Immunogenicity and protective role of antigenic regions from five outer membrane proteins of Flavobacterium columnare in grass carp Ctenopharyngodon idella

Flavobacterium columnare causes columnaris disease in freshwater fi sh. In the present study, the antigenic regions of fi ve outer membrane proteins(OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 k Da, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purifi ed recombinant protein was used to vaccinate the grass carp, C tenopharyngodon idella. Following vaccination of the fi sh their Ig M antibody levels were examined, as was the expression of I g M, Ig D and Ig Z immunoglobulin genes and other genes such as MHC Iα and MHC I I β, which are also involved in adaptive immunity. Interleukin genes( IL), including I L- 1β, IL- 8 and I L- 10, and type I and type II interferon(I FN) genes were also examined. At 3 and 4 weeks post-vaccination(wpv), signifi cant increases in Ig M antibody levels were observed in the fi sh vaccinated with the recombinant fusion protein, and an increase in the expression levels of I g M, Ig D and Ig Z genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fi sh. At four wpv, the fi sh were challenged with F. column a re, and the vaccinated fi sh showed a good level of protection against this pathogen, with 39% relative percent survival(RPS) compared with the control group. It can be concluded, therefore, that the fi ve OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fi sh and protection against F. columnare.

Evaluation of spatial epitope computational tools based on experimentally-confirmed dataset for protein antigens

Antibody molecules interact with antigen proteins through the epitope area,where the epitope residues are found to be discontinuous or spatial or conformational rather than linear on the protein surface.There are various computational algorithms to predict the spatial epitopes,and each of them have an outstanding performance based on their individual testing dataset.In this work,an independent dataset was created through collection of the epitope residual sites which have been confirmed by experiments. Based on this dataset,6 popular web-servers developed for B-cell structural epitope prediction,including SEPPA,CEP,DiscoTope,ElliPro,PEPOP and BEpro,were evaluated and compared according to sensitivity,the positive predictive value,the successful pick-up rate and the area under the curve of the receiver operator characteristic(AUC).The results showed that the general performance of spatial epitope prediction tools did obtain substantial advancement,and SEPPA gave the best performance among the 6 tools.However,the current prediction accuracy was still far from satisfaction.Moreover,our comparison elucidated that the performance of the web-servers was significantly affected by their training datasets and the algorithms adopted.In this sense,the results of our research may improve the design of B-cell epitope prediction tools and provide additional clues when the users utilize these tools in their related research.

Human antigen R mediated post-transcriptional regulation of inhibitors of apoptosis proteins in pancreatic cancer

AIM To determine the association of human antigen R(HuR) and inhibitors of apoptosis proteins(IAP1, IAP2) and prognosis in pancreatic cancer.METHODS Protein and mRNA expression levels of IAP1, IAP2 and HuR in pancreatic ductal adenocarcinoma(PDAC) were compared with normal pancreatic tissue. The correlations among IAP1/IAP2 and HuR as well as their respective correlations with clinicopathological parameters were analyzed. The Kaplan-Meier method and log-rank tests were used for survival analysis. Immunoprecipitation assay was performed to demonstrate HuR binding to IAP1, IAP2 mRNA. PANC1 cells were transfected with either anti-HuR siRNA or control siRNA for 72 h and quantitative reverse transcription polymerase chain reaction(RT-PCR), western blot analysis was carried out.RESULTS RT-PCR analysis revealed that HuR, IAP1, IAP2 mRNA expression were accordingly 3.3-fold, 5.5-fold and 8.4 higher in the PDAC when compared to normal pancreas(P < 0.05). Expression of IAP1 was positively strongly correlated with HuR expression(P < 0.05, r = 0.783). Western blot analysis confirmed RTPCR results. High IAP1 expression, tumor resection status, T stage, lymph-node metastases, tumor differentiation grade, perineural and lymphatic invasion were identified as significant factors for shorter survival in PDAC patients(P < 0.05).Immunohistological analysis showed that HuR was mainly expressed in the ductal cancer cell's nucleus and less so in cytoplasm. RNA immunoprecipitation analysis confirmed IAP1 and IAP2 post-transcriptional regulation by HuR protein. Following siHuR transfection, IAP1 mRNA and protein levels were decreased, however IAP2 expression levels were increased.CONCLUSION HuR mediated overexpression of IAP1 significantly correlates with poor outcomes and early progression of pancreatic cancer. Further studies are needed to assess the underlying mechanisms.

