Preparation and application of a novel monoclonal antibody specific for the heat shock protein 60 of Lawsonia intracellularis

Porcine proliferative enteropathy(PPE),an important infectious disease in pig production caused by an obligate intracellular bacterium Lawsonia intracellularis,is commonly associated with diarrhea and reduced weight gain in growing pigs widespread.An accurate method for detecting L.intracellularis is particularly important for preventing and controlling PPE.Heat shock protein 60(Hsp60)is an immunodominant bacterial antigen found in all eukaryotic and prokaryotic organisms.Thus,the purpose of the current investigation was to produce a novel L.intracellularis Hsp60 monoclonal antibody(mAb)useful for immunodiagnostics.Three hybridomas secreted anti-Hsp60 termed 3E5,4E2,and 9G6 were generated,and the titers of ascitic fluids of 3E5,4E2,9G6 were 1:1024000,1:2048000 and 1:2048000,respectively.The Western blotting analysis demonstrated that recombinant Hsp60(rHsp60)was recognized by mAbs 3E5,4E2 and 9G6.Subsequently,analyses of specificity showed all the mAbs were highly specific to L.intracellularis while could not significantly react with other enteric bacteria commonly found in the ileum of pigs,such as Escherichia coli,Salmonella Choleraesuis,Salmonella Typhimurium,and Brachyspira hyodysenteriae.Furthermore,the mAbs were useful for detecting L.intracellularis in the infected monolayer cells and histological sections of the ileum from PPE-affected pigs.Our research will provide a foundation for the development of immunological diagnostic tests.

Monoclonal antibody targeting mu-opioid receptor attenuates morphine tolerance via enhancing morphine-induced receptor endocytosis

Morphine is a frequently used analgesic that activates the mu-opioid receptor(MOR),which has prominent side effects of tolerance.Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance,currently,there is no effective therapy to treat morphine tolerance.In the current study,we aimed to develop a monoclonal antibody(mAb)precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms.We successfully prepared a mAb targeting MOR,named 3A5C7,by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization,and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation.Treatment of two cell lines,HEK293T and SH-SY5Y,with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2(GRK2)/b-arrestin2-dependent mechanism,as demonstrated by immunofluorescence staining,flow cytometry,Western blotting,coimmunoprecipitation,and small interfering ribonucleic acid(siRNA)-based knockdown.This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR.We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid.Western blot,enzyme-linked immunosorbent assays,and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase,the in vitro biomarker of morphine tolerance,via the GRK2/b-arrestin2 pathway.Furthermore,in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice,and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence.Finally,intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/b-arrestin2 pathway.Collectively,our study provided a therapeutic mAb,3A5C7,targeting MOR to treat morphine tolerance,mediated by enhancing morphine-induced MOR endocytosis.The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.

UV/Vis-based process analytical technology to improve monoclonal antibody and host cell protein separation

Process analytical technology(PAT) is gaining more interest in the biomanufacturing industry because of its potential to improve operational control and compliance through real-time quality assurance.Currently, biopharmaceutical producers mainly monitor chromatographic processes with ultraviolet/visible(UV/Vis) absorbance. However, this measurement has a very limited correlation with purity and quantity. The current study aims to determine the concentration of monoclonal antibody(mAb) and host cell proteins(HCPs) using a build-in UV/Vis monitoring during Protein A affinity chromatography and to optimize the separation conditions for high purity of mAb and minimizing the HCPs content. The eluate was analyzed through in-line UV/Vis at 280 and 410 nm, representing mAb and HCPs concentration,respectively. Each 0.1 column volume(CV) fraction of UV/Vis chromatogram peak area were calculated,and different separation conditions were then compared. The optimum conditions of mAb separation were found as 12 CV loading, elution at pH 3.5, and starting the collection at 0.5 CV point, resulting in high m Ab recovery of 95.92% and additional removal of 49.98% of HCP comparing with whole elution pool. This study concluded that UV/Vis-based in-line monitoring at 280 and 410 nm showed a high potential to optimize and real-time control Protein A affinity chromatography for mAb purification from HCPs.

