Antibody Dilution Research Articles

Localization of MIF-II on mammalian spermatozoa: A study revealing its structure, function and motility inhibitory pathway

Motility of spermatozoa is a crucial factor for determining semen quality. Here we report motility inhibitory factor (MIF-II) from goat epididymal plasma, revealing its structure, function, localization and motility inhibitory pathway. Structural characterization with MALDI revealed novelty of this protein while circular dichroism data confirmed its alpha helical nature. Higher dilutions of MIF-II antibody increased cauda sperm motility and induced immature/immotile caput sperm motility as tested microscopically. Higher number of sperm cells and lower dilutions of antibody induced agglutination in cauda sperm showing surface localization. Indirect immuno-fluorescence showed MIF-II localization throughout the caput sperm surface which relocated more towards acrosomal region with maturation. ELISA assay revealed gradual increase and decrease in concentration of MIF-II in epididymal plasma and plasma membrane respectively from caput to cauda. Signaling cascade that leads to sperm motility inhibition elevates nitric oxide levels through cAMP dependent pathway. MIF-II treatment doesn't alter sperm surface morphology. Expression pattern of MIF-II during epididymal maturation goes hand-in-hand with gaining motility potential as well as dormancy of spermatozoa before ejaculation. Both MIF-II and its antibody inhibit fertilization in-vitro thus expected to open new gateway for future male infertility and contraceptive development research.

Analysis of membranous Ki-67 staining in breast cancer and surrounding breast epithelium

Membranous Ki-67 staining with the MIB-1 antibody has been described in hyalinising trabecular adenomas of the thyroid and sclerosing haemangiomas of the lung. Its relatively rare occurrence in breast tumours has also been documented. The aim of the present study was to assess the rate of any membranous MIB-1 staining in breast specimens. The staining was performed at room temperature with 1:100 dilution of the antibody. One hundred four core needle biopsies and 41 operative specimens were analysed. Membranous staining was noted in 36/144 invasive carcinomas, 20/42 in situ carcinomas and 46/99 cases of peritumoural benign/normal breast epithelium. Most often, it presented as focal and partial polarised luminal membranous staining although complete circumferential staining also occurred, and membranous labelling was sometimes accompanied by cytoplasmic staining, too. In a few cases tested, greater dilution of the primary antibody did not abolish the membranous staining, which was absent with the SP6 monoclonal Ki-67 antibody. The membranous staining of invasive tumours showed no association with histological grade, lumen formation, oestrogen or progesterone receptor status or the Ki-67 nuclear labelling. In contrast, it was associated with a HER2-positive status, although it occurred in all molecular subtypes approached by immunohistochemistry. The background of this membranous staining remains elusive. It is unlikely to represent an artefact. At least partial sharing of an epitope of the nuclear Ki-67 protein with an unidentified membranous protein and some functional differences between membranous staining producing tumours and tumours lacking this pattern of staining may both contribute to some extent.

Evaluation of methods to reduce background using the Python-based ELISA_QC program

Almost all immunological approaches [immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), Western blot], that are used to quantitate specific proteins have had to address high backgrounds due to non-specific reactivity. We report here for the first time a quantitative comparison of methods for reduction of the background of commercial biotinylated antibodies using the Python-based ELISA_QC program. This is demonstrated using a recombinant humanized anti-cocaine monoclonal antibody. Several approaches, such as adjustment of the incubation time and the concentration of blocking agent, as well as the dilution of secondary antibodies, have been explored to address this issue. In this report, systematic comparisons of two different methods, contrasted with other more traditional methods to address this problem are provided. Addition of heparin (HP) at 1 μg/ml to the wash buffer prior to addition of the secondary biotinylated antibody reduced the elevated background absorbance values (from a mean of 0.313 ± 0.015 to 0.137 ± 0.002). A novel immunodepletion (ID) method also reduced the background (from a mean of 0.331 ± 0.010 to 0.146 ± 0.013). Overall, the ID method generated more similar results at each concentration of the ELISA standard curve to that using the standard lot 1 than the HP method, as analyzed by the Python-based ELISA_QC program. We conclude that the ID method, while more laborious, provides the best solution to resolve the high background seen with specific lots of biotinylated secondary antibody.