Comparisons of voided urine cytology, nuclear matrix protein-22 and bladder tumor associated antigen tests for bladder cancer of geriatric male patients in Taiwan, China

Aim： To compare the results of bladder tumor associated antigen （BTA TRAK）, nuclear matrix protein 22 （NMP 22） and voided urine cytology （VUC） in detecting bladder cancer. Methods： A total of 135 elderly male and 50 healthy volunteers enrolled in this study were classified into three groups： （i） 93 patients with bladder cancer; （ii） 42 patients with urinary benign conditions; and （iii） 50 healthy volunteers. BTA TRAK and NMP 22 kits were used to detect bladder cancer. Voided urine cytology was used to compare the sensitivity and specificity of the screening tests. Results： The sensitivity and specificity of cytology, BTA TRAK and NMP 22 were 24% and 97%, 51% and 73%, 78% and 73%, respectively. The level of NMP 22 increased with tumor grading. The BTA TRAK kit has the lowest sensitivity among the screening tests. The NMP 22 with the best sensitivity can be an adjunct to cytology for evaluating bladder cancer. Conclusion： The NMP 22 test has a better correlation with the grading of the bladder cancer than BTA TRAK. As cytology units are typically not available in hospitals or in outpatient clinics, NMP 22 might be a promising tool for screening bladder cancer.

EXPRESSION OF P53 PROTEIN AND PROLIFERATING CELL NUCLEAR ANTIGEN IN HUMAN GESTATION TROPHOBLASTIC DISEASE

To study the relationship between p53 protein, proliferating cell nuclear antigen (PCNA) expression and benign or malignant gestational trophoblastic disease (MGTD). Methods: The histotomic sections of 48 patients with gestational trophoblastic disease and 24 patients of normal chorionic villi were stained using immunohistochemistry. The monoclonal antibodies were used to determine p53 protein and PCNA. Results: The frequency of p53 and PCNA positive expression were significantly different among the chorionic villi of normal pregnancy, hydratidiform mole (HM) and MGTD. But neither p53 nor PCNA has any relation with the clinical staging or metastasis of MGTD. Conclusion: Both P53 and PCNA are valuable in diagnosis of human gestational trophoblastic disease.

An efficient fusion protein system for expression of Bacillus anthracis protective antigen as immunogenic and diagnostic antigen

Objective:To produce high quantities of recombinant protective antigen(rPA) for human vaccine and diagnosis.Methods:The PA gene was amplified by PCR with pXO1 plasmid as template. The PCR product was cloned into pMAL-c2X vector using the BamH1 and SalI restriction enzymes.The recombinant plasmid was transformed into Escherichia coli DH5 a strain and then screened for transformation.The expression of protective antigen was analyzed by SDS-PAGE and Western blotting after isopropyl β-D-thiogalactopyranoside(IPTG) induction.Results: The full-length PA gene(2.2 kb) was cloned into pMAL vector system.The recombinant vector was confirmed by restriction enzyme and PCR analysis.The expression of cytoplasmic maltose-binding protein-protective(MBP-P) antigen fusion protein was detected by SDS-PAGE and Western blotting,and obtained a 125 kDa protein band,which was similar to expected size of fusion protein.Conclusions:This expression system can be used in the high production of rPA. After purification and immunization studies,the purified rPA may be used in the development of the human recombinant anthrax vaccine and also in diagnosis of anthrax disease.

