses in pediatric vaccinees born after
V. cholerae
O139 had receded in Bangladesh. We found that OSP responses were boosted in children who had previously received a single dose of bivalent OCV 3 yr previously but not in vaccinated immunologically naïve children. Our results suggest that OSP-specific responses occur during cholera caused by
V. cholerae
O139 despite the presence of capsules, that vaccination with bivalent OCV is poorly immunogenic in the short term in immunologically naïve individuals, but that OSP-specific immune responses can be primed by previous exposure, although whether such responses can protect against O139 cholera is uncertain.

IMPORTANCE

Cholera is a severe dehydrating illness in humans caused by
Vibrio cholerae
serogroups O1 or O139. Protection against cholera is serogroup-specific, which is defined by the O-specific polysaccharide (OSP) of
V. cholerae
LPS. Yet, little is known about immunity to O139 OSP. In this study, we assessed immune responses targeting OSP in patients from an endemic region with cholera caused by
V. cholerae
O139. We compared these responses to those of the age-gender-blood group-matched recipients of the bivalent oral cholera vaccine. Our results suggest that OSP-specific responses occur during cholera caused by
V. cholerae
O139 and that the OSP responses primarily target the terminal tetrasaccharide of OSP. Our results further suggest that vaccination with the bivalent vaccine is poorly immunogenic in the short term for inducing O139-specific OSP responses in immunologically naïve individuals, but OSP-specific immune responses can be primed by previous exposure or vaccination.