Development of quantitative suspension array assays for six immunoglobulin isotypes and subclasses to multiple Plasmodium falciparum antigens

BackgroundQuantitative suspension arrays are powerful immunoassays to measure antibodies against multiple antigens in large numbers of samples in a short time and using few microliters. To identify antigen targets of immunity for vaccine development against complex microbes like Plasmodium falciparum, such technology allows the characterization of the magnitude and antigenic specificity of Ig isotypes and subclasses that are important for functional responses. However, standardized assays are not widely available. MethodsWe developed six quantitative suspension array assays to measure IgG1, IgG2, IgG3, IgG4, IgM and IgE specific to multiple P. falciparum antigens. Secondary and tertiary antibodies, as well as human purified antibodies for standard curves, were tested among several commercially available sources. Positive and negative controls included plasmas from malaria hyper-immune African adults and from malaria-naïve European adults, respectively. Reagents were selected and optimal antibody and test sample dilutions established according to sensitivity, specificity and performance of the standard curves. The variability between replicates and plates was assessed with 30 test samples and controls. ResultsAssays were able to detect P. falciparum antigen-specific antibodies for all isotypes and subclasses in samples from malaria-exposed individuals, with low background signal in blank wells. Levels detected in malaria-naïve individuals were overall low except for IgM. For the IgG2 and IgE assays, a triple sandwich was required for sensitivity. Standard curves with 5-parameter logistic fit were successfully obtained in all assays. The coefficients of variation for measurements performed in different days were all <30%, and <5% when comparing duplicates from the same plate. ConclusionThe isotype/subclass assays developed here were sensitive, specific, reproducible and of adequate quantification dynamic range. They allow performing detailed immuno-profiling to large panels of P. falciparum antigens to address naturally- and vaccine-induced Ig responses and elucidate correlates of malaria protection, and could also be applied to other antigenic panels.

Development of an ELISA for identification of immunodominant protein antigens of Mycoplasma hyopneumoniae

We developed a method to identify serological humoral immunodominant proteinic antigen of Mycoplasma hyopneumoniae (Mhp). After constructing the recombinant plasmid pGEX-6P-1-mhp366 and transforming it into Escherichia coli BL21(DE3), the recombinant GST-Mhp366 protein was expressed successfully. The lysates of the recombinant GST-Mhp366 and genetic engineering GST were added into glutathione coated plates and reacted with 17 positive sera or 13 negative sera. Meanwhile, the optimization of experimental conditions, including coated antigen, blocking buffer, dilutions of sera and second antibody were determined. The optimal concentration of the coated antigen was the original bacteria lysates without dilution, and the optimal blocking buffer contained 10% FBS and 2.5% skim milk in PBS. Besides, the working concentration of serum samples and the HRP-tagged rabbit anti-pig IgG secondary antibody were 1:500 and 1:40 000, respectively. Thus, an indirect ELISA was established for identification of immunodominant protein antigens of Mhp. Meanwhile, this method was confirmed by the identified serological humoral immunodominant proteinic antigen Mhp156 and Mhp364. This method can be used for identification of the candidate vaccine antigens on a genome-wide scale. Furthermore, it can lay the foundation for identifying the candidate vaccine antigens through colostra and the nasal mucosal secretions.

Electrophoretic Detection and Confocal Microscopic Imaging of Tyrosine Nitrated Proteins in Plant Tissue.

Tyrosine nitrated proteins can be detected in plant cells electrophoretically and their distribution can be monitored by confocal laser scanning microscopy (CLSM) imaging. One-dimensional polyacrylamide gel electrophoresis (1D PAGE) followed by Western blotting using polyclonal antibody against 3-nitrotyrosine residues enables detection of tyrosine nitrated proteins in plant cells. Here we describe detection of tyrosine nitrated proteins in the homogenates derived from sunflower (Helianthus annuus L.) seedling cotyledons. Total soluble proteins obtained from tissue homogenates are resolved using vertical gel electrophoresis followed by their electrophoretic transfer on to a microporous membrane support for immunodetection. Spatial distribution of tyrosine nitrated proteins can be visualized using an antibody against 3-nitrotyrosine residues. Immunofluorescent localization is performed by cutting 7μm thick wax sections of tissue followed by incubation in primary anti-nitrotyrosine antibody (dilution 1:200) and secondary Cy-3 labeled anti-rabbit IgG antibody (dilution 1:1500). Confocal laser scanning microscopy analysis is undertaken using argon lasers (ex: 530-550 nm and em: 570nm) at pinhole 1. Modulation in the abundance and spatial localization of tyrosine nitrated proteins in plant tissues can be monitored using these techniques.

