MICROBIOLOGY and IMMUNOLOGY
Online ISSN : 1348-0421
Print ISSN : 0385-5600
ISSN-L : 0385-5600
44 巻, 2 号
選択された号の論文の9件中1~9を表示しています
  • Jun Abe, Yasuhiko Ito, Michiko Onimaru, Takao Kohsaka, Tae Takeda
    2000 年 44 巻 2 号 p. 79-88
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    Staphylococcal enterotoxins (SEs) are a family of structurally related pyrogenic exotoxins consisting of the five prototypic SEs (types A to E) and three newly characterized SEs (types G to I) produced by Staphylococcus aureus (S. aureus). They also work as superantigens and cause food poisoning and shock symptoms in humans. In this study, we cloned a new variant gene of the seg and characterized its superantigenic properties and distribution among the clinical isolates of S. aureus. The gene encodes a 233 amino acid protein which is highly homologous to SEG (97.7%). The variant SEG (SEGv) expressed by the cloned gene exerted mitogenic activity on human peripheral blood mononuclear cells at the concentration of 100pg/ml. T cells bearing Vβ3, 12, 13.1, 13.2, 14 and 15 were preferentially expanded after stimulation with the recombinant protein. The mRNA of the variant seg gene was detected in the total RNA of the organisms bearing this gene. By PCR, 27 out of 48 clinical isolates of S. aureus (56%) possessed either the seg or variant seg gene. These findings suggest that SEG, or SEGv, is one of the most frequently produced superantigen exotoxins by S. aureus and may participate in the inflammatory process of the host by activating a distinct set of Vβ families of T cells.
  • Emiko Isogai, Hiroshi Isogai, Shunji Hayashi, Toru Kubota, Koichi Kimu ...
    2000 年 44 巻 2 号 p. 89-95
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    There have been some reservations about the treatment of enterohemorrhagic Escherichia coli (EHEC) infection with antibiotics to prevent the occurrence of hemolytic uremic syndrome (HUS). However, the administration of antimicrobial agents for EHEC infection is under discussion. Therefore, we used an experimental mouse model to assess the advantage/disadvantage of two major antibiotics, levofloxacin (LVFX) and fosfomycin (FOM). Germ-free IQI mice were inoculated with EHEC O157 strain EDL931 or #7. Bacteria colonized feces at 109-1010CFU/g, and Shiga toxins (STXs) were detected in the feces. From 1 day after infection, mice were assigned to LVFX (20mg/kg) once daily or FOM (400mg/kg) once daily. A significant decrease in overall mortality was observed after treatment of LVFX, with EHEC disappearing immediately from the feces of mice. FOM also reduced mortality for one strain, the STX level decreased gradually. LVFX exhibited higher therapeutic efficacy than FOM. Strain differences were observed in the model during the treatment.
  • Toshiro Ochiai
    2000 年 44 巻 2 号 p. 97-104
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    The growth of Staphylococcus aureus 209P becomes unusually sensitive to a high-NaCl concentration by decreasing the Ca2+ concentration in growth media, and cells either autolyze or transform into protoplast-like forms when grown standing in high-NaCl and low-Ca2+ concentration media below 37C (Ochiai, T., Microbiol Immunol. 43 (7): 705-709, 1999). To assess the role of Ca2+ in the salt tolerance of this organism, cells grown in the presence of different concentrations of Ca2+ were treated with boiling SDS, and their susceptibilities to crude autolysin (3M LiCl extract of S. aureus 209P cells) were evaluated by turbidimetric assay and zymographic analysis. Susceptibilities of SDS-treated cells (SDS-cells) to crude autolysin were significantly influenced by Ca2+ concentration in the culture, and SDS-cells prepared from cultures grown in high-NaCl and high-Ca2+ concentration media exhibited marked resistance to crude autolysin when the assay system contained a high concentration of NaCl. On the contrary, SDS-cells prepared from cultures grown in high-NaCl and low-Ca2+ concentration media were rather susceptible to crude autolysin under the same assay conditions. A zymographic analysis revealed that the constitution of cell-associated autolysins was not influenced by the concentration of exogenous Ca2+. These results suggested that at least part of the mechanism of salt-induced autolysis in S. aureus 209P might be related to the synthesis of an autolysin susceptible cell wall.
