Two desired epitopes of cTnI benefit for preparation of standardized monoclonal antibodies.

Acute myocardial infarction (AMI) is one of the most severe cardiovascular diseases in humans, often resulting in unexpected death. Early detection is critical for patient survival. Sandwich ELISA is a common method for the detection of AMI. However, ELISA kits from different manufacturers can give different results, in part because of the lack of standardized epitopes. Therefore, the purpose of this study was to find two standardized epitopes. We predicted two antigen epitopes and respectively immunize mice to manufacture standardized monoclonal antibodies. Eight monoclonal antibodies were prepared. Monoclonal antibodies 7D2 and 2C3 were selected with high affinity, and their characteristics were explored. The results show that monoclonal antibodies 7D2 and 2C3 can both bind to various modified forms and complexes of cardiac troponin I (cTnI), were not cross-reaction with related antigens of normal human serum and can be paired. Therefore, we deem epitopes 30 to 42 and 77 to 89 standardized epitopes.

Plasmonic ELISA for Sensitive Detection of Disease Biomarkers with a Smart Phone-Based Reader.

Serum myoglobin is one of the earliest markers for the diagnosis of acute myocardial infarction. It is, therefore, critical to develop a point-of-care testing technology for myoglobin detection. In this work, we reported a sensitive plasmonic immunoassay-based on enzyme-mediated localized surface plasmon resonance change of gold nanorods for the point-of-care testing detection of myoglobin. In addition, we developed a novel plasmonic immunoassay reader using the ambient light sensor of smart phone to increase the accessibility and utility of the plasmonic immunoassay. The linear detection range of gold nanorods-based plasmonic immunoassay for myoglobin detection was 0.1-1000 ng mL-1 and the limit of detection was 0.057 ng mL-1. Myoglobin in serum samples was also analyzed by the plasmonic immunoassay. The results were significantly correlated with those of conventional enzyme-linked immunosorbent assay. The plasmonic immunoassay, coupled with smart phone-based reader, could be widely used for point-of-care testing application of acute myocardial infarction, especially in the regions with limited technological resources.

Construction of a human monoclonal antibody against bFGF for suppression of NSCLC.

Compelling evidence implicates that overexpression of basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor 1 (FGFR1) in non-small cell lung cancer (NSCLC) drives tumor progression, can serve as prognostic biomarkers or therapeutic targets for NSCLC patients. But at present, we still lack of effective drugs for bFGF. The preparation of monoclonal antibodies against bFGF or to understand its mechanism of action is urgently need. Previously, we used hybridoma technology to produce a murine anti-bFGF monoclonal antibody (E12). However, E12 carries risks of heterogeneity and immunogenicity. In the present work, we produced three humanized variants (H1L1, H2L2 and H3L3) based on E12 by substituting residues in or near the complementarity-determining region (CDR). In addition, we thoroughly explored VH/VL domain combinations to simulate full-length IgG1 antibodies using computational protein design. H3L3 was selected for further study, as it demonstrated the best humanization and strongest affinity for bFGF. Specially, humanization of H3L3's light chain and heavy chain were 100% and 98.89%, respectively. The FGF2 neutralizing effect of H3L3 were confirmed by ELISA. We also found that H3L3 can effectively suppress the growth and angiogenesis of cancer through reduce the phosphorylation of AKT and MAPK. Moreover, H3L3 dramatically reduced tumor size and micro-vessel density in nude mice. Altogether, our study demonstrates that H3L3 exerts anti-tumor effects by impeding NSCLC development.

[Effect of basic fibroblast growth factor antibody combined with irinotecan on proliferation and apoptosis of small cell lung cancer H223 cells in vitro].

