The expression mechanism of programmed cell death 1 ligand 1 and its role in immunomodulatory ability of mesenchymal stem cells.

Programmed cell death 1 ligand 1 (PD-L1) is an important immunosuppressive molecule, which inhibits the function of T cells and other immune cells by binding to the receptor programmed cell death-1. The PD-L1 expression disorder plays an important role in the occurrence, development, and treatment of sepsis or other inflammatory diseases, and has become an important target for the treatment of these diseases. Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cells with multiple differentiation potential. In recent years, MSCs have been found to have a strong immunosuppressive ability and are used to treat various inflammatory insults caused by hyperimmune diseases. Moreover, PD-L1 is deeply involved in the immunosuppressive events of MSCs and plays an important role in the treatment of various diseases. In this review, we will summarize the main regulatory mechanism of PD-L1 expression, and discuss various biological functions of PD-L1 in the immune regulation of MSCs.

MiR-125b attenuates retinal pigment epithelium oxidative damage via targeting Nrf2/HIF-1α signal pathway.

The retinal pigment epithelium cells (RPE) are sensitive to oxidative stimuli due to long-term exposure to various environmental stimuli. Thus, the oxidative injury of RPE cells caused by the imbalance of redox homeostasis is one of the main pathogenic factors of age-related macular degeneration (AMD). But the sophisticated mechanisms linking AMD to oxidative stress are not fully elucidated. Activation of Nrf2 signal pathway can protect RPE cells from oxidative damage. The present study investigated the regulating mechanism of miR-125b in Nrf2 cascade and evaluated its antioxidant capacity. The in vitro studies indicated that overexpression of miR-125b substantially inhibited Keap1 expression, enhanced Nrf2 expression and induced Nrf2 nuclear translocation. Importantly, functional studies demonstrated that forced expression of miR-125b could significantly elevate cell proliferation and superoxide dismutase (SOD) levels while reduce reactive oxygen species (ROS) overproduction and malondialdehyde (MDA) formation. Further studies showed that miR-125b had no effect when Nrf2 was silenced in ARPE-19 cells. Additionally, the results identified that Nrf2 silence induced ROS accumulation enhances HIF-1α protein expression, while miR-125b could offset this effect via promoting HIF-1α protein degradation. Subsequent in vivo studies demonstrated that sodium iodate induced outer retina thinner was reversed with exogenous supplementation of miR-125b, which was cancelled in Nrf2 knockout mice. In conclusion, this study illustrated that miR-125b can protect RPE from oxidative damage via targeting Nrf2/HIF-1α signal pathway and potentially may serve as a therapeutic agent of AMD.

Effects of TACE and preventive antiviral therapy on HBV reactivation and subsequent hepatitis in hepatocellular carcinoma: a meta-analysis.

BACKGROUND AND AIM: The impact of transarterial chemoembolization (TACE) and preventive antiviral therapy on the occurrence of hepatitis B virus (HBV) reactivation and subsequent hepatitis remains controversial. This meta-analysis aimed to evaluate the effect of TACE and preventive antiviral therapy on the risk of HBV reactivation and subsequent hepatitis. Meanwhile, we explored the role of HBeAg status in HBV reactivation after TACE. METHODS: We performed this meta-analysis with 11 included studies to assess the effect of TACE and preventive antiviral therapy on predicting clinical outcomes in HBV-related hepatocellular carcinoma (HCC). The pooled odds ratios (OR) were calculated using a random or fixed effects model. PUBMED, MEDLINE, EMBASE and the Cochrane Central Register of Controlled were searched for the included articles (from 2000 to December 2017). RESULTS: Our results showed that TACE significantly increased the risk of HBV reactivation (OR: 3.70; 95% CI 1.45-9.42; P < 0.01) and subsequent hepatitis (OR: 4.30; 95% CI 2.28-8.13; P < 0.01) in HCC patients. There was no significant difference in HBV reactivation after TACE between HBeAg positive and negative patients (OR: 1.28; 95% CI 0.31-5.34; P = 0.73). Preventive antiviral therapy could statistically reduce the rate of HBV reactivation (OR: 0.08; 95% CI 0.02-0.32; P < 0.01) and hepatitis (OR: 0.22; 95% CI 0.06-0.80; P = 0.02) in those with TACE treatment. CONCLUSIONS: The present study suggested that TACE was associated with a higher possibility of HBV reactivation and subsequent hepatitis. Preventive antiviral therapy is significantly in favor of a protective effect.

