O-Specific Polysaccharide Responses and Cholera

Massachusetts General Hospital, Boston MA

Investigators

Linked publications & trials

Abstract

PROJECT SUMMARY (See instructions): Cholera is a severe dehydrating illness of humans. It is endemic in over 50 countries and causes 3 to 5 million cases a year, resulting in approximately 100,000 deaths. Currently available cholera vaccines are poorly immunogenic in children under the age of 5 years, and often do not induce robust long-term memory responses in immunologically na"fve populations. Antibodies targeting O-specific polysaccharide (OSP) are associated with protection against cholera. We here propose to extend our highly productive ongoing R37 international program that is defining OSP-specific immune responses in humans with cholera, including how OSP-specific antibodies protect. Such knowledge would be high impact and would directly inform cholera control efforts, including advancement of next generation cholera vaccines. In Aim #1, we will continue to define mechanisms of protection against V. cholerae afforded by OSP-specific responses using human isogenic OSP-specific monoclonal antibodies and human enteroid models. In Aim #2, we will define single cell and population responses at the mucosal surface in mucosal tissue samples obtained through endoscopic biopsy of cholera patients using single-nuclei sequencing (snRNA-seq) with T cell receptor (TCR) and B cell receptor (BCR) sequencing. In Aim #3, we will (a) define the OSP-specific response in intestinal tissue and luminal contents of patients recovering from cholera in Bangladesh, (b) deeply interrogate peripheral blood antigen-specific and functional immune responses using a system serologybased approach, and correlate these responses to responses directly assessed at the mucosal surface [in (3a)], and (c) assess the validity of whether such peripheral markers predict protection against cholera in our ongoing household contact study in Bangladesh. This extension builds upon our fully-approved and ongoing human, animal and bench-top studies, protocols and samplings, including at the International Centre for Diarrhoeal Disease Research-Bangladesh (icddr.b); no new additions are proposed. One Page Project Summary/Abstract of the Research Plan for the R37 Extension This is an R37 extension request that proposes to continue to advance our understanding of antibodies targeting O-specific polysaccharide (OSP) of Vibrio cholerae, the cause of cholera. This extension builds upon our current proposal and does not involve expansion of efforts beyond the approved Scope of Work/Efforts. Our current scope focuses on understanding OSP-specific responses during cholera and includes vertebrae and human subjects work, and our extension continues these ongoing efforts (no new animal or human subject efforts other than period extension). Our current project period has been quite successful; we are meeting all of our current Specific Aims and our efforts have resulted in 22 Open Access peer-reviewed publications in the current period-to-date (2020-2023, to date). In our proposed extension to R37106878, we propose continuation of three specific aims. In Aim #1, we will continue to define mechanisms of protection against V. cholerae afforded by OSP-specific responses; this will include assessing isogenic clones of OSP-specific human lgA, lgM and lgG in our human intestinal organoid model, assessing impact on motility, toxin delivery, and bacterial genomic gene expression; and using a complement deficient mouse model to directly assess if vibriocidal activity of OSP-specific antibodies is required for mediating protection at mucosal surfaces. In Aim #2, we propose to define single cell and population responses at the mucosal surface in mucosal tissue samples obtained through endoscopic biopsy of cholera patients using single-nuclei sequencing (snRNA-seq) with T cell receptor (TCR) and B cell receptor (BCR) sequencing, building upon our previous bulk-cell transcriptional and proteomic analyses. In Aim #3, we propose to (a) define the OSP-specific response in intestinal tissue and luminal contents of patients recovering from cholera in Bangladesh, (b) deeply interrogate peripheral blood antigen-specific and functional immune responses using a system serology-based approach and correlate these responses to immune responses directly assessed at the mucosal surface in cholera patients in Bangladesh [in (a)]. Once we identify peripheral profiles associated with high level and durable mucosal OSP-specific responses, we will (c) assess the validity of whether such peripheral markers predict protection against cholera in our ongoing household contact study in Bangladesh. This extension builds upon our fully-approved and ongoing studies, protocols and samplings, including at the International Centre for Diarrhoeal Disease Research-Bangladesh (icddr.b); no new additions are requested. SPECIFIC AIM #1.A: Assess impact of human monoclonal J.gQ OSP-specific antibodies in a human intestinal organoid model. SPECIFIC AIM #1.B: Assess impact of isogenic human monoclonal OSP-specific 19.M and lgA antibodies in the human enteroid model. SPECIFIC AIM #1.C: Use complement-deficient mice to assess whether protection afforded by anti-OSP antibodies mechanistically involves vibriocidal functional activity at the intestinal surface. SPECIFIC AIM #2.A: Define duodenal tissue cell states during acute and convalescent V. cholerae infection via application of single-nuclei sequencing (snRNA-seq) with T cell receptor (TCR) and B cell receptor (BCR) sequencing. SPECIFIC AIM #2.B: Identify immune cell signatures in blood that track with V. cholerae infection via application of single-cell RNA-seq (scRNA-seq) with CITE-seq (cellular indexing of transcriptomes and epitopes) with TCR and BCR sequencing. SPECIFIC AIM #3.A: Define OSP-specific responses in intestinal tissue and luminal contents of patients recovering from cholera in Bangladesh. SPECIFIC AIM #3.B: Deeply interrogate peripheral blood OSP-specific and other-specific and functional immune responses using a system serology-based approach and correlate these responses to the directly assessed immune responses at the mucosal surface in cholera patients in Bangladesh. SPECIFIC AIM #3.C: Assess the validity of whether peripheral markers identified in Aim 3.B predict protection against cholera in our ongoing household contact study in Bangladesh. If successful, our work would define the contribution and mechanism of OSP-specific antibodies in affording protection against a pathogen of global significance, define at the single cell and population level the intestinal response during cholera, would allow us to define OSP-specific mucosal responses following cholera, and would identify peripheral markers associated with such mucosa I OSP-specific responses. Our work would be of high impact and would significantly advance the field by markedly improving our understanding of OSP-responses during cholera. Our extension would build upon our significant progress-to-date.