An adaptive mutation in NS2 is essential for efficient production of infectious 1b/2a chimeric hepatitis C virus in cell culture

The development of JFH1 based intergenotypic recombinants which exploit the unique replication characteristics of JFH1 has made it possible to study infectious HCV encoding the structural genes of additional HCV genotypes including genotype 1b. Although, intergenotypic 1b/2a chimeric genomes replicate efficiently in transfected cells they produce very low viral titers, limiting the utility of this system. Here, intergenotypic 1b/2a variants were generated by serially passaging the virus in a novel highly permissive Huh-7 cell clone. The adapted virus was 1000-fold more infectious than the parental unadapted virus and six adapted mutations were identified throughout the genome. Of the mutations identified, L839S in the NS2 gene was the most critical for the adapted phenotype by enhancing the infectivity of assembled viral particles. Overall, the efficient production of infectious 1b/2a virus particles will facilitate the discovery and characterization of inhibitors targeting steps that involve the structural genes of genotype 1b HCV.     

基于免疫分选的T淋巴细胞亚群嵌合性定量分析

目的:建立基于免疫分选的T淋巴细胞亚群嵌合性定量分析的方法。方法:以淋巴细胞不同比例混合制备14组人工嵌合体血样,以免疫磁珠阳性选择法获取CD4+和CD8+T细胞亚群,分选后的细胞再进行16位点的短串重复序列(STR)多态性分析。结果:分选后T细胞亚群提取的DNA量能满足STR检测要求,当嵌合体中受体比例≥10%时,16个STR位点均能检出受体和供体特异性等位基因,按照STR峰面积计算的受体比例与理论值相符;当受体比例≤1%时,仅有部分位点能检出受体特异性等位基因,实测嵌合率与理论值存在差异。结论:建立了基于免疫分选的T细胞亚群嵌合性定量分析方法,可用于造血干细胞移植术后嵌合体监测。     

Preclinical and clinical development of YFV 17D-based chimeric vaccines against dengue,West Nile and Japanese encephalitis viruses

Dengue viruses (DENV), West Nile virus (WNV) and Japanese encephalitis virus (JEV) are major global health and growing medical problems. While a live-attenuated vaccine exists since decades against the prototype flavivirus, yellow fever virus (YFV), there is an urgent need for vaccines against dengue or West Nile diseases, and for improved vaccines against Japanese encephalitis. Live-attenuated chimeric viruses were constructed by replacing the genes coding for Premembrane (prM) and Envelope (E) proteins from YFV 17D vaccine strain with those of heterologous flaviviruses (ChimeriVax™ technology). This technology has been used to produce vaccine candidates for humans, for construction of a horse vaccine for West Nile fever, and as diagnostic reagents for dengue, Japanese encephalitis, West Nile and St. Louis encephalitis infections. This review focuses on human vaccines and their characterization from the early stages of research through to clinical development. Phenotypic and genetic properties and stability were examined, preclinical evaluation through in vitro or animal models, and clinical testing were carried out. Theoretical environmental concerns linked to the live and genetically modified nature of these vaccines have been carefully addressed. Results of the extensive characterizations are in accordance with the immunogenicity and excellent safety profile of the ChimeriVax™-based vaccine candidates, and support their development towards large-scale efficacy trials and registration.     

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。     

鸡胚培养与嵌合体鸡的制备

目的探讨自X期鸡胚培养方法,制备嵌合体鸡.方法分离供体麻鸡种蛋的胚盘细胞,注入受体来航鸡种蛋胚盘,然后用以下两种方法培养鸡胚①钝端开窗法,沿鸡蛋气室边缘开口,内壳膜开小孔,注射胚盘细胞后再封口,置孵化器内,温度38℃,翻蛋角90°;②两次倒蛋法,胚盘细胞注入受体蛋后,倒入代用蛋壳Ⅰ,置孵化器内,温度38℃,翻蛋角90°,72h后,倒入代用蛋壳Ⅱ,改翻蛋角30°.结果用钝端开窗法注射83只种蛋,出雏35只(42.2%),表型嵌合体7只,3只存活;用两次倒蛋法,注射72只种蛋,出雏10只(13.9%),表型嵌合体5只,1只存活.结论钝端开窗法较经典的两次倒蛋法出雏率明显提高,用该方法制备嵌合体鸡更为方便可行.     

