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51.
Regarding biological products, increasing awareness of potential side effects have placed great importance not only at protein
purity regarding other proteins but on the removal of biologicals such as DNA and especially virus the importance of which
may not be known. Monoclonal antibodies (Mab) have come to be an important class of molecules obtained from hybridoma cells,
i.e., nonrecombinant cells in culture. It has been noted during the last years, that with rare exceptions hybridoma cell lines
contain retrovirus like particles. The infectious nature of the EM-visible particles has been tested for, however, in most
cases not been substantiated. In order to bring these valuable biological reagents, Mab's, to good use in man for imaging
or therapy, the remaining concern about a potential retroviral infection has to be reduced to an acceptable minimum. We describe
experimental approaches for the validation of chromatographic and ultrafiltration steps used in the production of monoclonal
antibodies to remove and inactivate murine retrovirus.
Present day biotechnological manufacturing processes have been devised incorporating a number of strategic preventive measures
that have found wide spread acceptance. They permit to answer the question: how can a potentially harmful infection by an
unknown virus be excluded.
Knowledge of the efficacy of purification steps to clear infectious model virus is fundamental to devise biotechnological
manufacturing processes yielding a purified antibody for use in man. 相似文献
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Gene structure and expression of a tobacco endochitinase gene in suspension-cultured tobacco cells 总被引:8,自引:0,他引:8
We have isolated and characterized the genomic clone CHN50 corresponding to tobacco basic endochitinase (E.C.3.2.1.14). DNA sequence and blotting analysis reveal that the coding sequence of the gene present on CHN50 is identical to that of the cDNA clone pCHN50 and, moreover, the CHN50 gene has its origin in the progenitor of tobacco, Nicotiana sylvestris. Tobacco basic chitinases are encoded by a small gene family that consists of at least two members, the CHN50 gene and a closely related CHN17 gene which was characterized previously. By northern blot analysis, it is shown that the CHN50 gene is highly expressed in suspension-cultured tobacco cells and the mRNA accumulates at late logarithmic growth phase. To identify cis-DNA elements involved in the expression of the CHN50 gene in suspensioncultured cells, the chimeric gene consisting of 1.1 kb CHN50 5 upstream region fused to the coding sequence of -glucuronidase (GUS) was introduced by electroporation into protoplasts isolated from suspension-cultured tobacco cells. Transient GUS activity was found to be dependent on the growth phase of the cultured cells, from which protoplasts had been prepared. Functional analysis of 5 deletions suggests that the distal region between -788 and -345 contains sequences that potentiate the high-level expression in tobacco protoplasts and the region (-68 to -47) proximal to the TATA box functions as a putative silencer. 相似文献
54.
Tracey C. Bourner Enrique Vargas‐Osuna Trevor Williams Candido Santiago‐Alvarez Jenny S. Cory 《Biocontrol Science and Technology》1992,2(4):315-326
Agrotis segetum nuclear polyhedrosis virus (AsNPV) and granulosis virus (AsGV), propagated in laboratory cultures of A. segetum in England and A. ipsilon in Spain, respectively, were applied to plots of maize plants at the one‐ to four‐leaf stage of growth. Plots were arranged in a 6 x 6 Latin square design and infested with second‐instar A. segetum larvae (the common cutworm). Each virus was applied in separate treatments by two application methods; as an aqueous spray containing 0.1% Agral as a wetting agent, and as a bran bait. The NPV was applied at a rate of 4 X 1012 polyhedra/ha, and the GV at 4 X 1013 granules/ha. Soil and plants were sampled for larvae on three occasions following virus treatment: 24 h, 4 days and 11 days. The larvae were reared on diet in the laboratory, until death or pupation, to examine the rate and level of viral infection. Infection data showed 87.5% and 91% NPV infection and 12.5% and 55% GV infection in spray and bait treatments, respectively, in larvae sampled 24 h after treatment. In larvae sampled 4 days after treatment, the results were 78% and 100% NPV infection, and 13% and 6% GV infection. A total of only six larvae were retrieved on day 11. In both treatments larvae infected with AsNPV died significantly more rapidly and at an earlier instar than those infected with AsGV, indicating that AsNPV appears to have better potential as a control agent for A. segetum. 相似文献
55.
The potato has tremendous potential as a transgenic crop and is a good model system by which to analyse metabolic regulation
and gene expression. The potato’s difficult genetics, but ease of genetic transformation and its clonal means of propagation
make it ideal for applied agricultural molecular genetics. Thus, the next 4 years promise to put the potato (with a diversity
of transgenic constructs expressed) in the limelight as many of the first transgenic agricultural products enter the marketplace. 相似文献
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几种药物抑制马传染性贫血病毒和人免疫缺陷病毒的实验研究 总被引:1,自引:0,他引:1
用马传染性贫血病毒—驴胚肺二倍体细胞(EIAV-DELDC)为实验体系,以细胞中病毒逆转录酶活性及病毒相关抗原的表达为观察指标,检测了叠氮胸苷(AZT)、三氮唑核苷(Ribavirin,病毒唑)、磷羧基甲酸钠(PFA)和苏拉明等4种已知抗人免疫缺陷病毒(HIV-1)药物对马传染性贫血病毒的抑制作用。结果表明,PFA、AZTTP(三磷酸AZT)和苏拉明均能抑制病毒相关抗原的表达,AZT虽无此作用,但能抑制细胞内逆转录酶活性。用~3H-TMP掺入法比较了PFA、AZTTP、苏拉明对体外无细胞系EIAV逆转录酶粗提物和HIV-1基因工程产物逆转录酶活性的抑制作用表明,两种逆转录酶对苏拉明的敏感性相近,而HIV-1逆转录酶对PFA和AZTTP的敏感性较EIAV者高约100倍。又以无细胞系中逆转录酶活性测定法,检测了12种中药提取物的抑制作用,其中小柴胡汤对EIAV和HIV-1逆转录酶活性都有抑制作用,IC_(50)为717μg/ml和700μg/ml(生药浓度)。小柴胡汤对两种病毒感染细胞中抗原的表达和HIV引起细胞病变都有抑制作用,对HIV-1的抑制比EIAV强。这些结果表明,EIAV-DELDC体系可考虑作为抗HIV-1药物筛选模型。 相似文献