Persistence of Human Noroviruses on Food Preparation Surfaces and Human Hands

The human noroviruses (NoV) are the major cause of acute non-bacterial gastroenteritis and are commonly transmitted by foodborne routes. Epidemiological evidence from propagated outbreaks, as well as environmental sampling, suggest that these viruses are environmentally stable. The purpose of this study was to examine the persistence of representative human NoV on the fingertips of volunteers and on commonly used food preparation surfaces. Human fingerpads and surfaces (stainless steel, Formica^®, and ceramic) were inoculated with 20% fecal suspensions of Norwalk virus (NV) or Snow Mountain virus (SMV). The virus inocula were recovered by elution at serial time points ranging from 0 to 120 min post-inoculation (for fingerpads) and after up to 42 days (for surfaces). The quantity of detectable viral RNA, expressed as genome equivalent particles (GEP) was evaluated using quantitative real-time RT-PCR (RT-qPCR). The amount of NV RNA on the surface decreased gradually over time, with an average reduction ranging from 1.5 to 2.9 log₁₀ GEP after 21–28 days storage under ambient conditions. SMV showed greater environmental persistence, with a 0.4–1.2 log₁₀ GEP reduction on all three surfaces after 42 days of ambient storage. On fingerpads, the amount of human NoV RNA declined slightly (<0.25 log₁₀) after 15 min and remained relatively unchanged thereafter (through 120 min). These results support the epidemiological evidence that food preparation surfaces and human hands can act as vehicles for human NoV transmission long after the initial contamination event has occurred.     

Prevalence of Human Parainfluenza Viruses and Noroviruses Genomes on Office Fomites

The aim of this study was to evaluate the potential role of office fomites in respiratory (human parainfluenza virus 1—HPIV1, human parainfluenza virus 3—HPIV3) and enteric (norovirus GI—NoV GI, norovirus GII—NoV GII) viruses transmission by assessing the occurrence of these viruses on surfaces in office buildings. Between 2016 and 2017, a total of 130 surfaces from open-space and non-open-space rooms in office buildings located in one city were evaluated for HPIV1, HPIV3, NoV GI, and NoV GII viral RNA presence. Detection of viruses was performed by RT-qPCR method. Study revealed 27 positive samples, among them 59.3% were HPIV3-positive, 25.9% HPIV1-positive, and 14.8% NoV GII-positive. All tested surfaces were NoV GI-negative. Statistical analysis of obtained data showed that the surfaces of office equipment including computer keyboards and mice, telephones, and desktops were significantly more contaminated with respiratory viruses than the surfaces of building equipment elements such as door handles, light switches, or ventilation tracts (χ ² p = 0.006; Fisher’s Exact p = 0.004). All examined surfaces were significantly more contaminated with HPIVs than NoVs (χ ² p = 0.002; Fisher’s Exact p = 0.003). Office fomites in open-space rooms were more often contaminated with HPIVs than with NoVs (χ ² p = 0.016; Fisher’s Exact p = 0.013). The highest average concentration of HPIVs RNA copies was observed on telephones (1.66 × 10² copies/100 cm²), while NoVs on the light switches (1.40 × 10² copies/100 cm²). However, the Kruskal–Wallis test did not show statistically significant differences in concentration levels of viral RNA copies on surfaces between the all tested samples. This study unequivocally showed that individuals in office environment may have contact with both respiratory and enteric viral particles present on frequently touched surfaces.     

Detection and Molecular Characterization of Human Noroviruses in Korean Groundwater Between 2008 and 2010

RT-PCR, nucleotide sequencing, and phylogenetic analysis were performed for genotyping and molecular characterization of noroviruses isolated from Korean groundwater. Among 160 samples collected from 80 sites between 2008 and 2010, 14 samples (8.7?%) from 12 sites were positive for noroviruses (NoVs). The percentages of NoV-positive samples in 2008, 2009, and 2010 were 22.2, 3.2, and 0?%, respectively, representing a yearly decrease. GII-positive samples (n?=?9, 5.6?%) outnumbered GI-positive samples (n?=?5, 3.1?%). The genotypes of the GI NoVs were GI.2, GI.5, and GI.6, and the genotypes of the GII NoVs were all GII.4. One sample, HM623465, was very similar to CUK-3 and CBNU2 and two GII.4 sequences isolated from the stool of Korean gastroenteritis patients. A BLASTN search revealed several nucleotide sequences highly similar to those of NoVs isolated in this study. The original isolation sources for these similar NoVs were mostly stool (n?=?731, 80.0?%) and groundwater (n?=?135, 14.8?%), and all the countries from which they were isolated were almost in Asia (96.0?%); specifically, China (n?=?192, 21.0?%), Japan (n?=?383, 41.9?%), Korea (n?=?296, 32.4?%), and other Asian countries (n?=?6, 0.7?%). These results suggest that Korean groundwater might be contaminated with NoVs from the stool of infected patients and that these NoVs in turn cause new cases of gastroenteritis through a typical fecal-oral route with region-specific circulation. Therefore, it is important to properly treat sewage, which may include waterborne viruses and manage point sources in groundwater for national health and sanitation. In addition, continuous molecular surveillance remains important for understanding circulating NoVs.     