Clinical application of SARS-CoV-2 antibody detection and monoclonal antibody therapies against COVID-19

The purpose of this study was to investigate the clinical application of severe acute respiratory distress syndrome coronavirus-2(SARS-CoV-2)specific antibody detection and anti-SARS-CoV-2 specific monoclonal antibodies(mAbs)in the treatment of coronavirus infectious disease 2019(COVID-19).The dynamic changes of SARS-CoV-2 specific antibodies during COVID-19 were studied.Immunoglobulin M(IgM)appeared earlier and lasted for a short time,while immunoglobulin G(IgG)appeared later and lasted longer.IgM tests can be used for early diagnosis of COVID-19,and IgG tests can be used for late diagnosis of COVID-19 and identification of asymptomatic infected persons.The combination of antibody testing and nucleic acid testing,which complement each other,can improve the diagnosis rate of COVID-19.Monoclonal anti-SARS-CoV-2 specific antibodies can be used to treat hospitalized severe and critically ill patients and non-hospitalized mild to moderate COVID-19 patients.COVID-19 convalescent plasma,highly concentrated immunoglobulin,and anti-SARS-CoV-2 specific mAbs are examples of anti-SARS-CoV-2 antibody products.Due to the continuous emergence of mutated strains of the novel coronavirus,especially omicron,its immune escape ability and infectivity are enhanced,making the effects of authorized products reduced or invalid.Therefore,the optimal application of anti-SARS-CoV-2 antibody products(especially anti-SARS-CoV-2 specific mAbs)is more effective in the treatment of COVID-19 and more conducive to patient recovery.

Therapeutic Implications of Monoclonal Antibody

Background: The coronavirus disease 2019 (COVID-19) pandemic is a distinct public health issue that calls for the quick development of novel treatments and viral detection. Due to their high specificity and reliability, monoclonal antibodies (mAbs) have emerged as useful diagnostic and therapeutic tools for a variety of diseases. As a result, several scientists have jumped right into developing Ab-based assays for the identification of SARS-CoV-2 and Ab drugs for use as COVID-19 therapy agents. Since the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is essential for viral infection and has a known precise structure, it has become a key target for the creation of therapeutic antibodies. The use of Ab cocktails is anticipated to be a key component of an efficient COVID-19 treatment plan since SARS-CoV-2 is an RNA virus with a high mutation rate, particularly when subjected to the selection pressure of aggressively applied preventive vaccinations and neutralizing Abs. Furthermore, SARS-CoV-2 infection could provoke an overzealous immune response, leading to a cytokine storm that accelerates the onset of a severe disease. Abs to counteract cytokine storms are also actively being researched as COVID-19 therapies. Abs are now used in SARS-CoV-2 detection assays, including immunoglobulin and antigen tests, in addition to their use as medicines. In order to stop the spread of COVID-19, such Ab-based detection tests are essential surveillance tools. In this article, we’ll go over several important ideas related to mAb-based COVID-19 pandemic detection tests and treatments. Objective: To understand the role of hybridoma technology in therapeutic implications. 1) To study the basic concepts and options in hybridoma technology;2) To study the applications of hybridoma technology;3) To explore how hybridoma technology is applied in diagnostic histopathology. Method: For this method generally there is use of mouse or mammals are transfect with the Ags to find out the formation of antibody afterwards isolate the antibody which has been formed after injecting the antigens for a number of weeks. Following are the steps for mAbs: Step 1: In this step immunization of mouse is done;Step 2: Spleen is used for the isolation of B cells;Step 3: Cultivation of cancerous cells;Step 4: Merging of B cells with Myeloma cells;Step 5: This step cell lines are separated;Step 6: in the next step screening the suitable cell lines;Step 7: observation of multiplication in vitro as well as in vivo;Step 8: Harvesting. Discussion: Now a day there are many diseases which has been cured easily at the mean time it’s very difficult to diagnose and get the treatment. Due to advancement of monoclonal antibodies are used in the diagnosis and treatments such as COVID-19, SARS and SARS COV-2. Therefore important part of the monoclonal antibodies are its used in the diagnosis as well as in the treatment tools.

