Although the 56-kDa protein of Rickettsia tsutsugamushi has been presumed to play important roles in generating protective immunity against scrub typhus, studies of this protein have been impeded. We used the recombinant 56-kDa protein of R. tsutsugamushi Boryong fused with the maltose-binding protein of Escherichia coli (MBP-Bor56) to analyze its ability to induce protective immunity in a C3H/HeDub murine model. Intraperitoneal immunization of mice with MBP-Bor56 resulted in an increase in the 50% minimal lethal dose of more than 160 times compared with that for the control mice. Splenic mononuclear cells from the mice immunized with MBP-Bor56 showed a dose-dependent pattern of lymphocyte proliferation response and secreted gamma interferon and interleukin-2 when stimulated with irradiated R. tsutsugamushi Boryong, which is a cytokine profile of Th1 cells. High titers of antibody to R. tsutsugamushi were also demonstrated by indirect immunofluorescent-antibody testing. These findings suggest that the 56-kDa protein of R. tsutsugamushi is one of the candidates for a vaccine against scrub typhus.
A 12-year-old Korean girl gave a 9-year history of recurrent necrotizing papules and vesicles on the face, scalp and extremities. Skin biopsy specimens showed an atypical lymphoreticular infiltrate with vasculitis in the dermis and subcutis. In situ hybridization demonstrated latent infection by Epstein-Barr virus (EBV) of the lymphoid cells in the dermis. The disease was diagnosed as an EBV-associated lymphoproliferative skin eruption presenting as recurrent necrotic papulovesicles. The patient subsequently developed large granular lymphocytic leukaemia of natural killer cell origin. Our observations suggest that a patient with an EBV-associated lymphoproliferative skin eruption presenting with recurrent necrotic papulovesicles might progress to develop leukaemia as well as lymphoma.
The stress gradient of gold micro-cantilever beams induced during dry-release in oxygen plasma is quantitatively studied, and the relaxation of the stress gradient by He and N2 ion implantation is investigated. An analytic model considering the finite anchor stiffness of a step-up anchor and the geometry of the beam cross-section is constructed to evaluate the induced stress gradient. Various measurements are carried out to verify the effectiveness of ion implantation in relaxing the stress gradient.
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