  • Tianwei Yu, Yun Bai, Manfred P. Dierich, Ying-Hua Chen
    2000 年 44 巻 2 号 p. 105-110
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    To test the immunogenicity of GPGRAFY-epitope-based candidate vaccines, a peptide with four repetitive GPGRAFY epitopes, V3-P1 [C-(GPGRAFY)4], and a peptide (PND) of the principal neutralizing domain (V3 loop: amino acid 301-328: C-TRPNNNTRKSIRIQRGPGRAFYTIGKI) on gp120 were synthesized and covalently coupled to a carrier protein BSA. Immunization of BALB/c mice and New Zealand White Rabbits with these conjugate vaccines engendered strong antibody responses against the PND (mouse serum titer by 1:12, 800-25, 600; rabbit serum titer by 1:6, 400-12, 800). Interestingly, the V3-P1-BSA conjugates and the PND-BSA conjugates could induce high levels of GPGRAFY-epitope-specific antibodies in the mice and rabbits (mouse serum titer by 1:25, 600; rabbit serum titer by 1:12, 800-25, 600), while a recombinant gp160 subunit vaccine induced a low level of GPGRAFY-epitope-specific antibodies (serum titer by 1:400-1, 600 in mice and rabbits). To confirm the above results, GPGRAFY-epitope-specific antibodies were isolated from rabbit sera induced by V3-P1-BSA, PND-BSA conjugates and rgp160 vaccine. In fact, 23-38 and 13-22μg epitope-specific antibodies per milliliter serum were isolated from rabbit sera induced by V3-P1-BSA and PND-BSA conjugate, respectively, while 1.34μg epitope-specific antibodies per milliliter serum were identified in rabbit serum induced by rgp160 vaccine. In the control group, only 0.069μg proteins per milliliter serum were found in pooled pre-immune serum (normal serum). These results from mouse and rabbit experiments indicate that epitope and peptide vaccines both induce high levels of GPGRAFY-epitope-specific antibodies in comparison with rgp160 subunit vaccine, suggesting that epitope/peptide vaccines may be a new strategy to induce protective activity.
  • Satoko Suzuki, Minoru Tobiume, Masanori Kameoka, Katsuaki Sato, Tsuneo ...
    2000 年 44 巻 2 号 p. 111-121
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    The depletion of immune T cells by human immunodeficiency virus type-1 (HIV-1) infection is a major mechanism involved in the pathogenesis of AIDS. Here, we examined a possible effector function of blood monocyte-derived dendritic cells (DCs) to induce apoptosis in bystander CD4+ and CD8+ T cells. The DCs were generated by culturing monocytes in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4. The DCs exposed to HIV-1 particles were co-cultured with healthy donor-derived blood T cells at a ratio of 1:20. Analyses by percent cell mortality, staining with propidium iodide and reactivity with Annexin V revealed the induction of apoptosis in both CD4+ and CD8+ target T cells. Further, this apoptosis occurred without stimulation with mitogens when the cell cycle of target T cells shifted from G0 to G1, probably due to the mitogenic effect of the DCs. Thus, induction of apoptosis in both CD4+ and CD8+ T cells occurred via interaction with DCs adsorbed with HIV-1 particles.
  • Kiyokazu Kakugawa, Keiko Udaka, Kosuke Nakashima, Kayo Inaba, Yoshihir ...
