Mechanisms of Immune Responses to Pathogens and Vaccines

<p>NON-TECHNICAL SUMMARY:<br/> Intracellular bacterial and viral pathogens (such as: Listeria monocytogenes, Mycobacterium tuberculosis, Francisella tularensis, lymphocytic choriomeningitis virus, rift valley fever virus, etc.) pose a major threat to livestock and public health. The prevention and treatment of infected animals and humans consume vast resources across the globe. This research is intended to build a detailed understanding of mechanisms regulating the quality and quantity of immune responses to these pathogens and candidate vaccine vectors. By doing so, we will aid the development of efficacious vaccines for use in livestock and humans. Ultimately, this will help alleviate the economic burden associated with these diseases. Previous work has shown that the quanitiy and quality of memory T cells, which prevent future invasions by the pathogen and form the basis
of vaccination, is regulated by the extent of their stimulation with anitgen, interleukin-2 growth factor and a variety of inflammatory signals. Researchers for this project will conduct a five-pronged approach to develop a detailed understanding of T cell-intrinsic and -extrinsic molecular and cellular factors that regulate the generation and maintainancy of memory T cells. The data researchers accumulate from the these studies is crucial for designing efficacious vaccines to prevent the threat of intracellular bacterial and viral pathogens to livestock and public health. Additionally, the data will be used to predict vaccine efficacy early after immunization, and help us identify the earliest time to boost. These studies will advance the rational development of efficacious vaccines against infectious diseases of the livestock and humans, and thereby will ease the associated economic
burden.
<p>APPROACH:<br/> We will employ transgenic mouse models to ablate regulatory T cells at distinct phases of T cell responses following infection or immunization. Phenotypic, functional and localization properties of memory cells will be assessed using routine flow cytometry and gene expression analyses. Mechanistic insight ino regulation of immune memory by regulatory T cells will be further gained using molecular supplementation studies both in vitro and in vivo. Towards understanding transcriptional regulation of immune memory, we will perform transcriptional profiling of memory- and death-fated T cells. Likewise microRNA regulation of T cell memory differentiation also will be probed by microarray analyses. Following initial profiling studies, candidate microRNA and transcription factor candidates will be tested in gene deletion studies. Epigenetic regulation of T cell
responses will be studied by measuring the methylation and acetylation status at key gene loci. In the context of acute infections and immunization with candidate vaccine vectors, we will investigate the impact of poor nutritional status (such as vitamin D deficiency, low protein diet) on primary as well as secondary immune responses. Standard criteria for assessment of T cell quantity and quality will be employed. Vitamin supplementation studies also will be performed to possibly rescue defective immune responses identified under conditions of poor nutrition. T cell proliferation will be measured in both memory-fated and death-fated T cells during early and late stages of T cell expansion as well as during memory maintenance phases using BrdU and CFSE cell labeling techniques. The role of cell-extrinsic stimuli such as IL-1, IL-2 and LAG-3 will be studied using specific gene deletion
mice and antibody mediated blockade of signals at specific time intervals after immunization or infection. Mathematical modeling of T cell expansion will be conducted to predict rates of T cell division and death, and guide biological experimentation to discern how rates and extent of cell division control immune memory development and maintenance. Genomic, proteomic, metabolomic and functional profiling of early immune responses induced by protective vaccines (smallpox, lymphocytic choriomeningitis virus vector, attenuated listeria monocytogenes vector) will be conducted to generate a "protective signature." Fidelity of these signatures will be tested in mouse models of immunization with vaccine vectors, such as adenovirus-5 and recombinant DNA, which are known not to induce protective immunity.
<p>PROGRESS: 2013/08 TO 2013/09<br/>Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Students have been trained in in vivo analysis of mouse immune responses to infections and vaccines. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? In the next reporting period, we will complete analyzing the T cell responses during murine infections of above mentioned gene knockout mice to further understand the role of specific genes and cell-types. These data will be presented at National and International conferences and possibly compiled for publication