OBJECTIVE: To study the synergistic inhibitory effects of basic fibroblast growth factor (bFGF) monoclonal antibody (bFGF mAb) and irinotecan on the proliferation of small cell lung cancer H223 cells. METHODS: CCK-8 assay and flow cytometry were used to assess the effects of bFGF mAb combined with irinotecan on the proliferation and apoptosis of H223 cells, respectively. Western blotting was performed to analyze the effect of bFGF-mAb combined with irinotecan on AKT and ERK1/2 phosphorylation in the cells. RESULTS: Both bFGF mAb and irinotecan alone inhibited H223 cell proliferation in a dose-dependent manner (P<0.05). The inhibitory rate was significantly higher in H223 cells treated with bFGF mAb + irinotecan (54.30%) than in cell treated with bFGF mAb (18.73%) or irinotecan (21.96%) alone (P<0.05). Both bFGF mAb and irinotecan induced H223 cell apoptosis in a dose-dependent manner (P<0.05), and the combined treatment resulted in a significantly higher early apoptosis rates (6.5%) than treatment with bFGF mAb (2.7%) or irinotecan (4.3%) alone (P<0.05). bFGF mAb and irinotecan, either alone or in combination, significantly inhibited the levels of p-AKT protein and p-ERK1/2 protein without obviously affecting AKT and ERK1/2 protein levels. CONCLUSION: bFGF mAb and irinotecan produce synergistic inhibitory effects on small cell lung cancer H223 cells by suppressing proliferation and promoting apoptosis of the cells, and can effectively block the MAPK/ERK and PI3K/AKT signaling pathways associated with bFGF.

BFGF neutralization stimulates VEGF secretion in melanoma B16 cells.

Fusarium root rot is a major cryptogamic disease in olive trees caused by the soil-borne fungus Fusarium solani. Controlling this disease requires the extensive use of chemicals. However, using BCAs such as some Trichoderma strains may be an opportune alternative to fungicides in protecting olive plantations. A new isolate (Fso14) was isolated from young olive trees showing severe dieback symptoms. The objective of this work was to analyze the biocontrol behavior of a Tunisian strain of T. harzianum (Ths97) on olive trees against Fso14 by assessing both mycoparasitic activity (in planta and in vitro) and ability to locally modulate different gene-related defenses of the plant. Ths97 was found to inhibit Fso14 growth in vitro. Optical microscopic analysis at the confrontation zone between hyphae showed that Ths97 grew alongside Fso14 with numerous contact points suggesting parasitic activity. On olive trees, Ths97 developed a strong protective role against root infestation by Fso14, whether inoculated before or after the pathogenic agent. When inoculated alone, Fso14 and Ths97 did not modulate (or only slightly with inhibitions or inductions, respectively) the expression of genes involved in plant immunity (oxidative stress, phenylpropanoid pathway, PR-proteins and JA/Et-SA hormonal status). However, when Ths97 was inoculated in combination with Fso14, several defense-related genes were highly up-regulated, indicating probable primed-plant events. These promising results provided valuable information on using Ths97 as a beneficial agent to control fusarium root rot disease caused by F. solani in olive trees.

(125)I-labeled anti-bFGF monoclonal antibody inhibits growth of hepatocellular carcinoma.