罕见46,XY/47,XYY嵌合体型女性患者病因诊断的遗传咨询模式探讨

目的:报道1例46,XY/47,XYY嵌合体女性性反转,探讨其病因诊断路径,提供临床的遗传咨询。方法:临床特征分析和家系调查。采用外周血淋巴细胞核型分析技术进行染色体核型分析,同时基于二代测序技术（NGS）的全基因组拷贝数变异测序（CNV-seq）进行外周血标本拷贝数变异检测及性别决定基因（SRY基因）及AZF基因位点检测。结果:家系调查表明,该患者具有伴X隐性遗传模式;临床上呈现共外显性特征;社会性别为女性,患者的外周血染色体核型结果为46,XY[57%]/47,XYY[13%],染色体拷贝数变异检测示:Arr[hg19]46,XY[70%]/47,XYY[30%],Yp11.31-q11.223×3,dup(6)(q14.1),SRY基因检测阳性,AZF基因所检测位点均未见缺失。结论:细胞遗传学染色体核型分析技术及CNV-seq均可确诊46,XY/47,XYY嵌合体女性性反转综合征,其遗传病因可能为DAX-1基因表达异常。整合了针对46,XY性反转快速诊断路径的遗传咨询模式,供临床参考。     

A single point mutation of the GABA(A) receptor alpha5-subunit confers fluoxetine sensitivity

Fluoxetine has been reported to be a novel allosteric modulator of GABA(A) receptors with the notable exception of receptors that contain the alpha5-subunit isoform [Robinson, R.T., Drafts, B.C., Fisher, J.L., 2003. Fluoxetine increases GABA(A) receptor activity through a novel modulatory site. J. Pharmacol. Exp. Ther. 304, 978-984]. A mutagenic strategy has been used to investigate the structural basis for the insensitivity of this subunit. An alpha1/alpha5-subunit chimeragenesis approach first demonstrated the importance of the alpha1-subunit N-terminal sequence E165-D183 (corresponding to alpha5 E169-D187) in fluoxetine modulation. Specific amino acid substitutions in this domain subsequently revealed that a single mutation in the alpha5-subunit to the equivalent residue in alpha1 (T179A) was sufficient to confer fluoxetine sensitivity to the alpha5-containing receptor. However, the reciprocal mutation in the alpha1-subunit (A175T) did not result in a loss in sensitivity, suggesting the involvement of additional determinants for fluoxetine modulation. A comparative modeling approach was used to probe amino acids that may lie in close proximity to alpha1A175. This led serendipitously to the identification of a specific residue, alpha1F45, which, when mutated to an alanine, resulted in a significant decrease in potency for activation of the receptor by GABA and also reduced the efficacies of the partial agonists, THIP and P4S.     

STEM CELL TRANSPLANTATION FOR SICKLE CELL DISEASE: CAN WE REDUCE THE TOXICITY?

Since the genetic basis of sickle cell anemia was discovered over 50 years ago, many therapies have been developed for the treatment of this disorder. Hematopoietic cell transplantation offers curative potential, but it is associated with a 5-10% risk of dying. Patients who undergo allografting but develop stable donor-host hematopoietic chimerism appear to experience a significant clinical benefit. Our paper discusses the risks and benefits of hematopoietic cell transplantation in patients with sickle cell disease and summarizes the outcome of 147 patients who received allografts for sickle cell disease. We also review the development of new approaches to establish stable mixed chimerism after transplantation for sickle cell disease.     

Chimeric AAV Cap sequences alter gene transduction

Recombinant adeno-associated viruses (rAAV) are vectors for gene delivery. rAAVs occur in several serotypes shown to have different transduction capabilities. Capsid sequences of the serotypes are different suggesting that differences in gene delivery are in large part due to capsid structure. Since the available serotypes are inefficient transducers of cell lines on a particle per cell basis and inefficiently transduce desired target cells in vivo there have been numerous attempts to create better vectors by modifying the capsids. A question of interest is whether natural selection has led, and whether laboratory-based selection methods will lead, to viruses with a sharply defined optimal specificity. Here we created multiple randomly recombined capsid species using the known AAV serotype capsid sequences by STEP and shuffling methods. We then used selection to identify a viral capsid better adapted to Hep G2 cells than the known serotypes. This capsid was then tested with other cells to determine whether the selection produced a virus specifically tailored by the selection methodology or one of wider applicability. The selected virus turned out to be surprisingly limited by its target cell and method of selection.