人腺病毒的研究进展

人腺病毒(Human adenovirus,HAdV)是引起婴幼儿急性呼吸道感染等多种疾病的重要病原体之一,本文回顾了有关HAdV的分子生物学特征、检测方法及分型、致病机制、相关疾病的临床特征、流行病学特征、HAdV感染的预防和控制研究的文献。迄今为止明确的HAdV有67种不同型别,包括近几年发现的重组变异株。导致急性呼吸道感染的主要流行株为HAdV-3和HAdV-7,属于B亚组,也可以引起其他系统的疾病,所致疾病的临床表现与其他呼吸道病毒相关病毒相似,但多伴消化道症状,其致病机制尚不清楚。对于新发现的变异重组株,其与疾病的相关性研究甚少,需要进一步研究证实。由于没有前瞻性的、大样本的随机对照治疗试验,HAdV感染的治疗目前存在争议。疫苗是降低呼吸道HAdV感染最有效的措施,但还没有上市的产品。     

汉坦病毒及所致疾病

汉坦病毒是引起多种人类疾病的病原体,为布尼亚病毒科的一个属.已发现至少有20个血清/基因型,每型均有其特定啮齿类动物宿主,病毒种系发生与宿主种系发生密切相关.不同病毒型别对人类致病性不同,其损伤器官和病情轻重各异.已发现2种主要疾病肾综合征出血热(HFRS)和汉坦病毒肺综合征(HPS).在过去的几十年里,对汉坦病毒及其所致疾病的认识有了很大进展病毒型别不断增加,病毒致病谱不断扩大.有证据表明,在英国,汉坦病毒也可引起人类疾病,但无明显特征.     

二代测序技术分析2018年济南市污水中的人星状病毒基因特征

人星状病毒（Human astrovirus,HAstV）是引起急性胃肠炎的主要致病病毒之一，为了解HAstV的型别分布和遗传变异特征，本研究于2018年在济南市按月采集12份生活污水样本，浓缩处理后提取RNA，进行HAstV部分ORF2编码区的PCR扩增，阳性产物进行下一代测序（Next generation sequencing, NGS）分析，探索HAstV各型别的动态变化和系统发生学特征。结果显示所有污水中均检出HAstV核酸，NGS分析显示所测读长分属于HAstV-1至HAstV-6共6个型别，其中HAstV-1型占比最大（27.4%），但不同月份的优势型别有所差别。系统发生学分析显示HAstV-1、HAstV-2、HAstV-5型山东株序列属于多个遗传分支，提示这些型别有多个传播链在当地循环。本研究描述了2018年济南市本地流行的人星状病毒基因型分布和序列特征，研究结果证明基于扩增子NGS的环境监测是探索人群中HAstV分子流行病学特征的有效手段。     

一株MLB1型星状病毒全基因组序列分析

了解我国MLB1型星状病毒基因组特征,为星状病毒腹泻的防控提供基础数据。使用星状病毒通用引物筛查北京市丰台区2017年72份儿童腹泻监测病例标本;扩增MLB星状病毒全基因组序列,采用在线比对、进化、重组等生物学信息学方法分析MLB1的全基因组序列。从72份标本中检出2份1型星状病毒（2.78%）和1份MLB1型星状病毒（MLB1-FT）(1.39%)。MLB1-FT与GenBank已报道的MLB1型星状病毒全基因组相似性为92.51%～98.28%;MLB1-FT的三个ORF区,仅5个位点氨基酸与其他株均不相同。依据其ORF2部分序列的进化分析,MLB1可分为A和B两个组,其中A组可分为a和b亚组,MLB1-FT为A组中的b亚组。未发现MLB1-FT具有重组现象。MLB1-FT具有星状病毒特征性的保守基序,部分保守基序与其他型别星状病毒不一样,为MLB1星状病毒特有。MLB1-FT具备新型星状病毒MLB的典型特征。我国新型星状病毒监测力度较弱,应加强监测。     

牛病毒性腹泻病毒生物型的遗传基础

牛病毒性腹泻病毒(BVDV)是黄病毒科、瘟病毒属成员,主要引起牛免疫抑制、腹泻及繁殖障碍,是影响全球养牛业的重要致病原。根据BVDV在体内对细胞的致病性,目前普遍将其分为2种生物型。不同生物型的基因结构及分子致病学机制明显不同,病毒基因变异可能产生新的生物型致病。我们简要综述BVDV生物型与基因结构及疾病发生之间的关系。     