Effects of heat shock protein-antigen peptide complexes (HACs) in melanoma B16 cell line on transplanted tumor development in mice

目的 :建立黑色素瘤 B16细胞热休克蛋白 -抗原肽复合物 (HACs)的制备方法并测其抑瘤效应。方法 :应用 Sephacryl S- 2 0 0凝胶过滤制备 HAC粗提物 ,应用 SDS- PAGE纯化 HACs,并测其抑瘤效应。结果 :应用 SDS- PAGE纯化的 HAC6 0、 HAC75和 HAC97不同程度地降低肿瘤发生率 ,延迟肿瘤发生时间和减慢肿瘤生长速度。结论 :6 0 0 0 0～ 970 0 0

The Secondary Structure of Heated Whey Protein andIts Hydrolysates Antigenicity

Fourier transform infrared spectroscopy(FTIR) and circular dichroism(CD) were used to investigate the conformational changes of heated whey protein(WP) and the corresponding changes in the hydrolysates immunoreactivity were determined by competitive enzyme-linked immunosorbent assay(ELISA).Results showed that the contents of α-helix and β-sheet of WP did not decrease much under mild heating conditions and the antigenicity was relatively high;when the heating intensity increased(70 ℃ for 25 min or 75 ℃ for 20 min),the content of α-helix and β-sheet decreased to the minimum,so was the antigenicity;However,when the WP was heated at even higher temperature and for a longer time,the β-sheet associated with protein aggregation begun to increase and the antigenicity increased correspondingly.It was concluded that the conformations of heated WP and the antigenicity of its hydrolysates are related and the optimum structure for decreasing the hydrolysates antigeniity is the least content of α-helix and β-sheet.Establishing the relationship between the WP secondary structure and WP hydrolysates antigenicity is significant to supply the reference for antigenicity reduction by enzymolysis.

The development of a recombinant hybrid protein of Plasmodium falciparum and analysis of its antigenicity and protectivity

A hybrid gene encoding several putative protective epitopes from erythrocytic stage antigens (MSA1,MSA2 and RESA) of P. falciparum as well as exgenous T cell enhancer epitopes from interleukin-1 and tetanus toxin was synthesized chemically. This gene (named HGFC) was cloned and connected with another hybrid gene (HPFA) synthesized previously to make a bigger hybrid gene (HGFCAC). HGFC and HGFCAC were cloned in an expression vector pWR450-1 and transformed into E. Coli JM109. The engineered bacteria could express fusion proteins with molecular weights of 65 and 77 kDa after inducing with isopropylthio-β-D-galactoside (IPTG). The expression rate was about 35% of total bacterial proteins. The expressed products showed sepcific immunological reaction with rabbit antibodies against P. falciparum peptide Glu-Glu-Asn-Val-Glu-His-Asp-Ala (EENVEHDA)by Western blotting. The fusion proteins were pruified by precipitation with amonium sulfate. gel filtration and ion-exchange chromatography and the purity was 82%. The purified protein reacted specifically with mouse immune serum against falciparum blood stage antigens by dot enzyme-linked immunosorbent assay (dot-ELISA).The fusion protein was emulsified with Freund's complete adjuvant (FCA) and used to immunize rabbits. The immune serum can recognize P. falciparum erythrocytic stage antigens of Fcc-1/HN strain and Yunnan strain and had weak cross reaction with P. vivax,but had no reaction with P. cynomlogi and P. berghei antigens. The protective effect of the antibody was tested by in vitro inhibition test to cultured falciparum parasites. Preliminary results indicated that the immune sera could effectively reduce the invasion rates of the parasites to red blood cells and inhibit the growth of the in vitro cultured falciparum parasites. The inhibitory capacity of the immune sera to parasite invasion is enhanced as the amount of the sera increases and the incubation time of the sera with the parasites is prolonged.It was shown that after 72 h incubation at 20% concentration with the parasites, the serum can suppress the multiplication of P.falciparum growth in vitro to a level of 80%.The immune sera caused dispersion of the parasite cytoplasm,atrophy of parasites,agglutination of free merozoites and degeneration of schizonts.

