On May 8, 2024, Cami Hippee, a graduate student in the Microbiology Graduate Program, effectively defended her PhD thesis entitled "Measles virus exits human airway epithelia via cell detachment pathways." She is pictured with her mentor, Patrick Sinn, PhD.
Research
Measles virus (MeV) is the most contagious human virus and yet, we do not understand how MeV transmits between hosts more effectively than other viruses. MeV is a respiratory virus and spreads primarily via respiratory aerosols; however, all respiratory viruses utilize this strategy. My thesis work investigates a series of phenomena specific to MeV that may explain the disparity between transmission of MeV and other respiratory viruses: infectious center detachment from human airway epithelia.
Previous studies uncovered that MeV is exceptionally proficient at spreading cell-cell through intercellular pores in human airway epithelia (HAE). MeV cell-cell spread occurs radially and culminates in a focus of infected cells, termed an “infectious center”. MeV is the only virus that forms infectious centers in human airway epithelia. Other viruses may spread to one or two neighboring cells, but infectious centers may contain up to 300 cells.
Here, we describe that infectious centers detach as a unit from HAE at later timepoints of infection. Detached infectious centers contain high titers of MeV and can spread virus to other cells, including those important for host-host transmission. When a person infected with MeV coughs, we suspect the aerosol may contain detached infectious centers alongside cell- free virus. MeV may be more stable within infectious centers because the cells’ plasma membranes protect the virus from host adaptive immunity and environmental conditions. We postulate infectious center detachment could help explain why MeV is so contagious as the virus may live longer on surfaces, allowing spread to more people.
Finally, we investigated how infectious center detachment is triggered and found two contributing wound healing pathways: epithelial-to-mesenchymal transition and live cell extrusion. Interestingly, MeV is not the only virus known to use these pathways to cause detachment of infected cells; however, other viruses will only extrude individual cells. This suggests detaching clumps of infected cells adds to the transmission potential of a virus, possibly by preventing desiccation or by delivering a large bolus of virus at once. Altogether, the process from infectious center formation to detachment may explain how MeV is the most contagious human virus.
Background
Cami was raised in Solon, Iowa with her parents and two older sisters. While she loved many subjects in school, she discovered her passion for science in middle school. Cami always had big questions about the world around her. The thrill of uncovering answers through the scientific method ignited a lifelong curiosity within her.
Encouraged by her family and teachers, Cami pursued her scientific interests throughout her education. In 2017, she graduated from Vassar College with a degree in Biology and a correlate in Mathematics and Statistics. Each summer during college, she returned to Iowa to participate in research at the University of Iowa. Serendipitously, Cami joined Dr. Sinn’s lab for the summer of 2015. Finding a supportive community of scientists, she returned to his lab every summer following. After graduating, Cami continued working in Dr. Sinn's lab as a research intern. Here, she gained valuable research experience and was inspired to pursue graduate studies.
During her graduate program, Cami honed her skills as a researcher and science communicator. She authored two manuscripts and contributed to three others, all while discovering her passion for sharing science with diverse audiences. She also interned with the Scientific Editing and Research Communication Core, which solidified her career aspirations in scientific communication. Cami is eager to embark on a career where she can utilize her skills in teaching, writing, editing, and even illustration.
Beyond science, Cami enjoys creating art, reading, and playing video games, often accompanied by feline companions. She cherishes spending quality time with family and friends, whether it’s enjoying delicious meals together, attending fitness classes, or laughing over board games. She has made so many great connections during graduate school and will certainly miss this time in her life.