Lack of correlation between virus barosensitivity and the presence of a viral envelope during inactivation of human rotavirus, vesicular stomatitis virus, and avian metapneumovirus by high-pressure processing

High-pressure processing (HPP) is a nonthermal technology that has been shown to effectively inactivate a wide range of microorganisms. However, the effectiveness of HPP on inactivation of viruses is relatively less well understood. We systematically investigated the effects of intrinsic (pH) and processing (pressure, time, and temperature) parameters on the pressure inactivation of a nonenveloped virus (human rotavirus [HRV]) and two enveloped viruses (vesicular stomatitis virus [VSV] and avian metapneumovirus [aMPV]). We demonstrated that HPP can efficiently inactivate all tested viruses under optimal conditions, although the pressure susceptibilities and the roles of temperature and pH substantially varied among these viruses regardless of the presence of a viral envelope. We found that VSV was much more stable than most food-borne viruses, whereas aMPV was highly susceptible to HPP. When viruses were held for 2 min under 350 MPa at 4°C, 1.1-log, 3.9-log, and 5.0-log virus reductions were achieved for VSV, HRV, and aMPV, respectively. Both VSV and aMPV were more susceptible to HPP at higher temperature and lower pH. In contrast, HRV was more easily inactivated at higher pH, although temperature did not have a significant impact on inactivation. Furthermore, we demonstrated that the damage of virion structure by disruption of the viral envelope and/or capsid is the primary mechanism underlying HPP-induced viral inactivation. In addition, VSV glycoprotein remained antigenic although VSV was completely inactivated. Taken together, our findings suggest that HPP is a promising technology to eliminate viral contaminants in high-risk foods, water, and other fomites.     

Enhanced performance of lipase-catalyzed kinetic resolution of secondary alcohols in monoether-functionalized ionic liquids

Several cationic monoether-functionalized ionic liquids (MEF-ILs) with different substituents were synthesized and used as media for kinetic resolution of secondary alcohols catalyzed by several lipases. The results indicate that Novozym 435 (an immobilized Candida antarctica Lipase B) had higher efficiency compared to other lipases in deracemization. The alkyl substituents at the 2- and 3-positions in the imidazolium ring of MEF-ILs were found to contribute to the increased enantioselectivity and enhancement of the reaction rate, respectively, while the higher stereo-hindrance of ether bonds decreased the activity. An enantioselectivity higher than 99% with 50% conversion of rac-1-phenylethanol was achieved using the catalyst system comprised of Novozym 435 and the MEF-IL 1-(3-ethoxypropyl)-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide. The catalytic system could be separated and reused without considerable activity loss. MEF-ILs can be a new class of enzyme-benign media suitable for lipase-catalyzed kinetic resolution of secondary alcohols.     

Prognostic Value and Staging Classification of Retropharyngeal Lymph Node Metastasis in Nasopharyngeal Carcinoma Patients Treated with Intensity-modulated Radiotherapy

Background

The development of intensity-modulated radiotherapy (IMRT) has revolutionized the management of nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the prognostic value and classification of TNM stage system for retropharyngeal lymph node (RLN) metastasis in NPC in the IMRT era.

Material and Methods

We retrospectively reviewed data from 749 patients with biopsy-proven, non-metastatic NPC. All patients received IMRT as the primary treatment. Chemotherapy was administered to 86.2% (424/492) of the patients with stage III or IV disease.

Results

The incidence of RLN metastasis was 64.2% (481/749). Significant differences were observed in the 5-year disease-free survival (DFS; 70.6% vs. 85.4%, P<0.001) and distant metastasis-free survival (DMFS; 79.2% vs. 90.1%, P<0.001) rates of patients with and without RLN metastasis. In multivariate analysis, RLN metastasis was an independent prognostic factor for disease failure and distant failure (P = 0.005 and P = 0.026, respectively), but not for locoregional recurrence. Necrotic RLN metastases have a negative effect on disease failure, distant failure and locoregional recurrence in NPC with RLN metastasis (P = 0.003, P = 0.018 and P = 0.005, respectively). Survival curves demonstrated a significant difference in DFS between patients with N0 disease and N1 disease with only RLN metastasis (P = 0.020), and marginally statistically significant differences in DMFS and DFS between N1 disease with only RLN metastasis and other N1 disease (P = 0.058 and P = 0.091, respectively). In N1 disease, no significant differences in DFS were observed between unilateral and bilateral RLN metastasis (P = 0.994).