THE LA ANTIGEN INHIBITS THE ACTIVATION OF THE INTERFERON-INDUCIBLE PROTEIN KINASEPKR BY SEQUESTERING AND UNWINDING DOUBLE-STRANDED RNA

The La (SS-B) autoimmune antigen is an RNA-binding protein that is present in both nucleus and cytoplasm of eukaryotic cells.The spectrum of RNAs that interact with the antigen includes species which also bind to the interferon-inducible protein kinase PKR.We have investigated whether the La antigen can regulate the activity of PKR and have observed that both the autophosphorylation of the protein kinase that accompanies its activation by dsRNA and the dsRNA-dependent phosphorylation of the subunit of polypeptide chain initiation factor eIF-2 by PKR are inhibited in the presence of recombinant La antigen. This inhibition is partially relieved at higher concentrations of dsRNA.Once activated by dsRNA the protein kinase activity of PKR is insensitive to the La antigen. We have demonstrated by a filter binding assay that La is a dsRNA binding protein.Furthermore, when recombinant La is incubated with a 900bp synthetic dsRNA or with naturally occurring reovirus dsRNA it converts these substrates to single-stranded forms.We conclude that the La antigen inhibits the dsRNA-dependent activation of PKR by binding and unwinding dsRNA and that it may therefore play a role in the regulation of this protein kinase in interferon-treated or virus-infected cells.

Abnormal expressions of proliferating cell nuclear antigen and P27 protein in brain glioma

Both proliferating cell nuclear antigen and P27 protein are important factors to regulate cell cycle. While, the combination of them can provide exactly objective markers to evaluate prognosis of patients with brain glioma needs to be further studied based on pathological level. OBJECTIVE： To observe the expressions of proliferating cell nuclear antigen and P27 protein in both injured and normal brain glioma tissues and analyze the effect of them on onset and development of brain glioma. DESIGN： Case contrast observation. SETTING： Department of Neurosurgery, the Second Affiliated Hospital of Xi＇an Jiaotong University. PARTICIPANTS： A total of 63 patients with brain glioma were selected from Department of Neurosurgery, the Second Affiliated Hospital of Xi＇an Jiaotong University from July 1996 to June 2000. There were 38 males and 25 females and their ages ranged from 23 to 71 years. Based on pathological classification and grading standards of brain glioma, patients were divided into grade I - II （n=30） and grade III- IV （n = 33）. All cases received one operation but no radiotherapy and chemiotherapy before operation. Sample tissues were collected from tumor parenchyma. Non-neoplastic brain tissues were collected from another 12 non-tumor subjects who received craniocerebral trauma infra-decompression and regarded as the control group. There were l0 males and 2 females and their ages ranged from 16 to 54 years. The experiment had got confirmed consent from local ethic committee and the collection was provided confirmed consent from patients and their relatives. All samples were restained with HE staining so as to diagnose as the brain glioma. While, all patients with brain glioma received radiotherapy after operation and their survival periods were followed up. METHODS： Primary lesion wax of brain glioma was cut into serial sections and stained with S-P immunohistochemical staining. Brown substance which was observed in tumor nucleus was regarded as the positive expressions of both proliferating cell nuclear antigen and P27 protein. Automatic imaging analytic system was used to quantitatively analyze staining results of tumor. MAIN OUTCOME MEASURES： To compare the expressions of proliferating cell nuclear antigen and P27 protein in brain glioma tissues and non-tumor brain tissues and investigate the effect of various sexes, ages, survival periods and severities on the expressions of them in brain tissues. RESULTS： There was no significant difference of sexes and ages in the expressions of proliferating cell nuclear antigen and P27 protein （P 〉 0.05）; however, the expressions of proliferating cell nuclear antigen and P27 protein were milder in non-tumor brain tissues than those in the brain glioma tissues （P 〈 0.05）. Expression of proliferating cell nuclear antigen in brain tissue of grade III- IV severity was stronger than that of grade I - II severity, and the expression in ≥ 5-year survival periods were also stronger than that in 〈 5-year survival periods （P 〈 0.05）. In addition, expression of P27 protein in brain tissue of grade III- IV severity was stronger than that of grade I - II severity, and the expression in ≥ 5-year survival periods were also stronger than that in 〈 5-year survival periods （P 〈 0.05）. CONCLUSION： Abnormal expressions of proliferating cell nuclear antigen and P27 protein in human brain glioma are closely related to onset, development and prognosis of tumor.

