Inhibition of Orientia tsutsugamushi infection by a truncated recombinant 56‐kDa outer membrane protein

Aims:  The objective of this study was to evaluate recombinant 56-kDa outer membrane protein as a potential inhibitor to infection from Orientia tsutsugamushi. Methods and Results:  The 56-kDa protein was cloned and expressed in an Escherichia coli system, and the degree of target cell attachment to immobilized 56-kDa protein was measured in a cell adhesion assay. The results showed that the 56-kDa protein has an ability to attach HeLa cells. Furthermore, treatment of target cells with a truncated 56-kDa 1–418 (amino acid residues) protein inhibited target cell infection by O. tsutsugamushi, demonstrated with an indirect immunofluorescence antibody assay. Conclusions:  The truncated 56-kDa protein (a.a. 1–418) plays an important role in O. tsutsugamushi infection, and the 56-kDa protein could be useful and effective in the inhibition of O. tsutsugamushi attachment and infection. Significance and Impact of the Study:  The attachment of the 56-kDa protein to target cells was directly determined by in vitro adherence test, and the invasion of target cells by O. tsutsugamushi was inhibited by treating the target cells with a truncated 56-kDa protein.