Richard Malley, United States of America
Author Of 2 Presentations
USE OF PNEUMOCOCCAL TRANSCRIPTOMICS FROM MURINE AND HUMAN SAMPLES TO IDENTIFY NEW PROTEIN ANTIGEN VACCINE CANDIDATES (ID 1026)
- Alan Basset,
- Emma C. Wall, United Kingdom
- Elena Mitsi, United Kingdom
- Yingjie Lu, United States of America
- Raecliffe Daly,
- Anna Muse,
- Jose Alfonso Guerra-Assuncao,
- Chloe Deshusses,
- David G Lallo,
- Brigit Denis,
- Robert S. Heyderman, United Kingdom
- Jeremy Brown, United Kingdom
- Daniela M Ferreira,
- Richard Malley, United States of America
Abstract
Background
Conjugate vaccines successfully target specific serotypes but also lead to serotype replacement. Alternative strategies include bacterial proteins. Selection of protein antigens would benefit from knowledge of those most abundantly expressed during stages of human pneumococcal pathogenesis. Furthermore, vaccine protein candidates must also be expressed in mice for testing of candidates.
Methods
We designed a Nanostring codeset and analyzed 200 genes encoding for bacterial surface-exposed proteins. We evaluated transcriptomic expression in mouse colonization, pneumonia and sepsis models, as well as clinical CSF samples and human controlled infection.
Results
The 30 genes most highly expressed in each system (mouse model, human samples) were identified. There was excellent correlation between mouse colonization, pneumonia and blood specimens (R>0.85). Correlations between human colonization and meningitis were moderate (R=0.56), as were those between mouse and human transcriptomic profiles. We identified several genes highly expressed in all mouse and human conditions. Two in particular encoded for proteins that we show conferred protection against colonization and induced opsonic antibodies.
Conclusions
We present a novel approach to identify putative protective pneumococcal antigens, based on transcriptomic analyses of pneumococcal RNA harvested in different conditions. We identified two novel potential candidates, which also highlights the utility of studying pneumococcal gene expression from human samples.
THE ROLE OF CARRIER-SPECIFIC T-HELPER CELLS IN FACILITATING PRIMING AND BOOST/RECALL OF ANTIBODY RESPONSE TO POLYSACCHARIDE ANTIGEN (ID 1022)
Abstract
Background
Coupling polysaccharides to protein-carriers enables generation of robust anti-polysaccharide response in a T-dependent manner. One mechanism is via engagement of polysaccharide-specific T-helper cells; it is unclear if carrier-specific T-helper cells (Tcarrier) play any role. We study the role of Tcarrier in priming and boost/recall of antibody response.
Methods
Rag1-/- mice were adoptively transferred with B cells from naïve mice or mice primed with 5-valent Multiple Antigen Presenting System (MAPS) PS-protein vaccine, with or without CD4+ T cells from naïve or carrier-primed mice, prior vaccination with 5-valent MAPS. Serum anti-polysaccharide IgG was compared between groups pre- and post-vaccination. Separately, wild-type mice were primed with type4-pneumolysoid MAPS and exposed to heat-killed wild-type or pneumolysin-/- type4 pneumococci for comparison of recalled anti-type4 polysaccharide response.
Results
For 3/5, and 4/5 polysaccharides, carrier-primed T cells, compared to unprimed T cells, enhanced vaccine-induced anti-polysaccharide IgG production by naïve B cells (priming) or memory B cells (recall), respectively. Priming mice with type4-pneumolysoid MAPS vaccine resulted in significantly higher recalled anti-type4 polysaccharide IgG after exposure to a pneumolysin-producing vs. pneumolysin-deficient strain.
Conclusions
Tcarrier facilitates priming and boosting of anti-polysaccharide response. Using pneumococcal proteins as vaccine carriers may lead to higher antibody level recall during active pneumococcal infection or colonization.