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Y Du

Publications and source records attributed to Y Du.

At least 73 records · Page 4Linked to original sources

Identification of an interleukin-3-regulated aldoketo reductase gene in myeloid cells which may function in autocrine regulation of myelopoiesis.

The EML hematopoietic progenitor cell line is a model system for studying molecular events regulating myeloid commitment and terminal differentiation. We used representational difference analysis to identify genes that are expressed differentially during myeloid differentiation of EML cells. One gene (named mAKRa) encoded a novel member of the aldoketo reductase (AKR) superfamily of cytosolic NAD(P)(H)-dependent oxidoreductases. mAKRa mRNA was detected in murine hematopoietic tissues including bone marrow, spleen, and thymus. In myeloid cell lines, mAKRa was expressed at highest levels in cells representative of promyelocytes. mAKRa mRNA levels increased rapidly in response to interleukin-3 over the first 24 h of EML cell differentiation when the cells undergo lineage commitment and extensive proliferation. mAKRa mRNA levels decreased later in the differentiation process particularly when the EML cells were cultured with granulocyte/macrophage colony-stimulating factor and retinoic acid to induce terminal granulocytic maturation. mAKRa mRNA levels decreased during retinoic acid-induced terminal granulocytic differentiation of the MPRO promyelocyte cell line. AKRs act as molecular switches by catalyzing the interconversion or inactivation of bioactive molecules including steroids and prostaglandins. We propose that mAKRa may catalyze the production or catabolism of autocrine factors that promote the proliferation and/or lineage commitment of early myeloid progenitors.

3T3 Cells↗

Alpha2 macroglobulin and the risk of Alzheimer's disease.

BACKGROUND: alpha2 Macroglobulin is a panproteinase inhibitor that is found immunohistochemically in neuritic plaques, a requisite neuropathologic feature of AD. Recently, a pentanucleotide deletion near the 5' end of the "bait region" of the alpha2 macroglobulin (A2M) gene was reported to be associated with AD in a large cohort of sibpairs, in which the mutation conferred a similar odds ratio with AD as the APOE-epsilon4 allele for carriers of at least one copy of the A2M gene (Mantel-Haenszel odds ratio, 3.56). METHODS: We studied three independent association samples of AD patients (n = 309) with an age range of 50 to 94 years and representative controls (n = 281) to characterize the allele frequency of the pentanucleotide deletion in this cohort. We detected the mutation near the 5' splice site of exon 18 using standard PCR and restriction fragment length polymorphism methods. The results were adjusted for age, gender, education, and APOE polymorphism. RESULTS: We found that the A2M gene polymorphism conferred an increased risk for AD, with an estimated Mantel-Haenszel ratio of 1.5 (95% CI 1.1 to 2.2; p = 0.025). There was no age- or gender-dependent increase in A2M gene allele frequencies in AD patients compared with controls. The combined sample showed the expected association between AD and APOE-epsilon 4. In one of our three samples there was an interaction between the A2M and APOE-epsilon4 genes, but the other two samples showed no interaction between the two risk factors. CONCLUSIONS: Our data support an association between the A2M gene and AD. This association is less pronounced, however, in our cohort than in the previously reported sample of sibpairs.

Aged↗

An integrated genetic linkage map with 1,137 markers constructed from five F2 crosses of autoimmune disease-prone and -resistant inbred rat strains.

The rat (Rattus norvegicus) is an important experimental model for many human diseases including arthritis, diabetes, and other autoimmune and chronic inflammatory diseases. The rat genetic linkage map, however, is less well developed than those of mouse and human. Integrated rat genetic linkage maps have been previously reported by Pravenec et al. (1996, Mamm. Genome 7: 117-127) (500 markers mapped in one cross), Bihoreau et al. (1997, Genome Res. 7: 434-440) (767 markers mapped in three crosses), Wei et al. (1998, Mamm. Genome 9: 1002-1007) (562 markers mapped in two crosses), Brown et al. (1998, Mamm. Genome 9: 521-530) (678 markers mapped in four crosses), and Nordquist et al. (1999, Rat Genome 5: 15-20) (330 markers mapped in two crosses). The densest linkage map combined with a radiation hybrid map, reported by Steen et al. (1999, Genome Res. 9: AP1-AP8), includes 4736 markers mapped in two crosses. Here, we present an integrated linkage map with 1137 markers. We have constructed this map by genotyping F2 progeny of five crosses: F344/NHsd x LEW/NHsd (673 markers), DA/Bkl x F344/NHsd (531 markers), BN/SsN x LEW/N (714 markers), DA/Bkl x BN/SsNHsd (194 markers), and DA/Bkl x ACI/SegHsd (245 markers). These inbred rat strains vary in susceptibility/resistance to multiple autoimmune diseases and are used extensively for many types of investigation. The integrated map includes 360 loci mapped in three or more crosses. The map contains 196 new SSLP markers developed by our group, as well as many SSLP markers developed by other groups. Two hundred forty genes are incorporated in the map. This integrated map should allow comparison of rat genetic maps from different groups and thereby facilitate genetic studies of rat autoimmune and related disease models.

