Human Immune Responses to Melioidosis and Cross-Reactivity to Low-Virulence <i>Burkholderia</i> Species, Thailand1
Patpong Rongkard, Barbara Kronsteiner, Viriya Hantrakun, Kemajittra Jenjaroen, Manutsanun Sumonwiriya, Panjaporn Chaichana, Suchintana Chumseng, Narisara Chantratita, Vanaporn Wuthiekanun, Helen A. Fletcher, Prapit Teparrukkul, Direk Limmathurotsakul, Nicholas Day, Susanna Dunachie
Abstract
Melioidosis is a neglected tropical disease with an estimated annual mortality rate of 89,000 in 45 countries across tropical regions. The causative agent is Burkholderia pseudomallei, a gram-negative soil-dwelling bacterium. In Thailand, B. pseudomallei can be found across multiple regions, along with the low-virulence B. thailandensis and the recently discovered B. thailandensis variant (BTCV), which expresses B. pseudomallei-like capsular polysaccharide. Comprehensive studies of human immune responses to B. thailandensis variants and cross-reactivity to B. pseudomallei are not complete. We evaluated human immune responses to B. pseudomallei, B. thailandensis, and BTCV in melioidosis patients and healthy persons in B. pseudomallei-endemic areas using a range of humoral and cellular immune assays. We found immune cross-reactivity to be strong for both humoral and cellular immunity among B. pseudomallei, B. thailandensis, and BTCV. Our findings suggest that environmental exposure to low-virulence strains may build cellular immunity to B. pseudomallei.