Human antibody reactivity against the lower matrix protein (pp65) produced by cytomegalovirus.

The lower matrix protein (pp65) is a major product of many laboratory strains of cytomegalovirus (CMV). It is thus an integral part of many CMV serological assays based on native antigen. Recombinant fragments of pp65 have previously been investigated for their usefulness in more-defined assays. The latter antigens have, however, failed to develop a positive response with serum samples derived from a substantial number of infected individuals. Here we show that the human humoral immune response to CMV pp65 is highly diverse and recognizes at least seven distinct but in some cases partly overlapping epitopes. Most of these epitopes could not be mimicked by any of the investigated recombinant or synthetic antigens. Furthermore, when we investigated the ability of human CMV-seropositive serum samples to block the reactivity of pp65-specific antibodies recognizing five different epitopes within pp65, it was evident that several sera did not contain significant levels of antibodies against any of these or overlapping structures. It was thus concluded that the antibody response against CMV pp65 is weak in some CMV-infected individuals, making this antigen unsuitable for use alone in serological screening systems for CMV infection.     

人源抗呼吸道合胞病毒基因工程单克隆抗体Fab段基因的筛选和表达

目的采用噬菌体表面呈现和重组抗体技术构建人噬菌体抗体基因库，筛选获得人源抗呼吸道合胞病毒（RSV）Fab段基因并在原核细胞中表达。为研制安全、有效的预防和治疗RSV感染的制剂奠定基础。方法从RSV感染患儿恢复期外周血淋巴细胞中提取细胞总RNA，用一组人IgGF出特异性引物，通过RT—PCR扩增得到一组轻链（κ和λ）和重链Fab段基因，并将此轻链和重链基因片段克隆于pComb3噬菌体载体，电转化XL1-Blu菌构建成抗RSV噬菌体抗体基因库。用纯化病毒颗粒作抗原对此抗体库进行了富集筛选，得到了特异性针对RSV的人源单克隆抗体Fab段基因，并在大肠杆菌中获得有效表达。用ELISA方法检测了此Fab抗体的抗原特异性，并对阳性克隆进行了基因序列分析。结果所构建的抗体库库容为108，从此抗体库中筛选得到的阳性克隆所表达的Fab抗体能与RSV纯化抗原特异性结合，保留了对RSV的抗原特异性。核苷酸序列分析证实，所获得的阳性克隆基因为人源IgG基因。结论本实验获得了特异性抗RSVFab抗体基因并在大肠杆菌中获得表达，表达产物能与RSV抗原特异性结合。     

The mode of attenuation of erythrocyte membrane Rh0(D) antigen activity by 5,5'-dithiobis-(2-nitrobenzoic acid) and protection against loss of activity by bound anti-Rh0(D) antibody

The Rh0(D) antigen activity of human erythrocyte membranes is lost on treatment with the aromatic disulfide, 5,5'-dithiobis-(2-nitrobenzoic acid), reacting by specific disulfide interchange with membrane thiols. The inactivation rate of the antigen was first order with respect to inhibitor concentration and a double reciprocal plot of the inactivation rate constants against the sulfhydryl reagent concentration was linear, giving an apparent dissociation constant of 1.25 mM and indicating that a binding step preceded covalent interaction. In a study of the binding characteristics of anti-Rh0(D) to the 2-nitro-5-thiobenzoate derivative of the membrane Rh0(D) antigen, the maximum number of binding sites fell with increasing sulfhydryl reagent concentration but the apparent association constant also diminished at the same rate. The inactivation of the Rh0(D) antigen was greatly retarded by the presence of bound anti-Rh0(D), a protective effect not seen with normal serum. Bound anti-Rh0(D) antibody protects against both the loss of sites and the change in affinity brought about by DTNB. It is concluded that a single critical thiol whose reactivity is altered by bound anti-Rh0(D) antibody is involved in the membrane Rh0(D) antigenic determinant site. These observations may permit extensive probing of the microenvironment of this essential cysteine residue.     

Establishment of a strategy for the rapid generation of a monoclonal antibody against the human protein SNEV (hNMP200) by flow-cytometric cell sorting

The screening for antigen-specific hybridoma cells with adequate production rates is still a time-, labour- and money-consuming procedure. A reduction in cell culture testing by specifically selecting those fused cells that produce antibody could therefore make hybridoma technology more attractive, even for small research groups or for newly discovered proteins at an early stage of research. Additional problems, such as the requirement to produce sufficient amounts of the unknown protein at a purity that allows specific immunisation of mice and testing of the resulting hybridoma clones, also need to be overcome. Here we present a new strategy to isolate rapidly and efficiently monoclonal antibodies against new proteins, for which only sequence information at the DNA level is known. The strategy consists of fusion of the protein to a hexa-His-tag to allow easy purification, production in yeast and insect cells to reduce background immunisation with host cell proteins and the selection of IgG-producing hybridoma cells by flow-cytometric cell sorting using the affinity matrix secretion assay technique.     