Animals↗

Synthesis of a tetrasaccharide representing a minimal epitope of an arabinogalactan.

The hydrophobic alkyl chain-containing tetrasaccharide, dodecyl beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranosyl-(1-->6)-[alpha-L - arabinofuranosyl-(1-->2)]-beta-D-galactopyranoside, was synthesized efficiently using a convergent strategy. In coupling reactions, protected trichloroacetimidates proved to be better donors than their corresponding bromides in the preparation of the dodecyl disaccharide and trisaccharide. Zemplén deacylation provided the target tetramer in good overall yield.

Carbohydrate Sequence↗

Murine toxin of Yersinia pestis shows phospholipase D activity but is not required for virulence in mice.

Purified murine toxin (Ymt) of Yersinia pestis is highly toxic for mice and rats but less active in other animals such as guinea pigs, rabbits, dogs and monkeys. This suggested that Ymt contributes to the very low infectious dose of Y. pestis in mice. The gene encoding Ymt (ymt) is localised on the 100-kb plasmid pFra, which is unique for Y. pestis. Sequence analysis revealed that Ymt showed homology to proteins of the phospholipase D (PLD) superfamily of proteins. Y. pestis strains expressing Ymt possessed PLD activity whereas strains carrying deletions in the ymt gene showed no detectable PLD activity. Western blot analysis showed that Ymt was associated with bacteria under normal growth conditions, and immunogold EM revealed that Ymt was mainly localised in the bacterial cytoplasm. Ymt was purified to homogeneity, and the purified toxin showed a dose-dependent PLD activity. Substitution of amino acids in the PLD consensus motif of Ymt essentially abolished the enzymatic activity and these variants of the toxin were no longer toxic to mice. Interestingly, an in-frame deletion mutant of ymt in the Y pestis strain KIM was not significantly attenuated for mouse virulence. Together with the observation that expression of Ymt was higher at room temperature compared to 37 degrees C this prompted us to investigate the role of Ymt in the flea vector. Fleas were infected with isogenic ymt+ or ymt- mutant strains of Y. pestis. Preliminary results suggest that Ymt is important for survival of Y. pestis in the flea and thereby also for the flea-borne route of infection.

Amino Acid Sequence↗

Dose-response relationship of megakaryocyte progenitors from the bone marrow of thrombocytopenic and non-thrombocytopenic neonates to recombinant thrombopoietin.

Megakaryocyte (MK) progenitors from the marrow of adults undergo dose-dependent clonogenic proliferation in response to recombinant thrombopoietin (rTpo). It is unknown whether progenitors from the marrow of thrombocytopenic neonates display rTpo dose-dependent proliferation and whether they are more or less sensitive to rTpo than progenitors from non-thrombocytopenic neonates or adults. To assess this, we cultured marrow from four thrombocytopenic and four non-thrombocytopenic neonates, and from six healthy adults, in a serum-free system in the presence of increasing concentrations of rTpo (0-100 ng/ml). Marrow from the thrombocytopenic and non-thrombocytopenic neonates generated three times more MK colonies/105 light density cells (129 +/- 39 and 167 +/- 30 respectively) than marrow from adults (54 +/- 30, P < 0.0001) at a rTpo concentration of 50 ng/ml. Neonatal and adult samples had a rTpo dose-dependent increase in MK colonies. However, neonates reached a maximal number of colonies at a rTpo concentration of 10 ng/ml, compared with 50 ng/ml in adults, resulting in a larger area under the rTpo dose-response curve for neonatal progenitors (P = 0. 0047). Neonates also generated more large MK colonies than the adults (24% vs. 2% at 100 ng/ml).

