Dot Enzyme-linked Immunosorbent Assay Research Articles

Development of monoclonal antibodies and serological assays specific for Barley yellow dwarf virus GAV strain

BackgroundBarley yellow dwarf virus (BYDV) is one of the most devastating plant viruses and belongs to a ubiquitous plant virus group. In China, four BYDV strains (GPV, GAV, PAV and RMV) have been identified based on their specific aphid vectors and serological properties. Among the four identified strains, the GAV is the most common BYDV strain in China. To diagnose, forecast of BYDV GAV, two reliable serological assays for BYDV GAV detection were established.MethodsWe purified virion from a confirmed BYDV GAV source and used it as the immunogen to produce monoclonal antibodies against the virus. Using the hybridoma technology, three highly specific murine monoclonal antibodies were produced and two serological assays [antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and dot enzyme-linked immunosorbent assay (dot-ELISA)] were established for the BYDV GAV detection.ResultsAll three monoclonal antibodies reacted strongly and specifically with the BYDV GAV strain in crude leaf extracts. Titers of the monoclonal antibodies in ascitic fluids were up to 10−7 by indirect-ELISA. These three monoclonal antibodies (18A1, 18A9 and 12A11) all belonged to the isotype IgG1, kappa light chain. The highest dilution points for the three antibodies during the ACP-ELISA using infected crude leaf extracts were 1:163,840, 1:81,920 and 1:81,920 (w/v, g · mL−1), respectively. Result of dot-ELISA showed a successful detection of BYDV GAV strain in 1:5,120 (w/v, g · mL−1) diluted wheat leaf crude extracts. Analysis of 22 field wheat leaf samples and 33 aphid samples from the Shaanxi Province in China, using the two newly developed assays confirmed the presence of BYDV GAV in about 80 % of the wheat samples and 18 % of the aphid samples.ConclusionsAll three monoclonal antibodies are highly sensitive and specific to the BYDV GAV. The two newly developed serological assays are simple and effective. These two assays, particularly the dot-ELISA, are useful for high throughput detection of BYDV GAV in host plants and aphid vectors.

Clinical features of 32 new Japanese cases with autoimmune haemorrha-philia due to anti-factor XIII antibodies.

Autoimmune haemophilia-like disease (or haemorrha-philia) due to anti-factor XIII (FXIII; F13 to avoid confusion with FVIII or FXII) antibodies (termed AH13) is a severe bleeding disorder. Although AH13 is thought to be rare, 'the number of its diagnosed patients' has recently increased in Japan. However, its prevalence remains unknown. To improve understanding of this disease, we examined and diagnosed 32 'new' Japanese patients with AH13. The presence of antibodies against F13-A subunit and/or F13-B subunit was confirmed by using a dot blot test and enzyme-linked immunosorbent assays. Most of our patients had autoantibodies against the F13-A subunit (88%). A predominance of men (59%) was observed. The mean age and residual F13 activity of our AH13 cohort were 71.7 years and 10.5% of normal, respectively, and 53% of cases were idiopathic. Autoimmune disorders and malignancies were the leading underlying disease (both 16%). Intramuscular and subcutaneous bleeding were the leading symptoms (both 72%). Most of our patients were treated with F13 concentrates (72%) to arrest bleeding and with prednisolone (81%) to eradicate anti-F13 autoantibodies. Cyclophosphamide and rituximab (both 25%) were also administered. The mortality of AH13 was high (22%), and haemorrhage was the major cause of death (71%). Moreover, 13% of our AH13 patients were diagnosed after haemorrhagic death. Physicians/haematologists must raise the awareness of AH13 as a life-threatening disease. This report represents the only experience of a nationwide survey, and may contribute to a diagnosis on potentially overlooked non-Japanese AH13 patients in other countries in the world.

Engineered Antibody Fragments for Immunodiagnosis of Papaya ringspot virus.

