West Nile virus (WNV) is a positive-sense single-stranded RNA flavivirus belonging to the Japanese encephalitis virus (JEV) serocomplex of the Flaviviridae family and causes mosquito-borne infections. Although most human infection cases are asymptomatic, approximately one in 150 infected individuals develops meningoencephalitis, with a mortality rate of 4-14%. While the development of human neutralizing antibody therapeutics against WNV is strongly anticipated, WNV is difficult to study in conventional laboratories due to its high safety level requirement. In this study, we established fully human WNV-neutralizing monoclonal antibodies from the peripheral blood mononuclear cells of inactivated-JEV-vaccinated individuals, and these antibodies exhibited WNV neutralization both in vitro and in vivo. Our results demonstrate a new antibody cross-reactivity strategy to develop immunological therapeutic reagents for WNV and other JEV serotype viruses.

異種反応性Ｔ細胞による異種移植片拒絶は異種移植に対する主要な障碍であり、この機序の解析を目的として、ＷＦラットの細胞により免疫されたＢ６マウスから、４種類のＣＤ８Ｔ細胞クローンと４種類のＣＤ４Ｔ細胞クローンを樹立した。全てのＣＤ８Ｔ細胞クローンは、Ｂ６マウスの抗原提示細胞が存在せずともＷＦラットの細胞に反応する直接認識を行い、その認識部位を詳細に解析したところ、ラットＭＨＣクラスⅠ分子であるＲＴ１Ｃｕを認識していた。また、全てのＣＤ８Ｔ細胞クローンは、細胞傷害性Ｔ細胞活性を有していた。一方、全てのＣＤ４Ｔ細胞クローンは、Ｈ－２ｂ陽性の抗原提示細胞の存在下にのみラットの細胞に対して反応するＨ－２ｂ拘束性の間接認識を行い、またＭＨＣハプロタイプの異なるあらゆる系統のラットの細胞に対しても反応することから、それらの認識部位はＭＨＣ分子以外のラットに共通する分子であることが示唆された。また、全ての

Specificities of cytotoxic T lymphocyte (CTL) effector cells induced in BALB/c mouse by immunization with the single modified CTL epitope peptide derived from NS3 of dengue virus types 1 and 3, or that of dengue virus types 2 and 4 were examined. The effector cells included CTLs specific for the epitope peptide used for immunization and those cross-reactive to epitope peptides of other flaviviruses. A CTL clone, 2F7, was established from the effector cells. The clone 2F7 was specific for the epitope peptide used for immunization. Recognition by the effector cells was remarkably impaired by amino acid substitutions at positions 3, 5, and 6 of the epitope peptides. These results indicate that immunization with a single CTL epitope peptide of dengue viruses induces serotype-specific CTLs as well as CTLs cross-reactive to the other flaviviruses, and that the a.a. residues at positions 3, 5, and 6 are critical for cross-reaction. (C) 2009 Elsevier B.V. All rights reserved.

デングウイルス由来Ｈ－２Ｋｄ拘束性マウスＣＴＬエピトープのＣＴＬ誘導能に関する免疫原性をテトラマーアッセイにより検討した。実験に用いたエピトープペプチドは、デングウイルス血清型２および４のＮＳ３蛋白アミノ酸配列２９８－２０６に相当するＧＹＩＳＴＲＶＥＭ（ＤＥＮＶ－２／４）、血清型１および３のＮＳ３蛋白２９９－３０７に相当するＧＹＩＳＴＲＶＧＭ（ＤＥＮＶ－１／３）、それぞれのＣ末端アミノ酸残基をＨ－２Ｋｄ結合モチーフを付与するためにＬに置換したＤＥＮＶ－２／４－９Ｌ（ＧＹＩＳＴＲＶＥＬ）およびＤＥＮＶ－１／３－９Ｌ（ＧＹＩＳＴＲＶＧＬ）である。元のＤＥＮＶ－２／４やＤＥＮＶ－１／３でＢＡＬＢ／ｃマウスを免疫した場合、ＣＴＬは全く誘導されなかったが、アンカー残基であるＣ末端をＬに置換したＤＥＮＶ－２／４－９ＬやＤＥＮＶ－１／３－９Ｌにより免疫したときは、特異的ＣＴＬであるエピトープペプチド／Ｈ

