Characterization of the Kilham Rat Virus

Kilham rat virus (KRV) was found to grow in a rat nephroma cell line and to form plaques on secondary rat embryo monolayers. The virus was purified by enzymatic treatment and isopycnic cesium chloride sedimentation. KRV bands at a density of 1.41 g/cm(3) in cesium chloride. It contains about 26.5% deoxyribonucleic acid (DNA). The sedimentation coefficient S(20,w) in sucrose gradients was 122 corresponding to a molecular weight of 6.6 x 10(6) daltons. The reaction of formaldehyde with the KRV virion suggests that the DNA in situ is single-stranded. DNA extracted from KRV had a buoyant density of 1.715 g/cm(3) in cesium chloride. The S(20,w) was determined in sucrose gradients to be 16, and the molecular weight was calculated to be approximately 1.7 x 10(6) daltons. The base composition of the DNA is 26.7% adenine, 30.8% thymine, 20.0% guanine, and 22.5% cytosine. On the basis of its noncomplementary nucleotide ratio, melting curve, and the reaction with formaldehyde, the DNA of KRV is believed to be single-stranded.     

Host Influence on the Antigenic Composition of the Kilham Rat Virus

The Kilham rat virus (RV) was found to vary in infectivity and antigenic characteristics when propagated in two different host systems. Both cross hemagglutination-inhibition (HI) and cross virus-neutralization tests revealed that a nonreciprocal or one way cross exists between RV propagated in rat embryo cell cultures (RE-RV) and RV propagated in suckling hamsters (H-RV). Specifically, immune serum to RE-RV inhibited hemagglutination and infectivity by both viruses to the same extent. Immune serum to H-RV, however, exhibited higher HI and neutralization titers to H-RV than to RE-RV. Infectivity studies demonstrated that, although both viruses were able to infect either host, the virus showed a higher infectivity titer for the last host in which it had been propagated. Serological studies indicated that H-RV possesses an antigen(s) not found on the RE-RV. This host-controlled variation did not result after a single passage in the new host, but rather required at least three passages for a complete conversion to occur, and did not appear to result from the incorporation of unaltered host antigens into the virus particle. Solubilization of purified RV propagated in each host with sodium dodecyl sulfate, 2-mercaptoethanol, and urea followed by electrophoresis in polyacrylamide gels indicated that the number of components in the protein of each virus was not the same.     

Linear, Single-Stranded Deoxyribonucleic Acid Isolated from Kilham Rat Virus

Kilham rat virus (KRV) was grown in a rat nephroma cell line and was purified by two isopycnic centrifugations in cesium chloride. The virus contains single-stranded deoxyribonucleic acid (DNA) with a molecular weight of approximately 1.6 x 10(6). The DNA was extracted from the virion by both phenol extraction and by 2% sodium dodecyl sulfate at 50 C. KRV DNA, extracted by both procedures, was observed in an electron microscope by using a cytochrome c or diethylaminoethyldextran monolayer. The DNA was also exposed to exonuclease I, an enzyme which hydrolyzes specifically linear, single-stranded DNA. Hydrolysis of 70 to 80% of the DNA was observed. Both the enzymatic and the electron microscope studies support the conclusion that extracted KRV DNA is a single-stranded, linear molecule. The length of the DNA was measured in the electron microscope and determined to be 1.505 +/- 0.206 mum.     

Inhibition of Mitosis and Macromolecular Synthesis in Rat Embryo Cells by Kilham Rat Virus

The effects of Kilham rat virus multiplication were studied in cultured rat embryo cells to examine the mechanisms by which virus infection might be related to developmental defects in rats and hamsters. The virus was found to inhibit motosis and deoxyribonucleic acid (DNA) synthesis within 2 to 10 hr after infection. However, total ribonucleic acid synthesis was relatively unaffected until about 20 hr after infection, and total protein synthesis did not decline significantly until loss of viable cells was apparent in the cultures. No effect on chromosomes was detected. The effect of Kilham rat virus on DNA synthesis appears to be due to inhibition of macromolecular synthesis rather than to an inhibition of uptake of precursors into cells. The effect of the virus on mitosis may be an addition to the effect on DNA synthesis, since mitosis is inhibited even in cultures in which cells are able to divide at the time of infection and which have presumably completed DNA synthesis.     

In Vivo Conversion of the Single-Stranded DNA of the Kilham Rat Virus to a Double-Stranded Form

Kilham rat virus (KRV) contains linear, single-stranded DNA in the virion. The fate of radioactive viral DNA was followed after infection of monolayer cells. Within 60 min after infection of cells, 28 to 42% of the parental viral DNA is converted to a new form. This new DNA form is believed to be double stranded and linear on the basis of its sedimentation in neutral and alkaline sucrose gradients, elution from hydroxyapatite columns, its buoyant density in equilibrium CsCl density gradients, and appearance in the electron microscope. The double-stranded linear KRV DNA may be analogous to the replicative form of certain bacteriophages, including phiX174, which contain single-stranded circular genomes.     

Enhancement of Murine Leukemia Virus Replication in Rat Tumor Cells Containing Rat C-Type Virus

The yield of Maloney leukemia virus (MLV) from MLV-infected rat cells was shown to be enhanced in rat cells containing rat C-type virus. The MLV produced in these cells was shown to be identical to murine-derived MLV and devoid of properties related to rat C-type virus.     

