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Tsuneo Kamiyama

Publications and source records attributed to Tsuneo Kamiyama.

5 recordsLinked to original sources
PubMed2003

Activation of natural killer T cells by alpha-galactosylceramide impairs DNA vaccine-induced protective immunity against Trypanosoma cruzi.

Innate immunity as a first defense is indispensable for host survival against infectious agents. We examined the roles of natural killer (NK) T cells in defense against Trypanosoma cruzi infection. The T. cruzi parasitemia and survival of CD1d-deficient mice exhibited no differences compared to wild-type littermates. NK T-cell activation induced by administering alpha-galactosylceramide (alpha-GalCer) to T. cruzi-infected mice significantly changed the parasitemia only in the late phase of infection and slightly improved survival when mice were infected intraperitoneally. The combined usage of alpha-GalCer and benznidazole, a commercially available drug for Chagas' disease, did not enhance the therapeutic efficacy of benznidazole. These results suggest that NK T cells do not play a pivotal role in resistance to T. cruzi infection. In addition, we found that the coadministration of alpha-GalCer with DNA vaccine impaired the induction of epitope-specific CD8(+) T cells and undermined the DNA vaccine-induced protective immunity against T. cruzi. Our results, in contrast to previous reports demonstrating the protective roles of NK T cells against other infectious agents, suggest that these cells might even exhibit adverse effects on vaccine-mediated protective immunity.

Animals↗
PubMed2003

Retrospective seroepidemiological survey for human babesiosis in an area in Japan where a tick-borne disease is endemic.

A total of 1,335 archived human sera collected in 1985 from an area in Japan where a tick-borne disease is endemic were examined by indirect immunofluorescence antibody test (IFAT) to estimate seroprevalence against three serologically distinct types of Babesia microti-like parasites; namely, Hobetsu, Kobe, and U.S. types. Eighteen sera (1.3%) were found to be IFAT-positive (titer 1:100-1:6,400), of which 14 and three were ascertained by Western blot analysis to be positive against the Hobetsu and Kobe types, respectively. In addition, four sera showed an IFAT titer of 1:100 against the U.S. type, but they appeared to be false-positive because they were cross-reactive against the Hobetsu and Kobe types, and also because a U.S.-type parasite has not been found in Japan. Our results suggest that human babesiosis in Japan occurred prior to the discovery of the index case in 1999 and that the infections were caused mainly by Hobetsu-type parasites.

Adult↗
PubMed2003

[Plague].

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Animals↗
PubMed2002

Coadministration of an interleukin-12 gene and a Trypanosoma cruzi gene improves vaccine efficacy.

We tested the immunogenicity of two Trypanosoma cruzi antigens injected into mice in the form of DNA vaccine. Immunization with DNA encoding dihydroorotate dehydrogenase did not confer protective immunity in all mouse strains tested. Immunization with DNA encoding trans-sialidase surface antigen (TSSA) protected C57BL/6 (H-2(b)) mice but not BALB/c (H-2(d)) or C3H/Hej (H-2(k)) mice against lethal T. cruzi infection. In vivo depletion of CD4(+) or CD8(+) T cells abolished the protective immunity elicited by TSSA gene in C57BL/6 mice. Enzyme-linked immunospot assay with splenocytes from T. cruzi-infected mice or TSSA gene-vaccinated mice identified an H-2K(b)-restricted antigenic peptide, ANYNFTLV. The CD8(+)-T-cell line specific for this peptide could recognize T. cruzi-infected cells in vitro and could protect naive mice from lethal infection when adoptively transferred. Coadministration of the interleukin-12 (IL-12) gene with the TSSA gene facilitated the induction of ANYNFTLV-specific CD8(+) T cells and improved the vaccine efficacy against lethal T. cruzi infection. These results reinforced the utility of immunomodulatory adjuvants such as IL-12 gene for eliciting protective immunity against intracellular parasites by DNA vaccination.

Amino Acid Sequence↗