共查询到20条相似文献，搜索用时 171 毫秒
1.
C Babinet H Farza D Morello M Hadchouel C Pourcel 《Science (New York, N.Y.)》1985,230(4730):1160-1163
Two transgenic mice were obtained that contain in their chromosomes the complete hepatitis B virus (HBV) genome except for the core gene. These mice secrete particles of HBV surface antigen (HBsAg) in the serum. In one mouse, HBV DNA sequences that had integrated at two different sites were shown to segregate independently in the first filial generation (F1) and only one of the sequences allowed expression of the surface antigen. Among these animals the males produced five to ten times more HBsAg than the females. A 2.1-kilobase messenger RNA species comigrating with the major surface gene messenger RNA is expressed specifically in the liver in the two original mice. The results suggest that the HBV sequences introduced into the mice are able to confer a tissue-specific expression to the S gene. In addition, the HBV transgenic mice represent a new model for the chronic carrier state of hepatitis B virus infection. 相似文献
2.
D R Milich G B Thornton A R Neurath S B Kent M L Michel P Tiollais F V Chisari 《Science (New York, N.Y.)》1985,228(4704):1195-1199
The 55 codons upstream of the gene sequence encoding the hepatitis B surface antigen (HBsAg) are called the pre-S(2) region. It has been proposed that polypeptides of high molecular weight that contain the pre-S(2) region should be included in future hepatitis B virus (HBV) vaccines. The pre-S(2) region and the S gene product [25 kilodalton (kD)] together compose a polypeptide of high molecular weight (33 kD). As an initial attempt to determine the relevance of the 33-kD polypeptide to development of an HBV vaccine, the murine immune response to pre-S(2)-encoded determinants as compared to S-encoded determinants on the same polypeptide was examined. The results indicate (i) the pre-S(2) region is significantly more immunogenic than the S region of HBsAg, (ii) the 26 amino acid residues at the NH2-terminus of the 33-kD polypeptide represent a dominant antibody binding site on the pre-S(2) region, (iii) the immune response to the pre-S(2) region is regulated by H-2-linked genes distinct from those that regulate the response to the S region, and (iv) immunization of an S region nonresponder strain with HBV envelope particles that contain both the pre-S(2) and S regions can circumvent nonresponsiveness to the S region. 相似文献
3.
用PCR和ELISA方法分析奶牛血清和奶中类乙型肝炎病毒 总被引：4，自引：0，他引：4
用人乙型肝炎病毒（ＨＢＶ）表面抗原（ＨＢｓＡｇ）和ｅ抗原（ＨＢｅＡｇ）ＥＬＩＳＡ试剂盒检测８５份奶牛血清和９３份奶样。结果测出３３份血清为ＨＢｓＡｇ阳性，其中４价亦为ＨＢｅＡｇ阳性；２２份奶样为ＨＢｓＡｇ阳性，其中１１份亦为ＨＢｓＡｇ阳性。７个双阳性的样本，用针对ＨＢＶ表面抗原基因不同部位的两对引物作ＰＣＲ分析，结果未能扩增出特异片段，排除了奶牛ＨＢＶ血清学阳性是由人ＨＢＶ感染所致。 相似文献
4.
Immunization with skin isografts taken from tolerant mice 总被引：9，自引：0，他引：9
D Steinmuller 《Science (New York, N.Y.)》1967,158(797):127-129
Skin isografts from mice that were immunologically tolerant to allogeneic tissue had the ability to immunize isogeneic recipients against subsequent skin allografts. The immunizing isografts showed no gross signs of rejection themselves and appeared to be only the vehicles for transplantation antigen. It seems likely that allogeneic leukocytes derived from the spleen and bone marrow cells used to confer tolerance were contained in the skin of the tolerant mice and were transferred by the skin isografts in sufficient numbers to stimulate transplantation immunity. 相似文献
5.
A new role for DNA virus early proteins in viral carcinogenesis 总被引：13，自引：0，他引：13
The T antigen proteins encoded by DNA tumor virus early genes are involved in the transformation of normal cells to immortalized neoplastic cells that may or may not be tumorigenic in immunocompetent animals. Studies have been made of the tumorigenicity of DNA virus-transformed cells and the interactions of these cells in vivo and in vitro with immunologically nonspecific host effector cells such as natural killer cells and macrophages. The results imply that the T proteins determine the capacity of transformed cells to induce tumors by governing the level of susceptibility that transformed cells express to destruction by such host cellular defenses. 相似文献
6.