Basic regulatory science behind drug substance and drug product specifications of monoclonal antibodies and other protein therapeutics

In this review,we focus on providing basics and examples for each component of the protein therapeutic specifications to interested pharmacists and biopharmaceutical scientists with a goal to strengthen understanding in regulatory science and compliance.Pharmaceutical specifications comprise a list of important quality attributes for testing,references to use for test procedures,and appropriate acceptance criteria for the tests,and they are set up to ensure that when a drug product is administered to a patient,its intended therapeutic benefits and safety can be rendered appropriately.Conformance of drug substance or drug product to the specifications is achieved by testing an article according to the listed tests and analytical methods and obtaining test results that meet the acceptance criteria.Quality attributes are chosen to be tested based on their quality risk,and consideration should be given to the merit of the analytical methods which are associated with the acceptance criteria of the specifications.Acceptance criteria are set forth primarily based on efficacy and safety profiles,with an increasing attention noted for patient-centric specifications.Discussed in this work are related guidelines that support the biopharmaceutical specification setting,how to set the acceptance criteria,and examples of the quality attributes and the analytical methods from 60 articles and 23 pharmacopeial monographs.Outlooks are also explored on process analytical technologies and other orthogonal tools which are on-trend in biopharmaceutical characterization and quality control.

IMpower210:A phase Ⅲ study of second-line atezolizumab vs. docetaxel in East Asian patients with non-small cell lung cancer

Objective: IMpower210(NCT02813785) explored the efficacy and safety of single-agent atezolizumab vs.docetaxel as second-line treatment for advanced non-small cell lung cancer(NSCLC) in East Asian patients.Methods: Key eligibility criteria for this phase Ⅲ, open-label, randomized study included age ≥18 years;histologically documented advanced NSCLC per the Union for International Cancer Control/American Joint Committee on Cancer staging system(7th edition);Eastern Cooperative Oncology Group performance status of 0 or 1;and disease progression following platinum-based chemotherapy for advanced or metastatic NSCLC. Patients were randomized 2:1 to receive either atezolizumab(1,200 mg) or docetaxel(75 mg/m^(2)). The primary study endpoint was overall survival(OS) in the intention-to-treat(ITT) population with wild-type epidermal growth factor receptor expression(ITT EGFR-WT) and in the overall ITT population.Results: Median OS in the ITT EGFR-WT population(n=467) was 12.3 [95% confidence interval(95% CI),10.3-13.8] months in the atezolizumab arm(n=312) and 9.9(95% CI, 7.8-13.9) months in the docetaxel arm[n=155;stratified hazard ratio(HR), 0.82;95% CI, 0.66-1.03]. Median OS in the overall ITT population was 12.5(95% CI, 10.8-13.8) months with atezolizumab treatment and 11.1(95% CI, 8.4-14.2) months(n=377) with docetaxel treatment(n=188;stratified HR, 0.87;95% CI, 0.71-1.08). Grade 3/4 treatment-related adverse events(TRAEs) occurred in 18.4% of patients in the atezolizumab arm and 50.0% of patients in the docetaxel arm.Conclusions: IMpower210 did not meet its primary efficacy endpoint of OS in the ITT EGFR-WT or overall ITT populations. Atezolizumab was comparatively more tolerable than docetaxel, with a lower incidence of grade3/4 TRAEs.