Adult↗

The genomic structure, chromosome location, and analysis of the human DKK1 head inducer gene as a candidate for holoprosencephaly.

Holoprosencephaly (HPE) is the most common developmental defect of the brain and face in humans. Here we report the analysis of the human ortholog of dkk-1 as a candidate gene for HPE. We determined the genomic structure of the human gene DKK1 and mapped it to chromosome 10q11.2. Functional analysis of four missense mutations identified in HPE patients revealed preserved activity in head induction assays in frogs suggesting a limited role for this gene in HPE pathogenesis.

Amino Acid Sequence↗

The thromboxane receptor antagonist S18886 but not aspirin inhibits atherogenesis in apo E-deficient mice: evidence that eicosanoids other than thromboxane contribute to atherosclerosis.

Atherosclerosis involves a complex array of factors, including leukocyte adhesion and platelet vasoactive factors. Aspirin, which is used to prevent secondary complications of atherosclerosis, inhibits platelet production of thromboxane (Tx) A(2). The actions of TxA(2) as well as of other arachidonic acid products, such as prostaglandin (PG) H(2), PGF(2alpha), hydroxyeicosatetraenoic acids, and isoprostanes, can be effectively antagonized by blocking thromboxane (TP) receptors. The purpose of this study was to determine the role of platelet-derived TxA(2) in atherosclerotic lesion development by comparing the effects of aspirin and the TP receptor antagonist S18886. The effect of 11 weeks of treatment with aspirin (30 mg. kg(-1). d(-1)) or S18886 (5 mg. kg(-1). d(-1)) on aortic root atherosclerotic lesions, serum levels of intercellular adhesion molecule-1 (ICAM-1), and the TxA(2) metabolite TxB(2) was determined in apolipoprotein E-deficient mice at 21 weeks of age. Both treatments did not affect body or heart weight or serum cholesterol levels. Aspirin, to a greater extent than S18886, significantly decreased serum TxB(2) levels, indicating the greater efficacy of aspirin in preventing platelet synthesis of TxA(2). S18886, but not aspirin, significantly decreased aortic root lesions as well as serum ICAM-1 levels. S18886 also prevented the increased expression of ICAM-1 in cultured human endothelial cells stimulated by the TP receptor agonist U46619. These results indicate that inhibition of platelet TxA(2) synthesis with aspirin has no significant effect on atherogenesis or adhesion molecule levels. The effects of S18886 suggest that blockade of TP receptors inhibits atherosclerosis by a mechanism independent of platelet-derived TxA(2), perhaps by preventing the expression of adhesion molecules whose expression is stimulated by eicosanoids other than TxA(2).

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

Interleukin-6-induced protection in hyperoxic acute lung injury.

Hyperoxic lung injury is commonly encountered in patients who require treatment with high concentrations of inspired oxygen. To determine whether interleukin (IL)-6 is protective in oxygen toxicity, we compared the effects of 100% O(2) in transgenic mice that overexpress IL-6 in the lung and transgene (-) controls. IL-6 markedly enhanced survival, with 100% of transgene (-) animals dying within 72 to 96 h, 100% of transgene (+) animals living for more than 8 d and more than 90% of transgene (+) animals living longer than 12 d. This protection was associated with markedly diminished alveolar-capillary protein leak, endothelial and epithelial membrane injury, and lung lipid peroxidation. Hyperoxia also caused cell death with DNA fragmentation in the lungs of transgene (-) animals and IL-6 markedly diminished this cytopathic response. The protective effects of IL-6 were not associated with significant alterations in the activities of copper/ zinc superoxide dismutase (SOD) or manganese SOD. They were, however, associated with the enhanced accumulation of the cell-death inhibitor Bcl-2, but not the cell-death stimulator BAX, and with the heightened accumulation of the cell-death regulator tissue inhibitor of metalloproteinase-1 (TIMP-1). These studies demonstrate that IL-6 markedly diminishes hyperoxic lung injury and that this protection is associated with a marked diminution in hyperoxia-induced cell death and DNA fragmentation. They also demonstrate that this protection is not associated with significant alterations in SOD activity, but is associated with the induction of Bcl-2 and TIMP-1.

