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Despite the various roles of type I interferon (type I IFN) responses during bacterial infection, its specific effects in vivo have been poorly characterized in scrub typhus caused by Orientia tsutsugamushi infection. Here, we show that type I IFNs are primarily induced via intracellular nucleic acids sensors, including RIG-I/MAVS and cGAS/STING pathways, during O. tsutsugamushi invasion. However, type I IFN signaling did not significantly affect pathogenesis, mortality, or bacterial burden during primary infection in vivo, when assessed in a mice model lacking a receptor for type I IFNs (IFNAR KO). Rather, it significantly impaired the induction of antigen-specific T cells and reduced memory T cell responses. IFNAR KO mice that recovered from primary infection showed stronger antigen-specific T cell responses, especially Th1, and more efficiently controlled bacteremia during secondary infection than wild type mice. Enhanced IL-10 expression by macrophages in the presence of type I IFN signaling might play a significant role in the suppression of antigen-specific T cell responses as neutralization or knock-out (KO) of IL-10 increased T cell responses in vitro. Therefore, induction of the type I IFN/IL-10 axis by O. tsutsugamushi infection might play a significant role in the suppression of T cell responses and contribute to the short longevity of cell-mediated immunity, often observed in scrub typhus patients.

Canoderma lucidum has a long history of use as a traditional medicine in Asian countries. However, the taxonomy of Ganoderma species remains controversial, since they were initially classified on the basis of their morphological characteristics. Recently, it was proposed that C. lucidum from China be renamed as C. sichuanense or C. lingzhi. In the present study, phylogenetic analysis using the internal transcribed spacer region rDNA sequences of the Ganoderma species indicated that all strains of the Korean 'G. lucidum' clustered into one group together with G. sichuanense and G. lingzhi from China. However, strains from Europe and North American, which were regarded as true G. lucidum, were positioned in a clearly different group. In addition, the average size of the basidiospores from the Korean cultivated Yeongji strains was similar to that of G. lingzhi. Based on these results, we propose that the Korean cultivated Yeongji strains of 'G. lucidum' should be renamed as G. lingzhi. [ABSTRACT FROM AUTHOR]