Development of a blocking ELISA based on a single-domain antibody target the S1 protein of porcine epidemic diarrhea virus / 生物工程学报

The aim of this study was to develop a blocking enzyme-linked immunosorbent assay (bELISA) based on a biotinylated nanobody target the S1 protein of porcine epidemic diarrhea virus (PEDV) for detecting the anti-PEDV antibodies and evaluating the immune effect of the vaccine. The gene encoding the single-domain antibody sdAb3 target the PEDV S1 protein was amplified and the Avitag sequence was fused at its 3'-end. The PCR product was cloned into the expression vector pET-21b for expression and purification of the sdAb3-Avitag protein. The purified sdAb3-Avitag fusion protein was biotinylated and its activity was determined. Using the recombinant S1 protein as a coating antigen, a bELISA was established and optimized. Serum samples were tested in parallel by the bELISA and a commercial kit. The recombinant vector pET21b-sdAb3-Avitag was constructed to express the tagged sdAb3. After induction for expression, the biotin-labeled sdAb3 (sdAb3-Biotin) with high purity and good activity was obtained. For the optimized bELISA, the coating concentration of the S1 protein was 200 ng/well, the serum dilution was 1:2 and incubated for 2 h, the dilution ratio of the biotinylated sdAb3 was 1:8 000 and incubated for 30 min, the dilution of the enzyme-labeled antibody was 1:5 000 and incubated for 30 min. The bELISA had no cross reaction with the sera of major porcine viruses including transmissible gastroenteritis virus, porcine reproductive and respiratory syndrome virus and showed good specificity and reproducibility. For a total of 54 porcine serum samples tested, the overall compliance rate of the bELISA with a commercial kit was 92.56%. This study developed a rapid and reliable bELISA method, which can be used for serosurveillance and vaccine evaluation for PEDV.

Comparison of anterograde tracing methods of mouse corticospinal tract with adeno associated virus and biotinylated dextran amine / 基础医学与临床

Objective To compare the differences between adeno associated virus ( AAV) and biotinylated dextran amine ( BDA) in anterograde tracing of mouse corticospinal tract ( CST) , and to explore the advantages of the ap-plication of AAV in anterograde tracing of mouse CST axons as a neural tracer. Methods AAV8-CAG-GFP-2A and BDA were stereotactically injected into the mouse sensorimotor cortex of normal and spinal cord injury mice respec-tively, and immunohistochemistry was employed to observe the distribution of the labeled CST axons. The relative fluorescence of axon bundles and branches was analyzed. Results Both AAV and BDA labeled the bundles of cor-ticospinal tract and surrounding axon branches projecting into the gray matter of cervical and thoracic cords in both coronal and saggital sections of normal and spinal cord injury mice. Meanwhile, more axon branches were labeled in the AAV injected mice as compared with those in the BDA injected ones. Conclusions AAV exhibits more superior performance in mouse CST axon tracing in comparison with BDA, and can be applied as a better neural tracer for the morphological study of mouse CST and related neural circuits.

Development & evaluation of biotinylated DNA probe for clinical diagnosis of chikungunya infection in patients’ acute phase serum & CSF samples.

Background & objectives: The resurgence of chikungunya virus (CHIKV) in the Indian Ocean Islands and India has drawn worldwide attention due to its explosive nature, high morbidity and complex clinico-pathological manifestations. The early confirmatory diagnosis of CHIKV is essential for management as well as control of unprecedented epidemics. The present study describes the development and evaluation of a highly sensitive and specific E1 structural gene specific biotinylated DNA probe for detection of chikungunya virus in clinical samples using a dot blot format. Methods: The complementary DNA (cDNA) of CHIKV was spotted on to nylon membrane. The membrane was subjected to prehybridization and hybridization and developed using a colour development solution containing DAB chromogen. Results: The CHIKV E1 specific DNA probe was highly sensitive detecting picogram levels of target nucleic acid. The comparative evaluation with SYBR Green I based real-time RT-PCR revealed 99 per cent accordance with a sensitivity and specificity of 99 and 98 per cent, respectively. The specificity of this assay was further confirmed through cross-reaction studies with confirmed dengue and Japanese encephalitis (JE) patient serum samples along with infected culture supernatant of Ross River and Saint Louis encephalitis and plasmid DNA of O’Nyong Nyong, Semlinki forest and Sindbis viruses. Interpretation & conclusion: The DNA probe reported in this study may be useful for specific, sensitive and confirmatory clinical diagnosis of chikungunya infection in acute phase human patient serum and CSF samples. This assay can also be used in the laboratory for quantification of viral antigen in cell culture supernatant for research purpose.