Conclusions

In the IMRT era, RLN metastasis remains an independent prognostic factor for DFS and DMFS in NPC. It is still reasonable for RLN metastasis to be classified in the N1 disease, regardless of laterality. However, there is a need to investigate the feasibility of classifying RLN metastasis as N1a disease in future by a larger cohort study.     

Inactivation of a Norovirus by High-Pressure Processing

Murine norovirus (strain MNV-1), a propagable norovirus, was evaluated for susceptibility to high-pressure processing. Experiments with virus stocks in Dulbecco's modified Eagle medium demonstrated that at room temperature (20°C) the virus was inactivated over a pressure range of 350 to 450 MPa, with a 5-min, 450-MPa treatment being sufficient to inactivate 6.85 log₁₀ PFU of MNV-1. The inactivation of MNV-1 was enhanced when pressure was applied at an initial temperature of 5°C; a 5-min pressure treatment of 350 MPa at 30°C inactivated 1.15 log₁₀ PFU of virus, while the same treatment at 5°C resulted in a reduction of 5.56 log₁₀ PFU. Evaluation of virus inactivation as a function of treatment times ranging from 0 to 150 s and 0 to 900 s at 5°C and 20°C, respectively, indicated that a decreasing rate of inactivation with time was consistent with Weibull or log-logistic inactivation kinetics. The inactivation of MNV-1 directly within oyster tissues was demonstrated; a 5-min, 400-MPa treatment at 5°C was sufficient to inactivate 4.05 log₁₀ PFU. This work is the first demonstration that norovirus can be inactivated by high pressure and suggests good prospects for inactivation of nonpropagable human norovirus strains in foods.     

The disulfide bond pattern of salmon egg lectin 24K from the Chinook salmon Oncorhynchus tshawytscha

The disulfide bonds in the galactose-specific lectin SEL 24K from the egg of the Chinook salmon Oncorhynchus tshawytscha were determined by mass spectrometry. Four predictive in silico tools were used to determine the oxidation state of cysteines in the sequence and possible location of the disulfide bonds. A combination of tryptic digestion, HPLC separation, and chemical modifications were used to establish the location of seven disulfide bonds and one pair of free cysteines. After proteolysis, peptides containing one or two disulfide bonds were identified by reduction and mass spectral comparison. MALDI mass spectrometry was supported by chemical modification (iodoacetamide) and in silico digestion. The assignments of disulfide bonds were further confirmed by mass spectral fragmentation studies including in-source dissociation (ISD) and collision-induced dissociation (CID). The experimentally determined disulfide bonds and free Cys residues were only partially consistent with those generated by several automated public-domain algorithms.     

艾比湖湿地植物群落土壤酶活性特征及影响因素

为研究艾比湖湿地不同植物群落土壤酶活性的季节变化规律及影响因素,2015—2016年5、8和11月以绕湖一周范围内的梭梭-柽柳、梭梭、胡杨、芦苇为研究对象,对4种植物群落下不同月土壤过氧化氢酶、磷酸酶和脲酶活性及理化因子进行分析。结果表明:(1)各植物群生境的差异使酶活性有明显变化,呈现出芦苇群落梭梭群落胡杨群落梭梭-柽柳群落。不同植物群落下酶活性具有明显的季节变化,梭梭-柽柳、梭梭、胡杨群落土壤过氧化氢酶、磷酸酶、脲酶的峰值分别出现在5月(2.72、3.31和2.94 mg/g)、(1.18、1.32和0.69 mg/g)和(0.18、0.34和0.17 mg/g),而芦苇群落3种酶活性的峰值出现在8月(5.18、1.20和0.66 mg/g);谷值均出现在11月。(2) 4种植物群落下各月土壤酶活性与土壤有机质、全磷呈显著正相关,而与土壤盐分呈负相关;除芦苇群落外,其他群落8月土壤温度与酶活性呈负相关。(3) 4种植物群落各月间土壤酶活性受多因素的共同影响,土壤盐分、有机质、全磷是影响艾比湖湿地不同植物间土壤酶活性的主导因素,土壤温度和含水量对不同月土壤酶活性的影响更为显著。     