ß2-AR regulates the expression of AKR1B1 in human pancreatic cancer cells and promotes their proliferation via the ERK1/2 pathway.

Psychological stress has been recognized as a well-documented risk factor associated with ß2-adrenergic receptor (ß2-AR) in the development of pancreatic cancer. Aldo-keto reductase 1 member B1 (AKR1B1) is a potential interacting partner of ß2-AR, but the effect of their interaction on pancreatic cancer cells is not known at present. We found a positive correlation between AKR1B1 and ß2-AR expression in pancreatic cancer tissue samples, and co-localization of these proteins in the human pancreatic cancer BXPC-3 cell line. Compared to the controls, the CFPAC-1 and PANC-1 pancreatic cancer cells overexpressing ß2-AR and AKR1B1 respectively showed significantly higher proliferation rates, which is attributed to higher proportion of cells in the S phase and decreased percentage of early apoptotic cells. Furthermore, overexpression of ß2-AR led to a significant increase in the expression of AKR1B1 and phosphorylated extracellular signal-regulated kinase (p-ERK1/2). Overexpression of AKR1B1 significantly decreased ß2-AR levels and increased that of p-ERK1/2. Taken together, ß2-AR directly interacted with and up-regulated AKR1B1 in pancreatic cancer cells, and promoted their proliferation and inhibited apoptosis via the ERK1/2 pathway. Our findings also highlight the ß2-AR-AKR1B1 axis as a potential therapeutic target for pancreatic cancer.

Risk Factors for Prognosis of Hepatocellular Carcinoma After Curative Resection In Patients with Low Hepatitis B Viral Load.

BACKGROUND: A retrospective cohort study was conducted to investigate the effect of hepatitis B surface antigen (HBsAg) level on prognosis in low viral load (< 2000 IU/mL) patients with hepatitis B-related hepatocellular carcinoma (HCC) after curative resection. MATERIAL AND METHODS: A total of 192 patients with low viral load who had received curative resection of pathologically confirmed HCC were analyzed to determine the factors affecting prognosis. The risk factors for survival, early and late recurrence (2 years as a cut-off) were studied. RESULTS: The median follow-up time was 38.5 months. The overall survival rates at 1-, 3-, and 5-year after curative resection were 94.2%, 64.0%, and 45.2%, respectively. The cumulative recurrence rates at 1-, 3, and 5-year after curative resection were 22.4%, 46.5%, and 67.0%, respectively. Patients with high serum HBsAg levels (> 250 IU/mL) had significantly lower survival rates than those with low HBsAg levels (HR: 1.517, 95% CI: 1.005-2.292, P = 0.047). Stratified analysis showed that patients with high HBsAg levels had a significantly higher late recurrence incidence than those with low HBsAg levels (HR: 2.155, 95% CI: 1.094-4.248, P = 0.026), but did not have a significantly higher risk of early recurrence postoperatively (HR: 1.320, 95% CI: 0.837-2.082, P = 0.233). Multivariate analysis revealed that HBsAg > 250 IU/mL was an independent risk factor associated with late recurrence (HR: 2.109, 95% CI: 1.068-4.165, P = 0.032). CONCLUSIONS: HBsAg > 250 IU/mL at the time of tumor resection was an independent risk factor for late recurrence in low viral load HCC patients.

Effect of serum hepatitis B surface antigen levels on predicting the clinical outcomes of chronic hepatitis B infection: A meta-analysis.

AIM: The impact of serum hepatitis B surface antigen (HBsAg) levels on the prognosis of chronic hepatitis B virus (HBV) infection remains unclear. This meta-analysis aimed to determine whether serum HBsAg levels influenced the risk of cirrhosis and hepatocellular carcinoma (HCC) development. Furthermore, we explored the role played by serum HBsAg levels in prediction of spontaneous HBsAg seroclearance. METHODS: We performed this meta-analysis including 11 studies to assess the effect of HBsAg levels on predicting clinical outcomes in chronic HBV carriers. The pooled odds ratios (OR) were calculated using a random or fixed effects model. PUBMED, EMBASE, MEDLINE and the Cochrane Database were searched for articles published from 1990 to May 2014. RESULTS: Our results showed that high HBsAg levels significantly increased the risk of developing cirrhosis (OR, 2.51; 95% confidence interval [CI], 2.00-3.14; P < 0.01). Pooled data from two studies revealed that high HBsAg levels increased the risk of HCC occurrence (OR, 2.21; 95% CI, 1.52-3.22; P < 0.01). High HBsAg levels were associated with a significant increased risk of late HCC recurrence after curative resection (OR, 2.02; 95% CI, 1.48-2.77; P < 0.01), but not early recurrence (OR, 1.06; 95% CI, 0.89-1.27; P = 0.53). The pooled data indicated that low HBsAg levels were significantly in favor of spontaneous HBsAg seroclearance (OR, 7.89; 95% CI, 4.74-13.13; P < 0.01). CONCLUSION: High HBsAg levels were associated with development of cirrhosis and HCC comparatively. Therefore, lower serum HBsAg levels were associated with a higher rate of spontaneous HBsAg seroclearance.