Focus on current and emerging treatment options for glioma:A comprehensive review

This comprehensive review delves into the current updates and challenges associated with the management of low-grade gliomas(LGG),the predominant primary tumors in the central nervous system.With a general incidence rate of 5.81 per 100000,gliomas pose a significant global concern,necessitating advancements in treatment techniques to reduce mortality and morbidity.This review places a particular focus on immunotherapies,discussing promising agents such as Zotiraciclib and Lerapolturev.Zotiraciclib,a CDK9 inhibitor,has demonstrated efficacy in glioblastoma treatment in preclinical and clinical studies,showing its potential as a therapeutic breakthrough.Lerapolturev,a viral immunotherapy,induces inflammation in glioblastoma and displays positive outcomes in both adult and pediatric patients.Exploration of immunotherapy extends to Pembrolizumab,Nivolumab,and Entrectinib,revealing the challenges and variabilities in patient responses.Despite promising preclinical data,the monoclonal antibody Depatuxizumab has proven ineffective in glioblastoma treatment,emphasizing the critical need to understand resistance mechanisms.The review also covers the success of radiation therapy in pediatric LGG,with evolving techniques,such as proton therapy,showing potential improvements in patient quality of life.Surgical treatment is discussed in the context of achieving a balance between preserving the patient’s quality of life and attaining gross total resection,with the extent of surgical resection significantly influencing the survival outcomes.In addition to advancements in cancer vaccine development,this review highlights the evolving landscape of LGG treatment,emphasizing a shift toward personalized and targeted therapies.Ongoing research is essential for refining strategies and enhancing outcomes in the management of LGG.

Efficacy and safety of bamlanivimab in patients with COVID-19:A systematic review and meta-analysis

BACKGROUND Monoclonal antibodies(mAbs)have shown clinical benefits against coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Several studies have reported the use of bamlanivimab as a promising treatment option for COVID-19.AIM To synthesize the latest evidence for the efficacy and safety of bamlanivimab alone in the treatment of adult patients with COVID-19.METHODS A literature search was conducted in PubMed,Cochrane Library,Web of Science,medRxiv,and Google Scholar using“SARS-CoV-2”,“COVID-19”,“LY-CoV555”,and“Bamlanivimab”keywords up to January 25,2023.The quality of included studies was assessed using the Cochrane bias tools.The Comprehensive Meta-Analysis software version 3.0 was used to analyze the data.RESULTS A total of 30 studies involving 47368 patients were included.A significant difference was observed between the bamlanivimab and standard of care/placebo groups in terms of mortality rate[risk ratio(RR)=50,95%confidence interval(CI):0.36-0.70],hospitalization rate(RR=0.51;95%CI:0.39-0.68),and emergency department(ED)visits(RR=0.69;95%CI:0.47-0.99);while the two groups exhibited no significant difference in terms of intensive care unit(ICU)admission(P>0.05).Compared to other mAbs,bamlanivimab was associated with a higher rate of hospitalization(RR=1.44;95%CI:1.07-1.94).However,no significant difference was detected between the bamlanivimab and other mAbs groups in terms of mortality rate,ICU admission,and ED(P>0.05).The incidence of any adverse events was similar between the bamlanivimab and control groups(P>0.05).CONCLUSION Although the results suggest the efficacy and safety of bamlanivimab in COVID-19 patients,further research is required to confirm the efficacy of this drug for the current circulating SARS-CoV-2 variants.

Hepatitis B virus reactivation in patients treated with monoclonal antibodies

Hepatitis B virus(HBV)reactivation poses a significant clinical challenge,espe-cially in patients undergoing immunosuppressive therapies,including mono-clonal antibody treatments.This manuscript briefly explores the complex rela-tionship between monoclonal antibody therapy and HBV reactivation,drawing upon current literature and clinical case studies.It delves into the mechanisms underlying this phenomenon,highlighting the importance of risk assessment,monitoring,and prophylactic measures for patients at risk.The manuscript aims to enhance the understanding of HBV reactivation in the context of monoclonal antibody therapy,ultimately facilitating informed clinical decision-making and improved patient care.This paper will also briefly review the definition of HBV activation,assess the risks of reactivation,especially in patients treated with monoclonal antibodies,and consider management for patients with regard to screening,prophylaxis,and treatment.A better understanding of patients at risk can help clinicians provide optimum management to ensure successful patient outcomes and prevent morbidity.