MAPK信号转导通路与人巨细胞病毒感染

MAPK信号转导通路参与了人巨细胞病毒的致病过程。MAPK通路中的ERK和p38通路在人巨细胞病毒复制周期中起重要作用,通过磷酸化转录因子引起病毒及宿主相关基因的转录,从而调控人巨细胞病毒的复制;人巨细胞病毒的包膜糖蛋白及其他多种基因表达产物可通过不同机制以一定时序激活MAPK通路,调节自身及宿主细胞相应基因表达,以利于病毒完成其生活周期,并参与病毒的致病过程。深入研究MAPK信号转导通路与人巨细胞病毒感染的关系可为治疗该病毒感染引起的疾病提供新的治疗靶点。     

建立新型的常见腹泻相关病毒的多重检测方法

利用GenomeLab(tm)GeXP遗传分析系统建立一种同时检测A组轮状病毒、诺如病毒GI、GII型、札如病毒、肠道腺病毒、星状病毒、人博卡病毒II型7种常见腹泻相关病毒的方法。对反应条件进行优化后,非同日三次重复实验表明至少在104拷贝/μL水平可同时特异地检测出7种病毒,对Enterovirus71、Human Parechovirus、Picobir-navirusII阳性标本无交叉反应。本研究初步建立了一种高通量、快速的常见腹泻相关病毒的检测方法,为腹泻病原的分子诊断提供了新的方法。     

猪7种腹泻相关病毒的临床检测及猪嵴病毒的遗传进化分析

为了解引起猪腹泻疫病的病毒性病原种类及感染现状,本研究首先针对7种报道较少但可引起猪腹泻的病毒性病原建立了多重RT-PCR检测方法,包括猪捷申病毒(PTV)、猪萨佩罗病毒(PSV)、猪丁型冠状病毒(PDCo V)、猪嵴病毒(PKV)、猪札幌病毒(PSa V)、猪星状病毒(PAst V)和猪环曲病毒(PTo V)。利用该方法对419份临床腹泻粪便样品进行筛检,结果显示PKV检出率最高,阳性率达26.98%–45.79%;PKV和其他病原混合感染率达9.52%–18.54%。基于PKV的高检出率及其可能在猪腹泻疾病中发挥的作用,本试验进一步选取3个PKV阳性样品进行全基因组序列测定及遗传进化分析。结果表明,这3个阳性样品PKV均归属于猪嵴病毒属,且与其他动物嵴病毒遗传距离较远,分别标记为CM-PKV、JS-PKV和PD-PKV;它们的全基因组同源性为88.1%–89.1%;CM-PKV与2013年报道的中国株JS-02a-CHN/2013同源性最高,而JS-PKV和PD-PKV则与2008年报道的匈牙利株K-30-HUN/2008/HUN同源性最高。表明上海不同地区猪群中存在的PKV有明显的遗传差异,但毒株遗传特性的差异与其致病力的相关性需进一步研究。本研究为深入了解PKV的流行现状及探讨其在猪腹泻疫情中的作用提供了参考。     

不同致泻性大肠杆菌感染调控细胞信号通路的研究进展

腹泻性大肠杆菌是在全世界引起人类和动物疾病的主要病原之一,也给社会经济带来巨大损失。根据致病机理的不同,可将腹泻性大肠杆菌分为6种:肠致病性大肠杆菌、肠出血性大肠杆菌、肠凝集性大肠杆菌、产肠毒素大肠杆菌、扩散黏附性大肠杆菌和肠侵袭性大肠杆菌。不同致病型大肠杆菌侵入宿主的方式及引起的炎症反应有所不同。文章综合分析了致病机制不同的大肠杆菌在调控宿主细胞信号通路方式上的不同,从炎症级联反应方面阐述了不同致病类型大肠杆菌的感染特征,并探讨了炎症信号通路与病原感染、预防和治疗的关系,以期为腹泻性大肠杆菌致病机制及治疗方案的研究提供帮助。     

Identification and Characterization of a Novel Recombinant Porcine Astrovirus from Pigs in Anhui,China