SKG mice, a newly established model of rheumatoid arthritis (RA), spontaneously develop autoimmune arthritis accompanying extra-articular manifestations, such as interstitial pneumonitis. To examine possible roles of T cells for mediating this systemic autoimmunity, we generated T cell clones from arthritic joints of SKG mice. Two distinct CD8(+) clones were established and both showed in vitro autoreactivity by killing syngeneic synovial cells and a variety of MHC-matched cell lines. Transfer of each clone to histocompatible athymic nude mice elicited joint swelling and histologically evident synovitis accompanying the destruction of adjacent cartilage and bone. Notably, the transfer also produced diffuse severe interstitial pneumonitis. Clone-specific TCR gene messages in the inflamed joints and lungs of the recipients gradually diminished, becoming hardly detectable in 6-11 months; yet, arthritis and pneumonitis continued to progress. Thus, the same CD8(+) T cell clones from arthritic lesions of SKG mice can elicit both synovitis and pneumonitis, which chronically progress and apparently become less T cell dependent in a later phase. The results provide clues to our understanding of how self-reactive T cells cause both articular and extra-articular lesions in RA as a systemic autoimmune disease.

デングウイルス２型及び４型のＮＳ３アミノ酸残基２９８－３０６（ＧＹＩＳＴＲＶＥＭ）もしくはデングウイルス１型及び３型のＮＳ３アミノ酸残基２９９－３０７（ＧＹＩＳＴＲＶＧＭ）に相当する細胞傷害性Ｔ細胞（ＣＴＬ）のエピトープペプチド（Ｄｅｎ２．４及びＤｅｎ１．３）のＣ末端アミノ酸残基を、Ｈ－２Ｋｄ結合モチーフを付与するためにＬに置換した改変エピトープペプチド（Ｄｅｎ２．４－９Ｌ及びＤｅｎ１．３－９Ｌ）を作製した。元のＤｅｎ２．４もしくはＤｅｎ１．３を、フロイント完全アジュバント（ＣＦＡ）と共にＢＡＬＢ／ｃマウスに免疫してもＣＴＬは全く誘導されなかったが、それぞれのＣ末端のアミノ酸残基をＬに置換したＤｅｎ２．４－９ＬもしくはＤｅｎ１．３－９ＬをＣＦＡと共にＢＡＬＢ／ｃマウスに免疫することによりＣＴＬが誘導された。また、Ｄｅｎ１．３－９Ｌの免疫に、結核死菌を含まないフロイント不完全アジュバント（Ｉ

Background: The induction of xenogeneic hematopoietic chimerism is an attractive approach for overcoming the host response to xenografts, but establishing xenogeneic chimerism requires severe myeloablative conditioning of the recipient. The goal of this study was to determine if co-stimulation blockade would facilitate chimerism and xenograft tolerance in irradiation-conditioned concordant recipients. Methods: Wistar Furth rat bone marrow (BM) cells were injected into irradiation-conditioned C57BL/6 mice with or without co-administration of anti-mouse CD154 monoclonal antibody (mAb). Chimerism was quantified by flow cytometry, and mice were transplanted with WF rat skin and islet xenografts. Results: Blockade of CD40-CD154 interaction facilitated establishment of xenogeneic chimerism in mice conditioned with 600 cGy irradiation. Anti-CD154 mAb was not required for establishment of chimerism in mice treated with 700 cGy. However, mice irradiated with 700 cGy but not treated with anti-CD154 mAb developed a "graft-versus-host disease (GVHD)-like" wasting syndrome and died, irrespective of their development of chimerism. Xenogeneic chimeras established with irradiation and anti-CD154 mAb treatment exhibited prolonged skin and, in many cases, permanent islet xenograft survival. Chimerism was unstable and eventually lost in most recipients. Skin xenografts were rejected even in mice that remained chimeric, whereas most islet xenografts survived to the end of the observation period. Conclusions: Blockade of host CD40-CD154 interaction facilitates the establishment of xenogeneic chimerism and prevents wasting disease and death. Chimerism permits prolonged xenograft survival, but chimerism generated in this way is unstable over time. Skin xenografts are eventually rejected, whereas most islet xenografts survive long term and perhaps permanently.