The present study was undertaken to clone and express the genes encoding antibody to the recombinant coat protein (rCP) of Papaya ringspot virus (PRSV) and to assess the engineered antibody for the detection of PRSV. A 33-kDa rCP of PRSV, which was produced in Escherichia coli, generated PRSV specific antibody in immunized mouse. The heavy and light chain variable domain genes (VH and VL) of 351 and 360 nucleotides, respectively, were cloned from the mRNA isolated from the spleen of the immunized mouse with rCP of PRSV. The VH and VL belong to the family IgG1 and kappa chain, respectively, and contained the framework regions and complementarity determining regions. The VH and VL genes were individually used to develop the expression constructs in pET28a (+) vector and 14-kDa proteins were obtained in E. coli. The amount of purified VH and VL proteins was 3-4 mg/l of bacterial culture. Both the antibody fragments recognized PRSV in the crude sap; however, the VL antibody fragment showed higher affinity to PRSV. The mixture of VH and VL detected PRSV as effectively as polyclonal antibody. The recombinant antibody fragments mixture detected PRSV in the field samples with 100 % accuracy in dot immunobinding assay (DIBA) and enzyme-linked immunosorbent assay (ELISA). The sensitivity of the detection of PRSV using antibody fragments was 1.0 and 10.0 ng in DIBA and ELISA, respectively. The results showed successful isolation of functional single-domain antibody encoding genes to PRSV directly from the immunized spleen cells of mouse. This study for the first time demonstrates application of bacterial expressed recombinant antibody fragments in immunodiagnosis of PRSV.

Use of biotin-labeled IgY overcomes protein A interference in immunoassays involving Staphylococcus aureus antigens

Staphylococcal protein A (SpA) is an immunoglobulin-binding protein secreted by all Staphylococcus aureus strains and is responsible for high false positives during immunoassays. Avian IgY were reported to eliminate SpA interference when used as a capture antibody in a double antibody sandwich format. But this procedure requires generating two antibodies in different animals for capture and revealing antibodies. In the present study, a simple enzyme-linked immunosorbent assay (ELISA) was developed and evaluated for detection of staphylococcal enterotoxin B without any interference by SpA. Biotin-labeled IgY were used for probing for staphylococcal enterotoxin B (SEB) so that streptavidin-horseradish peroxidase (HRP) could be used for color development instead of anti-chicken IgG-HRP, which interferes in the assay by binding to SpA. Western blotting, dot ELISA, and polymerase chain reaction (PCR) were performed to validate the results of the biotin IgY ELISA to show that the assay was free from SpA interference. Large numbers of S. aureus strains were screened for SEB production. Sensitivity of the assay was ~10 ng/ml of SEB in spiked milk samples. The ELISA was specific to SEB, with no cross-reactivity to other closely related enterotoxins (SEA, SEC, SED, SEE). The presently described ELISA is highly effective in eliminating SpA interference and this method does not require the need for two different antibodies, as in the sandwich ELISA.

Development of a High-Throughput Immunoassay for Rapid Detection of Multiple Antibiotic Residues in Cosmetics

Antibiotic residues in cosmetics can cause seriously healthy problems such as sensitization, systemic toxicity, or even death. The developments of rapid methods for multiple antibiotics detection are needed to conveniently detect out the illegal additives. In this study, a simple, cost-effective and time-saving immunoassay, multi-analyte dot enzyme-linked immunosorbent assay (Multi-Dot-ELISA), for the simultaneous detection of three most common abused antibiotics (CPFX, TC, and SMD) was successfully designed and developed. Based on the competitive Multi-Dot-ELISA, real samples from 5 of 15 (33%) commercial cosmetic products were found CPFX and SMD additives which are banned in China. We demonstrate that this rapid and low-cost platform is a promising tool in human health protection.

