Immunological tools for a seroprevalence and immune status map of Burkholderia pseudomallei and thailandensis in Vietnam

This Newton Fund application seeks to enhance existing research links between immunology/microbiology researchers in Hanoi and at Imperial College London. The biomedical research question concerns appraisal in Vietnam of the risk of melioidosis. This is a potentially severe or lethal bacterial infection caused by the bacterium, Burkholderia pseudomallei, found in many temperate countries in the soil and in the water supply. The disease is associated with thousands of deaths annually in neighbouring Thailand. It has been predicted that the disease may be under-diagnosed in several other countries including Vietnam, but no comprehensive data exists. With more precise data, it would be possible to put appropriate plans in place for diagnosis and antibiotic treatment protocols. This proposal thus brings together researchers who have a strong, ongoing, interest in this question, from Hanoi and London. We plan to appraise the situation at several levels. The first is to take soil samples from sites across the country, determining distribution and load of the bacterium. As part of this work we will also assess presence of a closely related but non-pathogenic bacterium called Burkholderia thailandensis. This is important as immunity to the two bacteria is partly cross-reactive and there is a view that exposure to environmental thailandensis may protect against melioidosis. We will then work with collaborators at five regional hospitals across the country, collecting a small blood sample from 200 volunteer donors at each centre, during routine health-checks. This sample will be used to check for antibodies to the two bacteria, giving a dataset for 'seroprevalence' - that is, a regional map of human exposure to the bacteria, which can be overlaid with the mapped soil samples. This will not tell us how many people have melioidosis. Rather, it will give a picture of whether or not there are indeed regions of Vietnam similar to high-risk regions of N. Thailand, where a majority of people develop high levels of antibody after bacterial exposure. Since those people who show immunity to the bacterium but show no signs of disease must have functional protection, we will do collaborative studies to characterise the nature of this protection at the level of white blood cells termed 'T cells.' A closely related issue is that diabetes is by far the strongest risk factor for development of severe disease in individuals exposed to the bacterium. For this reason, we will use the serum samples to build a parallel, regional map of the prevalence of diabetes, believed to be growing rapidly in Vietnam. This study will include point-of-care blood glucose and analysis of pancreatic autoantibodies. A strong component of the work will be the interactive and training component, including annual workshops held in Vietnam

This Newton Fund project aims to strengthen links between immunology and microbiology researchers in Hanoi and London. We will assess potential consequences of human exposure to Burkholderia pseudomallei (Bp) or B. thailandensis (Bt). Bp is a Gram-negative bacterium, found in soil and water, and capable of causing outcomes in exposed people ranging from asymptomatic seroconversion to sepsis and death. In neighboring Thailand there are thousands of fatal cases annually. The picture in Vietnam is unclear: case-finding is identifying an increasing number of cases and facilitating appropriate antibiotic treatment. We here define a sample area encompassing 5 hospitals in 4 regions of Northeast, Northwest, North Central and South Central Vietnam, a catchment area of 33,621km2. Blood samples will be collected from 200 healthy donors at each hospital, giving a dataset of 1000 individuals for assessment of Bp and Bt seroprevalence, relating clinical sampling sites to analysis of Bp/Bt load in soil samples from these regions. ELISA analysis for seroprevalence focuses on OPS as a validated antigen for Bp seroprevalence studies and Hcp1, which shows only ~35% homology with Bt. We will collaborate closely with world leading authorities on Bp serology and genomics, from Thailand and the USA, . Because diabetes is the key risk factor for development of melioidosis and also correlated with Bp responsiveness, we will collect a dataset of diabetes serum biomarkers, screening for HbA1c as well as antibodies to glutamic acid decarboxylase 65, C peptide, ZnT8 and islet antigen 2. To look at correlates of protection at the CD4 T cell level, tetramers will be used to sort Bp epitope-specific cells, using a multi-parameter phenotyping antibody panel to define phenotype and cytokine profile. There is strong interest in building enhanced expertise in infection, immunity/flow cytometry and diabetes research with Hanoi researchers, including staff exchange visits and annual joint workshops.

1 The primary impact of this research is anticipated to be considerable advance in the available dataset for Vietnam of soil and seroprevalence of Burkholderia.
2 This work has potential impact for healthcare planning and provision, both with respect to bacterial sepsis and diabetes.
3 Findings will be made accessible through timely publication in journals, presentation at meetings and communications via social media.
4 Much of the impact will be of specific interest to immunologists, microbiologists and bacteriologists with an interest in host defence to bacterial infection.
5 There is an anticipated impact from long-term, academic cross-fertilisation between immunology, microbiology and bacteriology researchers in Vietnam, the UK, Thailand and the USA, hopefully catalysing new, collaborative interactions.
6 The work offers potential impacts through refinement of Burkholderia serodiagnostics.