Expression,production, and renaturation of a functional single-chain variable antibody fragment (scFv) against human ICAM-1

Intercellular adhesion molecule-1 (ICAM-1) is an important factor in the progression of inflammatory responses in vivo. To develop a new anti-inflammatory drug to block the biological activity of ICAM-1, we produced a monoclonal antibody (Ka=4.19×10⁻⁸ M) against human ICAM-1. The anti-ICAM-1 single-chain variable antibody fragment (scFv) was expressed at a high level as inclusion bodies in Escherichia coli. We refolded the scFv (Ka=2.35×10⁻⁷ M) by ion-exchange chromatography, dialysis, and dilution. The results showed that column chromatography refolding by high-performance Q Sepharose had remarkable advantages over conventional dilution and dialysis methods. Furthermore, the anti-ICAM-1 scFv yield of about 60 mg/L was higher with this method. The purity of the final product was greater than 90%, as shown by denaturing gel electrophoresis. Enzyme-linked immunosorbent assay, cell culture, and animal experiments were used to assess the immunological properties and biological activities of the renatured scFv.     

条件培养液中杂交瘤生长因子对人—鼠杂交瘤生长、克隆化及抗体分泌的影响

本文报道了含有杂交瘤生长因子的人纤维母细胞系CRL1506和EB病毒转化经克隆化的人B淋巴母细胞系N23两种条件培养液,对分泌肾综合征出血热病毒人单克隆抗体的人-鼠杂交瘤和人—(人—鼠)杂交瘤细胞系的生长、克隆化及抗体分泌有明显促进作用,并排除了白细胞介素2和白细胞介素4作用的可能性。结合文献报道,初步认为来自这两种条件培养液的杂交瘤生长因子很可能含有白细胞介素6。正确选择促进人—鼠杂交瘤生长、克隆化和抗体分泌的条件培养液,对于克服生产人单克隆抗体杂交瘤技术所存在的融合率低、克隆化难、抗体产量少等困难具有较大的应用价值。     

Time course of protection by N,N'-Diphenyl-p-phenylendiamine (DPPD) against carbon tetrachloride hepatotoxicity

A preliminary treatment with DPPD (N,N'-diphenyl-p-phenylendiamine) prevents liver fatty infiltration early after carbon tetrachloride poisoning. Double bond shifting in microsomal lipids appears to be depressed 30 minutes after intoxication. A more active protection takes place when low doses of CCl₄ are given (25 μl per 100 g body weight) than after a large dose of the poison (250 μl). In later stages of the halogenoalkane challenge, both triglyceride accumulation and lipid peroxidation take place despite of the antioxidant treatment. However, they are less severe and more transient than in unprotected animals. Similarly, liver necrosis, as evidenced by changes in serum activity of alanine aminotransferase appears, to be prevented by DPPD. This compound does not interfere with the hepatic metabolism of carbon tetrachloride, as suggested by the findings of¹⁴C binding to liver lipids and exhalation of radioactive CO₂ after administration of¹⁴CCl₄. Moreover, pretreatment with antioxidant partially inhibits the in vitro demethylation of aminopyrine by liver microsomes and significantly potentiates the hypnotic effect of hexobarbital. Further, DPPD, when injected along with phenobarbital, blocks the barbiturate stimulation of microsomal enzymes. A combined dosing with both DPPD and CCl₄ causes a more severe inhibition of demethylase activity and hexobarbital metabolism. Our results indicate that DPPD can act as an inhibitor of the enzymes bound to the endoplasmic reticulum, beside its antioxidant properties, during CCl₄ intoxication.     

Production of a monoclonal antibody against the 128 kDa (CagA) protein of Helicobacter pylori

Helicobacter pylori is recognised as an important factor in gastroduodenal pathology. The 128 kDa CagA protein has been established as a useful marker of H. pylori strains associated with more severe forms of disease. A mouse monoclonal antibody raised against the CagA protein has been produced and characterised as belonging to the IgG1 subtype. It identified the protein in all clinical isolates (10/10) from this laboratory and in two NCTC reference strains (NCTC 11637 and NCTC 11961). No cross-reacting proteins were detected in H. pylori L2, a well characterised strain known not to contain the cagA gene, or in four Helicobacter sp. from non-human sources (H. canis, H. mustelidae, H. muridarum and H. acinonyx). The monoclonal antibody was used to develop an antigen capture ELISA system for detecting the presence of antibodies to the CagA protein in human serum samples.     