Transient Expression of Foot and Mouth Disease Virus (FMDV)Coat Protein in Tobacco (Nicotiana tabacom) via Agroinfiltration

Background: Transient and stable transformation of host plants are the common techniques to produce transgenic plants. However, the main drawback of stable transformation is the fact that it takes quite a long time to produce a transgenic line. While, transient gene expression is a quick method to produce recombinant proteins in plants. Objective: The main goal of the present study was to evaluate efficient agroinfiltration as an efficient and rapid method for production of recombinant antigen of FMDV. Materials and Methods: Tobacco leaves were transformed via agroinfiltration using a needle-free syringe. Presence of the gene cassette was verified by polymerase chain reaction (PCR). Expression of the foreign gene was evaluated using Real Time PCR, protein dot blot and enzyme-linked immunosorbent assay (ELISA). Results: PCR analysis confirmed successful transformation of plant leaves. Expression of foreign protein was confirmed at both transcription and translation levels. Results of Real Time PCR assay indicated that the foreign gene was transcribed in transformed leaves. ELISA results showed that the foreign gene was expressed in the transformed leaves in high level. Conclusion: Here, the efficacy of agroinfiltration for transient expression of FMDV coat protein in tobacco was illustrated. Accordingly, transient agroinfilteration expedites the process of recombinant antigens expression in plant tissues.

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-C2X 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.

Recombinant hexon antigen based single serum dilution ELISA for rapid serological profiling against fowl adenovirus-4 causing hydropericardium syndrome in chickens

A recombinant hexon antigen based single serum dilution enzyme linked immunosorbent assay (ELISA) was developed to measure the specific antibody in sera of chickens against Fowl adenovirus-4 (FAdV) causing Hydropericardium syndrome (HPS). An immunodominant partial hexon gene of 737bp was cloned into pRSET vector and expressed in Escherichia coli strain BL21 DE3 pLys S. Expression was tested by Western Blot test. The purified recombinant protein antigen was used in coating ELISA plate for FAdV-4 serology. A linear relationship was found between the predicted antibody titres at a single working dilution of 1:100 and the corresponding observed serum titres as determined by the standard serial dilution method. Regression analysis was used to determine a standard curve from which an equation was derived that allowed the demonstration of this correlation. The equation was then used to convert the corrected absorbance readings of the single working dilution directly into the predicted ELISA antibody titres. The assay proved to be sensitive, specific and accurate as compared to Q-AGID test. Recombinant antigen was also used in Dot ELISA. In an experimental vaccination of broiler chicken at 10 days old age, the geometric mean (GM) antibody titres as measured by ELISA ranged from 5.006±0.11log10 to 4.526±0.04log10 and by Dot ELISA titre were from 2.240±0.08log10 to 0.180±0.04log10 during 5th–8th weeks of age, results were compared with Q-AGID results. Field samples were collected randomly from breeder flocks, found to have antibody titre by both ELISA and Dot ELISA at 10th and only 75% samples were positive at 14th weeks of age. After revaccination at 16th weeks of age, all sera samples were found have considerably high antibody titre on 24th week but all samples were negative at 32nd weeks. Advantages of recombinant hexon antigen based ELISA and Dot ELISA in FAdV-4 serology have been discussed.

Determination of Deoxynivalenol, Zearalenone, Aflatoxin B1, and Ochratoxin by an Enzyme-Linked Immunosorbent Assay

Despite efforts to control fungal contamination, some mycotoxins, including deoxynivalenol, zearalenone, aflatoxin, and ochratoxin, are ubiquitous in the rural China. The purpose of this study was to establish a simple method for noninstrumental detection of these residues by a multianalyte dot enzyme-linked immunosorbent assay. The multianalyte dot enzyme-linked immunosorbent assay was simple, inexpensive, and fast and is expected to have broad applications in the food processing industry in rural China.

Apoptotic function of tumor-associated antigen RCAS1 in oral squamous cell carcinoma.