<i>Mycoplasma hominis</i>Variable Adherence-Associated Antigen: A Major Adhesin and Highly Variable Surface Membrane Protein

Mycoplasma hominis is a member of the genus mycoplasma and has only been isolated from humans. It is most frequently isolated from the urogenital tract in the absence of symptoms, but has been isolated from wounds, brain abscess, inflamed joints, blood and placenta from pregnancy with adverse outcomes (especially preterm birth and occasionally term stillbirth). Controversy surrounds whether this organism is a commensal or a pathogen;however, Mycoplasma hominis has been shown to induce preterm birth and foetal lung injury in an experimental primate model as a sole pathogen. These bacteria are known to exist as a parasitic infection, due to a number of missing synthetic and metabolism pathway enzymes from their minimal genome;therefore, the ability to adhere to host cells is important. Here we provide a review that clarifies the different nomenclature (variable adherence-associated antigen and P50) that has been used to investigate the major surface adhesin for this organism, as well as reported mechanisms responsible for turning off its expression. Variation in the structure of this protein can be used to separate strains into six categories, a method that we were able to use to distinguish and characterise 12 UK strains isolated from between 1983 and 2012. We propose that the Vaa should be used in further investigations to determine if commensal populations and those that are associated with disease utilise different forms of this adhesin, as this is under-studied and identification of pathogenic determinants is overdue for this organism.

Combined Detection of Serum Heat Shock Protein-90<i>α</i>and Prostate Specific Antigen for Prostate Cancer Diagnosis

Objective: To explore the relationship between heat shock protein-90α (HSP-90α) and occurrence of prostate cancer, and clinical value of combined detection of serum HSP-90α and prostate specific antigen (PSA) in the diagnosis of prostate cancer. Method: A total of 30 patients with prostate cancer, 30 patients with benign prostatic hyperplasia (BPH) and 30 healthy men (control group) were selected from September 2018 to September 2019, then to detect levels of serum HSP-90α, total PSA and free PSA (FPSA) by ELISA, serum testosterone level by radioimmunoassay, prostate cancer tissue was removed by operation, and relative expression of tissue HSP-90α protein by Western blot. Results: The levels of serum HSP-90α and total PSA in prostate cancer group were significantly higher than other two groups, and testosterone level was lower than other two groups (P < 0.05);there was no difference of serum FPSA level between the three groups (P > 0.05). It was found by Pearson test that serum HSP-90α was positively correlated with total PSA level (r = 0.659, P = 0.005), while negatively correlated with testosterone level (r = -0.549, P = 0.006). According to TNM stage of prostate cancer, there were 17 cases of stage I - II, 13 cases of stage III - IV, 6 cases of Gleason score 1 - 4, 13 cases of 5 - 7, 11 cases of 8 - 10, tumor diameter range from 0.8 to 6.2 cm, with average of (3.9 ± 1.5) cm. The relative expression of HSP-90α protein in tumor tissue was closely related to TNM stage, Gleason score and tumor diameter (P < 0.05). By ROC analysis, it was found that accuracy of combined detection of serum HSP-90α and PSA levels for prostate cancer diagnosis was 0.896, and that of single PSA detection was 0.852. Conclusion: Higher expressions of HSP-90α in prostate cancer tissue and serum may be closely related to occurrence and development of prostate cancer, and combined detections of serum HSP-90α and PSA levels are of great significance in improving early diagnosis of prostate cancer.

Diversity of Helicobacter pylori isolates in expression of antigens and induction of antibodies