Development of Recombinant Nucleocapsid Protein-based Enzyme-linked Immunosorbent Assay for Serological Detection of Winter Dysentery Disease

Winter Dysentery Disease is an acute and contagious viral disease that adversely affects dairy cattle on farms in Thailand. An indirect enzyme-linked immunosorbent assay (ELISA) based on the recombinant nucleocapsid (rN) protein which has been developed for antibodies detection against Winter Dysentery Disease was produced by an Escherichia coli protein expression system. The epitope antigen N protein was designed using almost total N gene fragments (8-430 aa, N gene). It was identified to be approximately 48 kDa as the rN protein and can bind bovine coronavirus dairy cattle positive serum by western blot analysis. The conditions of the ELISA method were optimized. The rN protein was standardized with a coating antigen concentration of 5 μg/well. The rN protein was tested with sera in both infected and uninfected dairy cattle. The dilution of the primary antibodies was identified as 1:50 using a checkerboard titration. The intra- and inter-assays were repeatable. The cut-off of the corrected OD450 value from mean ± 2SD (standard deviations) was established at 0.049. The percentage of specificity, sensitivity and accuracy between the developed rNELISA and a SVANOVIR® BCV-Ab ELISA kit was 96.3, 84.8 and 86.1%, respectively. Cohen’s kappa value of the developed ELISA compared with the commercial test kit was 0.71. The correlation coefficient of absorbance values from these two tests was 0.68. The recombinant nucleocapsid protein ELISA method might be helpful for bovine coronavirus diagnosis and surveillance.

Isotype-specific agglutination-PCR (ISAP): A sensitive and multiplex method for measuring allergen-specific IgE

Isotype-specific agglutination-PCR (ISAP): A sensitive and multiplex method for measuring allergen-specific IgE

Expression and evaluation of recombinant P32 protein based ELISA for sero-diagnostic potential of capripox in sheep and goats

The study is aimed to develop and evaluate a recombinant P32 protein based ELISA for sero-monitoring and sero-surveillance using known and random/suspected serum samples for capripox infections from sheep and goats. Truncated P32 gene of goatpox virus (with an ORF of 750 bp) was expressed in E. coli BL-21 CodonPlus (DE3)-RIPL cells using pET32a vector and characterized by SDS-PAGE analysis and confirmed by western blotting as 48 kDa polyhistidine-tagged fusion protein. The protein was purified under denaturing conditions using 8M urea and characterized by SDS-PAGE and immunoblotting. The purified protein was used for optimizing ELISA in a chequerboard titration method using anti-GTPV serum as known positive. The optimized conditions were found to be 300 ng of protein/well, 1:10 dilution of antibody, 1:10000 dilution of rabbit anti-goat/sheep conjugate with 3% skim milk powder and 2% gelatin in phosphate buffer saline containing tween-20 as blocking buffer. The expressed protein was specific only for goatpox virus and sheeppox virus but did not react with related viruses of sheep and goats namely orf virus, peste de petits ruminants virus, bluetongue virus and foot and mouth disease virus. The optimized ELISA was evaluated using pre-vaccinated, post-vaccinated and also post-challenge sera. The assay was found to have a diagnostic specificity of 100/98.7% and sensitivity of 97.1/98.1% when compared to whole virus antigen based ELISA/SNT by receiver operating characteristic (ROC) analysis. The optimized ELISA is able to determine the progression of antibody response against GTPV and SPPV following vaccination and challenge in sheep and goats. The rP32 protein based ELISA was evaluated using random field serum samples (n = 1008) suspected for sheeppox and goatpox and it has shown positivity rate as 24.4%. The rP32 protein based ELISA was found to be specific and sensitive for sero-evaluation of sheeppox virus and goatpox virus following vaccination and infection in sheep and goats.