Prevalence of Human Noroviruses in Frozen Marketed Shellfish,Red Fruits and Fresh Vegetables

Noroviruses (NoVs), currently recognised as the most common human food-borne pathogens, are ubiquitous in the environment and can be transmitted to humans through multiple foodstuffs. In this study, we evaluated the prevalence of human NoV genogroups I (GI) and II (GII) in 493 food samples including soft red fruits (n = 200), salad vegetables (n = 210) and bivalve mollusc shellfish (n = 83), using the Bovine Enterovirus type 1 as process extraction control for the first time. Viral extractions were performed by elution concentration and genome detection by TaqMan Real-Time RT-PCR (RT-qPCR). Experimental contamination using hepatitis A virus (HAV) was used to determine the limit of detection (LOD) of the extraction methods. Positive detections were obtained from 2 g of digestive tissues of oysters or mussels kept for 16 h in seawater containing 2.0–2.7 log₁₀ plaque-forming units (PFU)/L of HAV. For lettuces and raspberries, the LOD was, respectively, estimated at 2.2 and 2.9 log₁₀ PFU per 25 g. Of the molluscs tested, 8.4 and 14.4 % were, respectively, positive for the presence of GI NoV and GII NoV RNA. Prevalence in GI NoVs varied from 11.9 % for the salad vegetables samples to 15.5 % for the red soft fruits. Only 0.5 % of the salad and red soft fruits samples were positive for GII NoVs. These results highlight the high occurrence of human NoVs in foodstuffs that can be eaten raw or after a moderate technological processing or treatment. The determination of the risk of infection associated with an RT-qPCR positive sample remains an important challenge for the future.     

不同生态工程及其组合系统除藻效率的比较研究

比较了不同水力负荷条件下,由水平流碎石床湿地、下行流湿地、上行流湿地、好氧塘和兼性塘等不同生态工程单元组合而成的5组8套小型处理系统对藻类的去除效率及其变化趋势,并根据适宜水力负荷下各系统除藻效率的季节变化研究了各种组合形式对藻类的去除效果.结果表明:当水力负荷为0.8m³/(m²·d)时,各处理单元对藻类生物量的去除效率均达到最高;好氧塘+下行流湿地系统和水平流碎石床系统均表现出较强的抗水力冲击负荷能力;各生态工程组合系统的除藻效率在夏季最高,对藻类的去除率均超过94%;冬季最低,藻类去除率变动范围为34%～90%.不同类型生态工程的组合方式决定了系统的除藻效率,下行流-上行流湿地的组合对藻类去除效果优于其它组合,季节变化对其运行效果影响不大;水平流碎石床湿地系统对藻类去除效果略逊于其它组合且受季节影响较大.     

Comparison of the Activity of Alcohol-Based Handrubs Against Human Noroviruses Using the Fingerpad Method and Quantitative Real-Time PCR

Noroviruses (NoV) are the most common cause of acute nonbacterial gastroenteritis in the United States, and human hands play an important role in their transmission. Little is known about the efficacy of hand hygiene agents against these highly infectious pathogens. We investigated the activity of seven commercially available hand hygiene products against human noroviruses by in vivo fingerpad tests. The in vivo activity of alcohol-based handrubs ranged from 0.10 to 3.74 log reduction and was not solely dependent on alcohol concentration. A handrub (VF481) based on 70% ethanol and a blend of other skin care ingredients reduced Norwalk virus (NV) by 3.74 log in 15 s and provided significantly greater NV reduction than all the other products tested (P < 0.001). Furthermore, VF481 was the most effective product tested against the NoV genogroup II strains Snow Mountain virus (GII.2) and a GII.4 strain. These results demonstrate that alcohol by itself is not effective against NoV, but effective formulation of alcohol-based handrubs can achieve significant reduction of norovirus RNA on fingers.     