BackgroundReceptor-binding cancer antigen expressed on SiSo cell (RCAS1) is derived from uterine adenocarcinoma and can induce apoptosis in lymphocytes, allowing tumor cells to escape from immune surveillance. RCAS1 is reportedly expressed in a membranous pattern on tumor cell or soluble one in serum of patients. The aim of this study was to investigate expression patterns of RCAS1 and the effect on apoptosis in oral squamous cell carcinoma (OSCC) cell lines.MethodsIn four kinds of OSCC cell lines (HSC-2, HSC-3, SQUU-A, and SQUU-B), RCAS1 mRNAs and proteins were determined by RT-PCR and immunocytochemistry. Membranous RCAS1 was determined by flow cytometry. Culture supernatants were analyzed for detection of soluble RCAS1 by dot blotting and enzyme-linked immunosorbent assay. Apoptotic ability of RCAS1 on the erythroid leukemia cell line K562 with the putative receptor was evaluated by flow cytometry in co-culture with highly metastatic SQUU-B, with knocked-down RCAS1 cells or in a no-cell contact condition.ResultsRCAS1 mRNA and proteins were expressed in all of OSCC cell lines. Membranous pattern were expressed in all cell lines, while soluble pattern was detected in all supernatants. RCAS1 mRNA, membranous and soluble RCAS1 were significantly seen in SQUU-B more than the other 3 cell lines (P < 0.05). K562 apoptosis was induced in co-culture with each of all cell lines, particularly with SQUU-B. Apoptosis was markedly reduced in co-culture with RCAS1 knockdown cells, but was induced in co-culture without cell contract of SQUU-B.ConlusionsOur study suggests that RCAS1 has an apoptotic function via membranous/soluble expression pattern in OSCC cells. RCAS1 may thus affect tumor escape from immune surveillance in OSCC by inducing apoptosis.

Monoclonal antibody-based serological assays and immunocapture-RT-PCR for detecting Rice dwarf virus in field rice plants and leafhopper vectors

Rice dwarf virus (RDV) causes Rice dwarf disease, which leads to considerable losses in rice production in Asia. Purified RDV virions were used as the immunogen to prepare monoclonal antibodies (mAbs). Three murine mAbs against RDV were prepared. Plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA), dot enzyme-linked immunosorbent assay (dot-ELISA) and immunocapture-RT-PCR (IC-RT-PCR) were then developed for sensitive, specific, and rapid detection of RDV in rice and leafhopper samples obtained in the field using the mAbs. The PTA-ELISA, dot-ELISA and IC-RT-PCR detected the virus in infected tissue crude extracts diluted at 1:81,920, 1:10,240 and 1:655,360 (w/v, gmL−1), in individual viruliferous rice green leafhopper crude extracts diluted at 1:25,600, 1:6400 and 1:3,276,800 (individual leafhopper/μL), respectively. 878 rice field samples and 531 leafhopper field samples from ten provinces of China were screened for the presence of RDV using the two serological assays and the IC-RT-PCR and the results indicated that 37 of the 878 rice samples and 22 of the 531 leafhopper samples were infected by RDV. All positive samples were from Yunnan Province, indicating that RDV is prevalent in this province, but not in the other nine provinces. The dot-ELISA is suitable for routine detection of large-scale rice and leafhopper samples in field surveys.

AB0393 Comparison of multi-line dot assay and enzyme-linked immunosorbent assay for detection of autoantibody profile in antiphospholipid syndrome

BackgroundDiagnosis of antiphospholipid syndrome (APS) still remains a laboratory challenge due to the great diversity of antiphospholipid antibodies (aPL) and their significance regarding APS classification criteria. Standardized enzyme-linked immunosorbent assay...

Epitopes of the Highly Immunogenic Trichomonas vaginalis α-Actinin Are Serodiagnostic Targets for Both Women and Men