Quantitative Analysis of Kynurenine Aminotransferase II in the Adult Rat Brain Reveals High Expression in Proliferative Zones and Corpus Callosum

Kynurenic acid, a metabolite of the kynurenine pathway of tryptophan degradation, acts as an endogenous antagonist of alpha7 nicotinic and NMDA receptors and is implicated in a number of neurophysiological and neuropathological processes including cognition and neurodegenerative events. Therefore, kynurenine aminotransferase II (KAT II/AADAT), the enzyme responsible for the formation of the majority of neuroactive kynurenic acid in the brain, has prompted significant interest. Using immunohistochemistry, this enzyme was localized primarily in astrocytes throughout the adult rat brain, but detailed neuroanatomical studies are lacking. Here, we employed quantitative in situ hybridization to analyze the relative expression of KAT II mRNA in the brain of rats under normal conditions and 6 h after the administration of lipopolysaccharides (LPSs). Specific hybridization signals for KAT II were detected, with the highest expression in the subventricular zone (SVZ), the rostral migratory stream and the floor of the third ventricle followed by the corpus callosum and the hippocampus. This pattern of mRNA expression was paralleled by differential protein expression, determined by serial dilutions of antibodies (up to 1:1 million), and was confirmed to be primarily astrocytic in nature. The mRNA signal in the SVZ and the hippocampus was substantially increased by the LPS treatment without detectable changes elsewhere. These results demonstrate that KAT II is expressed in the rat brain in a region-specific manner and that gene expression is sensitive to inflammatory processes. This suggests an unrecognized role for kynurenic acid in the brain’s germinal zones.

Development of ochratoxin a in cereal by chemiluminescence enzyme immunoassay

A rapid, simple and sensitive chemiluminescence enzyme immunoassay method (CLEIA) was established to detect ochratoxin A (OTA) in cereal. Optimal conditions including antibody dilution ratio and enzyme conjugate, ionic strength, pH value and organic solvent. Established indirect competition inhibition curve to determine the linear working range, detection limit and recovery rate. Results: The 50% inhibitory concentration and the detection limit of the CLEIA were78.8pg/mL and 14.86 pg/mL, respectively, with a linear range of 0.015-0.4ng/mL. At 1∼4μpg/kg fortified levels in wheat, mean recoveries ranged from 67.47% to100.35%.

Significance of Ki-67 in non-muscle invasive bladder cancer patients: a systematic review and meta-analysis.

PurposeThis meta-analysis evaluated the prognostic significance of Ki-67 in non-muscle invasive bladder cancer (NMIBC).Materials and MethodsWe selected 39 articles including 5,229 patients from Embase, Scopus, and PubMed searches. The primary outcomes, recurrence-free survival (RFS), progression-free survival (PFS), disease-specific survival (DSS), and overall survival (OS) were determined using time-to event hazard ratios (HRs) with 95% confidence intervals (CIs). Study heterogeneity was tested by chi-square and I2 statistics. Heterogeneity sources were identified by subgroup meta-regression analysis.ResultsTwo studies were prospective; 37 were retrospective. Immunohistochemistry was performed in tissue microarrays or serial sections. A wide range of antibody dilutions and Ki-67 positivity thresholds were used. Study heterogeneity was attributed to analysis results in studies of RFS (p < 0.0001). Meta-regression analysis revealed that region and analysis results accounted for heterogeneity in PFS studies (p = 0.00471, p < 0.0001). High Ki-67 expression was associated with poor RFS (pooled HR, 1.78; 95% CI, 1.48–2.15), poor PFS (pooled HR, 1.28; 95% CI, 1.13–2.15), poor DSS (pooled HR, 2.24; 95% CI, 1.47–2.15), and worse OS (pooled HR, 2.29; 95% CI, 1.24–4.22).ConclusionsThe meta-analysis found that current evidence supports the prognostic value of Ki-67 in NMIBC patients.

Analysis of cholyglycine acid as a biomarker for the early diagnosis of liver disease by fluorescence polarization immunoassay

Trace concentrations of cholyglycine acid (CG) are useful to reflect the damage degree in liver cells, and useful in the diagnosis and prognosis of liver diseases. Therefore, developing an effective strategy to detect the concentration of CG is of great importance. A homogeneous fluorescence polarization immunoassay (FPIA) was developed for determination of CG concentrations. The effects of tracer concentration, antibody dilution and incubation time on FPIA performance were studied. The FPIA was used to detect CG in sera from 522 patients with liver diseases and 449 healthy controls. The results were compared with those obtained through enzyme multiplied immunoassay technique (EMIT). The FPIA showed a detection limit of 50.9ng/mL for CG and the cross-reactivity of antibodies with nine structurally and functionally related analogs were negligible. Concentrations of CG in patients with chronic hepatitis B virus, liver cirrhosis and decompensated cirrhosis were 5.4, 7.9 and 6.5-fold higher than those in controls, respectively, and hence were significantly different from controls (P <0.001). The FPIA developed in this study is a rapid, convenient, and simple method, suitable to be used as a screening tool for homogeneous detection of CG in serum. The detection results of FPIA demonstrate that concentrations of CG were much higher in liver patients than in controls. Therefore, CG may be a good biomarker for the diagnosis of liver diseases.