Monoclonal antibody-based serological detection of Citrus yellow vein clearing virus in citrus groves

Citrus yellow vein clearing virus （CYVCV） is considered as the causal agent of Citrus yellow vein clearing disease and belongs to the genus Mandarivirus in the family Alphaflexiviridae. Capsid protein （CP） of CYVCV Chongqing isolate （CYVCV- CQ） was produced using a prokaryotic expression system and used as the immunogen for monoclonal antibody （MAb） production. Four highly specific and sensitive murine MAbs and one polyclonal antibody were prepared in this study. Titers of the four MAbs in ascites fluids ranged from 10-6 to 10-7 as determined by indirect enzyme-linked immunosorbent assay （ELISA）. Three serological assays, including dot enzyme-linked immunosorbent assay （dot-ELISA）, tissue blot-ELISA, and double-antibody sandwich （DAS）-ELISA, were developed for quick and reliable detections of CYVCV in citrus samples. The developed dot-ELISA and DAS-ELISA methods could detect CYVCV in the infected citrus leaf crude extracts diluted at 1：2 560 and 1：10 240 （w/v, g mL^-1）, respectively. The detection result of 125 citrus leaf samples collected from citrus groves in Yunnan Province and Chongqing Municipality of China showed that approximately 36% samples were positive for CYVCV. This virus was, however, not＇detected in any sample collected from Zhejiang or Jiangxi Province, China.

Highly Sensitive and Specific Monoclonal Antibody-Based Serological Methods for Rice Ragged Stunt Virus Detection in Rice Plants and Rice Brown Planthopper Vectors

Rice ragged stunt virus（RRSV） is a serious rice disease in Asia, causing serious yield losses on rice. The capsid protein（CP） gene of the major outer capsid protein of RRSV was expressed in Escherichia coli BL21（DE3） using the pMAL-C2 X expression vector. The recombinant protein was used as the immunogen to immunize BALB/c mice. A hybridoma cell line 8A12 secreting monoclonal antibody（MAb） against RRSV was obtained by fusing mouse myeloma cells（Sp 2/0） with spleen cells from the immunized BALB/c mice. Western blot analysis showed that the MAb 8A12 can specifically react with RRSV CP. Using the MAb, an antigen-coated-plate enzyme-linked immunosorbent assay（ACP-ELISA）, a dot enzyme-linked immunosorbent assay（dot-ELISA）, and immunocapture-RT-PCR（IC-RT-PCR） assay were developed to detect RRSV. The established ACP-ELISA, dot-blot ELISA and IC-RT-PCR methods could detect RRSV in infected rice tissue crude extracts with dilutions of 1：40 960, 1：1 280 and 1：655 360（w/v, g mL-1）, respectively. The ACP-ELISA and dot-blot ELISA methods could detect RRSV in infected insect vector crude extracts with dilutions of 1：12 800 and 1：1 600（an individual planthopper μL-1）, respectively. The field survey revealed that Rice ragged stunt disease occurs on rice in Hainan, Yunnan, Guangxi, Sichuan, Guizhou, Fujian, Hunan, Jiangxi and Zhejiang in China.