气候变化对新疆雪岭云杉潜在适宜分布及生态位分化的影响

探究气候变化对天山森林植物潜在空间分布的影响及其模拟预测有助于揭示中尺度下植物分布格局对气候变化的适应对策和反馈机制,对促进干旱区山地森林生态系统的生物多样性保育和森林资源可持续管理有着重要的科学和实践意义。基于雪岭云杉的分布点数据和环境因子数据,利用最大熵(MaxEnt)模型、GIS工具及R软件估计其在基准气候(1970—2000年)及2050(2041—2060年)和2070(2061—2080年)时段基于RCPs气候情景下的潜在分布范围、空间格局变化及生态位分化。结果表明：(1)雪岭云杉在基准气候下的潜在分布与2019年秋季的NDVI植被覆盖变化基本保持一致,高适生分布区主要分布在东疆的哈密、巴里坤和伊吾,北疆主要分布在天山北坡、博格达山、北塔山和伊犁河谷,南疆主要分布在天山南坡。另外,在阿尔泰山南坡、塔城、裕民、托里、西昆仑山和小帕米尔山地也有分布。(2)限制雪岭云杉潜在分布的关键因子为降水(最干月降水量、最冷季降水量和降水季节性)和温度(最干季平均温度、年均温、等温性和气温年较差)、土壤剖面有效含水量、土壤碳密度及海拔,其累计贡献率之和达到87.28%。(3)2050和207...     

Strategy for Identifying Dendritic Cell-Processed CD4(+) T Cell Epitopes from the HIV Gag p24 Protein

Mass Spectrometry (MS) is becoming a preferred method to identify class I and class II peptides presented on major histocompability complexes (MHC) on antigen presenting cells (APC). We describe a combined computational and MS approach to identify exogenous MHC II peptides presented on mouse spleen dendritic cells (DCs). This approach enables rapid, effective screening of a large number of possible peptides by a computer-assisted strategy that utilizes the extraordinary human ability for pattern recognition. To test the efficacy of the approach, a mixture of epitope peptide mimics (mimetopes) from HIV gag p24 sequence were added exogenously to Fms-like tyrosine kinase 3 ligand (Flt3L)-mobilized splenic DCs. We identified the exogenously added peptide, VDRFYKTLRAEQASQ, and a second peptide, DRFYKLTRAEQASQ, derived from the original exogenously added 15-mer peptide. Furthermore, we demonstrated that our strategy works efficiently with HIV gag p24 protein when delivered, as vaccine protein, to Flt3L expanded mouse splenic DCs in vitro through the DEC-205 receptor. We found that the same MHC II-bound HIV gag p24 peptides, VDRFYKTLRAEQASQ and DRFYKLTRAEQASQ, were naturally processed from anti-DEC-205 HIV gag p24 protein and presented on DCs. The two identified VDRFYKTLRAEQASQ and DRFYKLTRAEQASQ MHC II-bound HIV gag p24 peptides elicited CD4(+) T-cell mediated responses in vitro. Their presentation by DCs to antigen-specific T cells was inhibited by chloroquine (CQ), indicating that optimal presentation of these exogenously added peptides required uptake and vesicular trafficking in mature DCs. These results support the application of our strategy to identify and characterize peptide epitopes derived from vaccine proteins processed by DCs and thus has the potential to greatly accelerate DC-based vaccine development.     

Echinochloa Chloroplast Genomes: Insights into the Evolution and Taxonomic Identification of Two Weedy Species

The genus Echinochloa (Poaceae) includes numerous problematic weeds that cause the reduction of crop yield worldwide. To date, DNA sequence information is still limited in the genus Echinochloa. In this study, we completed the entire chloroplast genomes of two Echinochloa species (Echinochloa oryzicola and Echinochloa crus-galli) based on high-throughput sequencing data from their fresh green leaves. The two Echinochloa chloroplast genomes are 139,891 and 139,800 base pairs in length, respectively, and contain 131 protein-coding genes, 79 indels and 466 substitutions helpful for discrimination of the two species. The divergence between the genus Echinochloa and Panicum occurred about 21.6 million years ago, whereas the divergence between E. oryzicola and E. crus-galli chloroplast genes occurred about 3.3 million years ago. The two reported Echinochloa chloroplast genome sequences contribute to better understanding of the diversification of this genus.