ＢＡＬＢ／ｃマウスに、デングウイルス血清型２・４の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープペプチドを、フロイント完全アジュバント（ＣＦＡ）を用いて免疫してもＣＴＬは誘導されなかったが、それをＨ－２Ｋｄ結合モチーフをもつように改変した上で、骨髄細胞よりＧＭ－ＣＳＦを用いて誘導した樹状細胞にパルスして免疫したところ、特異的なＣＴＬが誘導できた。（英文）

We examined whether immunization with a single peptide induces cytotoxic T lymphocytes (CTLs) of heterogeneous specificities in vivo, Immunization of BALB/c mice with the peptide H2:529-537, which corresponded to amino acid residues 529-537 on the HA2 subunit transmembrane region of influenza A/Jap virus (H2N2) and possessed an H-2K(d)-binding motif, induced CD8(+)CD4(-) CTLs. These CTLs lysed influenza A/Jap virus-infected target cells as well as those pulsed with the H2:529-537 peptide, H2:529-537 peptide-induced CTLs also lysed to lower but significant levels the target cells pulsed with the H1:533-541 peptide, which corresponded to amino acid residues 533-541 on the HA2 subunit transmembrane region of influenza A/PR/8 virus (H1N1) and were compatible to H2:529-537. Immunization with the H1:533-541 peptide, which also possessed an H-2K(d)-binding motif, induced CTLs in vivo, H1:533-541-induced CTLs lysed influenza A/PR/8 virus-infected target cells and those pulsed with the peptide H1:533-541. Subtype cross-reactive CTLs to the H2:529-537 peptide were not induced by immunization with the H1:533-541 peptide, Two peptides, H2:3S and H2:7S, which had one amino acid substitution, serine at the third and seventh positions, respectively, induced CTLs that lysed target cells pulsed with the respective peptides to the highest levels. These results indicate that immunization with a single peptide induces CTLs of heterogeneous specificities in vivo.

We defined an epitope on the Japanese encephalitis virus (JEV) envelope (E) protein recognized by CD8(+) cytotoxic T lymphocytes (CTLs). CTLs induced in JEV-infected BALB/c (H-2(d)) mice recognized E and/or premembrane (PrM) proteins, while CTLs in C57BL/6J (H-2(b)) and C3H/HeJ (H-2(k)) mice did not. JEV-specific CTLs had a phenotype of CD3(+) CD4(-) CD8(+). Twenty-four 9-amino acid (a.a.) peptides, which had binding motifs for H-2K(d), H-2L(d) or H-2D(d), were synthesized according to the amino acid sequences of PrM and E proteins. CTLs induced by JEV infection recognized only the peptide K-3. Immunization of BALB/c mice with only a group of peptides including K-3 induced CTLs which recognized the homologous K-3 peptide, while immunization with other peptides did not. The peptide K-3 had a binding motif for H-2K(d). This is consistent with the finding that JEV-specific CTLs in BALB/c mice was H-2K(d)-restricted. These results indicate that the epitope recognized by CTLs in BALB/c mice is located between a.a. 60 and 68 on the E protein, corresponding to an a.a. sequence of CYHASVTDI.

It is known that anti-alpha(1 --> 3) dextran antibodies of BALB/c mice are ordinarily of distinctive idiotypes (Id), one of which is the individual idiotype (IdI) that is represented by J558 or M104E to myeloma protein. In the present study, we established T cell line of Th1 type which recognized the Id of anti-alpha(1 --> 3) dextran antibody, and investigated its specificity and functions. The T cell line, named J-2R, had a phenotype of CD3(+) CD4(+) CD8(-) and expressed alpha beta-T cell receptors (TcR). J-2R proliferated in response to J558 in an I-E(d)-restricted manner but did not respond to M104E which had substitution at amino acids 100 and 101. We confirmed that J-2R recognized J558 IdI, using synthetic peptides corresponding to two serial amino acid residues, Arg(100) and Tyr(101), spanning the J558 IdI in the third hypervariable region (hv3) of the heavy chain. alpha(1 --> 3) dextran-binding B cells which were isolated from dextran-immunized mice activated J-2R, but B cells from nonimmune mice did not. J-2R produced IL-2, IFN-gamma and IL-6, but did not produce IL-4, IL-5, or IL-10. Furthermore, J-2R inhibited the growth of J558 myeloma cells inoculated to the syngeneic mice in vivo. These findings suggest that Id-specific CD4(+) T cells, J-2R, are involved in Id network and may play a role in vivo. J-2R is useful for analysis of the role of the Id-specific helper T cells in immune network because J558 IdI is frequently present on anti-alpha(1 --> 3) dextran antibodies. (C) 1996 Academic Press, Inc.