Evaluation of a Porcine Gastric Mucin and RNase A Assay for the Discrimination of Infectious and Non-infectious GI.1 and GII.4 Norovirus Following Thermal,Ethanol, or Levulinic Acid Plus Sodium Dodecyl Sulfate Treatments

Human noroviruses (NoVs) are a major source of foodborne illnesses worldwide. Since human NoVs cannot be cultured in vitro, methods that discriminate infectious from non-infectious NoVs are needed. The purpose of this study was to evaluate binding of NoV genotypes GI.1 and GII.4 to histo-blood group antigens expressed in porcine gastric mucin (PGM) as a surrogate for detecting infectious virus following thermal (99 °C/5 min), 70 % ethanol or 0.5 % levulinic acid (LV) plus 0.01 or 0.1 % sodium dodecyl sulfate (SDS) sanitizer treatments and to determine the limit of detection of GI.1 and GII.4 binding to PGM. Treated and control virus samples were applied to 96-well plates coated with 1 µg/ml PGM followed by RNase A (5 ng/µl) treatment for degradation of exposed RNA. Average log genome copies per ml (gc/ml) reductions and relative differences (RD) in quantification cycle (Cq) values after thermal treatment were 1.77/5.62 and 1.71/7.25 (RNase A) and 1.73/5.50 and 1.56/6.58 (no RNase A) for GI.1 and GII.4, respectively. Treatment of NoVs with 70 % EtOH resulted in 0.05/0.16 (GI.1) and 3.54/10.19 (GII.4) log reductions in gc/ml and average RD in Cq value, respectively. LV (0.5 %) combined with 0.1 % SDS provided a greater decrease of GI.1 and GII.4 NoVs with 8.97 and 8.13 average RD in Cq values obtained, respectively than 0.5 % LV/0.01 % SDS. Virus recovery after PGM binding was variable with GII.4 > GI.1. PGM binding is a promising surrogate for identifying infectious and non-infectious NoVs after capsid destruction, however, results vary depending on virus strain and inactivation method.     

Temperature Dependent Depuration of Norovirus GII and Tulane Virus from Oysters (Crassostrea gigas)

Raw oysters are considered a culinary delicacy but are frequently the culprit in food-borne norovirus (NoV) infections. As commercial depuration procedures are currently unable to efficiently eliminate NoV from oysters, an optimisation of the process should be considered. This study addresses the ability of elevated water temperatures to enhance the elimination of NoV and Tulane virus (TuV) from Pacific oysters (Crassostrea gigas). Both viruses were experimentally bioaccumulated in oysters, which were thereafter depurated at 12 °C and 17 °C for 4 weeks. Infectious TuV and viral RNA were monitored weekly for 28 days by TCID₅₀ and (PMAxx-) RT-qPCR, respectively. TuV RNA was more persistent than NoV and decreased by?<?0.5 log₁₀ after 14 days, while NoV reductions were already?>?1.0 log₁₀ at this time. For RT-qPCR there was no detectable benefit of elevated water temperatures or PMAxx for either virus (p?>?0.05). TuV TCID₅₀ decreased steadily, and reductions were significantly different between the two temperatures (p?<?0.001). This was most evident on days 14 and 21 when reductions at 17 °C were 1.3–1.7 log₁₀ higher than at 12 °C. After 3 weeks, reductions?>?3.0 log₁₀ were observed at 17 °C, while at 12 °C reductions did not exceed 1.9 log₁₀. The length of depuration also had an influence on virus numbers. TuV reductions increased from?<?1.0 log₁₀ after seven days to?>?4.0 log₁₀ after 4 weeks. This implies that an extension of the depuration period to more than seven days, possibly in combination with elevated water temperatures, may be beneficial for the inactivation and removal of viral pathogens.

     

Resilience of Norovirus GII.4 to Freezing and Thawing: Implications for Virus Infectivity

Genogroup II.4 norovirus (NoV) remains the predominant NoV strain in food- and water-borne outbreaks. Capsid integrity as well as viral RNA persistence were determined for GII.4 NoV by real-time RT-PCR after 1?C14 freeze/thaw (F/T) cycles (?80?°C/+22?°C) or after ?80?°C storage for up to 120?days. In both cases, capsid integrity and viral RNA titers remained stable. RNase was exogenously added after 1?C14 F/T cycles, but did not alter the amount of genomic NoV RNA detected, indicating that capsids remained intact. Presumptive NoV infectivity was evaluated in functional studies by a porcine gastric mucin binding assay. Viruses frozen and thawed up to 14× bound similarly to porcine mucin, suggesting no reduction in virus infectivity. Overall, this study shows that a) NoV particles retain their integrity for at least 14 F/T cycles, b) long-term (120?day) frozen storage does not decrease NoV RNA titers, and c) capsid binding to receptor-like glycoprotein moieties remains unaltered after 14 F/T cycles. This work indicates that freezing and thawing of foods or beverages would not be a practical processing intervention to reduce NoV contamination. Likewise, repeated freezing and thawing, as might be encountered during winter months, is not expected to inactivate NoV in the environment. Results do show that laboratory samples destined for molecular biological analyses or for use as positive controls may be repeatedly frozen and thawed without any anticipated reduction in NoV RNA titers. This study documents the cryostability of NoV capsids and RNA to freezing and thawing and to the possible retention of virus infectivity.     