AIM: To investigate the inhibitory efficacy of (125)I-labeled anti-basic fibroblast growth factor (bFGF) monoclonal antibody (mAb) in hepatocellular carcinoma (HCC). METHODS: bFGF mAb was prepared by using the 1G9B9 hybridoma cell line with hybridization technology and extracted from ascites fluid through a Protein G Sepharose affinity column. After labeling with (125)I through the chloramine-T method, bFGF mAb was further purified by a Sephadex G-25 column. Gamma radiation counter GC-1200 detected radioactivity of (125)I-bFGF mAb. The murine H22 HCC xenograft model was established and randomized to interventions with control (phosphate-buffered saline), (125)I-bFGF mAb, (125)I plus bFGF mAb, bFGF mAb, or (125)I. The ratios of tumor inhibition were then calculated. Expression of bFGF, fibroblast growth factor receptor (FGFR), platelet-derived growth factor, and vascular endothelial growth factor (VEGF) mRNA was determined by quantitative reverse transcriptase real-time polymerase chain reaction. RESULTS: The purified bFGF mAb solution was 8.145 mg/mL with a titer of 1:2560000 and was stored at -20 °C. After coupling, (125)I-bFGF mAb was used at a 1: 1280000 dilution, stored at 4 °C, and its specific radioactivity was 37 MBq/mg. The corresponding tumor weight in the control, (125)I, bFGF mAb, (125)I plus bFGF mAb, and (125)I-bFGF mAb groups was 1.88 ± 0.25, 1.625 ± 0.21, 1.5 ± 0.18, 1.41 ± 0.16, and 0.98 ± 0.11 g, respectively. The tumor inhibition ratio in the (125)I, bFGF mAb, (125)I plus bFGF mAb, and (125)I-bFGF mAb groups was 13.6%, 20.2%, 25.1%, and 47.9%, respectively. Growth of HCC xenografts was inhibited significantly more in the (125)I-bFGF mAb group than in the other groups (P < 0.05). Expression of bFGF and FGFR mRNA in the (125)I-bFGF mAb group was significantly decreased in comparison with other groups (P < 0.05). Groups under interventions revealed increased expression of VEGF mRNA (except for (125)I group) compared with the control group. CONCLUSION: (125)I-bFGF mAb inhibits growth of HCC xenografts. The coupling effect of (125)I-bFGF mAb is more effective than the concomitant use of (125)I and bFGF mAb.

Development of SPR biosensor for simultaneous detection of multiplex respiratory viruses.

A surface plasmon resonance (SPR)-based biosensor was developed for specific detection of nine common respiratory virus, including influenza A and influenza B, H1N1, respiratory syncytial virus (RSV), parainfluenza virus 1-3 (PIV1, 2, 3), adenovirus, and severe acute respiratory syndrome coronavirus (SARS). The SPR biosensor was developed by immobilizing nine respiratory virus-specific oligonucleotides in an SPR chip. To increase the biosensor sensitivity, biotin was used to label the PCR primer and further amplify the signal by introducing streptavidin after hybridization. Throat swab specimens representing nine common respiratory viruses were tested by the innovative SPR-based biosensor to evaluate the sensitivity, specificity and reproducibility of this method. Results suggest that this biosensor has the potential to simultaneously identify common respiratory viruses.

[Preparation and application of monoclonal antibody against human myoglobin].

OBJECTIVE: To prepare the monoclonal antibody (mAb) against human myoglobin (MYO) of high titer and specificity and develop double-antibody sandwich ELISA for detecting MYO in human serum samples. METHODS: The BALB/c mice were immunized with natural human MYO, and the hybridoma cell lines secreting anti-MYO mAb were established using cell fusion and hybridoma screening techniques. The characteristics of the mAb were identified after affinity purification from ascites. Then the best antibody pair was selected from mAb to establish a one-step sandwich ELISA method. Sixty human serum samples were detected by the homemade ELISA kit and the imported one, respectively. RESULTS: Nine strains of hybridoma cell lines stably secreted anti-MYO mAb. Four strains named 2M1, 3M4, 5M7 and 10M4 could secrete high-quality mAb and the titers of them were in the range of 1.0×10(6) to 2.6×10(6) (A450 value was about 1.0). Three antibody pairs (2M1/HRP-3M4, 5M7/HRP-3M4, 10M4/HRP-5M7) were selected by double-antibody sandwich ELISA. Among them, the 5M7/HRP-3M4 had higher sensitivity and larger linear range. The homemade ELISA kit had a larger linear range (25-1000 ng/mL) than the imported one (25-500 ng/mL) and showed high accuracies in detecting human serum samples, being 95% (19/20) in positive samples and 100% (40/40) in negative samples. CONCLUSION: With the anti-human MYO mAbs of high specificity and affinity, a one-step sandwich ELISA for detecting human MYO has been established successfully, which provides a basis for the development of domestic ELISA kit.

A novel method to detect Listeria monocytogenes via superparamagnetic lateral flow immunoassay.