Preparation and Initial Application of a Monoclonal Antibody Specific for a Newly Discovered Conserved Linear Epitope of Rabies Virus Nucleoprotein

Objective To prepare monoclonal antibodies against a newly discovered and conserved linear epitope of Rabies virus nucleoprotein and to use them in a rabies diagnostic test. Methods Synthetic peptide containing the epitope was used as immunogen to prepare hybridoma cell lines by classical hybridoma technology. Anti-peptide monoclonal antibodies produced in ascites of inoculated Balb/c mice were labeled with fluorescein isothiocyanate （FITC） after purification and used in fluorescent antibody test （FAT）. Results Two positive hybridoma cell lines, RVNP-mAbl-CL and RVNP-mAb2-CL, were obtained. RVNP- mAbl-CL produced a higher concentration of monoclonal antibody RVNP-mAbl in Balb/c ascites. FITC-labeled RVNP-mAbl showed correct results on certain Rabies virus-positive canine brain tissue samples and cells of a small subclone of baby hamster kidney 21 cell line （BSR）. Conclusion FITC-labeled RVNP-mAbl has potential application for laboratory diagnosis of rabies

Production and Characterization of Anti-estrone Monoclonal Antibody

Objective Determination of estrone (E1) levels has a significant meaning in evaluating physiological effect and diagnosing some diseases. In order to detect free E1 in biological fluids, a monoclonal antibody specific for E1 was prepared after the complete antigen of E1 was synthesized. The purified monoclonal antibody was fully characterized for later immunoassay. Methods 3-O-carboxymethyl ether derivative of E1 was synthesized and in turn coupled to bovine serum albumin (BSA) to form complete antigen E1-BSA. A monoclonal antibody (McAb) specific for E1 was produced both in vitro and in vivo by a hybridoma anti-E1. Anti-E1 was prepared by fusion of SP2/0 murine myeloma cells with spleen cells isolated from immunized BALB/c mouse. The McAb was characterized by enzyme-linked immunosorbent assay (ELISA), SDS-PAGE and Western-blotting. The specificity of the immunoassay was investigated by determining the cross-reactions of E1 analogs when free E1 was detected by competitive indirect enzyme-linked immunosorbent assay (CI-ELISA). Results Analysis revealed that anti-E1 McAb (E1-McAb) was of the IgG1 type, the molecular weight of E1-McAb was 164 000 daltons. The affinity constant of E1-McAb with coated complete antigen was 8.2108L/mol. The linear range for free E1 determined by CI-ELISA was 10pg/mL^10ng/mL. The detection limit was 21.4 pg/mL (defined as twice the standard deviation of the blank). Conclusion The CI-ELISA developed with E1-McAb was both sensitive and specific. The prepared E1-McAb can be used in some immunoassays.

Preparation of Monoclonal Antibody and Development of Enzyme-linked Immunosorbent Assay Specific for Escherichia coli O157 in Foods

To prepare monoclonal antibodies （MAb） and antisera specific for Escherichia coli （E.coli） O157, and to develop a sandwich enzyme-linked immunosorbent assay （ELISA） to detect Eocoli O157 in foods. Methods Spleen cells from BALB/c mice immunized with the somatic antigen of E.coli O157：H7 were fused with routine Sp2/0 myeloma cells. The hybridoma cell line specific for E.coli O157 was established after having been subcloned. Antisera specific for E.coli O157 was prepared by intravenous injection into New Zealand rabbits with a stain of E.coli O157：H7. The sandwich ELISA was developed with the polyclonal antibody as the capture antibody and the MAb 3A5 as the detection antibody. The inoculated ground poultry meat and pasteurized miLk were tested to confirm efficiency of the method. Results MAb 3A5 specific for E.coli O157 and O 113：H21 belonged to subtype IgM. The ascetic titers of the antibody was 1：1× 10^6. No cross-reactivity of the MAb was observed with strains of Salmonella spp, Yersinia enterocolitica, Shigella dysenteriae, etc. The purified polyclonal antibody had a titer of 1： 1× 10^5 with E.coli O 157. The detection limit of this sandwich ELISA was 10^3- 10^4 cfu E.coli O157/mL in pure culture with a high specificity, which was characterized by every non-O157 strain with negative response. With 10h enrichment procedure, E.coli O157：H7 recovered well from inoculated ground poultry meat and pasteurized milk at levels of 0.1 cfu/g and 0.1 cfu/mL. Conclusion MAb 3A5 specific for E.coli O 157 and O 113：H21 can be produced by immunizing BALB/c mice with a strain of E.coli O157：H7. Then a sandwich ELISA can be developed with the polyclonal antibody as the capture antibody and the MAb 3A5 as the detection antibody. The method is proved to be a sensitive and specific technique to detect low number of E.coli O157 in food.