Significance of viral status on recurrence of hepatitis B-related hepatocellular carcinoma after curative therapy: A meta-analysis.

AIM: The impact of viral status on recurrence of hepatitis B-related hepatocellular carcinoma (HCC) after curative therapy remains controversial. This meta-analysis aimed to determine whether the presence of viral load, genotype, specific mutation and antiviral therapy influenced HCC recurrence after curative therapy. METHODS: We performed a meta-analysis including 20 studies to assess the effect of viral status and antiviral therapy with nucleoside analog on recurrence of HCC after curative therapy. The pooled odds ratios (OR) were calculated using a random or fixed effects model. PUBMED, MEDLINE, EMBASE and the Cochrane Database were searched for articles published from 1990 to December 2012. RESULTS: Our results showed that the presence of high viral load significantly increased overall HCC recurrence risk after curative therapy. Pooled data from four studies on the recurrence rate among patients with genotype C infection compared with genotype B showed an increased risk of recurrence. Basal core promoter (BCP) mutation was associated with a significant risk in the recurrence of HCC. The pooled estimate of treatment effect was significantly in favor of a preventive effectiveness of antiviral therapy. CONCLUSION: The present study suggested that HCC patients with high viral load, genotype C and BCP mutation had a significantly higher risk of recurrence. Antiviral therapy has potential beneficial effects after the curative treatment of HCC in terms of tumor recurrence.

Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines.

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3 h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1ß (IL-1ß), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

Clinical progress and risk factors for death in severe fever with thrombocytopenia syndrome patients.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by the SFTS virus (SFTSV) with an average fatality rate of 12%. The clinical factors for death in SFTS patients remain unclear. METHODS: Clinical features and laboratory parameters were dynamically collected for 11 fatal and 48 non-fatal SFTS cases. Univariate logistic regression was used to evaluate the risk factors associated with death. RESULTS: Dynamic tracking of laboratory parameters revealed that during the initial fever stage, the viral load was comparable for the patients who survived as well as the ones that died. Then in the second stage when multi-organ dysfunction occurred, from 7-13 days after disease onset, the viral load decreased in survivors but it remained high in the patients that died. The key risk factors that contributed to patient death were elevated serum aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and creatine kinase fraction, as well as the appearance of CNS (central nervous system) symptoms, hemorrhagic manifestation, disseminated intravascular coagulation, and multi-organ failure. All clinical markers reverted to normal in the convalescent stage for SFTS patients who survived. CONCLUSIONS: We identified a period of 7-13 days after the onset of illness as the critical stage in SFTS progression. A sustained serum viral load may indicate that disease conditions will worsen and lead to death.

GSK-3ß-dependent Nrf2 antioxidant response modulates ferroptosis of lens epithelial cells in age-related cataract.

Oxidative stress-induced lens epithelial cells (LECs) death plays a pivotal role in age-related cataract (ARC) with severe visual impairment, in which ferroptosis is gradually receiving numerous attention resulting from lipid peroxide accumulation and reactive oxygen species (ROS) overproduction. However, the essential pathogenic factors and the targeted medical strategies still remain skeptical and indistinct. In this work, by transmission electron microscopy (TEM) analysis, the major pathological courses in the LECs of ARC patients have been identified as ferroptosis, which was manifested with remarkable mitochondrial alterations, and similar results were found in aged mice (24-month-old). Furthermore, the primary pathological processes in the NaIO3-induced mice and HLE-B3 cell model have also been verified to be ferroptosis with an irreplaceable function of Nrf2, proved by the increased sensitivity to ferroptosis when Nrf2 was blocked in Nrf2-KO mice and si-Nrf2-treated HLE-B3 cells. Importantly, it has been found that an increased expression of GSK-3ß was indicated in low-Nrf2-expressed tissues and cells. Subsequently, the contributions of abnormal GSK-3ß expression to NaIO3-induced mice and HLE-B3 cell model were further evaluated, inhibition of GSK-3ß utilizing SB216763 significantly alleviated LECs ferroptosis with less iron accumulation and ROS generation, as well as reversed expression alterations of ferroptosis markers, including GPX4, SLC7A11, SLC40A1, FTH1 and TfR1, in vitro and in vivo. Collectively, our findings conclude that targeting GSK-3ß/Nrf2 balance might be a promising therapeutic strategy to mitigate LECs ferroptosis and thus probably delay the pathogenesis and development of ARC.