    2000 年 44 巻 2 号 p. 123-133
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    Lipopolysaccharides of Gram-negative bacteria are potent activators of B cells, dendritic cells and monocytes/macrophages. We have investigated the use of LPS-activated spleen cells as antigen-presenting cells to induce CD8+ cytotoxic T lymphocytes in vivo that are reactive to MHC class I binding peptides. Compared with resting spleen cells, CTL induction was more efficient and less variable for different peptides with LPS-activated spleen cells. Cytotoxic responses were specific for the immunized peptides and contained high affinity CD8+ T cells. The removal of dendritic cells and monocytes/macrophages by Sephadex G10 column did not show profound effects on CTL induction, indicating that B-cell blasts were largely responsible. This easily accessible method should facilitate the screening of MHC class I binding peptides to determine whether or not the host's T-cell repertoire contains reactive T cells.
  • Akihito Yonezawa, Toshiyuki Hori, Hitoshi Sakaida, Takashi Uchiyama
    2000 年 44 巻 2 号 p. 135-141
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    Stromal cell-derived factor-1 (SDF-1) is an efficacious chemoattractant for lymphocytes, monocytes and hematopoietic progenitor cells. In the present study, we examined whether SDF-1 has growth promoting activity on human peripheral T cells and analyzed the possible underlying signal transduction pathways. SDF-1 augmented the proliferation of anti-CD3- or PHA-stimulated normal human PBMC in a dose-dependent manner but not that of resting PBMC. It was noted that SDF-1 alone could induce a significant proliferation of PHA-preactivated T cells. Anti-SDF-1 sera could inhibit the augmentation of T-cell proliferation in each experiment. Furthermore, Western blot analysis revealed that mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase 2 (ERK2), but not c-Jun N-termimal kinase (JNK) was activated by SDF-1. Considering that costimulatory signals have been reported to involve ERK2 activation, these results indicate that SDF-1 has costimulatory effects on T cells that are possibly mediated by ERK2 activation and may play a role in not only migration but also the potentiation or maintenance of T cells.
  • Karen F. Novak, Michael R. Nonnemacher, Jaleh Pourhamidi
    2000 年 44 巻 2 号 p. 143-148
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    Results of Southern blot analyses and polymerase chain reaction revealed that the Gram-negative pathogen, Actinobacillus actinomycetemcomitans, harbored DNA homologous to the secA gene of Escherichia coli. In E. coli, the secA gene product is essential for translocation of proteins across the inner membrane via the Sec system. This A. actinomycetemcomitans secA homolog was cloned and its nucleotide sequence determined. Amino acid sequence analysis of the cloned gene revealed significant homology to the SecA proteins of Haemophilus influenzae, E. coli, Caulobacter crescentus and Bacillus subtilis. Although the cloned gene did not complement a temperature sensitive mutation in the E. coli secA gene, strains harboring the cloned gene did produce a protein that cross-reacted with anti-SecA antibody. In addition, the cloned gene did restore sensitivity to sodium azide in an E. coli azideR mutant. These data support the hypothesis that A. actinomycetemcomitans may use a system similar to the Sec system of E. coli to transport proteins across the cytoplasmic membrane, but suggest that the A. actinomycetemcomitans gene product may require genera-specific Sec proteins to complement some Sec mutations in E. coli.
  • Kewei Bi, Lei Shi, Yoko Maehara, Shin-ichi Miyoshi, Ken-ichi Tomochika ...
    2000 年 44 巻 2 号 p. 149-153
    発行日: 2000年
    公開日: 2008/03/17
    ジャーナル フリー
    A total of 51 Vibrio mimicus clinical strains from different geographic locations were examined by arbitrarily primed polymerase chain reaction (AP-PCR). The primer VMH-3 divided them into 28 groups, although 18 groups consisted of a single strain at present. All groups had a common 1.0-kb amplification fragment. Most of the groups consisted of strains from same region, although two exceptional groups showed a few amplification fragments including strains from different regions. AP-PCR groups were not consistently associated with serogroups. AP-PCR is thought to be a valuable and easy method for the epidemiological study of V. mimicus.
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