A novel strip test system combining immunomagnetic separation with lateral flow immunoassay (LFIA) was established for the accurate detection of Listeria monocytogenes. In this system, a pair of matched monoclonal antibodies was used to construct a sandwich immunoassay, in which superparamagnetic particles were coupled with one of the antibodies as a labeled antibody to capture the target bacteria, while the other antibody was immobilized on the detection zone. After a 20-min reaction, the strips were analyzed by a novel instrument which could detect the magnetic signal of the immunocomplex in a magnetic field. Sensitivity evaluation showed that the limit of detection (LOD) of the superparamagnetic LFIA system for L. monocytogenes was 10(4) CFU/mL, which was at least one log lower than conventional LFIA. No cross-reaction was observed when Salmonella, Escherichia coli O157:H7, or three types of harmless Listeria strains were tested. Further evaluation with actual food samples indicated that the superparamagnetic LFIA system showed 100 % concordance with real-time PCR. Therefore, this novel superparamagnetic LFIA system could be used as a rapid, sensitive, and specific method for the detection of L. monocytogenes.

[Rapid detection of Listeria monocytogenes by immunomagnetic separation combined with selective medium].

Listeria monocytogenes is a pathogenic bacterium, therefore, it is essential for food safety monitoring to establish a rapid and specific detecting method. In this study, immunomagnetic beads and selective medium were combined to detect Listeria monocytogenes at different concentrations (10(1)-10(5) CFU/mL). Other three types of Listeria spp., Staphylococcus aureus and Vibrio parahaemolyticus were also detected to conduct the cross-reaction analysis. Meanwhile, contaminated milk samples were prepared to explore the limit of detection of immunomagnetic beads combining with selective medium. Results showed that Listeria monocytogenes with the concentration of 10(3) CFU/mL and above was successfully detected. Milk samples were detected within 6 hours, with a detection limit of 0.7 CFU/mL. The method developed is capable of detecting milk samples within 30 h, which is 38 h faster compared with national standard method with the same sensitivity.

[Preparation of anti-zearalenone monoclonal antibody and preliminary establishment of colloidal gold immunochromatographic assay for zearalenone].

OBJECTIVE: To prepare the monoclonal antibody against zearalenone (ZEN) toxin and preliminarily establish the colloidal gold immunochromatographic detection method for ZEN. METHODS: The artificial antigen ZEN-BSA and ZEN-OVA were prepared by active ester method. Mice were immunized with ZEN-OVA and monoclonal antibodies against ZEN were prepared by regular cell fusion and subcloning approach. The titer, subtype and specificity of the antibodies were identified by ELISA. To establish a method of colloidal gold immunochromatographic assay (GICA) for the determination of ZEN, colloidal gold binding cushion was coated with anti-ZEN monoclonal antibody-colloidal gold complex, and the synthetic ZEN-BSA and goat anti-mouse immunoglobulins were sprayed on cellulose nitrate film to form the test (T) band and control (C) band. RESULTS: Identified by SDS-PAGE and UV spectroscopy, the artificial antigen ZEN-BSA and ZEN-OVA were successfully coupled respectively. One hybridoma line (1G4) which could secrete monoclonal antibody specifically against ZEN was obtained by three-time cloning. The ascites titer of this monoclonal antibody reached 1:1.6×10(5);. The antibody subtype was IgG2b. The IC50; to ZEN was 10.2 ng/mL, and the detction limit was 0.58 ng/mL. In addition, the mAb was proved highly specific for ZEN. ZEN metabolites α-zearalanol, ß-zearalanol, zearalanone and other similar toxins deoxynivalenol, fumonisin B1, ochratoxin A showed very low or no cross-activity with the monoclonal antibody. The whole assay using the prepared colloidal gold immunochromatographic strip could be finished in 5 min, which could be read by naked eyes. The limit of detection was 100 ng/mL. CONCLUSION: The anti-ZEN mAb was successfully prepared. And the gold immunochromatographic assay(GICA) for ZEN was preliminarily established with the limit of detection being 100 ng/mL.