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method.

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. However, similar to other antibody-based protein assays, optimization of capillary-based immunoassay parameters, such as protein concentration, antibody dilution, and exposure time is an important prerequisite to the generation of meaningful and reliable data. Measurements must fall within the linear range of the assay where changes in signal are directly proportional to changes in lysate concentration. The process of choosing appropriate lysate concentrations, antibody dilutions, and exposure times in the human bronchial epithelial cell line, BEAS-2B, is demonstrated here. Assay linearity is shown over a range of whole cell extract protein concentrations with p53 and α-tubulin antibodies. An example of signal burnout is seen at the highest concentrations with long exposure times, and an α-tubulin antibody dilution curve is shown demonstrating saturation. In addition, example experimental results are reported for doxorubicin-treated cells using optimized parameters.

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. However, similar to other antibody-based protein assays, optimization of capillary-based immunoassay parameters, such as protein concentration, antibody dilution, and exposure time is an important prerequisite to the generation of meaningful and reliable data. Measurements must fall within the linear range of the assay where changes in signal are directly proportional to changes in lysate concentration. The process of choosing appropriate lysate concentrations, antibody dilutions, and exposure times in the human bronchial epithelial cell line, BEAS-2B, is demonstrated here. Assay linearity is shown over a range of whole cell extract protein concentrations with p53 and α-tubulin antibodies. An example of signal burnout is seen at the highest concentrations with long exposure times, and an α-tubulin antibody dilution curve is shown demonstrating saturation. In addition, example experimental results are reported for doxorubicin-treated cells using optimized parameters.

Immunoblotting Detection of Immunoglobulin G Post Subcutaneous Immunization Of Protein Hemaglutinin Pili Klebsiella pneumoniae 12,8 kDa on Mice BALB / C

Klebsiella pneumoniae is the second most common cause of community infection and nosocomial infections due to Gram-negative bacteria. These bacteria are able to induce the onset of immune response, especially humoral immune response.Humoral immunity acts through the activation of B cells that produce antibodies. Antibodies, especially IgG, will cause encapsulated bacteria such as Klebsiella pneumoniae to be better phagocytosed. The purpose of this study was to determine the IgG response to hemagglutinin protein pili K. pneumoniae 12.8 kDa. The method used in this research is Immunoblotting method with western blot and dot blot. The primary antibodies used for the western blot and dot blot tests were isolated from BALB / C mice serum induced with the subcutaneous pili K. pneumoniae 12.8 kDa protein. To get the standard in assessing the results of dot blot were used Corel Photo-paint X6. The semi-quantitative result of dot blot was obtained with the strongest reaction of the antibody dilution at 1/100 while the antigen dilution titer at 1 / 10.000. Results from western blotting showed a positive reaction of the pili protein subunit with a molecular weight of 128.1 kDa, 114.4 kDa, 64.9 kDa, 31.1 kDa, 27.7 kDa, 24.8 kDa, 20.9 kDa, 12.8 kDa, and 10 kDa. The conclusion of this study is the immunization of hemagglutinin pili K. pneumoniae 12.8 kDa subcutaneously capable of inducing the formationof Immunoglobulin G in BALB / C mice.

Abstract 3228: Development and characterization of in vitro assays to detect and quantitate tubulysin B hydrazide in biological samples