We attempted to identify the minimal residual leukemic clone as related to the clinical course in patients with acute B lymphocytic leukemia (B-ALL). DNA was extracted from stored bone marrow slides, and the third complementarity determining region (CDRIII) was amplified by polymerase chain reaction (PCR) using primers with consensus sequences for V-H and J(H). After amplification of the CDRIII band, the DNA fragment of CDRIII was inserted into the cloning vector PUC118. After cloning, the DNA sequences for CDRIII were determined. Clonospecific DNA sequences in CDRIII were selected, and clonospecific primers for each patient were synthesized. Using the clonospecific primers, we carried out second-round PCR to detect minimal residual disease (MRD) during several stages of the clinical course. Basically, the sensitivity of detection for MRD was between 10(-4) and 10(-5) cells. Even when leukemic cells were not detected in the morphologic study, with this detection system, the MRD was identified as an amplified CDRIII band stained with ethidium bromide on agarose gel. After bone marrow transplantation (BMT), MRD was detected for at least 4 months. In this article, we discuss the difference in sensitivity of detection for MRD between the BCR-ABL fusion gene and CDRIII in Philadelphia chromosome-positive (Ph(+)) B-ALL, as well as the possible clinical application of this method to predict relapse and prognosis.

Immunological abnormality of T lymphocytes in patients with adult T cell leukaemia (ATL) is characterized by abnormal expression of the 55 kD chain of the receptor for interleukin 2 (IL-2R/p55) (Tac), and the down-regulation of CD3 expression. Using serum and culture supernatants of leukaemic cells from ATL patients (Group A) whose CD3 expression was down-regulated and those (Group B) whose CD3 was not low, the possible mechanism of CD3 down-regulation on ATL cells was discussed. When PBMC from normal individuals were cultured with sera from ATL patients for 24 h, CD3 expression revealed by mean fluorescent intensity (MFI) was down-regulated by sera from ATL patients in Group A (MFI: Pt 1=51.6+/-4.5, Pt 2=48.0+/-6.9, control=96.5+/-6.6), not by sera from patients in Group B (MFI: Pt 3=105.5+/-7.9, Pt 4=102.5+/-8.3, control=96.5+/-6.6).When normal PBMC were cultured with supernatants of leukaemic cells from ATL patients in Group A, this CD3 down-regulating activity was also detected (MFI: Pt 1=78.0+/-10.2, Pt 2=70.6+/-8.7, control=94.0+/-6.6). By using gel-chromatography, the fractionated supernatants from ATL patients in Group A decreased CD3 expression of normal PBMC significantly (MFI: Pt 1=22.9+/-5.8, Pt 2=28.8+/-7.4, control=92.1+/-9.6). This CD3 down-regulating activity in fractionated supernatant was not inhibited by any lymphokine antibodies, anti-IL-1alpha antibody (Ab), anti-IL-1B Ab, anti-IL-2 Ab, anti-IL-3 Ab, anti-IL-4 Ab, anti-IL-6 Ab, anti-TNF-alpha Ab and anti-IFN-gamma Ab. Any known cytokines (IL-1, IL-2, IL-3, IL-4, IL-6, TNF-alpha and IFN-gamma) could not modulate CD3 expression of normal PBMC. These findings suggested that there are novel factor(s) with CD3 down-regulating activity in the serum and culture supernatant of ATL patient and those factor(s) are involved in progression of ATL.

