Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

I study viruses that infect parasites. My research theme is “The impact of persistent infection viruses on parasites and their hosts.” Traditionally, infectious disease research focuses on the “pathogen and host” one-on-one relationship, where pathogens infect hosts, including humans and other mammals. It has long been known that some viruses infect parasites that parasitize humans, but their roles were unclear and often ignored. I am interested in understanding how these viruses, like Matryoshka dolls, affect the parasites and their hosts. Essentially, I study the interactions among the virus, parasite, and host. So far, it has been revealed that parasites carrying viruses are more pathogenic to their hosts than those without viruses. Currently, I am investigating the detailed mechanisms by which these viruses contribute to the pathogenicity of parasites.

Through this research, I aim to discover new biological phenomena that could not be understood by studying a single pathogen alone and propose new methods for controlling parasites and viruses.

Yes, I focus on parasites of humans and livestock. Parasites are broadly divided into two categories: protozoa and helminths. Protozoa are single-celled and microscopic, while helminths are multicellular and can be seen with the naked eye. I study protozoa. Many protozoa cause severe symptoms, with the malaria parasite infecting red blood cells being particularly well-known. My research mainly centers on viruses that infect Leishmania, a protozoan causing issues in Africa, Southern Europe, and South America.

It has long been known that some parasites are infected with viruses, but the reason for the persistent infection has yet to be elucidated. Viruses are foreign entities for parasites, and maintaining a viral infection requires energy, which suggests that it would be better for the parasite not to carry the virus. However, some viruses have been infecting the same lineage of parasites for generations. Upon analysis, it appears that when humans or animals are infected with parasites carrying viruses, the host’s body reacts by trying to eliminate the virus rather than the parasite. This suggests that the host's body is tricked into thinking it is infected with the virus carried by the parasite rather than the parasite itself.

We are currently investigating this. We have found that parasites infected with viruses have higher pathogenicity, which means that infections become more severe. Additionally, the nature of the parasite itself seems to change when it is infected with a virus. Traditionally, treating parasitic diseases in humans and animals has targeted only the parasites. However, we hypothesize that by also targeting the viruses infecting the parasites, we may be able to control the disease better.

Parasitic infections are a significant problem worldwide for both humans and livestock. Through my research, I hope to reduce the impact of these parasitic diseases, even if just a little.

I first encountered parasitology as an undergraduate. Parasites, which have evolved to be unable to live without a host, rely on the host for essential nutrients and undergo significant morphological changes to move from one host to another. I started researching parasites because I wanted to uncover their sophisticated strategies for survival. Later, while working in a virology lab, I discovered that some parasites are infected with viruses. Now, I leverage my experience with both viruses and parasites to study viruses that infect parasites.

Since I was young, I have loved living things, keeping insects and fish, and reading illustrated books. I have loved nature and animals and often watched educational programs on NHK. Watching programs about global environmental issues and infectious disease pandemics scared me. I vaguely thought, “Can I somehow help save the Earth?” which sparked my interest in becoming a researcher. When I was in the lower grades of elementary school, my father and I kept a notebook. Each day, I would write down my questions, and when my father came home, he would write down answers or advice. This helped foster my enjoyment of learning new things. Now as an adult, I realize it must have been quite a burden for my father. (laughs)

Parasites are visible under a microscope and move, making them attractive to observe. While parasitic diseases might not be prevalent in Japan, they still cause significant problems in veterinary fields and abroad. Besides the biological fascination, the ability to contribute to human and animal health is also a significant allure. Additionally, I find great fulfillment in conducting field research, such as visiting livestock farms to survey or collecting ticks in grasslands to investigate their pathogens. Field research is essential for my studies, and being able to engage in it is one of the most exciting aspects of my work.

Yes, I do. As an undergraduate, I joined the animal science course in the Faculty of Agriculture. Most of the labs in that course focused on livestock production, but I joined a lab that researched infectious diseases. Initially, it wasn't because I wanted to study infectious diseases; instead, I was attracted to the lab's location. This lab was uniquely situated on a farm in a rural area an hour and a half away from the university. I thought it would be wonderful to spend a few years conducting research away from the city, surrounded by nature, so I joined that lab. (laughs) There, I discovered how fascinating the study of living organisms, such as parasites, could be, and I've continued with that theme ever since. I love research that allows me to interact with living things in a natural environment.

My mentor, Professor Kentaro Kato from the Graduate School of Agricultural Science at Tohoku University, introduced me to FRIS. Many enthusiastic researchers of a similar age are working hard, and they are the kind of people I want to become, so I decided to apply. I had never really had the opportunity to talk with people close to me regarding age and circumstances, so joining FRIS was eye-opening. I was particularly impressed by everyone here's independence and forward-thinking plans. I have access to research equipment through my mentor's lab, and I am fortunate to have a favorable environment with sufficient research funding. However, seeing my colleagues allocate budgets, purchase equipment, and prepare for the future when they become independent in a few years has been very stimulating for me as a researcher.

The open and lively atmosphere where discussions are actively conducted is very appealing. The director is kind, and there are ample support systems to enhance a researcher’s career. There are programs for financial assistance for studying abroad and systems that allow collaboration with students, helping researchers gain the necessary experience to become independent. Typically, students are not assigned to FRIS, but researchers who wish to work with students can utilize the FRIS URO system to hire students individually. This allows for collaborative research and mentorship. I am currently using this system to conduct research with a second-year undergraduate student, and their fresh perspective is quite valuable.

Additionally, I am preparing for collaborative research with other FRIS members. For instance, I aim to elucidate the molecular-level phenomena occurring within organisms with Assistant Professor Shingo Kanemura (biochemistry, biophysics, virology), who studies structural biochemistry. I am also discussing with Assistant Professor Izumi Matsudaira (neuroscience, developmental psychology, biological psychiatry) the potential of investigating infectious disease changes using MRI brain imaging. FRIS provides an environment where we can have active and casual discussions.

Since joining FRIS, I have become increasingly determined to become an independent researcher, both in terms of research and funding. I still want to gain various experiences at FRIS and aspire to be a researcher who values interdisciplinary research. Additionally, I want to remember that issues occur in the field and not confine my research to the laboratory. I aim to be a researcher who values fieldwork and the application of research in real-world settings. Above all, I want to stay true to my initial motivation for becoming a researcher—to contribute, even a little, to saving the Earth.

(Interview conducted in May 2024)