There is a need for a point-of-care serodiagnostic test for women and men for sexually transmitted infections (STIs) caused by Trichomonas vaginalis. Sera from women with this STI and sera from men that were analyzed in studies showing a relationship between serostatus and prostate cancer are highly seropositive in response to trichomonad α-actinin and its truncated protein (ACT-P2) (positive control sera). Epitope mapping experiments showed that positive control sera from women had antibodies to 13 distinct epitopes, 5 of which were detected by positive control sera from men. Sera from women and men that were unreactive with α-actinin (negative control sera) failed to detect any of the epitopes or other α-actinin amino acid sequences. The T. vaginalis α-actinin amino acid sequence and the sequences of the epitopes showed little or no identity with those of other proteins of microbial pathogens or the human α-actinin 1 (HuACTN1) homolog. Immunoassays such as dot blot, immunoblot, and enzyme-linked immunosorbent assays were used. Positive control sera did not detect HuACTN1 in immunoassays, and the range of levels of identity of α-actinin epitopes with HuACTN1 was 0% to 50%. Comparison of the T. vaginalis α-actinin epitopes with proteins in data banks, such as Tritrichomonas suis, Candida albicans, and Saccharomyces cerevisiae proteins, gave a range of identity levels of 0% to 22%. Specific 15-mer peptide epitopes of α-actinin with low to no identity with other proteins were synthesized and were reactive with positive control sera only. These findings identify epitopes of α-actinin as candidate serodiagnostic targets and suggest strongly that a highly seropositive reaction to α-actinin suggests exposure to T. vaginalis.

Development and use of three monoclonal antibodies for the detection of rice black-streaked dwarf virus in field plants and planthopper vectors

BackgroundRice black-streaked dwarf virus (RBSDV) causes great losses in rice, maize and wheat production in Asian countries. The use of serological methods for RBSDV detection depends on the availability of antibodies. In this study, three highly sensitive and specific murine monoclonal antibodies (MAbs) against RBSDV antigens were produced using crude extracts from tumors of RBSDV-infected maize as the immunogen, and two serological assays, antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and dot enzyme-linked immunosorbent assay (dot-ELISA) were developed for RBSDV detection.ResultsAll three MAbs reacted strongly and specifically with the crude extracts from RBSDV-infected plant and planthopper tissues. The detection endpoints of three MAbs (12E10, 18F10 and 5G5) in ACP-ELISA were respectively 1:40,960, 1:40,960, 1:81,920 (w/v, g mL-1) with the crude extract of infected maize, 1:10,240, 1:20,480, 1:20,480 (w/v, g mL-1) with the crude extract of infected rice, 1:5,120, 1:10,240, 1:10,240 (w/v, g mL-1) with the crude extract of infected wheat, 1:9,600, 1:9,600, 19,200 (individual planthopper/μL) with the crude extract of infected planthopper. The newly developed ACP-ELISA could detect the virus in the infected maize, wheat, rice tissue crude extracts diluted at 1:81,920, 1:20,480, 1:10,240 (w/v, g mL-1), respectively, and in individual viruliferous planthopper extract diluted at 1:19200 (individual planthopper/μL). The dot-ELISA was proved to detect the virus in the infected maize, wheat and rice tissue crude extracts diluted at 1:320 (w/v, g mL-1), and in individual viruliferous planthopper extract diluted at 1:1,600 (individual planthopper/μL), respectively. Field plants (915) and planthopper samples (594) from five provinces of China were screened for the presence of RBSDV using the two developed serological assays. The results indicated that 338 of the 915 plant samples and 19 of the 594 planthopper samples were infected by RBSDV.ConclusionsThe newly developed ACP-ELISA and dot-ELISA were highly sensitive and specific to detect RBSDV in field plant and planthopper samples. The field survey demonstrated that RBSDV is widespread in rice, maize and wheat crops in Jiangsu, Zhejiang, Shandong provinces of China.