It is known that human lymphotropic virus type I (HTLV-I) is closely associated with adult T cell leukemia (ATL). The immunological abnormality of T lymphocytes in patients with ATL is characterized by their abnormal expression of the 55 kDa chain of the receptor for interleukin 2 (IL-2 R/p55 (Tac)), and the down-regulation of CD 3 antigen. HTLV-I gene products such as p 40 tax or ATL-derived factor (ADF) have been shown to enhance the expression of IL-2 R/p55 (Tac). However, the mechanism of down-regulation of CD 3 antigen on T lymphocytes in ATL patients still remains unclear. We found that CD 3 expression on peripheral blood mononuclear cells (PBMC) in healthy individuals was decreased significantly by treatment with sera and cell culture supernatants from ATL patients whose CD 3 expression on PBMC was decreased markedly, but not by sera and cell culture supernatants from ATL patients whose CD 3 expression was normal. Gel-chromatography for cell culture supernatant showed that CD 3 down-regulating activity was fractioned in the fraction number 11 which arrowed 40~60 kDa. Next, after culture with various cytokines (IL-1, IL-2, IL-4, IL-6, IFN γ and TNF α), the expression of CD 3 on normal PBMC was not reduced significantly. Furthermore, by treatment of cell culture supernatant with various anti-cytokine antibody, the expression of CD 3 antigen on normal PBMC was down-regulated. As mentioned above, there are novel factor (s) with CD 3 down-regulating activity in the sera and cell culture supernatants of those acute ATL patients. In this study, we tried to clarify the mechanism of down-regulation of CD 3 expression on ATL cells, based on the finding of soluble factor (s) down-regulating CD 3 molecule. © 1993, The Japan Society for Clinical Immunology. All rights reserved.

T cells that recognize the cross-reactive idiotype expressed on the heavy (H) chain of M104E (IgM, lambda(1)) were induced in BALB/c mice by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or lesser amounts of Dextran B-1355 did not. BCL1Id, which had an immunoglobulin isotype identical to M104E, did not induce proliferation of the T cells. These T cells also proliferated against J558 (IgA, lambda(1)) which shared the cross-reactive idiotype of the anti-alpha (1 --> 3) glucosidic linkage antibody with M104E on the H chain. The T cells proliferated more efficiently against F(ab')2-104E. Fab-104E and H104E, the H chain of M104E, than against intact M104E. The T cell proliferative response against the idiotype on M104E or even H104E required macrophages as antigen-presenting cells (APC) and the response was inhibited when APC were treated with NH4Cl or chloroquine, inhibitors of antigen processing. Moreover, anti-CD4 antibody or anti-Ia antibody inhibited the proliferative response. These results indicated that anti-idiotypic T cells of the helper type, which recognized a cross-reactive idiotype associated with Ia molecules in processed form, could be induced physiologically through a network mechanism.

BALB/c mouse T cells that recognized the idiotype expressed on M104E(mu, lambda-1) were induced by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or smaller amounts of Dextran B-1355 did not. BCL1Id, which had an identical isotype, did not induce proliferation of T cells. The T cell proliferative response against the idiotype on M104E required macrophages as antigen-presenting cells. The proliferative response was inhibited when antigen-presenting cells were treated with NH4Cl or chloroquine, which are antigen-processing inhibitors. These results indicate that anti-idiotypic T cells which recognized processed idiotopes could be induced physiologically through a network mechanism.

管理栄養士の国家試験対策を目的とした本書において、感染症総論と細菌・マイコプラズマ・リケッチア・クラミジア・ウイルス・真菌・原虫・ぜん虫・プりオンの感染症各論について概説した。

We have established 3 human monolonal antibodies, which neutralize West Nile virus (WNV) as well as protect from WNV infection, from the volunteers immunized with WNV-related Japanese Encephalitis virus vaccine by using ISAAC technology.

日本脳炎ワクチン被接種者の内、その血清にウエストナイルウイルス中和活性が認められた者の末梢血単核球から、ISAAC(ImmunoSpot Array Assay on a Chip)法を用いて、ウエストナイルウイルス中和活性を持つ高親和性の３種類のヒトモノクローナル抗体を樹立した。

日本脳炎ワクチン被接種者の内、その血清にウエストナイルウイルス中和活性が認められた者の末梢血単核球から、ISAAC(ImmunoSpot Array Assay on a Chip)法を用いて、ウエストナイルウイルス中和活性を持つ高親和性の３種類のヒトモノクローナル抗体を樹立した。