Development of Double Antibody Sandwich ELISA for Detection of Duck or Goose Flavivirus

In order to establish double antibody sandwich enzyme-linked immunosorbent assay （DAS-ELISA） for detection of duck or goose flavivirus, polyclonal antibody against the flavivirus strain JS804 in geese and monoclonal antibody against the E protein of flavivirus strain JS804 in geese were used as the capture antibody and detection antibody, respectively. The optimal dilution of the capture antibody and detecting antibody capable of detecting the flavivirus strain JS804 in geese were 1：3 200 and 1：160 in the check-board titration, respectively. The reaction time of sample was 1 h, and the optimal working dilution of HRP-labeled goat-anti-mouse IgG was 1：10 000. The positive standard value was 0.247 （OD450.m）. The geese flavivirus could be detected at a minimal concentration of 1.875 μg mL^-1. The ELISA had no cross-reaction with Newcastle disease virus （NDV）, Avian influenza virus （AIV）, Infectious bronchitis virus （IBV）, Infectious bursal disease virus （IBDV）, Duck hepatitis virus （DHV）, and Gosling plague virus （GPV）. Twenty clinical samples were detected by the DAS-ELISA and RT-PCR respectively, with the agreement rate of 75%. The results revealed that the DAS-ELISA possessed favorable specificity and higher sensitivity, indicating a suitable method for rapid detection of the duck or goose flavivirus.

Generation and characterization of an anti-GP73 monoclonal antibody for immunoblotting and sandwich ELISA

Recently, serum Golgi protein 73 （GP73） levels have been found to be elevated in patients with hepatocellu- lar carcinoma （HCC）, and GP73 has been proposed as a novel marker for HCC. However, GP73 levels in patients remain controversial due to the specificity of the anti-GP73 antibody-based enzyme linked immunosorbent as- say （ELISA）. Therefore, an anti-GP73 antibody with high specificity was highly demanded. In the present study, by hybridoma screening, we generated an anti-GP73 monoclonal antibody （mAb） designated as 6A2 using recom- binant GP73 protein produced by prokaryotic expression. The specificity of 6A2 was evaluated by Western blot- ting, immunohistochemistry and immunoprecipitation. The results showed that 6A2 recognized GP73 in both native and denatured forms. In addition, we have developed a sandwich ELISA using 6A2 and GP73 polyclonal antibody generated in New Zealand white rabbits according to standard procedures, and measured the serum GP73 level of patients using this assay. Our results showed that serum GP73 levels of HCC patients were significantly higher than those of healthy controls （P = 0.0036）. Furthermore, for the first time, GP73 serum level was found to be elevated in patients with breast cancer compared with healthy controls （P = 0.0172）.

Mechanisms of resistance to anti-EGFR monoclonal antibody treatment in metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) continues to be counted as a major health problem. The introduction of newer cytotoxics, irinotecan and oxaliplatin, has achieved a significant improvement in survival rates. Novel targeted therapies (bevacizumab, and cetux-imab) in combination with most efficient chemotherapy regimens have pushed the median survival beyond the 2-year mark and increased the proportion of patients which could benefit from resection of metastatic lesions. In addition, several studies have proved that the CRC mutation profiles should influence patient selection or stratif ication in prospective trials. KRAS mutational status represents a paradigm for biomarker development in the era of molecular targeted therapies. The present article is an overview of the most important studies in the development of biomarkers for the optimization of anti-epidermal growth factor receptor (anti-EGFR) treatment in mCRC, beyond KRAS mutations, which is a work in progress. The aim will be to identify molecular markers that might be used to select patients with a higher probability of response to anti-EGFR monoclonal antibodies. Overall the accumulating evidence of the molecular biology of CRC has substantially changed the approach to mCRC treatment and has given clinicians more rational options for treating this illness.