Animals↗

IL-13 stimulates vascular endothelial cell growth factor and protects against hyperoxic acute lung injury.

Hyperoxia is an important cause of acute lung injury. To determine whether IL-13 is protective in hyperoxia, we compared the survival in 100% O(2) of transgenic mice that overexpress IL-13 in the lung and of nontransgenic littermate controls. IL-13 enhanced survival in 100% O(2). One hundred percent of nontransgenic mice died in 4-5 days, whereas 100% of IL-13-overexpressing mice lived for more than 7 days, and many lived 10-14 days. IL-13 also stimulated VEGF accumulation in mice breathing room air, and it interacted with 100% (2) to increase VEGF accumulation further. The 164-amino acid isoform was the major VEGF moiety in bronchoalveolar lavage from transgenic mice in room air, whereas the 120- and 188-amino acid isoforms accumulated in these mice during hyperoxia. In addition, antibody neutralization of VEGF decreased the survival of IL-13-overexpressing mice in 100% (2). These studies demonstrate that IL-13 has protective effects in hyperoxic acute lung injury. They also demonstrate that IL-13, alone and in combination with 100% (2), stimulates pulmonary VEGF accumulation, that this stimulation is isoform-specific, and that the protective effects of IL-13 are mediated, in part, by VEGF.

Animals↗

Origin and fate of erythropoietin in human milk.

Erythropoietin (Epo) is a normal constituent of human milk, but the origin and fate of this cytokine in milk are not known. Regarding its origin, we hypothesized that cells of the mammary gland secrete Epo into milk actively and, therefore, that concentrations in milk do not correlate with concentrations in serum. Regarding its fate, we hypothesized that Epo concentrations in milk change with time postpartum and that Epo in milk is protected from digestion in the neonatal gastrointestinal tract. To address these issues, we measured Epo concentrations in 103 milk samples (ELISA), 55 of which were paired with serum. Mammary duct epithelial cells were evaluated as a source of Epo by breast tissue immunohistochemistry and by cell culture. Circulating and milk Epo were compared by Western analysis to detect size differences, possibly reflecting differences in processing. Epo stability in simulated conditions of digestion was evaluated. We observed that milk Epo concentrations increase as a function of duration of breast-feeding and have a negative correlation with serum Epo or milk protein concentration. Mammary duct epithelial cells from breast biopsies of lactating women had marked immunoreactivity to Epo, but such activity was minimal to absent in nonlactating breast tissue. Further evidence that mammary duct epithelia produce Epo was obtained by observing Epo mRNA and protein expression in cultured human mammary epithelial cells. The molecular size of Epo in milk and serum is identical. Recombinant Epo added to human milk or commercial infant formulas was relatively stable in conditions that simulate gastric and small intestinal conditions of newborn infants; however, recombinant Epo added to D(5)W was not protected from digestion. We conclude that Epo concentrations in milk increase as a function of the duration of breast feeding, that Epo is actively secreted into human milk by mammary duct epithelia, and that the Epo within milk is largely protected from digestion.

Adult↗

Granulocyte colony-stimulating factor is present in human milk and its receptor is present in human fetal intestine.