ＲＡ様関節炎・関節外病変を自然発症するＳＫＧマウスの罹患関節よりＴ細胞クローンを樹立した。１クローンはＣＤ４陽性、２クローンはＣＤ８陽性でいずれもin vitroで自己反応性を示した。これらのクローンを同系ヌードマウスに移入すると３～６ヶ月後に関節腫脹が始まり慢性に進行した。組織学的に骨・軟骨の破壊を伴う増殖性関節炎が誘導され、興味深いことに全ての個体で組織学的に激しい間質性肺炎がみられた。対照として用いたウイルス抗原特異的クローンの移入ではいずれの病変も観察されなかった。移入したＴ細胞クローンの検出頻度は移入後経時的に減少し、病変部位で増殖しているのも非Ｔ細胞であった。本関節炎の発症初期はＴ細胞に依存しているが、パンヌス形成・骨髄の活性化などＴ細胞非依存性に進行すると考えられる。さらに、同一の抗原特異性を持つ自己反応性Ｔリンパ球が関節炎のみならず間質性肺炎を起こす可能性が考えられる。

デングウイルス血清型１・３の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来ペプチドの免疫により誘導した血清型交差反応性ＣＴＬと血清型２・４のＣＴＬエピトープ由来のそれの免疫により誘導した血清型交差反応性ＣＴＬ、および血清型１・３のＣＴＬエピトープ由来のそれの免疫により誘導した血清型１・３特異的ＣＴＬクローン（２Ｆ７）のそれぞれの細特異性を１アミノ酸残基置換ペプチドを用いて解析したところ、いずれの交差反応性ＣＴＬの抗原認識においても３・５・６番目のアミノ酸残基が、また血清型１・３特異的ＣＴＬクローン（２Ｆ７）の抗原認識においては３番目から８番目のすべてのアミノ酸残基が重要であることが判った。

デングウイルス血清型１・３の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来ペプチドの免疫により誘導した血清型１・３特異的ＣＴＬクローン（２Ｆ７）の細特異性を１アミノ酸残基置換ペプチドを用いて解析したところ、エピトープペプチドの３番目から８番目のすべての残基が重要であり、同様にして誘導した血清型交差反応性ＣＴＬの抗原認識のそれとオーバーラップしていた。

デングウイルス血清型１・３の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来ペプチドの免疫により誘導した血清型１・３特異的ＣＴＬクローン（２Ｆ７）の細特異性を１アミノ酸残基置換ペプチドを用いて解析したところ、エピトープペプチドの３番目から８番目のすべての残基が重要であり、同様にして誘導した血清型交差反応性ＣＴＬの抗原認識のそれとオーバーラップしていた。（英文）

デングウイルス１・３型の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来のペプチドでマウスを免疫した所、１・３型特異的ＣＴＬのみならず２・４型や他のフラビウイルスに交差反応性のＣＴＬも誘導され、それらの抗原認識には３・５・６番目のアミノ酸残基が重要であった。（英文）

デングウイルス血清型１・３の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来ペプチドの免疫により誘導した血清型交差反応性ＣＴＬと血清型１・３特異的ＣＴＬクローン（２Ｆ７）の細特異性を１アミノ酸残基置換ペプチドを用いて解析したところ、交差反応性ＣＴＬの抗原認識には３・５・６番目のアミノ酸残基が、また血清型１・３特異的ＣＴＬクローン（２Ｆ７）の抗原認識には３番目から８番目のすべてのアミノ酸残基が重要であった。

デングウイルス血清型２・４の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来のペプチドでマウスを免疫した所、血清型２・４特異的ＣＴＬのみならず、１・３型や他のフラビウイルスに交差反応性のＣＴＬも誘導され、それらの抗原認識には３・５・６番目のアミノ酸残基が重要であった。

デングウイルス１・３型の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来のペプチドでマウスを免疫した所、１・３型特異的ＣＴＬのみならず２・４型や他のフラビウイルスに交差反応性のＣＴＬも誘導され、それらの抗原認識には３・５・６番目のアミノ酸残基が重要であった。

デングウイルス１・３型の細胞傷害性Ｔ細胞（ＣＴＬ）エピトープ由来のペプチドでマウスを免疫した所、１・３型特異的ＣＴＬのみならず２・４型や他のフラビウイルスに交差反応性のＣＴＬも誘導され、それらの抗原認識には３・５・６番目のアミノ酸残基が重要であった。

