Chosen Area of Study and Research Issue of Interest: Listeria monocytogenes (Lm) causes a mild infection in healthy adults but is associated with serious pregnancy complications, including miscarriage, stillbirth, preterm birth, neonatal sepsis and meningitis. However, the effect and mechanism of Lm pathogenesis during pregnancy at the maternal-fetal interface and impact on the host microbiome are not understood. Emerging studies have found connections between overall health and patient microbial diversity, which may link causation for susceptibility to disease and inflammation. To adapt this concept to a non-human primate model, current 16S bacterial rRNA sequencing techniques will be utilized to define the changes in microbial diversity in response to listeriosis in pregnancy. This study has the additional potential to advance our understanding of how Lm can cross the maternal-fetal interface to infect the fetus.
How The Proposed Research Relates To Society As A Whole: During pregnancy many mothers are warned of the importance of food safety due to their immunocompromised state. However, during pregnancy the fetus is still in development, and thus its immune system is not yet full enabled to ward off infectious microbes. Due to this, the FDA has recommended guidelines specifically for preventing foodborne illness during pregnancy. The FDA also recognizes the higher risk of pregnant women and their children for developing illnesses associated with L. monocytogenes and Toxoplasma gondii as well as listeriosis causing miscarriage, premature delivery, and sickness or death of the fetus. The impact on reproductive health and repercussions of this disease implore the development of understanding the pathogenesis of L. monocytogenes.
Suitability of Chosen Institution- Support & Resources: The University of Wisconsin, Madison is an ideal location for conducting such a study. It supports the Wisconsin National Primate Research Center (WNPRC) which houses extensive animal and research resources to provide investigators with tools to work with nonhuman primates. My mentor Dr. Golos currently holds NIH funding to conduct studies with Lm in pregnant nonhuman primates. UW-Madison is a consistently top-ranking research institution which provides its students with many resources, including research cores, resources, and services with facilities crucial for developing new techniques and optimizing my research. Furthermore, graduate programs at UW-Madison are unmatched in flexibility and collaboration. Faculty members have appointments within multiple departments (e.g., key collaborators in Listeria biology (J.D. Sauer) and microbiome research (Federico Rey) are in Medical Microbiology and Immunology, Chuck Czuprynski is in Pathobiological Sciences (Veterinary School) and Director of the Food Research Institute, and students participate in a unique environment in which my passions for bacteriology, endocrinology, and translational research can thrive.
Relevancy of Courses and Proposed Plan of Study: My program, Cellular & Molecular Pathology, is housed within the School of Medicine & Public Health, and provides the opportunity to work closely with physicians in a clinical setting. The foundational courses required for my program include a Histopathology multiple semester series, which is an expansive kinesthetic-based course with components including tissue slide analysis and diagnosis, as well as anatomic pathology through autopsy-based learning. Electives include Research Ethics, Biomedical Statistics, Population Epidemiology, and Pathologic & Infectious Microbes. I also attend Medical Rounds with the Clinical Microbiology and Infectious Disease departments at the hospital, exposing me to different types of pathogens and complications within an educational setting, unlike any traditional course.
Research Methods and Theoretical Framework: We will base this study on the recent report of Wolfe et al (mBio, 2017). Pregnant cynomolgus macaques (Macaca fascicularis) will receive an intragastric dose of Lm during the first trimester of gestation. This strain of L. monocytogenes was isolated from a human abortion cluster. Inoculated dams will be monitored by abdominal ultrasound and maternal bacteremia and fecal shedding will be monitored daily for 14 days and twice weekly thereafter. Fetal loss will prompt the surgical collection of maternal reproductive tissues and fetal tissues. The human placenta has been reported to harbor a unique microbiome (Aagaard et al, Sci Trans Med 2014). However neither the placental nor the decidual microbiome have been assessed in nonhuman primates or in pregnancy listeriosis. Tissue and fecal samples 16S rRNA will be sequenced(Illumina Next-Gen Sequencing) and sequence data will be examined with the Qiime 2 CLI open source program and associated packages to ascertain diversity and relative abundance of each microbiota through the varying stages of infection. We hypothesize that through comparisons of microbial diversity and abundance of pregnancy pre- and post- L. monocytogenes infection that a distinct alteration in microflora will be observed, with implications for microbiome alterations in response to infection during pregnancy.