Preparation of Monoclonal Antibody Against HPT and Its Application to Detecting Marker Protein in Genetically Modified Rice

To produce the monoclonal antibodies （mAbs） against hygromycin B phosphotransferase （HPT） and to develop immunoassay based on mAbs for biosafety assessment of HPT in genetically modified rice （GM rice）. Methods BALB/c mice were immunized with purified recombinant 6His. HPT protein, and the conventional hybridoma technology was used to generate the monoclonal hybridoma cells. ELISA and Western blot were used to analyze the specificity of mAbs recognizing HPT and the cross reaction with other proteins. A double-Ab sandwich ELISA method was established to detect HPT expression level in the sck gene-modified rice plants. Results Four hybridomas, named F1,D4-2, D4-4, and D4-5, producing the mAbs against HPT were successfully obtained with the titer of ascetic mAbs ranging from 10×10^-4 to10×10^-5. Identification of subclass showed that all the produced mAbs belonged to IgG1. Western blot showed specific binding reaction between the mAbs to the HPT proteins expressed in the GM rice. A double sandwich ELISA coated with anti-HPT polyclonal antibody was established with mAbs as sandwich antibody, which showed a sensitivity of 30ng/mL and did not crossreact with other proteins. The expression level of HPT in the leaves of sck-transformed lines was detected （80-150ng/mL）. But HPT protein in the grain and seed of GM rice could not be detected using this ELISA assay, Conclusion Anti-HPT mAbs prepared herein have a high specificity and can be used for rapid assay of HPT antigen. The expression level of HPT in the GM rice grain and seed is lower than our ELISA detection limit.

Development of a cELISA for effective detection of the antibody against H7 subtype of avian influenza virus

H7 avian influenza viruses(AIVs) normally circulated among birds before. From 1996 to 2012, human infections with H7 AIVs(H7 N2, H7 N3, and H7 N7) were reported in Canada, Italy, Mexico, the Netherlands, the United Kingdom and the USA. Until March 2013, human infections with H7 N9 AIVs were reported in China. Since then, H7 N9 AIVs have continued to circulate in both humans and birds. Therefore, the detection of antibodies against the H7 subtype of AIVs has become an important topic. In this study, a competitive enzyme-linked immunosorbent assay(cELISA)method for the detection of antibody against H7 AIVs was established. The optimal concentration of antigen coating was 5 μg mL^(-1), serum dilution was 1/10, and enzyme-labeled antibody was 1/3 000. To determine the cut-off value of cELISA, percent inhibition(PI) was determined by using receiver operating characteristic(ROC) curve analysis in 178 AIVs negative samples and 368 AIVs positive serum samples(n=546). When PI was set at 40%, the specificity and sensitivity of cELISA were 99.4 and 98.9%, respectively. This method could detect the antibodies against H7 Nx(N1–N4, N7–N9) AIVs, and showed no reaction with AIVs of H1–H6 and H8–H15 subtypes or common avian viruses such as Newcastle disease virus(NDV), Infectious bronchitis virus(IBV) and Infectious bursal disease virus(IBDV), exhibiting good specificity. This method showed a coincidence rate of 98.56% with hemagglutinin inhibition(HI) test. And the repeatability experiment revealed that the coefficients of variation(CV) of intra-and inter-batch repetition were all less than 12%. The data indicated that the cELISA antibody-detection method established in this study provided a simple and accurate technical support for the detection of a large number of antibody samples of H7-AIV.