一种利用HCIC快速纯化抗rhTF_(243)单克隆抗体方法的研究

目的:建立从小鼠腹水中快速纯化抗人重组组织因子243(recombine human tissue factor243,rhTF243)单克隆抗体(monoclonal antibody,mAb)的方法。方法:含抗rhTF243单克隆抗体的腹水经离心、过滤及缓冲溶液变换等预处理后,先经疏水电荷诱导层析纯化处理,去除大部分杂蛋白,再经Protein A-Sepharose CL-4B亲和层析柱进一步纯化。结果:经两步纯化后获得抗rhTF243单克隆抗体,其生物学活性高、纯度大于95%,抗体效价保持良好,抗体总回收率达73%,且具有明显的抗促凝作用。结论:建立的单克隆抗体纯化方法简便、高效,所得mAb的纯度高、生物学活性好。     

5'-RACE法扩增抗人乳头瘤病毒16型L1蛋白单克隆抗体轻链可变区基因及序列分析

目的 获得抗人乳头瘤病毒16型(HPV16)L1蛋白单克隆抗体的轻链可变区(VL)基因并分析序列.方法 从分泌抗HPV16L1蛋白单克隆抗体的杂交瘤细胞中提取总RNA,逆转录形成cDNA,用5'-RACE策略扩增抗体轻链可变区基因,经琼脂糖凝胶电泳鉴定,并测序及进行序列分析.结果 VL基因全长336bp,编码112个氨基酸,基因测序结果符合小鼠抗体轻链可变区特征.结论 5'-RACE法成功获得了抗HPV16L1蛋白的单克隆抗体轻链可变区基因的真实序列,为基因工程抗体研究奠定了良好基础.     

Mapping of an epitope defined by a human hybridoma antibody (TrD3): a new HLA-B supertype associated with a subset of HLA-Bw6.

The new human-human hybridoma TrD3 secretes a cytotoxic IgM mAb, which reacted with 28 of a panel of 56 HLA-typed lymphoblastoid cells. All 28 TrD3+ cells expressed the HLA-B supertype Bw6, whereas 10 Bw6+ cells were not recognized by the mAb. None of the 17 Bw4 homozygous cells were positive with TrD3. Thus, TrD3 divided the Bw6+ HLA-B specificities of the cell lines into two subgroups, namely, Bw6+TrD3+ and Bw6+TrD3-, and therefore defines a new HLA-B supertype. TrD3 reacted strongly with some B8+ cell lines and weakly or not at all with others, suggesting a new split of HLA-B8. Compared with cell lines, TrD3 reacted more weakly with freshly isolated T cells from blood. The Bw6-specific rat mAb SFR8-B6 partially blocked the binding of 125I-labeled TrD3 to a Bw6+ cell line. By using cell lines transfected with hybrid genes between HLA-B7 (Bw6+) and HLA-B27 (Bw6-) as targets in flow cytometry, critical residues for the TrD3 epitope could be mapped to the amino acid region 24-62 of the HLA class-I alpha 1 domain. Comparison of deduced amino acid sequences of TrD3-positive and -negative cells indicated that a tryptophane residue at position 95 destroyed the TrD3 epitope, and that one or more of the residues in positions 24, 45, and 46 may be critical, suggesting that it is a discontinuous epitope. It is notable that none of these residues are located on alpha-helixes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of the antibody specificities of human convalescent-phase sera against the attachment (G) protein of human respiratory syncytial virus: influence of strain variation and carbohydrate side chains

The C-terminal third of the attachment protein (G) of several human respiratory syncytial virus isolates was obtained as either a glycosylated protease-resistant fragment of the purified protein or a nonglycosylated GST fusion protein expressed in bacteria. The reactivity of human convalescent-phase sera with both forms of the protein segment was evaluated in immunoblots. While all serum samples reacted with the mature intact protein of the different isolates, only certain samples reacted with the nonglycosylated C-terminal segment of some viral isolates. The number of human serum samples reacting with the glycosylated C-terminal fragment was even more limited. These results highlight the heterogeneity of the human antibody response against epitopes located in the C-terminal hypervariable region of the G molecule and the influence of carbohydrate side chains for expression of these epitopes. We also have analysed the specificities of human sera by competitive enzyme-linked immunosorbent assay with murine monoclonal antibodies (MAbs). Most human serum samples inhibited virus binding of MAbs that recognised conserved or group-specific epitopes of the G protein, while only a limited fraction of those samples inhibited binding of MAbs that recognised strain-specific epitopes. These results are discussed in terms of the antibody repertoire induced after human respiratory syncytial virus infection and the relevance of escape mechanisms to preexisting antibodies for the evolution of this virus.     