A poliovirus neutralization epitope expressed on hybrid hepatitis B surface antigen particles 总被引：18，自引：0，他引：18
F Delpeyroux N Chenciner A Lim Y Malpièce B Blondel R Crainic S van der Werf R E Streeck 《Science (New York, N.Y.)》1986,233(4762):472-475
The hepatitis B virus (HBV) envelope protein carrying the surface antigen (HBsAg) is assembled with cellular lipids in mammalian cells into empty viral envelopes. In a study to evaluate the capacity of such particles to present foreign peptide sequences in a biologically active form, in-phase insertions were created in the S gene encoding the major envelope protein. One of the sequences inserted was a synthetic DNA fragment encoding a poliovirus neutralization epitope. Mammalian cells expressing the modified gene secreted hybrid particles closely resembling authentic 22-nanometer HBsAg particles. These particles reacted with a poliovirus-specific monoclonal antibody and induced neutralizing antibodies against poliovirus. The results indicate that empty viral envelopes of HBV may provide a means for the presentation of peptide sequences and for their export from mammalian cells. 相似文献
7.
Isotypic exclusion of gamma delta T cell receptors in transgenic mice bearing a rearranged beta-chain gene 总被引：11，自引：0，他引：11
R G Fenton P Marrack J W Kappler O Kanagawa J G Seidman 《Science (New York, N.Y.)》1988,241(4869):1089-1092
The rearrangement of T cell antigen receptor beta- and gamma-chain gene segments was studied in transgenic mice that bear a functional beta-chain gene. Virtually all CD3-positive T cells derived from transgenic mice express beta chains containing the transgene-encoded V beta 8.2 variable region on their surfaces and do not express endogenous beta-chain variable regions. Expression of endogenous V beta genes is inhibited at the level of somatic recombination during thymic ontogeny. Furthermore, rearrangements of the TCR gamma-chain genes are also markedly inhibited in these transgenic animals. Hence expression of the TCR beta transgene has led to allelic exclusion of alpha beta receptors and isotypic exclusion of gamma delta T cell receptors. 相似文献
8.
【目的】研究超表达小麦基因TaSOD1.1和TaSOD1.2对烟草耐低温能力的影响。【方法】采用农杆菌介导的遗传转化技术,获得融合靶基因的转基因烟草植株;通过比较低温处理后对照和转基因系的表型和生理指标,鉴定超表达靶基因对烟草耐低温能力的调控效应。【结果】以分子检测鉴定的插入单拷贝基因的4个转基因系和对照为材料,低温处理后超表达外源基因的转基因植株叶片失绿缓慢,叶片超氧化物歧化酶（SOD）活性明显增加,反映细胞膜质过氧化程度的丙二醛（MDA）含量明显下降;叶片叶绿素a、b和类胡萝卜素含量、可溶性糖含量和可溶性蛋白含量均明显提高。【结论】超表达小麦TaSOD1.1和TaSOD1.2的烟草植株,具有增强SOD活性、明显缓解低温造成的细胞膜质过氧化程度、改善低温胁迫下植株的生理功能,可进而改善植株抵御低温胁迫的能力。 相似文献
9.
对甘肃省兰州市周边地区采集的300份猪血清的表面抗原(HBsAg)、E抗原(HBeAg)、E抗体(抗-HBe)、核心抗体(抗-HBc)、表面抗体(抗-HBs)5项指标进行检测,并从HBsAg和抗-HBs抗体阳性血清中提取DNA,进行乙型肝炎病毒(HBV)S基因和C基因的巢式PCR扩增、克隆、测序和序列分析.结果表明:血清学检测的上述5项指标阳性率分别为10.7%3、.0%、6.1%、3.3%和88.5%,大三阳(即HBsAg、HBeAg、抗-HBs抗体均为阳性)的猪血清样本6份,阳性率为2%;序列分析表明,猪类HBV的S基因和C基因与GenBank中的人HBV同源性达到99%,说明猪存在类HBV感染,且猪类HBV与人HBV存在相关关系. 相似文献
10.
Newborn mice infected with lymphocytic choriomeningitis virus are not immunologically tolerant to the agent but, rather, appear to make antibody to the virus. This antibody was detectable only in the kidneys, where presumably it had been deposited in the glomeruli in the form of complexes of antibody, virus, and complement. 相似文献
11.