OBJECTIVE: Human milk provides neonates with a meaningful degree of protection from infection, but the responsible mechanisms are not well understood. Discovering these mechanisms is important, because of the possibility of supplementing infant formulas with factors that simulate human milk's protective capacity. We postulated that granulocyte colony-stimulating factor (G-CSF), a cytokine known to augment antibacterial defenses through its salutory effect on neutrophil production, might be one such factor. To test this hypothesis, we quantified G-CSF in milk of healthy women and those with intraamniotic infection, and sought the presence of functional G-CSF receptors (G-CSF-R) in fetal/neonatal intestinal villi. STUDY DESIGN: G-CSF was measured by enzyme-linked immunoassay in 126 milk samples obtained from breast-feeding women, and the concentrations were analyzed according to gestational age, postpartum day of collection (first 2 days vs greater 2 days), and the presence versus absence of intraamniotic infection. G-CSF-R messenger ribonucleic acid transcripts were sought from fetal/neonatal intestine using reverse transcriptase polymerase chain reaction, and localized using in situ RT-PCR. G-CSF-R protein, and specific intracellular signaling proteins (Janus tyrosine kinase-1, Janus tyrosine kinase-2, and tyrosine kinase-2), were sought by immunohistochemistry. RESULTS: All milk samples contained G-CSF, and significantly more G-CSF was contained in milk collected during the first 2 postpartum days than during subsequent days. Milk from women who delivered prematurely had less G-CSF during the first 2 postpartum days than milk from women who delivered at term. When intraamniotic infection was present, the concentration of G-CSF in milk was elevated significantly compared with concentrations in milk of noninfected women. G-CSF concentrations were also higher in milk collected during the first 2 postpartum days from women who had received intrapartum recombinant G-CSF treatment, compared with milk obtained from women with intraamniotic infection, regardless if they delivered prematurely or at term. G-CSF-R messenger ribonucleic acid and protein were expressed on fetal villus enterocytes, and Janus tyrosine kinase-1, Janus tyrosine kinase-2, and tyrosine kinase-2 were present within the cytoplasm of these cells. CONCLUSIONS: Human milk contains substantial quantities of G-CSF. G-CSF-R are abundant on villus enterocytes, and specific proteins associated with G-CSF-R signaling are present in these cells.

Chorioamnionitis↗

Granulocyte colony-stimulating factor serum and urine concentrations in neutropenic neonates before and after intravenous administration of recombinant granulocyte colony-stimulating factor.

BACKGROUND: Recombinant granulocyte colony-stimulating factor (rG-CSF) has been suggested as a treatment for certain varieties of neonatal neutropenia, but little is known about the pharmacologic disposition of rG-CSF in that population. METHODS: Ten neutropenic neonates were treated with rG-CSF, 10 micrograms/kg intravenously once daily for 3 to 5 days. Serum and urine samples were obtained before rG-CSF dosing and at intervals thereafter for G-CSF quantification by enzyme-linked immunosorbent assay. RESULTS: Five of the neutropenic neonates (termed group 1) were not infected but likely had hyporegenerative neutropenia (4 were born after pregnancy-induced hypertension/intrauterine growth restriction, and 1 had Rh hemolytic disease). Five other infants (group 2) had neutropenia accompanying bacterial sepsis and shock. Before receiving the first dose of rG-CSF, endogenous G-CSF serum and urine concentrations were relatively low in group 1, averaging 130 pg/mL (range: 48-209) in serum and 53 pg/mL (range: 15-141) in urine. Serum concentrations immediately before the final dose were much higher (range: 81-24 835 pg/mL), whereas urine concentrations were unchanged (range: <7 pg/mL-126 pg/mL). In group 2 patients, before receiving the first-dose of rG-CSF, endogenous concentrations were very high, averaging 59 575 pg/mL (range: 20 028-98 280) in serum and 3189 pg/mL (range: 23-4770) in urine. Predose serum concentrations before the final dose (range: 427-14 460 pg/mL) were lower than before the first dose. The area under the concentration curve after the first dose of rG-CSF administration in group 1 was significantly lower than after the first dose in group 2, but no difference in area under the concentration curve was observed between groups 1 and 2 after the last dose of rG-CSF. SPECULATION: The principal means of clearing G-CSF from the serum is by saturable binding to specific G-CSF receptors (G-CSF-Rs). Therefore, the very high G-CSF serum and urine concentrations of group 2 patients before the first rG-CSF dose implies that their G-CSF-Rs were saturated before the dose was given. We speculate that if G-CSF-Rs are saturated with endogenous G-CSF, treatment with rG-CSF will add little or nothing to the granulocytopoietic effort. On this basis, we judge that neonates with septic shock and neutropenia are unlikely to derive benefit from rG-CSF administration.

Enzyme-Linked Immunosorbent Assay↗

[Epitope mapping of HIV-1 using phage-display random peptide library and the purified IgG from HIV patient].

