Department of Infection and Immunity

Research Unit for Vector Biology

Associate Professor Shinya Fukumoto

Certain infectious diseases such as malaria, sleeping sickness, Japanese encephalitis, and filariasis are transmitted by arthropods. The transmission of these infectious diseases requires “vectors”. In other words, if the vector stage is cut off, infections of animals and humans can be avoided. Based on this concept, we raise the following questions: How do etiological agents behave within vectors? How do a vector and an etiological agent interact with each other? What are etiological agents to vectors in the first place? We are researching the items above in an effort to achieve the suppression of protozoan diseases by controlling the vector stage. We systematically integrate a wide range of information, from data generated by basic laboratory experiments to field research in endemic areas, as well as thoroughly analyzing unique life phenomena caused by the relationship between such etiological agents and vectors.

Research Unit for Host Defense

Professor Xuenan Xuan

The main focus of this lab is to elucidate the host defense mechanisms against protozoan diseases, and to develop medical agents and recombinant vaccines that could efficiently stimulate the host protective immunity.

Main Reserch Projects
  • Elucidation of the mechanism of hemolytic anemia caused by babesiosis.
  • Analysis of the host protective immunity against babesiosis.
  • Identification of genome-wide metabolic pathways and vaccine candidate molecules of Babesia parasites.
  • Development of molecule- targeting treatments and recombinant vaccines against babesiosis.
  • International epidemiological surveys of tick-borne protozoan diseases.
Proteomic analysis of autoimmunity agaist platelets caused by Babesia parasite infection.

Professor Yoshifumi Nishikawa

We are researching functional disorders of the central nervous system (CNS) and behavioral changes in host animals, as well as the mechanism of miscarriage or vertical transmission of protozoan infections. In addition, we are attempting to identify and analyze parasite-derived factors that control inflammatory response and immuno-suppression. Based on the results of this research, we are developing a new type of next-generation vaccine that can effectively transport a vaccine antigen to lymphoid tissues by utilizing multifunctional materials and can effectively stimulate immune cells. For practical application of our vaccine, we investigate the effects of the model vaccine based on infection models of mice and natural hosts.

Main Research Projects
  • Study on behavioral changes of host animals and CNS disorder following Toxoplasma and Neospora infection.
  • Study on immune evasion mechanisms of Toxoplasma and Neospora
  • Pathological study of malaria, toxoplasmosis, neosporosis and cryptosporidiosis
  • Vaccine development based on multifunctional materials
  • Screening of anti-parasite drug from natural products
  • Study on intestinal flora associated with bovine diarrhe
Cyst Toxoplasma in brain tissue
Comparative transcriptome using the brain tissue of a mouse infected with Toxoplasma
Aborted fetus from cow infected with Neospora

Research Unit for Functional Genomics

Professor Hiroshi Suzuki

We use developmental biotechnology to analyze the gene function of hosts and protozoa. The development of new techniques for developmental biotechnology and reproductive biotechnology is also one of our missions. In this research field, we are investigating the possibility of preventing and treating protozoan infectious diseases by modifying the hosts’ physiological condition. For example, recent research using alpha-tocopherol transfer-protein knockout mice has found that a vitamin E deficiency in the host inhibits the growth of malarial protozoa and Trypanosoma. Moreover, we utilize developmental and reproductive biology techniques to improve the breeding of assistance dogs, including guide dogs, for the purpose of contributing to society.


The nuclei of malarial protozoa infecting the red blood cells of a wild-type mouse (A).
Disturbances in the DNA of protozoa infecting the red blood cells of an α-TTP deficient mouse (B).

Assistant Professor Rika Umemiya-Shirafuji

Ticks are obligatory hematophagous arthropods and are known to be important vectors for various pathogens in vertebrates, such as Babesia and Theileria parasites. Our laboratory focuses on the molecular mechanisms underlying nutrient metabolism in unfed or fed ticks and tick oogenesis. Our aim is to contribute to the development of new methods for controlling ticks and tick-borne pathogens.

Nutrient metabolism in unfed ticks

Most hard tick species have a life span of several months or years. Their life is essentially composed of relatively short parasitic periods and long non-feeding periods, without intake of blood. This remarkable viability is important for understanding the biology and epidemiology of ticks and tick-borne pathogens.

Nutrient metabolism in fed ticks

Energy and nutrient reserves provided by digestion of a blood meal in female ticks allow the synthesis of vitellogenin (Vg), the yolk protein precursor. Synthesis and uptake of Vg are essential processes in the oogenesis of ticks.

Vector biology

Using ticks infected with parasites, we are studying the relationship between transmission of parasites and nutrient metabolism of ticks.