A single M protein mutation affects the acid inactivation threshold and growth kinetics of a chimeric flavivirus

Numerous viruses of the Flaviviridae family, including dengue, yellow fever, Japanese encephalitis, and West Nile, cause significant disease in humans and animals. The structure and function of the molecular components of the flavivirus envelope are therefore of significant interest. To our knowledge, a membrane (M) protein mutation which affects the pH at which flavivirus particles are inactivated in vitro has never been reported. Here we show that substitution of proline for glutamine at residue M5 (MQ5P) of a Japanese encephalitis-yellow fever chimera (ChimeriVax-JE) increases its acid sensitivity in vitro by 0.3 pH units (i.e., increases the pH at which virus titer is reduced by 50% from 6.08 to 6.38). In addition, growth kinetics of this mutant virus are accelerated in Vero cells, while neurovirulence and neuroinvasiveness measured in a mouse model are unaffected. A possible interpretation of these observations is that M can modulate the envelope (E) protein function during cell infection.     

染色体嵌合体及单亲二体的研究现状

染色体嵌合体(CM)和单亲二体(UPD)均与胚胎发育过程中的细胞分裂错误有关。目前多数研究认为,CM与胚胎细胞有丝分裂错误有关。利用辅助生殖技术结合单细胞高通量测序技术(NGST)进行研究发现,胚胎发育早期处于细胞分裂错误和自我纠正的动态变化中,其变化结果决定胚胎染色体的构成。染色体异常细胞可能以不同比例存在于不同组织和器官中,从而导致CM患者临床症状和染色体异常表型差异很大。UPD来源于发育过程中,胚胎对于细胞减数分裂错误或有丝分裂错误的“自救”,其致病性与印迹基因有关,除明确的UPD相关疾病外,未含有印迹基因的UPD致病性尚有待进一步研究。在产前诊断中,对CM与UPD这2种染色体异常的检出率,随着NGST的发展而不断提高,但是有关其致病性判断及胎儿风险评估,则由于缺乏足够研究证据支持,而成为临床遗传咨询难点。笔者拟就上述2种染色体异常的发生机制、致病性及其产前诊断与遗传咨询的最新研究现状等进行阐述,旨在为临床对这2种染色体异常的研究提供参考。     

猪-人-鼠嵌合体动物模型的建立及介导人T细胞对猪异种抗原的耐受

目的： 通过共移植人胎胸腺、胎肝组织及猪骨髓细胞于SCID鼠体内,建立猪-人-鼠嵌合体模型,介导人T细胞对猪异种抗原的免疫耐受。方法:实验鼠分成3组：A组为猪骨髓细胞移植组,B组为人胎胸腺、肝脏组织移植组,C组为猪骨髓细胞＋人胎胸腺+肝脏组织移植组;在移植后每3周,用流式细胞仪测定猪和人嵌合体的水平,直至20周;通过混和淋巴细胞反应确定人T细胞的功能及对猪异种抗原的耐受情况。 结果:猪嵌合体在所有实验鼠（包括共移植人组织的实验鼠）中持续时间均超过20周;在移植人胎组织20周时,T细胞的数量为0.7×106/L,在外周血细胞中所占的百分比为0.14%±0.01%;人嵌合体在所有实验鼠（包括共移植猪骨髓细胞的实验鼠）中持续时间亦超过20周。结论: 通过共移植人胎胸腺、胎肝组织及猪造血干细胞于SCID鼠体内,可以建立猪-人-鼠嵌合体模型,并能诱导人T细胞对猪异种抗原的免疫耐受。     

IL-2 pathway blocking in combination with anti-CD154 synergistically establishes mixed macrochimerism with limited dose of bone marrow cells and prolongs skin graft survival in mice

To facilitate the establishment of mixed chimerism with limited dose of bone marrow (BM) cells, and to achieve tolerance in skin graft model, combined blocking of costimulatory pathway and IL-2 pathway was used in minimally myeloablative model using busulfan. BM cells (2.5x10(7)) of BALB/c were injected into C57BL/6 mice at day 0 with full thickness skin graft after single dose injection of busulfan (25 mg/kg) on day-1. Recipients were grouped and injected the anti-CD154, CTLA4-Ig, anti-IL-2R at days 0, 2, 4, and 6 according to protocol. Mixed macrochimerism were induced in groups treated with anti-CD154+anti-CTLA4-Ig, anti-CD154+anti-IL-2R, and anti-CD154+anti-CTLA4 Ig+anti-IL-2R. Three groups having chimerism enjoyed prolonged graft survival more than 6 months. Superantigen deletion study revealed deletion of alloreactive T cells in combined blockade treated groups. In graft versus host disease model using CFSE staining, CD4+ T cell and CD8+ T cell proliferation were reduced in groups treated with CTLA4-Ig or anti-IL-2R or both in combination with anti-CD154. However, anti-IL-2R was not so strong as CTLA4-Ig in terms of inhibition of T cell proliferation. In conclusion, IL-2 pathway blocking combined with anti-CD154 can establish macrochimerism with limited dose of BM transplantation and induce specific tolerance to allograft.     