应用聚合酶链反应(PCR)技术扩增38例 HBsAg 携带者和58例正常人血清中的HBV DNA 特异性片段,通过与 HBsAg 滴度及 HBV 血清标志物进行对比分析发现 HBV DNA 阳性率与 HBsAg 滴度呈正相关(r=0.981,p<0.005),与 HBeAg 减低,抗-HBe 产生以及其后的 e系统消失过程呈相应递减趋势。并且在单项抗-HBs 阳性的血清中,HBVDNA 检出率可达10%。 相似文献
12.
Location and chemical synthesis of a pre-S gene coded immunodominant epitope of hepatitis B virus 总被引：27，自引：0，他引：27
Immunodominant, disulfide-bond independent epitopes recognized by human antibodies to hepatitis B virus (HBV) are located within the 55-residue amino terminal portion (coded for by the pre-S region of HBV DNA) of minor HBV envelope components larger than the major protein constituents encoded by the S gene. A peptide having the sequence of the first 26 amino acids from the amino terminal methionine was synthesized and elicited antibodies (at dilutions of greater than or equal to 1 to 10(5) ) to the HBV envelope. These antibodies can be utilized for diagnostic tests. The immunogenicity of the peptide was substantially increased by covalent attachment to liposomes. The disulfide bond-independent determinants on sequences coded for by the pre-S gene may be more easily mimicked by peptide analogs than "conformational" determinants on the S-gene product. 相似文献
13.
利用转基因技术创造甜菜耐盐新种质 总被引：9，自引：0，他引：9
采用农杆菌介导法将来源于E coli的胆碱脱氢酶 (CDH)基因 (betA)和来源于拟南芥的Na+ /H+antiport基因分别转入 5个糖甜菜品种的丛生芽细胞 ,获得了转基因植株。在耐盐性筛选中 ,转基因植株存活率高 ,部分植株生长较好 ,表现出比对照植株明显提高的耐盐性。在 2 %～ 3%NaCl胁迫下 ,少数转基因植株仍生长正常 ,显示出高耐盐性。本研究表明 ,转入在不同盐胁迫反应途径中起关键作用的酶基因均可提高甜菜耐盐性 ,采用转移多个耐盐基因的策略有可能创造出高耐盐特性的新材料 相似文献
14.
四环素诱导表达系统（Tet-off／Tet-on系统）是比较成熟的真核生物基因诱导表达系统之一,具有高效、无毒、严密开／关功能的特点。猿猴病毒40T（SV40T）是一种病毒癌蛋白,其与肿瘤抑制蛋白p53和Rb结合,并使之失活,从而消除它们抑制细胞生长的功能,使细胞分裂加速,形成肿瘤。利用Tet-on系统首先稳定筛选获得了表达Tet-on系统调节元件rtTA的阳性细胞CHO-pTet-on,再通过稳定筛选又成功得到导入其反应元件的双阳性细胞CHO-pTet-on-pTRE2-SV40T-Hyg,经强力霉素诱导表达了目的基因SV40T,建立了Tet-on基因诱导表达系统的细胞诱导表达研究平台。 相似文献
15.
ELISA法与FQ-PCR对HBV三种血清标志物检测结果的比较 总被引：1，自引：1，他引：0
为了探讨与评价联合检测乙型肝炎HBeAg和Pre-S1Ag、HBV-DNA等血清免疫标志物在乙型病毒性肝炎临床诊断、治疗中的意义,利用酶联免疫吸附试验（ELISA）和荧光实时定量聚合酶链式反应（FQ-PCR）,对619例疑似或确诊乙肝患者的血清样本分别进行乙肝免疫标志物HBeAg、Pre-S1Ag和HBV-DNA的联合检测。结果表明,血清乙肝免疫标志物HbeAg检测为阴性时,不能完全表明患者乙肝病毒复制终止或病毒血症的消失;血清Pre-S1Ag检测结果有助于乙型肝炎的早期诊断,也可以作为乙肝病毒DNA复制的指标之一;而FQ—PCR检测血清HBVDNA结果则有助于乙型肝炎病毒的抗原或抗体血清滴度较低时肝炎的诊断。 相似文献
16.
17.