AIM: To obtain evidence for selection of antigens used in genetically engineered vaccine against Helicobacter pylori (H pylori). METHODS: Enzyme linked immunoabsorbent assay (ELISA) was established on the basis of recombinant protein antigens rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB of H pylori to detect expression rates of the antigens in bacterial isolates as well as positive rates of the antibodies in sera from H pylori-infected patients. PCR was applied to the detection of carrying rates of the genes encoding antigens in the isolates. RESULTS: The outputs of rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB were approximately 35%, 32%, 15%, 23%, 56%, 25% and 20% of the total bacterial proteins, respectively. One hundred and fifty-one strains of H pylori were isolated from 347 biopsy specimens of chronic gastritis, peptic ulcer or gastric adenocarcinoma, with a positive rate of 43.5%. All of the isolates expressed UreB, HpaA, FlaA and FlaB while 52.3%, 92.1% and 93.4% of the isolates expressed VacA, CagA and NapA, respectively. In the sera of 151 H pylori-infected patients, the positive ratesof IgG antibodies against UreB, HpaA, VacA, CagA, NapA, FlaA and FlaB were 100%, 87.4%, 43%, 71.5%, 89.4%, 84.8% and 79.5%, respectively. Furthermore, the expression frequencies of VacA and NapA were found to be relative to the severity of gastric diseases (P = 0.016 and P < 0.0001, respectively). CONCLUSION: UreB antigen is the top option of developing genetically engineered vaccine against H pylori followed by NapA or HpaA.

Electrochemical Impedance Analysis of Biofunctionalized Conducting Polymer-Modified Graphene-CNTs Nanocomposite for Protein Detection

We report an electrodeposited poly(pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen(cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI detection.The results show that the hybrid exhibits a pseudo capacitive behaviour with a maximum phase angle of 49° near 1 Hz,which is due to the inhomogeneous and porous structure of the hybrid composition. The constant phase element of copolymer is 0.61(n = 0.61), whereas, it is 0.88(n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic(R_(et)) on cTnI immunoreaction for spiked human serum in the concentration range of 1.0 pg mL^(-1)–10.0 ng mL^(-1). The sensitivity of the transducer is 167.8 ± 14.2 Ω cm^2 per decade, and it also exhibits high specificity and good reproducibility.

禽白血病病毒p27蛋白单克隆抗体制备及抗原表位的鉴定

为制备禽白血病病毒(ALV)p27蛋白特异性单克隆抗体,利用原核表达系统表达并纯化ALV p27蛋白,将其作为免疫原免疫注射Balb/c小鼠,用杂交瘤细胞融合和ELISA等筛选出阳性单克隆抗体细胞,对制备的单克隆抗体的抗体亚型、效价及特异性进行鉴定,将目的蛋白截短成4段,初步鉴定单克隆抗体识别的抗原表位区域。结果表明,共筛选出4株单克隆细胞,其抗体亚类皆为IgG1型,其中3A1抗体效价为1∶64000,3B2为1∶256000,5F1为1∶128000,5G2为1∶8000;4株单克隆抗体识别的抗原表位在1-60 aa之间。研究结果为进一步建立ALV相关免疫学检测方法提供了重要的材料。

Neuron specific enolase,p53蛋白和proliferating-cell nuclear antigen在肺癌组织中的表达及意义

目的：研究神经元特异性烯醇化酶（neuronspecificenolase，NSE）的表达，与p53蛋白和增殖细胞核抗原（prolif－erating－cellnuclearantigen，PCNA）表达的关系及意义．方法：用特异性鼠抗人单克隆抗体，按LSAB免疫组织化学方法检测石蜡包埋的肺癌标本中NSE，p53蛋白和PCNA的表达．结果：在小细胞性肺癌（SmallCellLungCancer，SCLC）中，NSE阳性表达者，PCNA标记指数（LabellingIndex，LI）高于NSE阴性者，而p53蛋白的表达与NSE的表达无关．在非小细胞性肺癌（non－smallcelllungcancr，non－SCLC）中，p53蛋白的表达和PCNALI均与NSE的表达无关．结论：在SCLC的发生及发展过程中，神经内分泌功能可能起了部分作用．而p53抑癌基因在SCLC的发生中并不起着重要的作用．

Genotypic Analysis, Construction of the Expression System and Immunological Identification of the Recombinant Proteins of the LipL32 Gene in the Dominant Serogroups of Leptospira interrogans in China