Abstract EC1456 is a folate-targeted small molecule drug conjugate (SMDC) of tubulysin B hydrazide (TubBH) that is currently in Phase I clinical studies for treatment of patients with folate receptor (FR)-positive tumors. The ability to detect, quantitate, and localize drug in tissues and biological fluids is particularly important for the characterization of its biodistribution and pharmacodynamic properties. To aid in the biological characterization of our targeted TubBH conjugates, our lab had a rabbit polyclonal antibody produced against TubBH for use in various assays. An IgG-purified fraction of antiserum was used to develop competitive ELISA, immunohistochemical, and flow cytometry methods for analysis of biological samples, such as xenograft tumors from animals dosed with drug. Before assay development, a direct ELISA was performed to determine antibody titer and specificity. The TubBH antibody showed excellent binding to immobilized TubBH, whereas a rabbit IgG negative control antibody had minimal binding. Next, a competitive ELISA was developed in which soluble TubBH competed for antibody binding to immobilized antigen. Multiple experimental parameters were optimized, including coating antigen concentration, antibody dilution, and sample matrix extraction method. Using the optimized conditions, the resulting standard curves for TubBH in acetonitrile-extracted KB tumor sample matrix showed good sensitivity and dose-response. It was determined that, in addition to untargeted TubBH, the antibody could also be used to quantitate intact EC1456, as well as a metabolite of the drug lacking the hydrazide. The utility of the antibody was further demonstrated utilizing a PSMA-targeted version of TubBH. Once optimized, the ELISA method was used to analyze FR-positive KB and FR-negative A549 xenograft tumor homogenates from animals dosed with either EC1456 or untargeted TubBH. The levels of TubBH were higher 4h-post EC1456 dose in the FR-positive KB tumors compared to the FR-negative A549 tumors; however, levels were similar after 24h. Moreover, untargeted TubBH resulted in lower tumor concentrations of the drug compared to EC1456 in KB tumors. An immunohistochemical method developed using the antibody showed strong, focal, cytoplasmic staining in FFPE tumor sections of KB tumors from animals dosed with EC1456, while no staining was observed in tumors from undosed animals. Finally, the antibody was successfully used to detect cell surface FR-bound EC1456 on fixed and unfixed KB cells in vitro by flow cytometry. This experiment confirmed that the antibody is able to recognize the conjugate even when it is situated in the FR binding pocket. Collectively, these results show that this antibody against TubBH can be used as a powerful tool for analysis of tumor drug uptake for folate-targeted TubBH in xenograft models and could hold great potential for use in patient sample analysis as well. Citation Format: Nikki L. Parker, Jonathan M. Shillingford, Melissa Nelson, Joseph A. Reddy, Christopher P. Leamon. Development and characterization of in vitro assays to detect and quantitate tubulysin B hydrazide in biological samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3228. doi:10.1158/1538-7445.AM2017-3228

Abstract 3472: Separase overexpression defines a new subset of acute myeloma leukemia patients characterized by high CD34 and MYC levels

Abstract The endopeptidase Separase, encoded by the ESPL1 gene, plays a key role in faithful segregation of sister chromatids by cleaving the cohesin complex at the metaphase to anaphase transition. Its overexpression associates with aneuploidy and bad prognosis in solid tumors. Little is known in Acute Myeloid Leukemia (AML). We profiled the genomic landscape of 405 and 78 AML cases by SNP array (SNP 6.0 and Cytoscan HD, Affymetrix) and whole exome sequencing (100 bp, paired-end, Illumina), respectively. Bone marrow blasts from 61 patients were analyzed by gene expression profiling (HTA 2.0, Affymetrix). Separase expression was determined by Immunohistochemistry (1:600 antibody dilution Abnova, clone 6H6) in 44 AML and 4 control bone marrow specimens. One patient exhibited a nonsynonimous mutation in ESPL1 (1.3%), which was predicted to alter the protein function. Moreover, ESPL1 copy number gain was observed in 5/405 cases (1.2%): 2 hyperdiploid AML, one trisomy 12 and 2 cases with a short gain at 12q. Notably, protein level detection in one of the 12q-gain cases confirmed Separase overexpression. To determine the incidence of Separase overexpression, we performed Immunohistochemistry on additional 43 AML. Separase was overexpressed in 29/44 AML (66%, Separase-high), being comparable to control marrow biopsies in the remaining 15 samples (Separase-low). Sixty-two percent of Separase-high AML were aneuploid. However, no significative association was observed, as previously reported for mutations in the cohesin genes in AML. Separase overexpression correlated with increased patients’ age (median age 64 vs. 57 years, p=.01), 17-fold upregulation of CD34 (p=.004) and a trend towards reduced overall survival (6-years follow-up). Separase overexpression was not mutually esclusive with cohesin gene mutations, it co-occurred with NPM1 and FLT3 lesions and frequent mutations in genes involved in protein post-translational modification and ubiquitination (p=.04). Separase-low cases were enriched for mutations in RAS signaling pathway (NRAS, KRAS, NF1, RIT1, GRAP2, RALGDS; p=4.5x10-5) and in cell migration-related genes (LIMS2, S1PR1, PPIA, PLXNB1, FAT1). Separase-high cases also showed a defined transcriptomic profile, characterized by reduced expression of HOXA/B family genes, the DNA damage repair gene ATM, the p53 regulator MDM2 and forced expression of the cell cycle markers CDC20, AURKB, NUSAP1 and of MYC, independently of chromosome 8 gain. Taken together, our data suggest that genomic lesions targeting ESPL1 are a rare event in AML. However, Separase overexpression is a common feature and defines a new subset of AML cases with a distinct gene expression profile, which may benefit of innovative targeted therapies including CDC20 and bromodomain inhibitors. Supported by: ELN, AIL, AIRC, progetto Regione-Università 2010-12 (L. Bolondi), FP7 NGS-PTL project. Citation Format: Giorgia Simonetti, Antonella Padella, Simona Righi, Maria Chiara Fontana, Marco Manfrini, Cristina Papayannidis, Giovanni Marconi, Carmen Baldazzi, Marianna Garonzi, Alberto Ferrarini, Massimo Delledonne, Nicoletta Testoni, Elena Sabattini, Giovanni Martinelli. Separase overexpression defines a new subset of acute myeloma leukemia patients characterized by high CD34 and MYC levels [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3472. doi:10.1158/1538-7445.AM2017-3472

