Participant: PROMISE AGEP Research Symposium, 2014.
Bre-Onna DeLaine, Doctoral Candidate
Department: Molecular Medicine Program
Institution: University of Maryland, Baltimore (Center for Vaccine Development)
Profiling in vitro Host Response to Shigella Vaccine Candidates
Each year, Shigella causes approximately 150 million shigellosis cases of severe diarrhea and 1 million deaths worldwide. Shigellaflexneri is the most prevalent endemic strain in developing nations. While several candidates are under development, there is currently no licensed vaccine available against Shigella. CVD 1208S, a live, oral attenuated S.flexneri vaccine, is currently in Phase II clinical trials. We are using in vitro methods to profile the host intestinal cell response to wild type S. flexneri versus CVD 1208S to identify characteristic patterns of a safe and immunogenic vaccine. We investigated the use of intestinal cells in monolayers and 3D organoid models. Host cell responses, including gene expression and cytokine secretion, were quantified following infection with each strain. We also quantified bacterial invasion and intracellular replication to show that CVD 1208S is unable to survive and replicate with the efficiency of wild type Shigella. Using ELISAs, we found an early induction of IL-8 and CXCL-1 in cells infected with both wild type and CVD1208S but the vaccine induced responses decreased over subsequent time points as intracellular replication decreased. Cellular responses to Shigella infection were also measured by quantitative RT PCR with genes associated with Shigella induced immune response. Based on quantitative RT-PCR, cytokine transcript levels are highest within 2 hours following initial invasion and transcripts decrease over the course of 12 hours. To date, we have determined that CVD 1208S is able to induce cytokine secretion at similar levels to wild type Shigella during initial invasion, correlating with immune activation.
Bre-Onna DeLaine grew up in New Jersey and began her science training at the Academy of Allied Health and Science. Following her high school graduation in 2007, she became a Richmond Scholar at the University of Richmond where she studied Biology and Medical Humanities. At the University of Richmond, Bre-Onna spent four years researching the phylogenetics of the sea sponge under the guidance of Dr. April Hill. Bre-Onna’s interest in research and infectious diseases grew while she studied public health in a rural district of Cusco, Peru for a summer in 2009. After graduating with her Bachelor’s Degree in 2011, Bre-Onna started her graduate work at the University of Maryland, Baltimore in the Molecular Medicine program. Now, she is enjoying her time working with Dr. Eileen Barry at the University of Maryland School of Medicine Center for Vaccine Development.
GENERAL SUMMARY OF GRADUATE RESEARCH
The bacterial pathogen Shigella is one of the leading causes of severe diarrhea in travelers, military personnel and, most significantly, young children in the developing world. Our lab has created several vaccine candidates against the most prevalent Shigella serotypes and one, CVD 1208S, was successful during phase I clinical trials. My research focuses on the initial intestinal cell responses to wild type Shigella and our vaccine candidates to determine how these responses can be used to predict the viability of a vaccine candidate at pre-clinical stages of development. Using a variety of cell culture systems, ELISAs, qRT PCR, and RNA sequencing, we are gaining a better understanding of these responses lead to downstream immune activation. RNA sequencing has already revealed upregulation of 1,100 genes in host cells after inoculation with the wild type Shigella and CVD 1208S. One hundred and forty four of these genes are significantly higher in wild type infected cells than vaccine infected cells and future experiments will involve validating these results. The whole transcriptome results are guiding our effort to investigate the mechanisms of differential host responses that correlate with vaccine success.
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