Assoc Prof Narisara Chantratita
Mahidol University, Thailand
Risk of Burkholderia pseudomallei infection, host immune response and biomarkers for melioidosis
Melioidosis causes high mortality in northeast Thailand despite antibiotic treatment. Infection routes of the causative agent, Burkholderia pseudomallei include inoculation, ingestion and inhalation. Several environmental sources serve as niches for persistence, providing a mechanism for further dissemination of the bacterium across distances, increasing the risk of human infection through repeated exposure or consumption. Understanding the exposure-relevant environmental sources is required to prevent and control the infection and for diagnostic and vaccine development. Our studies suggest that antigenic variation and diversity of bacteria in the environment may play role in infection and induction of host immune response. Distinct classes and subclasses of antibodies against different B. pseudomallei antigens are associated with some characteristics of melioidosis patients. Recently, we demonstrated that hemolysin-coregulated protein 1 (Hcp1) and O-polysaccharide (OPS) antigen are promising candidates for serodiagnosis of melioidosis in endemic areas. The two antigens have been used for serological surveys of B. pseudomallei exposure in febrile patients in Myanmar and Cambodia. Further, a rapid immunochromatography test based on Hcp1 (Hcp1-ICT) has been developed as a Point-of-Care test and evaluated for IgG detection in patients providing 88% sensitivity and 86-92% specificity. Our longitudinal study demonstrated that a set of plasma cytokines may be used to predict outcomes in melioidosis. Persistent inflammatory markers precede death. We also found that whole blood transcriptomic profile of acute melioidosis patients may be used to identify host prognostic biomarkers and response to treatment. Our research has provided insights into how variability in B. pseudomallei components and host characteristics are associated with the diagnostics and impacts on severity of illness and outcome in people living in northeast Thailand.
I am an Associate Professor at Mahidol University. I have studied the interactions between the pathogen and human host in melioidosis for over twenty years, combining laboratory investigation with clinical studies. Based in the Department of Microbiology and Immunology, Faculty of Tropical Medicine at Mahidol University in Bangkok. I have conducted or been involved in numerous studies relating to melioidosis and other bacterial infections in northeast Thailand. For example, my Wellcome Trust Intermediate Fellowship Project, "Association between genetic polymorphisms, innate immune responses and outcomes from sepsis in Thai patients with melioidosis and S. Aureus infection" involved recruitment of hospitalized patients at four clinical sites in northeast Thailand: Ubon Rachathani, Udon Thani, Khon Kaen and Srinagarind Hospitals. I have worked since 2006 on studies of host genetic susceptibility, human immune responses and laboratory diagnosis. I have developed a substantial repertoire of expertise in immunology, bacteriology, molecular diagnostics, and bacterial and host genetics pertaining to melioidosis. I am currently a principal investigator of NIH/NIAID grant for the project "Determinants of outcomes and reinfection in melioidosis". This project involved recruitment of melioidosis patients at nine study sites in northeast Thailand.