OKAMURA Masashi Professor

ThemeElucidating host-specific pathogenesis and understanding pathogen-host co-evolution for control of infectious diseases

My DreamGlobal food safety and stable food supply based on control of infectious diseases in animals
Field Microbiology, Infectious Diseases, Zoonoses, Molecular Bacteriology
Keyword Salmonella, Genome, Host specificity, Chicken, Bovine, Horse


Salmonella are classified into as many as 2,700 serovars according to the combination their somatic and flagellar antigens. Many of the pathogenic serovars cause diarrhea and other gastrointestinal symptoms in a variety of animals (food poisoning in humans). On the other hand, only a few serotypes (less than 10) cause septicemia in specific animals, leading to death. However, the mechanism that causes this strong host-specific virulence has not yet been elucidated. We have identified 50 antigens that are expressed by serovar Gallinarum (fowl typhoid) in infected chickens. We have also used mutant strains lacking the genes encoding these antigens to elucidate how these genes are involved in the pathogenesis of fowl typhoid, and been attempting to identify the genes essential for host-specific virulence and lethality and the mechanisms involved, compared with those of serovar Typhimurium, which has been commonly used in studies of Salmonella. We are also currently working on serovars Dublin and Abortusequi, which infects cattle and horses, respectively, and hope to eventually update our overall understanding of the pathogenicity of Salmonella spp.
Through this research, we hope to unravel the history of the co-evolution of pathogenic bacteria and their host animals, and furthermore, to elucidate how zoonotic pathogens have become able to infect various animal species, thereby contributing to the development of control measures for human and animal infectious diseases.

Classification of Salmonella species.
Differential biochemical characterization for Salmonella.
A chicken suffuring from fowl typhoid shows ruffled feathers and lethalgy.
A chicken suffuring from fowl typhoid shows diffuse white necrotic foci in the liver.

List of current research topics

  • Elucidation of pathogenic mechanisms of fowl typhoid/pullorum disease
  • Epidemiological investigation of bovine salmonellosis and establishment of control strategies
  • Elucidation of pathogenic mechanisms of equine paratyphoid
Academic degree Ph.D.in Veterinary Sciences
License Veterinarian
Self introduction

I was born in Osaka , but have spent more than half of my life in Aomori and Hokkaido.
I have mainly conducted research on salmonellosis in poultry. In Obihiro, I am continuing this and starting research on salmonellosis in cattle and horses.
My hobbies are reading, traveling, and eating. Thanks to the delicious food in Obihiro, I have gained about 10 pounds in the three years since I was appointed here, and I need to resume some workout.

Room addressGeneral Research Building 1
Room numberS2102-1
Mail address okamuram atmark obihiro.ac.jp


Research Department/Department of Veterinary Medicine/Division of Veterinary Sciences/Section of Applied Veterinary SciencesOffice for International Accreditation of Veterinary Education/Staff
Related industries Poultry/livestock industry, Animal Health, Pharmaceutical products (vaccines etc.) for animals, Food Safety
Affiliated academic society The Japanese Society of Veterinary Science, The Japanese Society on Poultry Diseases, Japanese Society for Bacteriology, Japan Society of Veterinary Epidemiology, Japanese Society of Zoo and Wildlife Medicine, Japanese Society of Food Microbiology
Academic background 1992-1998: BVSc in Kitasato University School of Veterinary Medicine and Animal Sciences
1998-2002: Ph.D. in Osaka Prefecture University Graduate School of Agriculture and Biological Sciences
Mar 2001-Mar 2002: Visiting Scientist in USDA-ARS (Beltville, MD, USA)
Apr 2002-Nov 2002: Postdoc Scientist in USDA-ARS (Beltville, MD, USA)
Dec 2002-Dec 2004: Postdoc in National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinar Medicine
Jan 2005-Dec 2020: Research Associate - Associate Professor in Kitasato University School of Veterinary Medicine
Jan 2021-Present: Professor in Obihiro University of Agriculture and Veterinar Medicine