A novel fluorescence-quenching immunochromatographic sensor for detection of the heavy metal chromium.

A novel fluorescence quenching immunochromatographic sensor (ICS) was developed for detecting chromium (Cr(3+)) within 15 min utilizing the fluorescence quenching function of gold nanoparticles (Au-NPs). The sensor performed with a positive readout. When the low concentrations of Cr(3+) samples were applied, detection signals of the test line (T line) were quenched, whereas when higher concentration Cr(3+) samples (1.56 ng/mL) were applied, the detection signal of the T line appeared. The detection signal intensity of the T line increased with increasing concentrations of Cr(3+). The low detection limit of developed fluorescence quenching ICS was 1.56 ng/mL. The fluorescence quenching ICS has a linear range of detection of Cr(3+) comprising between 6.25 ng/mL to 800 ng/mL. The recoveries of the fluorescence quenching ICS to detect Cr(3+) in tap water ranged from 94.7% to 101.7%. This result indicated that the developed sensor gave higher sensitivity and reliable reproducibility. It could provide a general detection method for small analyte in water samples.

Colloidal gold nanoparticle probe-based immunochromatographic assay for the rapid detection of chromium ions in water and serum samples.

An immunochromatographic assay (ICA) using gold nanoparticles coated with monoclonal antibody (McAb) for the detection of chromium ions (Cr) in water and serum samples was developed, optimized and validated. Gold nanoparticles coated with affinity-purified monoclonal antibodies against isothiocyanobenzyl-EDTA (iEDTA)-chelated Cr(3+) were used as the detecting reagent in this completive immunoassay-based one-step test strip. The ICA was investigated to measure chromium speciation (Cr(3+) and Cr(6+) ions) in water samples. Chromium standard samples of 0-80 ng mL(-1) in water were determined by the test strips. The results showed that the visual lowest detection limit (LDL) of the test strip was 50.0 ng mL(-1). A portable colorimetric lateral flow reader was used for the quantification of Cr. The results indicated that the linear range of the ICA with colorimetric detection was 5-80 ng mL(-1). The ICA was also validated for the detection of chromium ions in serum samples. The test trips showed high stability in that they could be stored at 37°C for at least 12 weeks without significant loss of activity. The test strip also showed good selectivity for Cr detection with negligible interference from other heavy metals. Because of its low cost and short testing time (within 5 min), the test strip is especially suitable for on-site large-scale screening of Cr-polluted water samples, biomonitoring of Cr exposure, and many other field applications.

[Mass spectrometry identification and immune cross-reactivity of a minor shrimp allergen-sarcoplasmic calcium binding protein from Litopenaeus vannamei].

AIM: To identify sarcoplasmic calcium-binding protein (SCP) as a minor shrimp allergen by mass spectrometry, and to analyze the immune cross-reactivity among crustacean SCPs. METHODS: The M(r); 21 000 allergen from Litopenaeus vannamei was identified by MALDI-TOF/TOF-MS. BLAST and ClustalW were used to compare amino acid sequence identity of the allergen among crustaceans. The puritifed M(r); 21 000 allergen was injected subcutaneously in mice to produce the specific polyclonal antibodies to analyze immune cross-reactivity of the allergen with proteins from 8 other species of crustaceans by Western blotting. RESULTS: The M(r); 21 000 shrimp allergen was identified as SCP. Sequence comparison revealed that SCP had 81%-100% amino acid identity among crustaceans. Western blotting showed that the proteins with M(r); about 21 000, corresponding to SCP from Metapenaeus ensis, Penaeus monodon, Oratosquilla oratoria, Macrobrachium rosenbergii, Procambarus clarkii, Portunus pelagicus, Charybdis feriatus, Eriocheir sinensis were recognized by polyclonal antibodies against SCP of Litopenaeus vannamei. CONCLUSION: SCP is a minor shrimp allergen, and SCPs have a high sequence homology and strong immune cross-reactivity among crustaceans, which can be used as detective, diagnostic and safe immunotherapeutic agents for subjects with shrimp allergy.