[Serum 25-hydroxyvitamin D concentration is negatively related to carotid artery intima-media thickness in type 2 diabetic patients].

OBJECTIVE: To evaluate the relationship between 25-hydroxy vitamin D [25(OH)D] and carotid artery intimal medial thickness (IMT) in type 2 diabetic (T2DM) patients. METHODS: Serum 25(OH)D and carotid IMT were measured in 300 T2DM patients. Patients were divided into four quartile groups according to the serum 25(OH)D levels (Q1: < 26.17 nmol/L, 74 cases; Q2: 26.17 - 32.75 nmol/L, 76 cases; Q3: 32.75 - 42.93 nmol/L, 78 cases; Q4 > 42.93 nmol/L, 72 cases). RESULTS: Carotid IMT, carotid artery plaque prevalence, duration of diabetes, HbA1c, CRP and PTH were significantly higher in subjects with low 25(OH)D compared subjects with high 25(OH)D (P < 0.05). Carotid artery IMT in Q1 and Q2 groups were significantly higher than that in Q4 group (1.03 ± 0.21 vs. 0.90 ± 0.20, 1.01 ± 0.26 vs. 0.90 ± 0.20, P < 0.05), was similar among Q1 and Q2 and Q3 groups. Prevalence of carotid atherosclerotic plaque in Q1 group (50.0%) was also significantly higher than in Q3 (29.5%, P < 0.05) and Q4 (16.7%, P < 0.05). Similarly, 25(OH)D concentration was significantly lower in patients with carotid plaque compared patients without carotid plaque [(28.31 ± 4.91) nmol/L vs. (36.31 ± 4.31) nmol/L, P < 0.01]. Pearson correlation analysis showed that carotid IMT was positively correlated with age, smoking, BMI, HbA1c, CRP, LDL-C, PTH/25(OH)D ratio (P < 0.05), and was negatively correlated with 25 (OH) D (r = -0.51, P < 0.01). Multivariate regression analysis showed that 25(OH)D concentration was an independent predictor of carotid IMT in this cohort (ß = -0.39, P < 0.01). CONCLUSION: Serum 25(OH)D concentration is negatively correlated with carotid IMT and low 25 (OH) D level is a risk factor for preclinical atherosclerosis in T2DM patients.

High expression of Anxa2 and Stat3 promote progression of hepatocellular carcinoma and predict poor prognosis.

AIM: To elucidate whether the interaction between Anxa2 and Stat3 could promote the progression of hepatocellular carcinoma (HCC) and that high co-expression of Anxa2 and Stat3 could predict poor prognosis in HCC patients. METHODS: We investigated Anxa2 and Stat3 expression using Western blot analysis in 4 HCC and adjacent nontumor tissues and using immunohistochemistry in 100 patients' paraffin sections. Then we assessed the expression of Stat3, Anxa2 and co-expression of Stat3 and Anxa2 with relevant clinical pathological parameters and their prognostic value in HCC patients. The recurrence and overall survival rates were estimated using the Kaplan-Meier method and compared with the log-rank test. The prognostic analysis was carried out with univariate and multivariate Cox regressions models. RESULTS: The incidence of high Stat3 expression in HCC tissues (35%) was significantly higher than that in non-HCC tissues (8%) (P < 0.001). The same result was observed in Anxa2 (P < 0.001). Also, the overexpression of Stat3 or Anxa2 showed a significant relationship with the recurrence of the 100 HCC patients (P = 0.012; P = 0.003). Additionally, tumor size >3 cm in diameter, multiple tumor number, and the presence of microvascular tumor thrombus were also significantly associated with recurrence in 100 patients. Then, all enrolled patients were divided into four groups according to IHC score of Stat3 and Anxa2, and the results indicated a significant difference in recurrence time between the subgroups (P < 0.001). What's more, co-highexpression of Stat3 and Anxa2 was related to the presence of microvascular tumor thrombus (P = 0.003) and poor tumor differentiation (P < 0.001), but not relevant with other clinical features (All P > 0.05). CONCLUSION: The expression of Stat3, Anxa2, or co-high-expression of the two proteins was associated with HCC recurrence and survival.