Location of exogenous α-crystallin in retinal ganglion cells / 中华实验眼科杂志

Background There is no effective method to regenerate the optic nerve after injury. It has been recently reported that α-crystallin could promote the survive rate and axon regeneration of retinal ganglion cells (RGCs) effectively. However,the molecular mechanism is not clear. Objective This study was to identify the site of RGCs where the exogenous α-crystallin bind to. Methods RGCs was isolated from retinas of two 2-day-old Long Evans rats and primarily cultured. The positive rate of the RGCs was assessed by counting the number of positive cells for fluorescently-labeled thy1. 1 and cy3 under the fluorescence microscope. The biotinylated exogenous α-crystallin was evaluated by direct coloration and the activity of molecular chaperones was measured by insulin test.After identifying the success of biotinylation along with the activity of molecular chaperones,biotinylated α-crystallin was co-incubated with RGCs and the cells then were reacted to fluorescently labeled avidin for the observation of binding site of exogenous α-crystallin under the laser confocal microscope. Results RGCs of 94% were survived through primary culture. The coloration of biotinylated α-crystallin labeled by the direct coloration method was more intensive, and the value of A450 descended as the decrease of biotinylated α-crystallin concentration,indicating that the α-crystallin was biotinylated successfully. The activity of molecular chaperones of biotinylated α-crystallin was significantly strong but no significant change after being biotinylated after co-incubation of RGCs with biotinylated α-crystallin. Laser confocal microscope examination revealed that co-incubated RGCs with biotinylated α-crystallin showed the red fluorescence on membrane and axon of RGCs rather than cytoplasm and nucleus. The absent response was seen in the control group. Conclusion Exogenous α-crystallin can specifically combine with the membrane of RGCs to play the biological function,but its binding mode and mechanism need further study.

Development of Capture ELISA Using a Biotinylated Monoclonal Antibody for Detection of Botulinum Neurotoxin Type A

A capture enzyme-linked immunosorbent assay (capture ELISA) was developed to detect Clostridium botulinum neurotoxin type A (BoNT/A) in assay buffer and human serum. The assay is based upon affinity-purified rabbit polyclonal and biotinylated monoclonal antibodies directed against the BoNT/A complex purified from C. botulinum ATCC19397. For the capture ELISA, the optimized amount (2 microgram/ml) of rabbit polyclonal antibody was immobilized on ELISA plates to detect BoNT/A (ranging from 0 to 500 ng/ml), which was recognized by 2 microgram/ml of the monoclonal antibody. From three independent repeated experiments, standard curves were linear over the range of 0~31.25 ng/ml BoNT/A and the coefficients (r(2)) ranged from 0.9951~0.9999 for all assays. The inter-variations were typically 0.50~6.93% and the specificity was confirmed by showing no cross-reactivity against BoNT/B and /E. The detection limit of capture ELISA was 0.488 ng/ml, which was close to mouse LD(50). In addition, application with BoNT/A-spiking human sera showed a possibility to detect BoNT/A with capture ELISA from the contaminated human sera. Taken together, the newly developed capture ELISA could serve as a rapid and sensitive screening tool for detecting BoNT/A simultaneously from massive specimens.

Development of Enzyme Linked Immunosorbent Assay for Erythropoietin / 대한진단검사의학회지

BACKGROUND: The aim of our study was to optimize and establish erythropoietin (EPO) enzyme linked immunosorbent assay (ELISA) system. METHODS: We prepared several monoclonal and polyclonal antibodies specific to human-EPO. The best combinations of antibodies for coating and detecting antibodies were selected for the establishment of ELISA. We tested several methods such as a competitive EIA and a sandwich ELISA. RESULTS: The best sandwich ELISA was optimized compared to competitive EIA when purified polyclonal antibody (PoAb) was used as a coating antibody and biotinylated PoAb as a detecting antibody. This sandwich ELISA easily detected EPO when PoAb pairs were used compared to the ELISA using monoclonal antibody and PoAb. There were no significant differences between the effects of various blocking solutions on the performance of sandwich ELISA using biotinylated antibody. The ELISA system using PBST containing 3% BSA as a blocking solution can sensitively detect EPO (10 mU/mL) in a broad range of EPO concentrations (10-2,000 mU/mL) and there were cross-reactions with other cytokines). CONCLUSIONS: EPO can be easily determined by using biotinylated PoAb as a detecting antibody and another PoAb as a coating antibody.

