Allison Christiaansen defends PhD thesis

Thursday, April 14, 2016

Allison Christiaansen successfully defended her thesis on Thursday, April 14, 2016. Her dissertation is titled, “T Cell Regulation of Acute and Chronic Viral Infection.” She is pictured with her mentor, Dr. Steven Varga.  

Development of new vaccines and treatments against infectious disease requires an in-depth understanding of how the immune system is regulated. In some infections, an individual’s own immune system causes more damage to the individual than the pathogen itself. My thesis focuses on understanding the regulatory mechanisms of both CD4 and CD8 T cells during viral infection.

During respiratory syncytial virus (RSV), the leading cause of respiratory infection in infants, severe disease is mediated by an excessive immune response. I found that RSV infection induces a robust immune response that is not associated with an elevated regulatory T cell (Treg) response in hospitalized infants. Thus, lack of immune regulation by Tregs may contribute to disease severity in RSV-infected infants. Furthermore, chronic viral infections, such as human immunodeficiency virus (HIV), result from the inability of the immune system to eliminate the virus from the infected individual. The immune system’s inability to eradicate the invading pathogen is partially due to excessive regulation of the T cell response. My project investigates the role of host genetic diversity on the T cell response during chronic viral infection in a murine model. I found that increasing the major histocompatibility complex (MHC) diversity resulted in enhanced viral control in two mouse genetic backgrounds. Thus, induction of a broader T cell response was associated with enhanced viral control. I also found that the T helper 1 subset of CD4 T cells are associated with reduced suppression of the CD8 T cell response and enhanced viral control. Thus, viral infections require a balance between immune-mediated viral clearance and immune-mediated disease.

About Allison

Alli was born and raised in Appleton, WI, to Ellen and Bob Christiaansen. Having two older brothers each with a masters degree in architecture, going into college Alli knew she both had to attain a higher degree than her brothers and could not become an architect. With this in mind, she started at St. Olaf College as a biology major. During her sophomore year, she took a microbiology class that triggered her interest in virology. The following summer she gained her first research experience working at the University of Wisconsin-La Crosse creating mutant strains of human parainfluenza virus III. This first exposure to molecular biology techniques and infectious disease had her set on understanding how a microscopic virus could completely take over the host cells machinery to perform its evil deeds. Following a short detour studying the heritability of turtle sex ratios during her junior year of college, that is exactly what she did. The summer after her junior year, Alli set off for Argentina to work on dengue virus replication as a part of the HHMI Initiative for Colleges. Then, the summer after graduating from college, Alli was first introduced to immunology while working on the innate immune response to rotavirus infection at the NIH. This began her gradual transition from an interest in basic virology research to viral immunology.

Alli’s interest in understanding how a virus works and desire to surpass her brothers led her to pursue a PhD at the University of Iowa. Alli joined Steven Varga’s lab in 2011 and was soon exposed to the exciting world of T cell biology. Under the guidance and constant teasing from her many wonderful lab mates she worked her way through a variety of projects utilizing mouse models or human samples to understand the T cell response following Leishmania vaccination as well as RSV and LCMV infections. She had the opportunity to travel all over the country to present her research at the International Respiratory Syncytial Virus Symposium, two American Association of Immunology meetings, two Keystone meetings as well as several regional conferences. In her spare time, Alli enjoys traveling, playing tennis and volleyball, and spending time with friends and family. She hopes to pursue a postdoctoral fellowship in industry to translate her understanding of T cell biology into therapeutic and vaccine research.