[Preparation and application of monoclonal antibodies against Heavy Metal Chromium].

AIM: To produce the monoclonal antibodies (mAb) against Heavy Metal Chromium, and develop a competitive inhibition enzyme-linked immunosorbent assay (ciELISA) for the detection of Chromium. METHODS: Chromium ions was chelated with bifunctional chelating agent Isothio-cyanobenzyl- EDTA firstly and then conjugated with bovin serum alburmin(BSA) and ovalbmin(OVA) respectively to complete antigens . Four female BALB/c mice were immunized with Cr-iEDTA-BSA, the Hybridoma lines secreting monoclonal antibodies against Chromium ions were established by the hybridoma technology. The titer and the specificity of the antibodies were characterized in the way of indirect enzym-elinked immunosorbent assay (iELISA) and ciELISA. RESULTS: After immunization and cell fusion, three hybridomaes which can stably secrete mAbs against chromium were obtained. The antibody titer was up to 1×10(5);, only had 9.62% cross-reactivity to Fe(3+); and little to other ions. Linear detection of ciELISA for Chromium covered a range from 0.783 µg/L-50 µg/L with the limit at the level of 1 µg/L. An excellent correlation of results obtained by ciELISA and ICP-AES when the concentration more than 1 µg/L. CONCLUSION: The monoclonal antibody against Chromium with high sensitivity and specificity has been generated and a competitive inhibition enzyme-linked immunosorbent assay for the detection of Chromium ions has been established successfully, which was met the the national standard of water quality nonitoring.

Development of a lateral flow immunoassay (LFA) strip for the rapid detection of 1-aminohydantoin in meat samples.

UNLABELLED: Due to the potential toxic effects of the nitrofuran family of antibiotics, their use in animals in the food industry has raised health concerns. This study was aimed to develop a lateral flow assay (LFA) based on competitive format for the detection of 1-aminohydantoin (AHD) in meat samples. The assay could be completed in 1 min and detected AHDs derivates (CPAHD) at 3 ng/mL, equivalent to 1.40 ng/mL of AHD, which was much lower than that reported in the literature by similar method. The antibody showed no cross-reactivity with a panel of more than 10 nitrofuran analogs except for nitrofurantoin at a high concentration. The test strip was stable at room temperature for up to 8 wk or at 37 °C for 4 wk. Parallel analyses of meat samples with LFA and enzyme-linked immunosorbent assay (ELISA) obtained data in good agreement. This developed gold nanoparticle based LFA had a good specificity, sensitivity, stability, and reliability. It was potentially suitable for on-the-spot large-scale screening of meat samples, and even more other applications. PRACTICAL APPLICATION: Nitrofurantoin is one of antibiotics of the nitrofuran family, which has been used not only to prevent and treat diseases, but also to promote growth in animals. However, concerning the carcinogenicity of the metabolite of nitrofurantoin (AHD), a new fast and convenient method for monitoring AHD should be established. We describe the development of a new test assay for rapid screening of meat samples.

Monoclonal antibodies targeting basic fibroblast growth factor inhibit the growth of B16 melanoma in vivo and in vitro.

Up-regulated basic fibroblast growth factor (bFGF or FGF-2) plays an important role in the development and metastasis of melanoma; therefore, neutralizing antibodies to bFGF may suppress melanoma growth. In this study, we have developed three monoclonal antibodies against bFGF (anti-bFGF mAbs), which display remarkable anti-tumor and anti-angiogenic effects in vitro and in vivo. Anti-bFGF mAbs significantly inhibit the proliferation and induce apoptosis of B16 cells, and show inhibitory effects on the migration of B16F10 cells and the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. Treatment of B16 melanoma spheroids with anti-bFGF mAbs in vivo results in significant reduction in tumor size and prolonged survival time of animals. Moreover, TUNEL (terminal transferase dUTP nick end labeling) assay and CD31 staining confirmed the increase of apoptosis and decrease of intratumoral microvessel density in tumor sections from animals treated with anti-bFGF mAbs. Our data indicate that anti-bFGF mAbs are potential therapeutic candidates for melanoma therapy by effectively suppressing the melanoma growth through inhibition of angiogenesis and induction of apoptosis in the tumor.