To investigate the existence of the major outer membrane protein (MOMP) gene LipL32 in 15 dominant Chinese strains of 15 serogroups of Leptospira interrogans and 2 international strains of 2 serogroups of Leptospira biflexa, and to clone and construct the expression system as well as to identify the recombinant proteins, genomic DNAs from strains of leptospira were prepared by routine phenol-chloroform method, and the fragments of the LipL32 gene with the whole length from the strains were amplified with high fidelity PCR. The target amplification products were sequenced after T-A cloning, and the expression system for the genes were thereby constructed. Expression of the recombinant proteins was identified by using SDS-PAGE after induction with IPTG at different dosages. Western blot assays with rabbit antiserum against the whole cell of TR/PatocⅠ of Leptospira and immunized serum with rMOMPs were used to determine the immunoreactivity and immunogenicity of the recombinant proteins. Microscopic agglutination test was used to determine the cross- agglutination titres in rabbit sera immunized with rMOMPs, and the cell adherence model of Leptospira was used to examine the blocking effects of rabbit antisera against these rMOMPs. It was found that the LipL32 gene could be found in all the 17 strains of Leptospira mentioned above with two different genotypes, i.e. LipL32/1 and LipL32/2. Amounts of expressions of rMOMP1 and rMOMP2 after IPTG accounted for 40% and 10% of the total bacterial proteins respectively. Both rMOMP1 and rMOMP2 could combine with the rabbit antiserum against leptospiral TR/PatocⅠ, and could induce the production of agglutination antibodies to these 17 strains of Leptospira with 1∶2 to 1∶64 MAT titres. The rabbit anti-rMOMP1 and anti-MOMP2 antibodies at 1∶2 to 1∶16 dilutions could efficiently block adherence of Leptospira. It concludes that all the Leptospira tested in the present study possess LipL32/1 or LipL32/2 genes, and the constructed expression system can express the rMOMP1 and rMOMP2. These recombinant proteins are showed to have good immunogenicity and satisfactory immunoreactivity.

Preparation and application of monoclonal antibodies against hepatitis C virus nonstructural proteins

AIM To prepare hybridoma cell lines which secrete anti HCV recombinant NS3 and NS5 proteins′ monoclonal antibodies, and to evaluate their usage in the study of the distribution of HCV NS3 and NS5 antigen in liver tissues. METHODS The hybridoma cell lines were raised using the spleen cells of BALB/C mouse immunized with recombinant NS3 and NS5 proteins according to the conventional protocols. The antibody secreting cells were screened using solid phase ELISA and cloned by limited dilution method. In order to determine the specificity of these hybridoma cell lines, the culture supernatant of these cells was western blot assayed with expression and nonexpresion E. coli and ELISA with other antigens, including HCV core and NS3 and HBsAg. Immunohistochemistry of 51 cases paraffin embedded liver tissues was performed to determine the distribution of HCV NS5 antigen as well as NS3 antigen in liver tissues. RESULTS Eight hybridoma cell lines secreting monoclonal antibodies against HCV NS3 and NS5 proteins were raised. They are named 2B6, 2F3, 3D8, 3D9, 8B2, 6F11, 4C6 and 7D9. Among them only 2B6 against NS3 protein can react with the polypipetides of C7 that is another recombinant polypipetides of NS3 gene. Others have no reaction with HCV core and HBsAg of HBV, and there is no cross reaction between NS3Ag and anti NS5Ag McAb and between NS5Ag and anti NS3 McAb. The immunohistochemistry results indicate that no HCV antigen was detected in the specimens of HBV infection in 20 cases. In 31 HCV infected specimens the positive rate of NS3Ag and NS5Ag are 51 6% (16/31) and 54 9% (17/31), respectively. There were six pure HCV infected specimens in these 31 specimens and half of them were HCV NS3Ag and NS5Ag positive. In the co infection of HBV and HCV group the positive rate of NS3Ag and NS5Ag were 52% (13/25) and 56% (14/25), respectively, almost the same with that of pure HCV infected group. The positive rates of HCV antigens were 70 6% (12/17) and 76 5% (13/17) in CAC patients. CONCLUSION The monoclonal antibodies we prepared are specific to the recombinant HCV NS3 and NS5 proteins and can be used in the clinical immunohistochemistry diagnosis.