Evaluation of Dot-ELISA and enzyme-linked immuno-electrotransfer blot assays for detection of a urinary hydatid antigen in the diagnosis of cystic echinococcosis

Background:Several serological assays are used for detection of a hydatid antigen in serum for diagnosis of cystic echinococcosis (CE). However, it requires technical expertise and is associated with the risk of acquiring blood-borne infections. Of late, interests have been shifted to other body fluids like urine, saliva, tear drops as alternate specimens in the diagnosis of CE.Aim:The aim of the study was to evaluate the dot enzyme-linked immunosorbent assay (Dot-ELISA) and electro-immunotransfer blot (EITB) for detection of a hydatid antigen in the urine for diagnosis of CE.Materials and Methods:100 ml of urine samples were collected from the patients with confirmed CE (n=30), patients with suspected CE (n=30), patients with other diseases (n=30) and healthy controls (n=30). A hydatid antigen in urine was detected by Dot-ELISA and EITB using only polyclonal antibodies raised against a complete homogenate hydatid (CHH) antigen in rabbits.Results and Conclusions:The Dot-ELISA using polyclonal antibodies showed a sensitivity of 53.33% and specificity of 96.66%, whereas EITB showed a sensitivity of 46.66%. The Dot-ELISA and EITB employing polyclonal antibodies showed no significant difference in sensitivity (P=0.426). Hence, the Dot-ELISA being a simple procedure can be used for detection of a hydatid antigen in urine for diagnosis of CE.

Development of cathepsin-L cysteine proteinase based Dot-enzyme-linked immunosorbent assay for the diagnosis of Fasciola gigantica infection in buffaloes

Native cathepsin-L cysteine proteinase (28kDa) was purified from the excretory secretory products of Fasciola gigantica and was used for sero-diagnosis of F. gigantica infection in buffaloes by Dot-enzyme-linked immunosorbent assay (Dot-ELISA). The test detected F. gigantica field infection in these animals with a sensitivity of ∼90%. No specific IgG antibody binding was displayed by sera obtained from 76 buffaloes considered to be Fasciola and other parasite-free by microscopic examination of faeces and necropsy examination of liver, rumen and intestine. Additionally, sera from 156 Fasciola-free buffaloes, yet infected with Gigantocotyle explanatum, Paramphistomum epiclitum, Gastrothylax spp., Strongyloides papillosus and hydatid cyst were all negative, indicating that F. gigantica cathepsin-L cysteine proteinase does not cross-react with these helminth parasites in natural infection of the host. The data indicated that cathepsin-L cysteine proteinase based Dot-ELISA reached ∼90% sensitivity and 100% specificity with relation to above parasites in the detection of bubaline fasciolosis. The present Dot-ELISA diagnostic assay is relevant to the field diagnosis of F. gigantica infection in buffaloes.

Nitration of lysozyme by ultrasonic waves; demonstration by immunochemistry and mass spectrometry

Solutions containing hen egg white lysozyme (HEWL) and nitrite were exposed to ultrasonic irradiation in order to study the possible sonochemical modifications. This is the first demonstration of the nitration of tyrosine residues in a protein (lysozyme) by the use of an ultrasonic field alone. Sonochemically nitrated lysozyme was detected using the immunochemical techniques dot blot immunodetection and enzyme-linked immunosorbent assay (ELISA). The sonically oxidised and nitrated protein solutions were analysed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Hydroxylated species were found in the absence of nitrite, whereas nitration was the major modification in the presence of nitrating agent, implying a competing mechanism between hydroxyl radicals and nitrite. Circular dichroism (CD) indicated that the ultrasonic experimental conditions chosen in this study had little effect on the tertiary and secondary structures of HEWL. Whilst enzymatic assay showed that the presence of nitrite provided a protective effect on the inactivation of the protein under ultrasonic irradiation, nevertheless partially purified, sonically nitrated lysozyme showed a dramatic decrease in lytic activity.