OBJECTIVE: By using phage display random peptide library, the B cell epitope of HIV protein was studied. METHODS: The library displaying random dodecamers was biopanned first with human total IgG antibodies against HIV-1, and then non-specific phages were subtracted by purified IgG from non-HIV sera. After three rounds of screening, the positive phages were tested by ELISA for their reactivity with HIV(+)-IgG and HIV(-)-IgG antibodies. Phage that showed positive reactivity with HIV(+)-IgG, but negative to HIV(-)-IgG, were selected and their displayed peptides were determined by DNA sequencing. RESULTS: All the 13 positive clones sequenced displayed five kinds of peptides (SPKCLGKLLCAF, THQCLGKLQCGV, SCSAKFTCTTQI, KSDCSARFMCSV, DCLKQWACEWSR) that have homology to the HIV-I gp4l (602GCSGKLICTIN613). CONCLUSIONS: This method demonstrated there is a dominant epitope in the region of HIV-1 gp4l and can be used in the research of the B cell epitope of HIV protein.

Bacteriophages↗

[Chinese recognition on relationship between smoking and health in Ming - Qing dynasties].

Tobacco was introduced into China at the beginning of the Ming Dynasty. At first, people thought that smoking could cure a lot of diseases, and could do good to people's health. However, Chinese doctors discovered that smoking would do great harm to people's health through animal experiments and clinical observation. They found that the poisonous materials in smoking include virulent fire - evil, tar, and some other invisible materials harmful to spirit of the body. Doctors also discovered that smoking had a great effect on people's lungs, causing damage to multiple organs and eventually death. Hence, trading on tobacco was banned officially in the Ming dynasty. Propaganda movements against smoking during the Qing Dynasty were gradually developed among the people.

China↗

[Effect of far-ultraviolet radiation on lipid peroxidation and inherent protection system in seedlings of Taxus cuspidata].

The effect of far-ultraviolet radiation on lipid peroxidation and inherent protection system in seedlings of Taxus cuspidata was examined with simulated UV-BC irradiation treatments. The electrolyte leakage, lipid peroxidation, tissue autoxidation and H2O2 content increased, while the contents of soluble protein, ascorbic acid, carotenoids, and chlorophyll and the photosynthetic electron transport rate of Photosystem II decreased with the increasing time of treatment. The lipid peroxidation of the needles was inhibited by exogenous scavengers sodium benzoate and ascorbate, but enhanced to some extent by methyl viologen and DDC (an inhibitor of SOD). The mechanisms of the injury of the seedlings induced by UV-BC radiation might be similar to that of photooxidation injuries of conifers in winter. However, Taxus cuspidata was much more resistant to UV-BC radiation than crops.

Antioxidants↗

[Regulatory effect of Erbao granules on brain-gut peptide in juvenile animal model of anorexia].

OBJECTIVE: To study the regulatory effect of Erbao granules (EBG) on central and peripheral brain-gut peptide in juvenile animal model of anorexia. METHODS: Juvenile rat model of anorexia was established by imitating the major cause of infantile anorexia and treated with EBG. The cholocystokinin-octapeptide (CCK-8) and beta-endorphin (beta-EP) concentration in hypothalamus, antrum pyloricum and peripheral blood were examined by radioimmunoassay. RESULTS: CCK-8 concentration in hypothalamus and plasma in the model rats increased (P < 0.05), while blood beta-EP concentration decreased (P < 0.05). After EBG treatment, the CCK-8 concentration normalized and beta-EP increased significantly. CONCLUSION: EBG could reduce the central and peripheral CCK-8 and increase beta-EP secretion significantly in the juvenile anorexia model.

Animals↗

[Selection and recombinant expression of an immunodominant B cell epitope of HIV gp41].

A novel method was designed for disease-specific B cell epitope mapping and epitope expression in E. coli. A phage library displaying random dodecamers was biopanned first with human total IgG antibodies against HIV-1, and then non-specific phages were subtracted by HIV(-) polyclonal antibodies. After three rounds of screening, the positive phages were tested in an ELISA for their reactivity with HIV(+)-IgG and HIV(-)-IgG antibodies. Phages that showed positive reactivity with HIV(+)-IgG, but negative to HIV(-)-IgG, were selected and their displayed peptides were determined by DNA sequencing. All the 13 positive clones sequenced displayed five kinds of peptides (SPKCLGKLLCAF, THQCLGKLQCGV, SCSAKFTCTTQI, KSDCSARFMCSV, DCLKQWACEWSR) that have homology to the HIV-1 gp41(602GCSGKLICTTNV613), demonstrating there is a dominant epitope in the region.

Enzyme-Linked Immunosorbent Assay↗