Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Feb 6;8(2):e2683.
doi: 10.1371/journal.pntd.0002683. eCollection 2014 Feb.

Evaluation in mice of a conjugate vaccine for cholera made from Vibrio cholerae O1 (Ogawa) O-specific polysaccharide

Mohammad Murshid Alam  1 , Megan Kelly Bufano  2 , Peng Xu  3 , Anuj Kalsy  2 , Y Yu  2 , Y Wu Freeman  2 , Tania Sultana  1 , Md Rasheduzzaman Rashu  1 , Ishaan Desai  2 , Grace Eckhoff  2 , Daniel T Leung  4 , Richelle C Charles  5 , Regina C LaRocque  5 , Jason B Harris  6 , John D Clements  7 , Stephen B Calderwood  8 , Firdausi Qadri  9 , W F Vann  10 , Pavol Kováč  3 , Edward T Ryan  11
Affiliations

Evaluation in mice of a conjugate vaccine for cholera made from Vibrio cholerae O1 (Ogawa) O-specific polysaccharide

Mohammad Murshid Alam et al. PLoS Negl Trop Dis. .

Abstract

Background: Protective immunity against cholera is serogroup specific. Serogroup specificity in Vibrio cholerae is determined by the O-specific polysaccharide (OSP) of lipopolysaccharide (LPS). Generally, polysaccharides are poorly immunogenic, especially in young children.

Methodology: Here we report the evaluation in mice of a conjugate vaccine for cholera (OSP:TThc) made from V. cholerae O1 Ogawa O-Specific Polysaccharide-core (OSP) and recombinant tetanus toxoid heavy chain fragment (TThc). We immunized mice intramuscularly on days 0, 21, and 42 with OSP:TThc or OSP only, with or without dmLT, a non-toxigenic immunoadjuvant derived from heat labile toxin of Escherichia coli.

Principal findings: We detected significant serum IgG antibody responses targeting OSP following a single immunization in mice receiving OSP:TThc with or without adjuvant. Anti-LPS IgG responses were detected following a second immunization in these cohorts. No anti-OSP or anti-LPS IgG responses were detected at any time in animals receiving un-conjugated OSP with or without immunoadjuvant, and in animals receiving immunoadjuvant alone. Responses were highest following immunization with adjuvant. Serum anti-OSP IgM responses were detected in mice receiving OSP:TThc with or without immunoadjuvant, and in mice receiving unconjugated OSP. Serum anti-LPS IgM and vibriocidal responses were detected in all vaccine cohorts except in mice receiving immunoadjuvant alone. No significant IgA anti-OSP or anti-LPS responses developed in any group. Administration of OSP:TThc and adjuvant also induced memory B cell responses targeting OSP and resulted in 95% protective efficacy in a mouse lethality cholera challenge model.

Conclusion: We describe a protectively immunogenic cholera conjugate in mice. Development of a cholera conjugate vaccine could assist in inducing long-term protective immunity, especially in young children who respond poorly to polysaccharide antigens.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Structure of Ogawa OSP:TThc conjugate.
6.4 moles OSP per mole conjugate. TThc = recombinant tetanus toxoid heavy chain fragment.
Figure 2
Figure 2. Serum anti-OSP-BSA and anti-LPS IgG antibody responses in mice intramuscularly immunized with OSP:TThc (with dmLT), OSP (with dmLT), OSP:TThc (no dmLT), OSP (no dmLT), or dmLT alone.
Mean and standard error of the mean are reported for each group. An asterisk denotes a statistically significant difference (P<0.05) from baseline (day 0) titer. Responder frequencies are also listed. #, statistically significant difference among the compared cohorts (P<0.05).
Figure 3
Figure 3. Serum anti-OSP-BSA and anti-LPS IgM antibody responses in mice intramuscularly immunized with OSP:TThc (with dmLT), OSP (with dmLT), OSP:TThc (no dmLT), OSP (no dmLT), or dmLT alone.
Mean and standard error of the mean are reported for each group. An asterisk denotes a statistically significant difference (P<0.05) from baseline (day 0) titer. Responder frequencies are also listed. #, statistically significant difference among the compared cohorts (P<0.05).
Figure 4
Figure 4. Vibriocidal responses in mice intramuscularly immunized with OSP:TThc (with dmLT), OSP (with dmLT), OSP:TThc (no dmLT), OSP (no dmLT), or dmLT alone.
The columns indicate mean reciprocal end titers, and error bars represent the standard errors of the mean. An asterisk denotes a statistically significant difference (P<0.05) from baseline (day 0) titer. Responder frequencies are also listed. #, statistically significant difference among the vaccine cohorts (P<0.05).
Figure 5
Figure 5. Survival likelihood of neonatal CD-1 mice following oral challenge with wild-type O1 Ogawa V. cholerae O395.
Three- to five-day-old pups (cohort size 20) were orally gavaged with 50 µl of a preparation containing 2.3×109 CFU of wild type V. cholerae O395 mixed with a 1∶250 dilution of pooled day 56 serum from mice intramuscularly immunized with conjugate vaccine (OSP:TThc) and immunoadjuvantative dmLT, or dmLT alone. Survival curves were compared by log rank testing.
See this image and copyright information in PMC

References

    1. Harris AM, Chowdhury F, Begum YA, Khan AI, Faruque AS, et al. (2008) Shifting prevalence of major diarrheal pathogens in patients seeking hospital care during floods in 1998, 2004, and 2007 in Dhaka, Bangladesh. Am J Trop Med Hyg 79: 708–714. - PMC - PubMed
    1. Harris JB, LaRocque RC, Qadri F, Ryan ET, Calderwood SB (2012) Cholera. Lancet 379: 2466–2476. - PMC - PubMed
    1. Hisatsune K, Kondo S, Isshiki Y, Iguchi T, Kawamata Y, et al. (1993) O-antigenic lipopolysaccharide of Vibrio cholerae O139 Bengal, a new epidemic strain for recent cholera in the Indian subcontinent. Biochem Biophys Res Commun 196: 1309–1315. - PubMed
    1. Ito T, Higuchi T, Hirobe M, Hiramatsu K, Yokota T (1994) Identification of a novel sugar, 4-amino-4,6-dideoxy-2-O-methylmannose in the lipopolysaccharide of Vibrio cholerae O1 serotype Ogawa. Carbohydr Res 256: 113–128. - PubMed
    1. Wang J, Villeneuve S, Zhang J, Lei P, Miller CE, et al. (1998) On the antigenic determinants of the lipopolysaccharides of Vibrio cholerae O:1, serotypes Ogawa and Inaba. J Biol Chem 273: 2777–2783. - PubMed

Publication types

MeSH terms