Author Correction: Draft genomic and transcriptome resources for marine chelicerate Tachypleus tridentatus.

In the original version of this Data Descriptor the word "Gulf" was incorrectly spelled in the affiliation "Ocean College, Beibu Gulf University, Qinzhou, 535011, Guangxi, China". This has now been corrected in both the HTML and PDF versions.

Draft genomic and transcriptome resources for marine chelicerate Tachypleus tridentatus.

Chinese horseshoe crabs (Tachypleus tridentatus), ancient marine arthropods dating back to the mid-Palaeozoic Era, have provided valuable resources for the detection of bacterial or fungal contamination. However, excessive exploitation for the amoebocyte lysate of Tachypleus has dramatically decreased the population of the Chinese horseshoe crabs. Thus, we present sequencing, assembly and annotation of T. tridentatus, with the hope of understanding the genomic feature of the living fossil and assisting scientists with the protection of this endangered species. The final genome contained a total size of 1.943 Gb, covering 90.23% of the estimated genome size. The transcriptome of three larval stages was constructed to investigate the candidate gene involved in the larval development and validate annotation. The completeness of the genome and gene models was estimated by BUSCO, reaching 96.2% and 95.4%, respectively. The synonymous substitution distribution of paralogues revealed that T. tridentatus had undergone two rounds of whole-genome duplication. All genomic and transcriptome data have been deposited in public databases, ready to be used by researchers working on horseshoe crabs.

Nonenzymatic Amperometric Aptamer Cytosensor for Ultrasensitive Detection of Circulating Tumor Cells and Dynamic Evaluation of Cell Surface N-Glycan Expression.

Dynamic assessment of glycan expression on the cell surface and accurate determination of circulating tumor cells are increasingly imperative for cancer diagnosis and therapeutics. Herein, a unique and versatile nonenzymatic sandwich-structured electrochemical cytosensor was developed. The cytosensor was constructed based on a cell-specific aptamer, the lectin-functionalized porous core-shell palladium gold nanoparticles (Pd@Au NPs). To establish the cytosensor, amine-modified-SYL3C aptamer was first attached to the surface of aminated Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2-NH2 NPs) through cross-linked reaction via glutaraldehyde. Besides, in terms of noncovalent assembly of concanavalin A on Pd@Au NPs, a lectin-functionalized nanoprobe was established. This nanoprobe had the capabilities of both the specific carbohydrate recognition and the current signal amplification in view of the Pd@Au NPs as the electrocatalyst for the reduction of hydrogen peroxide (H2O2). Herein, we used MCF-7 cells as a model target, and the constructed cytosensor showed a low detection limit (down to three cells), a wide linear detection ranging from 100 to 1 × 106 cells mL-1. The established method sensitively realized the detection of the amount of cell and exact evaluation of glycan expression on cell surface, demonstrating great application prospects.

A Comparison of Traditional and Novel Methods for the Separation of Exosomes from Human Samples.

Exosomes are discrete populations of small (40-200 nm in diameter) membranous vesicles that are released into the extracellular space by most cell types, eventually accumulating in the circulation. As molecular messengers, exosomes exert a broad array of vital physiologic functions by transporting information between different cell types. Because of these functional properties, they may have potential as biomarker sources for prognostic and diagnostic disease. Recent research has found that exosomes have potential to be utilized as drug delivery agents for therapeutic targets. However, basic researches on exosomes and researches on their therapeutic potential both require the existence of effective and rapid methods for their separation from human samples. In the current absence of a standardized method, there are several methods available for the separation of exosomes, but very few studies have previously compared the efficiency and suitability of these different methods. This review summarized and compared the available traditional and novel methods for the extraction of exosomes from human samples and considered their advantages and disadvantages for use in clinical laboratories and point-of-care settings.

Serum resistin positively correlates with serum lipids, but not with insulin resistance, in first-degree relatives of type-2 diabetes patients: an observational study in China.