海水水质评价的突变模糊指数公式及效果验证

为了使突变模糊评价指数公式不受指标数多少的限制和评价指数值的分级标准不随指标的不同和指标数的不同而变化,通过适当设定海水各项指标的参照值及指标值的规范变换式,使海水不同指标的同级标准的规范值差异较小,从而用规范值表示的不同指标皆"等效"于某个规范指标,因此,只需构建海水水质评价的尖点突变和燕尾突变2种突变模糊模型。任意多项指标的海水水质评价可以分解为若干个尖点突变和(或)燕尾突变2种突变模糊评价模型的组合表示。将基于指标规范值的突变模糊指数公式应用于珠江口及青岛某海区的海水水质评价,并将评价结果与BP网络及模糊综合评价法评价结果进行了比较。结果表明,突变模糊指数公式的评价结果与其他方法的评价结果基本一致。与传统的其他评价方法相比,基于指标规范值的突变模糊指数公式具有通用性、普适性和简便性的特点。     

中国环境影响评价机构现状评价及优化调整思路

根据环境保护部环境工程评估中心公布的数据,中国环境影响评价机构现状特点是：环评机构的主要类型以科研院所占比例最大,其次是公司,最少的是高等院校;区域分布特点是东部多,西部少,经济发达地区多。经济欠发达地区少;评价范围特点是从事社会区域类别的环评机构最多,其次是化工石化医药类。同时,结合中国地区经济数据和市场化的要求,指出中国环评机构的数量与区域经济状况不对称,部分环评机构的评价范围与区域产业结构不匹配,环评机构市场化程度不高。最后,提出优化中国环境影响评价机构的建议。     

几种解离常数测定方法的比较与评价

介绍了电位滴定法、分光光度法、电导法和毛细管电泳法等几种测定物质解离常数的常用方法,分析了其测定原理及优缺点,讨论了解离常数测定方法的研究方向。     

居室装修污染对人体健康的危害及防治措施

对居室装修引起及居室污染的主要污染物的来源、对人体健康的危害及如何防范进行了阐述。     

南京工业区挥发性有机物来源解析及其对臭氧贡献评估

在南京工业区连续测量了2014年5月1日~7月31日和2015年6月1日~7月16日夏季两个高臭氧期的大气中的挥发性有机化合物(VOCs).结合正交矩阵分解(PMF)模型和箱模式(OBM)分析VOCs来源对局部O3生成的贡献.2014年和2015年夏季VOCs浓度平均分别为(36.47±33.44)×10-9和(34.69±34.08)×10-9.PMF模型确定了7种源类别,其中包括汽车尾气、液化石油气(LPG)排放、生物源排放、家具制造业、化工业、化学涂料行业、化学材料工业排放源.在OBM模拟中评估O3与前体物的关系.南京工业区是VOCs控制区,VOCs具有正RIR值,NO的RIR值为负值.烯烃(1.20~1.79)和芳香烃(1.42~1.48)呈现较高的RIR值,控制这两类物种是控制O3浓度最有效的途径.烯烃排放量减少80%时烯烃RIR值达到最高.汽车尾气(1.01~1.11)、液化石油气(0.74~0.82)、生物源排放量(0.34~0.42)和家具制造业(0.32~0.49)是O3形成贡献最大的四大类VOCs来源;减少汽车尾气,生物排放,LPG和家具制造业排放应成为减少局地O3生成最有效策略.     

中国生态环境质量与人类活动耦合机制及其影响因子

在可持续发展大背景下,深入探究中国生态环境质量与人类活动耦合机制并明确其影响因子,可为未来中国实现可持续发展目标提供一定的科学参考.运用趋势分析、耦合协调度、LMDI模型和最优参数地理探测器模型对中国生态环境质量与人类活动耦合机制进行探究和评价.结果发现:①在研究期间,中国耦合协调度、人类活动和生态环境质量均为增长趋势.人类活动和耦合协调度在空间上以胡焕庸线为界,呈现“东高西低”的分异规律.生态环境质量则表现出“南高北低”分异规律.②中国耦合协调类型转化的整体趋势为由低级向更高级的耦合协调类型转移.③基于最优参数地理探测器和LMDI模型分别发现,胡焕庸线以东绝大部分省区的耦合协调度其主导因子分别为社会经济因子和综合协调指数,该线以西绝大部分省区的耦合协调度主导因子分别为自然环境因子和耦合度.④评价人类活动变化对生态环境质量的影响,发现胡焕庸线以东主要为有利开发和有效保护类型,胡焕庸线以西主要为破坏开发和无效保护类型.胡焕庸线东西两侧地区应分别根据当地影响耦合协调度的先决条件以及人类活动和生态环境质量的相对关系,因地制宜选择优先发展地区,积极调整发展策略,走向生态环境质量与人类活动高级协调发展的可持续发展道路.