Horiguchi Lab／Division of Infectious Disease  Department of Molecular Bacteriology

Some pathogenic bacteria cause specific disease symptoms including flaccid/spastic paralyses, paroxysmal coughing, skin exfoliation, and osteogenesis imperfecta, besides general symptoms such as fever and inflammation. Our major questions are as to how these specific symptoms appear in response to bacterial infections or what kinds of bacterial virulence factors are involved in them. We hope that we will understand the nature of bacterial infections by answering these questions.

To understand the mechanism of infection

Bordetella pertussis, which is one of our research subjects is a representative pathogenic bacteria of Bordetella and causes whooping cough. In addition to B. pertussis, B. parapertussis and B. bronchiseptica are categorized in the genus Bordetella. Although these pathogenic organisms share homologous virulence factors and commonly cause respiratory infections with characteristic coughing, their host specificities and the course of disease manifestation are quite different: B. pertussis is a strict human pathogen causing the acute disease whereas B. bronchiseptica infects a wide range of mammals and causes chronic infections. We are trying to understand what determines host specificities and distinct disease manifestations in Bordetella infections. Understanding the molecular mechanism by which the bacteria cause coughing in hosts is our another goal of the Bordetella research. 

Analyzing the structure-function relationship of bacterial protein toxins.

Bacterial protein toxins cause a variety of specific symptoms manifested in bacterial infections. Many bacterial protein toxins are essentially multifunctional biomolecules, which travel in a host body, bind to target molecules or cells, and modify target molecules with high specificity. Some bacterial toxins are known as the most poisonous substances on the earth. We are analyzing the structure-function relationship of  these bacterial protein toxins to understand how they exert such powerful toxicities on target cells and intoxicated animals. We believe that these results should give an insight into the mechanism causing specific symptoms observed in bacterial infections.

 To achieve the above-mentioned goals, we are conducting the research work by using every experimental technique based on bacteriology, molecular and cellular biology, biochemistry, medical and veterinary science.