柑桔衰退病毒的提纯

从甜橙病株的嫩梢皮组织提纯柑桔衰退病毒(Citrus Tristeza Virus,CTV),冰冻组织按每克鲜组织加入5ml0.1mol/L Tris缓冲液pH8.4(内含0.15％Triton x—100)进行匀浆。经几次差速离心和两次PEG(分子量6,000)沉淀后,将获得的病毒粗提液铺在不连续蔗糖密度梯度液上,HITACHI RPS_(40)T转头30,000r/m离心3小时,收集位于300mg/ml和400mg/ml梯度层之间的分离带,洗脱、浓缩后获得CTV提纯物。提纯的CTV粒子大小为1.000—1,500x12urn,与美国的CTV抗血清起阳性反应。     

重组风疹病毒抗原的分离纯化

为了制备临床诊断用的风疹病毒抗原,建立了亲合色谱分离纯化的方法.风疹抗原以可溶性形式在大肠杆菌工程菌中获得高效表达,用GST亲合色谱在不变性的条件下直接从细菌裂解液中分离纯化.纯化的目的蛋白电泳为单一条带,EUISA试验表明,重组抗原与风疹病毒IgM阳性血清能特异反应,而与IgM阴性血清不反应,表明重组蛋白具有良好的抗原性,能满足临床检验要求.     

Purification and Properties of the Geminivirus Euphorbia Mosaic Virus

Euphorbia mosaic virus was purified from infected plants of Nicotiana benthamiana. Highest concentrations of virus particles were found in infected plant tissue between 10–12 days after inoculation. The enzyme driselase assisted in purification of the virus particles from the infected tissue yielding about 600 μg/kg of plant material. Purified preparations showed a maximum absorption at 260–263 nm and the ratio of absorption at 260 and 280 nm was 1.4. The viral nucleic acid was digestedby DNase I and S₁ Nuclease but not RNase A. A single coat protein with a MW of 32,000 d and two DNA bands with a MW 0.96 × 10⁶ d (2870 nucleotides) and 0.90 × 10⁶ d (2700 nucleotides) were associated with the purified virus particles. Virus specific DNA was isolated from infected tissue between 7 and 15 days after inoculations.     

肾综合征出血热病毒糖蛋白的提纯和鉴定

以感染肾综合征出血热病毒(HFRSV)的Vero E6细胞为材料,用免疫亲和层析结合制备聚丙烯酰胺凝胶电泳(PAGE)从感染细胞中提纯了HFRSV两种糖蛋白。先用免疫亲和层析从感染细胞的粗制抗原中获得含有四种蛋白的混合液,用[~3H]-氨基葡萄糖在感染细胞中标记病毒糖蛋白,观察到[~3H]-氨基葡萄糖只结合入78K和57K的病毒蛋白。再用制备SDS-PAGE从HFRSV混合液中提纯78K和57K两种蛋白。实验证明这两种糖蛋白均具中和抗原决定簇,57K的糖蛋白尚具血凝活性,初步鉴定表明这两种糖蛋白相当于文献报道的HFRSV G_1和G_2。     

Rat C-Type Virus induced in Rat Sarcoma Cells by 5-Bromodeoxyuridine

HALOGENATED derivatives of uridine are highly effective inducers of latent C-type RNA viruses^1,2 and have been successfully used to induce viruses identical to, or similar to, the C-type RNA tumour viruses in mouse, rat and human cells^3–6. In previous experiments we used 5-bromodeoxyuridine (BrUdR) for induction of focus-forming virus in non-productive rat cells that have been transformed by mouse sarcoma virus². We describe here the induction of a C-type RNA virus in the cells of the rat tumour cell line XC, which contains the Rous sarcoma virus genome⁷. The induced virus possesses the group specific (gs) antigens of rat C-type viruses but not those of chicken C-type viruses.     

SD大鼠视网膜小胶质细胞原代培养方法的改良

目的对经典的原代视网膜小胶质细胞体外纯化培养方法进行简单的改良以提高细胞产量。方法在视网膜小胶质细胞原代培养过程中以McCarthy等的经典方法为基础,寻找适当的初始种植密度,并在初次振荡分离后继续培养以获得多次产出,使用免疫细胞化学染色方法进行小胶质细胞纯度鉴定。结果视网膜小胶质细胞原代培养最宜初始种植密度为1×106/mL,多次分离纯化获得的视网膜小胶质细胞均达到97%以上的纯度。结论视网膜小胶质细胞原代培养过程中,以适当的初始种植密度和多次振荡分离方法可在保证有效纯度的基础上提高细胞产量。     

鼠肝中金属硫蛋白的纯化

旨在探索鼠肝中金属硫蛋白(MT)提取工艺并加以改进。按照经典方法工艺提取MT,用中空纤维柱超滤方法加以改进,依据MT自身特点进行分离和鉴定。结果显示,粗品符合MT特点:分子量在6.5kD左右;无280nm特征吸收峰,加酸后紫外吸收(200-300nm)肩峰消失;通过离子交换可以实现MT1、MT2的分离;通过原子吸收测定,含有锌、铜、镉3种金属,锌含量最高,具有重要的病理生理意义。因此,与其它方法比较,改进后方法更适宜实验室制备。