为建立表达含前S基因乙肝病毒表面抗原的细胞株,将笔者所在实验室构建的表达含前S基因乙肝病毒表面抗原(HBsAg)的真核表达质粒共转染CHO/dhfr 细胞,通过筛选,获得可表达含前S基因乙肝病毒表面抗原的重组CHO细胞,然后进行亚克隆,用氨甲喋呤(MTX)加压选择,以 ELISA 法检测目的蛋白表达量,筛选获得稳定表达目的蛋白的细胞株,并对其进行特性鉴定.最终获得了ClO和A10两株稳定高表达含前S基因乙肝病毒表面抗原的细胞株. 相似文献
18.
日本血吸虫新基因SjPP的筛选、克隆及对小鼠的免疫效果 总被引：8，自引：0，他引：8
【目的】筛选克隆东方田鼠血清识别的日本血吸虫靶抗原基因，并研究其免疫保护效果。【方法】利用东方田鼠感染血清免疫筛选日本血吸虫（中国大陆株）成虫cDNA表达文库获得阳性克隆，以5′ RACE技术扩增获基因全长序列，构建含目的基因的核酸疫苗并研究在小鼠中的免疫保护效果。【结果】（1）获得4个日本血吸虫新的EST序列，即mfs-1（GenBank登录号BE974942）、mfs-3（GenBank登录号BE974944）、mfs-4（GenBank登录号BE974945）和mfs-5（GenBank登录号BE974946）。（2）mfs-5进行全长序列克隆，获得的日本血吸虫新基因SjPP(GenBank登录号AY902477)长1311 bp, 编码302个氨基酸，理论分子量为34.7 kD，等电点为5.51；其氨基酸序列具有丝/苏氨酸蛋白磷酸酶（serine/threonine specific protein phosphatase，简称PP）的保守序列LRGNHE，并且含有该酶特异性抑制剂冈田酸的作用位点SAPNYC，与人的PP6、鼠PP6、果蝇PPⅤ等蛋白的氨基酸序列具有高度同源性，分别达72%、70%和70%。（3）成功构建核酸疫苗pCMV-Script／SjPP，免疫BALB/c小鼠诱导产生肝组织减卵率为23.91%，粪便减卵率为31.91%。【结论】（1）获得日本血吸虫新的抗原基因SjPP。（2）含SjPP基因的核酸疫苗在小鼠中诱导了部分免疫保护效果。 相似文献
19.
M A Goldman K R Stokes R L Idzerda G S McKnight R E Hammer R L Brinster S M Gartler 《Science (New York, N.Y.)》1987,236(4801):593-595
Mammalian X-chromosome inactivation involves a coordinate shutting down of physically linked genes. Several proposed models require the presence of specific sequences near genes to permit the spread of inactivation into these regions. If such models are correct, one might predict that heterologous genes transferred onto the X chromosome might lack the appropriate signal sequences and therefore escape inactivation. To determine whether a foreign gene inserted into the X chromosome is subject to inactivation, transgenic mice harboring 11 copies of the complete, 17-kilobase chicken transferrin gene on the X chromosome were used. Male mice hemizygous for this insert were bred with females bearing Searle's translocation, an X-chromosome rearrangement that is always active in heterozygous females (the unrearranged X chromosome is inactive). Female offspring bearing the Searle's translocation and the chicken transferrin gene had the same amount of chicken transferrin messenger RNA in liver as did transgenic male mice or transgenic female mice lacking the Searle's chromosome. This result shows that the inserted gene is not subject to X-chromosome inactivation and suggests that the inactivation process cannot spread over 187 kilobases of DNA in the absence of specific signal sequences required for inactivation. 相似文献
20.
Induction of self-tolerance in T cells but not B cells of transgenic mice expressing little self antigen 总被引：28，自引：0，他引：28
S Adelstein H Pritchard-Briscoe T A Anderson J Crosbie G Gammon R H Loblay A Basten C C Goodnow 《Science (New York, N.Y.)》1991,251(4998):1223-1225
Self-tolerance to a transgene-encoded protein, hen egg lysozyme, was examined in the T and B cell repertoires of a series of lines of transgenic mice that expressed different serum concentrations of soluble lysozyme. T cells were tolerant in all lines in which lysozyme was expressed irrespective of the antigen concentration, whereas B cell tolerance did not occur when the serum lysozyme concentration was less than 1.5 nanograms per milliliter (0.1 nM). Induction of elevated transgene expression could restore B cell tolerance. These findings support the hypothesis that autoimmune disease may in some instances arise through a bypass of T cell tolerance. 相似文献