[A Paralytic shellfish poisoning GTX2,3 mimic peptide isolated from phage display: characterization and potential applications].

AIM: To screen peptide mimics of PSP (Paralytic shellfish poisoning) GTX2,3 from a random 12-mer phage display peptide library and to identify and characterize the specificity and accuracy of the peptide mimotope of GTX2,3. METHODS: The monoclonal antibody against GTX2,3 (mAb E(9);F(10);) was used as a target to screen the 12-mer phage display peptide library and the specificity of phage clones were identified by sandwich ELISA and blocking assay. The peptide sequences of positive phage clones were determined and analyzed by DNA sequencing. The affinity and specificity of synthetic peptide were identified by a competitive ELISA. RESULTS: The 20 clones were identified to be specific reactivity with the mAb E(9);F(10);. Amino acid sequence analysis revealed seven different types of mimotope sequence, most of which contained a common motif DXLXPP(X presents random acid amino), X was random amino acid. The Phage No.2(phage 2), the clone with mimotope sequence WPSLDXLXPPSY showed the strongest binding, and inhibited the reactivity of the mAb with GTX2,3. Another ELISA result showed that synthetic peptide-1 (SP-1) which contain mimotope amino acid sequence was able to inhibit the mAb- GTX2,3 interaction. CONCLUSION: The mimotope peptide of GTX2,3 is obtained by using the phage display technology. The results also showed that SP-1 bind to mAb E(9);F(10); at the same site as GTX2,3.

[Identification, isolation, purification of allergens in shrimp and allergic analysis for the main allergens].

AIM: To identify the allergens in shrimp, and to isolate, purify and analyze the main allergen components. METHODS: The total shrimp proteins were extracted by PBS, the allergens were identified with 11 shrimp allergic patients' serum IgE by Western blot. Three main shrimp allergens 21,000, 36,000 and 80,000 were purified by ammonium sulfate precipitation, Sephadex G-50 chromatography and DEAE-exchange chromatography. Western blot and indirect ELISA were used to confirm and analyze allergenicity of the three main allergens. RESULTS: Western blot demonstrated that there were nine allergen components in shrimp proteins, and IgE binding to 21,000, 36,000 and 80,000 shrimp allergen by 5, 7, 5 (36.4%, 63.6%, 45.5%) of 11 shrimp allergic patients' sera. Results of indirect ELISA showed that the binding absorbency of allergic patients' sera IgE with the three main purified allergens were all higher than that with shrimp protein extraction. CONCLUSION: There are at least 9 allergens in shrimp; the 21,000, 36,000 and 80,000 proteins are the main allergen components; and the 36 000 protein is the primary main allergen, with the highest allergenicity and sensitization rate. In further investigation, we will use monoclonal antibody technique to verify weather the 21,000, 36,000, 80,000 allergens have common epitope, which will lay a foundation for shrimp allergy clinical diagnosis and shrimp allergen vaccine design.

Colloidal gold probe-based immunochromatographic assay for the rapid detection of lead ions in water samples.

One-step immunochromatographic assay (ICA) has been developed using colloidal gold-labeled monoclonal antibody probe for the rapid detection of lead ions in water samples. The ICA was based on the theory of competitive reactivity, and the results can be easily judged based on the presence or absence of a red colored test line with visual detection. Under optimal conditions, this method shows high detecting sensitivity with a LOD (limit of detection) of 50 ng/ml. Stability test indicates that the immunochromatographic strips are stable for 8 weeks at room temperature. During practical application, nanometer TiO2 is used to enrich the lead ions in water samples. The ICA is successfully applied in the measurement of lead ion concentrations in local water samples, and the results are highly consistent with that of ICP-MS. Detecting lead ions with ICA can be done within 4 min and is very useful for the rapid onsite testing.