Identification of Leukemia Surface Proteins Using a Proteomic Technique

BACKGROUND: Numerous cell surface proteins of leukemia cells such as CD33 and CD52 have been identified as diagnostic and therapeutic targets. Thus the profiling of the cell surface proteome and proteins restricted to specific leukemia(s) can provide a way to identify novel targets for leukemia diagnosis and therapy. However, there is a lack of data pertaining to the comprehensive analysis of surface membrane proteins because there are few effective strategies for profiling surface membrane proteomes. METHODS: We report on the application of quantitative proteomic techniques that incorporate affinity-capture and purification on monomeric avidin columns to identify all biotinylated cell surface proteins from leukemia cell lines. RESULTS: An analysis of a subset of biotinylated proteins among the different human leukemia cell lines using matrix-assisted laser desorption ionization and tandem mass spectrometry identified, among others, some widely expressed proteins in leukemia cells, such as CD11a, CD11c, CD18, CD31, CD44, and CD147, as well as a set of proteins identified as chaperone proteins, including HSP90, GRP78, GRP75, HSP70, HSP60 and protein disulfide isomerases. On the basis of their known functional roles, several of these proteins may participate in the progression of leukemogenesis and should be considered as potential markers of leukemia. CONCLUSION: Comprehensive profiling of the leukemia cell surface proteome provides an effective approach for the identification of commonly occurring proteins as well as proteins with restricted expression patterns to a specific cell line.

Detection of Human Papillomavirus DNA by In Situ Hybridization using Biotinylated DNA Probes in Cervical Intraepithelial Neoplasias and Squamous Cell Carcinomas

The authors examined 9 condylomas, 26 cervical intraepithelial neoplasms(CIN) and 22 invasive squamous cell carcinomas for the presence of human papillomavirus(HPV) DNA sequences by DNA-DNA in situ hybridization. In situ hybridization revealed target HPV DNA sequences mostly in the nuclei of the superficial cells from epithelium which contained either maturation or koilocytotic atypias. With the use of biotinylated HPV DNA probes 6/11, 16/18 and 31/33/35, 42 of the 57(73.7%) were positive with HPV-6/11, 23 with HPV-16/18, 32 with HPV-31/33/35 and 18 with two or more mixed probes. HPV-31/33/35 was wht most prevalent in CIN and invasive squamous cell carcinomas, follwed by HPV-16/18. The incidence of HPV DNA increased from 66.7% to 86.4% with increasing severity of the lesions from condylomas to invasive squamous cell carcinomas. Flat condyloma was most freuently accompanied by CIN.

Stick enzyme-linked immunosorbent assay using the avidin–biotin system for detection of circulating antigen in bancroftian filariasis.

Detection of filarial antigen in different groups of sera was carried out by sandwich as well as inhibition enzyme-linked immunosorbent assays using antibody-coated sticks. Both systems were found to be equally sensitive in detecting antigen in 90% of microfilariae carriers. Incorporation of avidin-biotin in the sandwich assay system increased the sensitivity of antigen detection from 10–6 to 10–16 pg. A 67% decrease in the number of false negative results was observed when the sensitive avidin-biotin inhibition enzymelinked immunosorbent assay system was used for analysis of filaria blood samples.

Experimental study on the cardiomyocyte apoptosis in the early myocardial ischemia / 中国法医学杂志

In order to explore the significance of cardiomyocyte apoptosis in the early myocardial ischemia,the rat model of acute myocardial ischemia was established,and the apoptotic cells were detected in the early phase of ischemia(within 6h)with TUNEL method.The results showed that scanty apoptotic cells could be observed in the ischemic region 1h after ischemia,and reached the peak 3h after ischemia,then decreased.No apoptotic cells were found in the normal region.In the peri ischemic region,apoptotic cells could also be observed 1h after ischemia,and reached the peak 5h after ischemia.It is indicated that apoptosis is the major form of early ischemic myocardial damage,and the detection of apoptotic cardiomyocyte may provide a new sensitive and objective method for the postmortem diagnosis of early myocardial infarction.

In Situ Hybridization and RNA Dot Blot Analysis of Alpha-fetoprotein Messenger RNA in Human Hepatocellular Carcinoma and Its Host Liver / 第二军医大学学报

The expression of the alpha-fetoprotein in 12 cases of human hepatocellular carcinoma and its host liver by in situ hybridization analysis of AFP mRNA in cryostat and paraffin - embeded tissue sections was studied. Total RNA was extracted in 3 cases of cancer tissues and its host liver tissues for RNA spot blot Both the tumor cells and the surrounding host liver cells showed positive hybridization with a biotinylated AFP cDNA probe. AFP mRNA existed in almost all tumor cells, but the distribution pattern of AFP mRNA in the host liver varied. The positive cells were dispersed in the tissue or formed foci or appeared to be a small piece of positive area. Our results showed that not only the tumor cells can synthesize AFP, but also the surrounding liver cells have the capacity to produce AFP.