To investigate whether serum resistin correlated with hypertension, obesity, dyslipidemia, or insulin resistance (IR) in Chinese type 2 diabetes mellitus (T2DM) patients and their first-degree relatives (DFDRs) in a case-control observational study.We determined the serum levels of resistin, plasma lipids, glucose, and insulin, and performed clinical assessments of hypertension, obesity, and IR for 42 T2DM patients, 74 of their DFDRs, and 51 healthy control participants with no family history of T2DM (NC group). The biochemical and clinical variables were compared between the 3 groups, and relationships between serum resistin and the other variables were evaluated using a Pearson correlation analysis.Significant trends were observed in the triglyceride, HbA1c, and resistin levels, in which the values observed in the DFDR group were intermediate to those of the T2DM and NC groups (P < .05 for all). A stratified analysis revealed significant trends in the resistin level and scores for homeostasis model assessment (HOMA) indexes for IR and insulin sensitivity in women and in the HbA1c and resistin levels in men (P < .05 for all), with DFDR subjects exhibiting intermediate values. The Pearson analysis showed that serum resistin positively correlated with total cholesterol and low-density lipoprotein cholesterol in the DFDR group only (P < .05 for both), and that resistin did not correlate significantly with HOMA indexes, blood glucose, insulin, HbA1c, triglyceride, high-density lipoprotein cholesterol, BMI, waist or hip circumference, or blood pressure.Our results suggest that elevated serum resistin might contribute to an increased risk of hyperlipidemia in DFDRs of Chinese T2DM patients.

Antigenic structure analysis of glycosylated protein 3 of porcine reproductive and respiratory syndrome virus.

The function of the glycosylated protein 3 (GP3), a porcine reproductive and respiratory syndrome virus (PRRSV) associated protein is poorly known. In the present study, the gene encoding GP3 (ORF3), lacking the highly hydrophobic domain in the N- and C-termini was expressed as GST-fusion proteins in E. coli. Monoclonal antibodies (MAbs) against GP3 were developed and used to probe a series of GP3 peptides using ELISA. After precise analysis by sequential deletion of the terminal amino acid residues from each peptide, the minimal epitopes recognized by the MAbs were localized to W(74)CRIGHDRCGED(85) and Y(67)EPGRSLW(74). The epitope sequences were well conserved among most of the North American-type isolates, with the exception of two amino acid mutations in both epitopes in a few of these isolates. Mutational analysis revealed that these mutants were not recognized by any of the five MAbs, indicating that genetic variation could lead to altered antigenicity. Eight out of nine peptide fragments, 58-72aa, 73-87aa, 88-101aa, 102-115aa, 50-65aa, 66-81aa, 80-95aa and 94-109aa were recognized by PRRSV-positive pig serum as determined by Western blot analysis. The results herein may elucidate partially the antigenic structure of GP3 and variations of PRRSV.

Identification of a conserved epitope cluster in the N protein of porcine reproductive and respiratory syndrome virus.

In this study, 4 overlapping fragments and 12 overlapping peptides of the nucleocapsid (N) protein from porcine reproductive and respiratory syndrome virus (PRRSV) were expressed as glutathione S-transferase (GST) fusion proteins and used to probe a panel of 16 anti-N protein monoclonal antibodies (mAbs) by ELISA. The minimal epitope sequence of the following seven mAbs was determined by sequential deletion of terminal amino acid residues from each peptide: N2H7 corresponded to H54FPLA58; N2F7 corresponded to K52PHFPLA58; and N1A2, N1E3, N1G4, and N2E5 were reactive against E51KPHFP56. Furthermore, a polypeptide containing this epitope cluster was recognized by PRRSV-immune pig serum by Western blot, suggesting that residues 51-58 represent an immunodominant region of the N protein. Sequence alignment revealed that these epitopes are well conserved among North American and European genotypes of PRRSV. These findings enhance our knowledge of the antigenic structure of N protein and may facilitate the development of better diagnostic methods for PRRSV.

[Preparation and luminescence of nanocrystalline ZrO2 : Pr3+ and ZrO2 : Pr3+, Sm3+].

The nanocrystalline ZrO2 : Pr3+ and ZrO2 : Pr3+, Sm3+ powders with room temperature sharp characteristic emissions were prepared by coprecipitation method. Luminescence properties of nanocrystalline ZrO2 : Pr3+ with different sintering temperatures and doping concentrations were studied. The energy transfer between the nanocrystalline ZrO2 host and the dopants was observed. The different Pr3+ concentration dependence of emission intensities of levels 3P0 and 1D2 was discussed. The dependence on Pr3+ concentration in nanocrystalline ZrO2 : Pr3+, Sm3+ of the emission intensity of 4G(5/2)-6H(7/2) transitions of Sm3+ ions and the energy transfer between Pr3+ and Sm3+ ions were investigated and discussed.