Outbreak of Leptospirosis among Adventure Race Participants in Florida, 2005

On 21 November 2005, a 32-year-old male resident of New York was hospitalized with suspected leptospirosis. He had participated in an endurance-length swamp race on 4-5 November 2005 outside of Tampa, Florida. We interviewed racers to assess illness, medical care, and race activities. A suspected case was defined as fever plus > or = 2 signs or symptoms of leptospirosis occurring in a racer after 4 November 2005. Individuals with suspected cases were referred for treatment as needed and were asked to submit serum samples for microscopic agglutination testing (MAT) and for rapid testing by the dot enzyme-linked immunosorbent assay dipstick immunoglobulin M immunoassay. The Centers for Disease Control and Prevention and participating state health departments interviewed 192 (96%) of 200 racers from 32 states and Canada. Forty-four (23%) of 192 racers met the definition for a suspected case. The median age of the patients was 37 years (range, 19-66 years), and 128 (66.7%) were male. Fourteen (45%) of the 31 patients with suspected cases who were tested had their cases confirmed by serological testing (a single sample with MAT titer > or = 400), including the index case patient. Organisms of a potential novel serovar (species Leptospira noguchii) were isolated in culture from 1 case patient. Factors associated with increased risk of leptospirosis included swallowing river water (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.6-7.0), swallowing swamp water (OR, 2.4; 95% CI, 1.1-5.2), and being submerged in any water (OR, 2.3; 95% CI, 1.1-4.7). This report describes a leptospirosis outbreak that resulted in a high rate of symptomatic infection among adventure racers in Florida. The growing popularity of adventure sports may put more people at risk for leptospirosis, even in areas that have not previously been considered areas of leptospirosis endemicity.

The HCV serum proteome: a search for fibrosis protein markers

Liver fibrosis/cirrhosis is a serious health issue in hepatitis C virus (HCV-) infected patients and is currently diagnosed by the invasive liver biopsy. The aim of this study was to find useful fibrosis markers in HCV-patients' sera of different fibrosis degrees (METAVIR F0-F4) based on proteomics. Serum proteome profiles were created by two-dimensional gel electrophoresis. Profiles were analysed between different degrees of fibrosis (F0-F4) and between early (F0F1) and late (F2F3F4) fibrosis by univariate analyses (P <or= 0.05). Differentially expressed proteins were subsequently identified by mass spectrometry. Mac-2-binding protein, alpha-2-macroglobulin and hemopexin were increased in F4 opposite F0/F1. A-1-antitrypsin, leucine-rich alpha-2-glycoprotein and fetuin-A were decreased in F4 opposite F0/F1. Late fibrosis was characterized by an increase in Mac-2-binding protein, alpha-2-macroglobulin and alpha-1B-glycoprotein expression and a decrease in haptoglobin expression. Mac-2-binding protein expression was confirmed by dot blot assay and enzyme-linked immunosorbent assay in a secondary population. In conclusion, serum proteome analysis enabled the detection/identification of existing and new candidate markers in line with fibrosis progression in HCV-patients.

Development of a sandwich Dot-ELISA for detecting bovine viral diarrhea virus antigen with E2 recombinant protein

The IgG antibodies of rabbit anti-E2 protein of the bovine viral diarrhea virus were prepared by a general method from high efficiency serum immunized by E2 recombinant protein antigen expressed in E. coli prokaryotic expression system and were labeled to make enzyme-labeled antibody with the method of NaIO4. A sandwich Dot enzyme-linked immunosorbent assay (Dot-ELISA) for the detection of BVDV was developed. The optimal reaction conditions of Dot-ELISA were determined. The results show that optimal coating antibody was 300 μg·mL−1, the working concentration of HRP-labeled antibody was 1:50. The optimal blocking reagent and time were 5% bovine serum and 45 min. The minimum detection of the content of antigen reached 1.35 μg·mL−1. Compared with the routine IDEXX ELISA test kit with the whole virus, its specificity, sensitivity and coincidence rate were 90.48%, 96.55% and 95.24%, respectively. Compared with the sandwich Dot-ELISA with the negative staining electron microscope and RT-PCR, the coincidence rates were 90.9% and 93.1%, respectively. In addition, Bovine viral diarrhea virus (BVDV) antigen of 178 samples collected from cow farms in the Hebei Province, China, were detected by the developed Dot-ELISA and the IDEXX BVDV antigen Test Kit simultaneously, BVDV antigen positive rate was 39.89%–41.01%. The result of detecting clinical samples demonstrated that the established method showed its specificity, sensitivity and repeatability, whereas the results were easily interpreted without an ELISA reader.