Novel polysaccharide antigen ofOrientia tsutsugamushirevealed by a monoclonal antibody

Abstract

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium that replicates in the cytosol of host cells. Although several protein antigens have been characterized and cloned, little information exists regarding the polysaccharide antigen of this bacterium. In this study, we identified and characterized a novel antigen defined by a monoclonal antibody (MAb), NT19, against O. tsutsugamushi. Immunofluorescence microscopic studies showed that the NT19 antigen is released from the bacteria in the cytosol of host cells forming aggregates with bacteria. Immunoblot analysis showed that MAb NT19 recognized a strong band with a molecular mass of 20 kDa that was resistant to proteinase K digestion and sensitive to periodate oxidation, suggesting that the NT19 antigen is a polysaccharide. The function of this polysaccharide is not known, but considering its distribution within a bacterial microcolony, it is suspected to be involved in forming a biofilm‐like structure within host cells.

Orientia tsutsugamushi Stimulates an Original Gene Expression Program in Monocytes: Relationship with Gene Expression in Patients with Scrub Typhus

“…It is tempting to speculate that the production of IFN-β and the expression of ISGs, at least in part, are related to the cytosolic location of the bacteria. Indeed, L. monocytogenes [54] and O. tsutsugamushi [55] are known to reside in the cytosol. Among the genes upregulated in response to O. tsutsugamushi , we detected TBK-1 and IRF-7.…”

Gene expression and involvement of signaling pathways during host–pathogen interplay in Orientia tsutsugamushi infection

“…The bacterial replication occurs within a polysaccharide-enriched microcolony (Lee et al 2009 ) when it traffics to the perinuclear region after evading autophagy in the cytoplasm (Ko et al 2013 ; Choi et al 2013 ). OT enters the host cells through a clathrin-mediated zipper-like mechanism and exits through late endosomes to avoid the endolysosomal route.…”

Buerger’s Disease May be a Chronic Rickettsial Infection with Superimposed Thrombosis: Literature Review and Efficacy of Doxycycline in Three Patients

“…We saw him first in January 2015 when he had continued smoking, felt mild cold sensation in both feet only while working outdoors in winter, and showed no signs of vascular insufficiency. A blood specimen was taken, inoculated into a cell culture using the ECV304 cell line, and examined with NT-14, a monoclonal antibody directed against an epitope of the polysaccharide antigen of O. tsutsugamushi [ 254 ], which showed intracellular fluorescent foci 3 weeks after inoculation ( Fig. 1 ).…”