In house ELISA based on recombinant ORF2 protein underline high prevalence of IgG anti-hepatitis E virus amongst blood donors in south Brazil.

Hepatitis E Virus (HEV) is a zoonotic pathogen responsible for causing acute hepatitis in human, especially in developing countries. Diagnosis of HEV usually relies on the detection of antibodies mostly by enzyme-linked immunosorbent assay (ELISA). In the present study, we designed a new indirect ELISA (iELISA) based on a short recombinant peptide derived from the capsid protein (ORF2p) and demonstrated its potential for detecting human IgG against HEV genotype 3. The best polystyrene plate (Maxisorp®), optimal ORF2p coating antigen concentration (0,67μg/well) and primary antibody dilution (1:100) were determined. This iELISA showed a sensitivity of 91.4% and specificity of 95.9%. The comparison of our in house iELISA with a commercial assay (RecomWell, Mikrogen®) showed 94.25% of agreement and a kappa index of 0.88. The ORF2 recombinant ELISA was used to screen 780 blood donors for anti-HEV IgG and we found that 314 (40,25%) of these donors were IgG positive. This high prevalence of antibodies suggests, for the first time, that the Southern Brazil region might be endemic to Hepatitis E Virus genotype 3.

A protocol for registration and correction of multicolour STED superresolution images.

Multicolour fluorescence imaging by STimulated Emission Depletion (STED) superresolution microscopy with doughnut-shaped STED laser beams based on different wavelengths for each colour channel requires precise image registration. This is especially important when STED imaging is used for co-localisation studies of two or more native proteins in biological specimens to analyse nanometric subcellular spatial arrangements. We developed a robust postprocessing image registration protocol, with the aim to verify and ultimately optimise multicolour STED image quality. Importantly, this protocol will support any subsequent quantitative localisation analysis at nanometric scales. Henceforth, using an approach that registers each colour channel present during STED imaging individually, this protocol reliably corrects for optical aberrations and inadvertent sample drift. To achieve the latter goal, the protocol combines the experimental sample information, from corresponding STED and confocal images using the same optical beam path and setup, with that of an independent calibration sample. As a result, image registration is based on a strategy that maximises the cross-correlation between sequentially acquired images of the experimental sample, which are strategically combined by the protocol. We demonstrate the general applicability of the image registration protocol by co-staining of the ryanodine receptor calcium release channel in primary mouse cardiomyocytes. To validate this new approach, we identify user-friendly criteria, which - if fulfilled - support optimal image registration. In summary, we introduce a new method for image registration and rationally based postprocessing steps through a highly standardised protocol for multicolour STED imaging, which directly supports the reproducibility of protein co-localisation analyses. Although the reference protocol is discussed exemplarily for two-colour STED imaging, it can be readily expanded to three or more colours and STED channels.