An ultrastructural,immunohistochemical, and cytogenetical study of a monophasic pulmonary synovial sarcoma: implications of the frequent ultrastructure of oligocilia and concentric membranous bodies with positive immunostaining for VS38c and MEF2

A rare case of a monophasic pulmonary synovial sarcoma is reported. A 44-year-old Japanese man underwent lower lobectomy for a nodular mass in his right lung. Immunohistochemical study of the excised primitive spindle cell sarcoma revealed occasional positive stains by hitherto reported antigens of S-100, cytokeratin 7, high molecular weight cytokeratin (34betaE12), pankeratin (AE1/AE3), and EMA, which were helpful for the differential diagnosis of other spindle cell sarcomas. Furthermore, positive immunostains for MEF2, VS38c (plasma cell antigen), and bcl-2 were rather significant findings in the present case. The definitive evidence that molecular genetic analysis showed a clonal single electrophoretic band of SYT-SSX mutated chimera gene was conclusive for the pathological diagnosis. The implications of the frequently seen ultrastructure of oligocilia and concentric membranous bodies with positive stains for VS38c and MEF2 are discussed. In the difficult pathological diagnosis of a rare and undifferentiated type of sarcoma with unusual clinicopathological features generated at an unusual site, comprehensive ultrastructural, immunohistochemical, and cytogenetic studies will lead to the correct pathological diagnosis and elucidate the detailed characteristics of the tumor.     

小鼠→大鼠异种移植耐受模型的建立

目的：用非清髓方法建立小鼠→大鼠混合嵌合体模型，探讨免疫耐受机制。方法：给SD大鼠亚致死全身照射(TBI)后，4h内输入Balb／c小鼠骨髓细胞(BMC)，2d后腹腔注射环磷酰胺(CTX)，分别于BMT后30、60和90d，检测小鼠源性BMC在大鼠体内植活情况。通过皮肤移植、迟发超敏反应(DTH)和混合淋巴细胞反应(MLR)检查，探讨其耐受机制。结果：经处理大鼠外周血可测出小鼠源性嵌合体，皮肤移植、DTH和MLR检查显示对Balb／c小鼠产生特异性耐受，且较持久。结论：应用7．5Gy TBI 腹腔注射50mg／kg CTX 供体BMT、可成功建立小鼠→大鼠混合嵌合体模型诱导特异性耐受，嵌合体与耐受有关系。     

嵌合型13环状染色体综合征的产前诊断

目的 对1例孕17周超声发现室间隔缺损,主动脉与肺动脉内径接近,单脐动脉的胎儿进行分子细胞遗传学分析。方法 对羊水细胞进行G显带染色体核型分析和染色体微阵列分析,父母外周血进行G显带染色体核型分析。结果 G显带分析提示胎儿核型为45,XY,-13[45]/46,XY,r(13)(p11q34)[35],父母核型均正常,胎儿染色体异常为新发突变。CMA检测胎儿为 13号染色体长臂q32.3q34存在13.6Mb缺失,为致病性CNVs,13号染色体长臂q31.3q32.3存在7.2Mb重复,为致病性未明CNVs。不同检测方法嵌合情况存在差异。结论 本例13单体,13环状染色体嵌合体胎儿产前超声诊断表现为心血管发育畸形,相关发育基因的缺失和重复可能是表型变异的主要原因。     

联体共生诱导大鼠心脏移植免疫耐受的实验研究

目的　通过联体共生模型 ,建立供、受者嵌合体 ,探讨嵌合体与免疫耐受的关系。方法　纯系雄性DA(RT1a)大鼠为供者 ,Lewis(RT11)大鼠为受者 ,随机分成 3组 ,每组供、受者各 15只。Ⅰ组 (未处理组 ) :仅行DA到Lewis大鼠的腹部心脏移植 ,手术前后不作任何处理。Ⅱ组 (环磷酰胺组 ) :DA到Lewis大鼠的心脏移植前后分别经腹腔注射环磷酰胺 80mg/kg。Ⅲ组 (联体组 ) :0d :供、受者大鼠腹腔注射环磷酰胺 80mg/kg ;第6d :供、受者联体 ;第 16d :联体大鼠腹腔注射环磷酰胺80mg/kg ;第2 1d :分开联体 ,行DA到Lewis大鼠的心脏移植。观察各组移植心存活时间 ,供心病理学改变 ,供、受者间的混合淋巴细胞反应 (MLR)。结果　Ⅲ组形成了稳定的供、受者嵌合体 ,供心平均存活时间为 :(76 .33± 10 .71)d ,较Ⅰ组 (7.17± 1.17)d、Ⅱ组 (8.5 0± 1.87)d显著延长 ,差异有显著性 (P <0 .0 1) ;Ⅲ组的供心仅见少量炎性细胞浸润 ;供、受者间MLR较正常对照组显著降低 ,差异有显著性 (P <0 .0 1)。结论　联体共生可形成稳定的外周和中枢嵌合体 ,嵌合体在同种心脏移植的免疫耐受中起重要作用。     

嵌合体大鼠诱导异种皮肤移植免疫耐受的初步研究

目的 探讨嵌合体大鼠诱导异种皮肤移植免疫耐受的可行性。方法 采集兔骨髓干细胞，经行宫内胎鼠移植以及对新生子鼠行肝内注射，制作兔骨髓干细胞嵌合体大鼠模型。6周后将15只嵌合体大鼠分为A组（8只）、B组（7只）。将A组大鼠皮肤移植给供髓兔，将7只非嵌合体大鼠皮肤移植给非供髓兔作A组对照；将B组大鼠、7只非嵌合体大鼠（B组对照）皮肤同时移植给供髓兔。记录移植后皮片成活时间、创面愈合时间。结果A组对照移植皮片成活（9．3±1．8）d，创面于（20．9±2．1）d愈合；A组移植皮片成活（15．1±2．6）d，创面于（18．5±1．3）d愈合。B组及其对照移植皮片的成活时间、创面愈合时间与A组相似。与各自对照皮肤移植相比，A、B组皮片成活时间延长（P〈0．01），创面愈合时间缩短（P〈0．05或P〈0．01）。结论 嵌合体大鼠行异种皮肤移植后能诱导移植皮片免疫耐受．使其成活时间明显延长．创面愈合时间缩短。