細胞傷害性Ｔ細胞（ＣＴＬ）エピトープペプチド自体でマウスを免疫してもＣＴＬは誘導されなかったが、Ｈ－２Ｋｄ結合モチーフを付与したもので免疫すればＣＴＬが誘導された。後者のＨ－２Ｋｄに対する親和性を測定した所、前者のおよそ１０倍であった。

ラット→マウスの異種骨髄移植時における抗マウスＣＤ４０Ｌ抗体による宿主側の補助刺激ブロックは、異種骨髄キメラ状態と宿主の生存を有意に促進した。異種骨髄キメラマウスは、骨髄供与ラット組織移植片に対して特異的な免疫寛容状態であった。（英文）

ラット→マウスの異種骨髄移植時における抗マウスＣＤ４０Ｌ抗体による宿主側の補助刺激ブロックは、異種骨髄キメラ状態と宿主の生存を有意に助長した。これに対して、抗ラットＣＤ４０Ｌ抗体は、そのいずれについても無効であった。（英文）

ウエストナイルウイルス（WNV）は、時に致死性の脳炎・髄膜炎を惹き起こすフラビウイルス科の蚊媒介性ヒト感染性ウイルスである。世界の広い地域に分布し我が国への感染拡大の危険性が指摘されているが、実用的な治療薬やワクチンは未だ無い。研究分担者らによって見出された WNV に働く中和抗体は、同じフラビウイルス科の日本脳炎ウイルス(JEV)とも交差反応を示すという興味深い性質を持つ。我々はその抗体と WNV のエンベロープタンパク質（Ｅタンパク質）との複合体の立体構造の決定に成功し、異なるウイルスを同時に認識する抗体の分子機構を明らかにした。その構造基盤を発展させ、(1) フラビウイルス科の各種ウイルスを同時に認識する抗体を開発し、異なるフラビウイルス感染症のどれにも効果のある抗体医薬開発につながる知見を得ること、(2) フラビウイルス科の中の特定のウイルスだけを認識する抗体を開発し、多重感染地域などでどのウイルスに感染しているかを判定できる診断薬の開発につながる知見を得ること、を研究の目的とし、フラビウイルス科の日本脳炎、黄熱病、ジカ熱の各ウイルス（JEV, YFV, ZIKV）のＥタンパク質とその中和抗体の認識機構を明らかにすべく、両者のタンパク質複合体の立体構造解析を目指し研究を行った。

West Nile virus (WNV) is a mosquito-borne human infectious virus of the Flavivirus family and sometimes causes lethal encephalitis and meningitis. We isolated interesting antibodies which neutralize both WNV and Japanese encephalitis virus (JEV) that also belongs to Flavivirus family. We determined the X-ray crystal structure of the complex of one of the antibodies and the enveloped protein of WNV at 2.6 A resolution. The three-dimensional structure and mutational analysis revealed that Arg388 which are conserved in JEV and WNV and CDR of L-chain are essential for the binding activity.

The aim of the present researh is to elucidate the role of flavivirus-cross-reactive immune responses in the pathogenesis of dengue hemorrhagic fever. We analyzed T lymphocytes which were cross-reactive for dengue and Japanese encephalitis viruses (JEV), using murine and human lymphocytes. T lymphocytes obtained from JEV-immune donors responded to JEV, but also responded to dengue viruses to lower levels. JEV-reactive CD4+ T cell clones established from the same donors did not respond to dengue viruses ; however, some T cell clones responded to West Nile virus (WNV). This may partly due to higher levels of amino acid homology between JEV and WNV.These results also suggest that T lymphocytes cross-reactive for JEV and dengue viruses exist only at the low frequency. These T cell clones did not possess unique T cell receptor motifs. We also analyzed murine T cell responses to JEV, in order to understand T cell responses cross-reactive for dengue and JEV.We analyzed induction of JEV-specific CD8+ cytotoxic T lymphocytes (CTL) in Balb/c mice, and attempted to determine epitope (s) recognized by specific CTL.JEV-specific CD8+CTL were induced by infection with JEV.There is one epitope on the envelope protein recognized by these CTL.The epitope is located between amino acids 60-68 on the envelope protein, and the recognition of this epitope is restricted by H-2Kd. We are analyzing flavivirus-cross-reactivity of these CTL, and determining other epitopes recognized by the CD8+CTL.