No association between a functional polymorphism in the promoter region of the neuropeptide Y gene (−485C > T) and schizophrenia

It has been suggested that hypoactivity of neuropeptide Y (NPY) may be involved in the pathophysiology of schizophrenia. A post-mortem study revealed a decreased level of NPY in the brain of patients with schizophrenia. An increased level of NPY after antipsychotic treatment was also reported in animal brain and cerebrospinal fluid of patients. Previously Itokawa et al. reported a positive association between the functional −485C > T polymorphism in the NPY gene and schizophrenia in a Japanese population. The aim of this study is to replicate their positive findings in an independent Japanese case-control sample. Our sample includes 260 patients with schizophrenia (DSM-IV) and 196 control subjects. No significant differences in distribution of genotype or allele frequencies between patients and controls were observed. Our results suggest that the NPY −485C > T polymorphism may not confer susceptibility to schizophrenia, at least in our sample. Further studies in larger samples are warranted.     

Survey of antibody against chicken anaemia agent (CAA) by an indirect immunofluorescent antibody technique in breeder flocks in Japan

Specific immunofluorescent antigens were detected in MDCC-MSB1 cells, a lymphoblastoid cell line from Marek's disease lymphoma, infected with chicken anaemia agent (CAA) by an indirect immunofluorescent antibody (IFA) technique. The large and small granular antigens were first recognised in a small proportion of the cells at 12 hours postinoculation (PI) with CAA. The antigen-positive cells increased gradually thereafter, and they were misshaped and stained irregularly, showing the occurrence of cytopathic effect, after 24 hours PI. Antibody against CAA was examined by an IFA test, in which the MDCC-MSB1 cells infected with CAA were used as a source of antigen, in breeder flocks in Japan. Thirty-nine out of 40 commercial breeder flocks (97.5%) were found to possess the antibody. Of the 381 individual serum samples, 357 (93.7%) were positive. Two positive flocks were found among the 19 specific-pathogen-free flocks examined, which have been maintained at our and six private research laboratories in Japan. The IFA test had the same sensitivity as the neutralisation test (NT) for detecting the antibody against CAA and could be performed more quickly and easily.     

The in vivo antibody response against exogenous antigens is not influenced by the mouse Bcg (Nramp1) gene.

The mouse Nramp1 (Bcg) gene on chromosome 1 exerts pleiotropic effects on macrophage function. The gene is known to affect presentation of mycobacteria, and other antigens in vitro, so that macrophages carrying the resistant Bcg allele better support the proliferation of antigen-specific T cells compared with macrophages of the sensitive phenotype. To determine whether the Bcg allele could affect in vivo the antibody response to antigens not related to mycobacterial infections, we tested the primary and secondary responses to sheep red blood cells (SRBC) and glycosylated bovine insulin (G-insulin) in two pairs of Bcg congenic strains: BALB/c (Bcgs) versus BALB/c.CD2 (Bcgr), and B10.A (Bcgs) versus B10Ar (Bcgr), and in C57BL/10ScSn (B10; Bcgs) and A/J (Bcgr) mice. Furthermore, the antigen-specific proliferative responses of T cells primed in vivo by protein antigens were also tested in Bcg congenic mice. We found no significant difference in in vivo antibody response either to SRBC or G-insulin between the Bcgr and Bcgs strains. The magnitude of in vitro antigen-specific proliferation of lymph node cells sensitized in vivo by hen egg lysozyme (HEL) or chicken ovalbumin (OVA) was also similar in Bcgs and Bcgr congenic mice. However, we have documented a higher antigen-presenting capacity of Bcgr macrophages in in vitro antigen-specific proliferation to OVA. Since the macrophages are the only cells in which the Nramp1 gene is expressed, we suggest that the activity of other types of antigen-presenting cells masks the effect of the Bcgr allele on antigen-presentation in vivo.     

RASA, a recombinant single-chain variable fragment (scFv) antibody directed against the human sperm surface: implications for novel contraceptives

BACKGROUND: A recombinant single-chain variable fragment (scFv) antibody was engineered to a tissue-specific carbohydrate epitope located on human sperm agglutination antigen-1 (SAGA-1), a sperm glycoform of CD52. METHODS AND RESULTS: cDNAs encoding the variable regions of the S19 [IgG(1)kappa] monoclonal antibody (mAb) were identified, linked, and cloned into the pCANTAB 5E vector. The recombinant anti-sperm antibody (RASA) was expressed in E. coli HB2151 cells as a 29 kDa monomer and, remarkably, also formed multimers of approximately 60 and 90 kDa. RASA reacted with the endogenous SAGA-1 antigen by Western blot analysis, labelled the entire human sperm surface by indirect immunofluorescence, and aggregated human spermatozoa in a tangled (head-to-head, head-to-tail, tail-to-tail) pattern of agglutination, as was also observed with the native S19 mAb. CONCLUSIONS: These results demonstrate that active recombinant antibodies can be produced to a tissue-specific carbohydrate epitope on the human sperm surface, thereby opening opportunities for novel contraceptive agents.