Porcine astroviruses (PAstVs) have wide distribution in swine herds worldwide. At present, five porcine astrovirus genotypes have been identified. In this study, using viral metagenomics, a novel PAstV strain (designated as Ahast) was identified in fecal samples from pigs in Anhui of China, and the complete genomic sequence of Ahast was obtained by assembling and PCR amplification. Genomic structural analysis indicated that Ahast had a typical ribosomal frameshifting signal, and some conserve amino acid motifs were also found in virally encoded proteins. Phylogenetic analysis and sequence comparison indicated that this virus belonged to porcine astrovirus genotype 4 (PAstV4), which formed a clade clustered with other PAstV4. Multiple recombinant events were confirmed by recombination analysis and indicated that Ahast was a potential recombinant. Epidemiological investigation indicated that PAstV4 has a 10.7% prevalence in this pig farm. The new recombinant identified in this study will be beneficial to comprehend the origin, genetic diversity, and evolution of porcine astroviruses in Anhui of China.Key words: porcine astroviruses, viral metagenomics, genome recombination     

Environmental surveillance and molecular characterization of human enteric viruses in tropical urban wastewaters

Aims: To study the prevalence and genotypes of waterborne pathogenic viruses in urban wastewaters in the tropical region. Methods and Results: Viruses in wastewaters collected at three water reclamation plants in Singapore were studied by molecular methods. Over a 6‐month sampling period, adenoviruses, astroviruses and both norovirus genogroups I (GI) and II (GII) were detected in 100% of the sewage and secondary effluent. Enteroviruses and hepatitis A viruses (HAV) were found in 94 and 78% of sewage, and 89 and 28% of secondary effluent, respectively. By using quantitative real‐time PCR, estimated concentrations of astrovirus in the sewage were 1–2 orders of magnitude higher than those for adenovirus, noroviruses GI and GII. Genotyping of environmental isolates revealed multiple genotypes of GI and GII noroviruses. Coxsackieviruses A, astrovirus type 1 and adenovirus type 41 were prevalent. Norovirus GII/4 and coxsackievirus A24 isolates in wastewaters were closely related to respective outbreak strains isolated previously in Singapore. Conclusions: This study showed the widespread occurrence of all tested enteric virus groups in urban wastewaters. Genetic diversity of astroviruses, enteroviruses and noroviruses in the tropical region was observed. Significance and Impact of the Study: The high prevalence and great genetic diversity of human enteric viruses in urban wastewaters strongly supports the need of further comprehensive studies for evaluating the public health risk associated with viral pathogens in water environments.     

Astrovirus increases epithelial barrier permeability independently of viral replication

Astrovirus infection in a variety of species results in an age-dependent diarrhea; however, the means by which astroviruses cause diarrhea remain unknown. Studies of astrovirus-infected humans and turkeys have demonstrated few histological changes and little inflammation during infection, suggesting that intestinal damage or an overzealous immune response is not the primary mediator of astrovirus diarrhea. An alternative contributor to diarrhea is increased intestinal barrier permeability. Here, we demonstrate that astrovirus increases barrier permeability in a Caco-2 cell culture model system following apical infection. Increased permeability correlated with disruption of the tight-junction protein occludin and decreased the number of actin stress fibers in the absence of cell death. Additionally, permeability was increased when monolayers were treated with UV-inactivated virus or purified recombinant human astrovirus serotype 1 capsid in the form of virus-like particles. Together, these results demonstrate that astrovirus-induced permeability occurs independently of viral replication and is modulated by the capsid protein, a property apparently unique to astroviruses. Based on these data, we propose that the capsid contributes to diarrhea in vivo.     

Seasonal Fluctuations of Astrovirus,But Not Coronavirus Shedding in Bats Inhabiting Human-Modified Tropical Forests

Emerging infectious diseases (EIDs) are considered a major threat to global health. Most EIDs appear to result from increased contact between wildlife and humans, especially when humans encroach into formerly pristine habitats. Habitat deterioration may also negatively affect the physiology and health of wildlife species, which may eventually lead to a higher susceptibility to infectious agents and/or increased shedding of the pathogens causing EIDs. Bats are known to host viruses closely related to important EIDs. Here, we tested in a paleotropical forest with ongoing logging and fragmentation, whether habitat disturbance influences the occurrence of astro- and coronaviruses in eight bat species. In contrast to our hypothesis, anthropogenic habitat disturbance was not associated with corona- and astrovirus detection rates in fecal samples. However, we found that bats infected with either astro- or coronaviruses were likely to be coinfected with the respective other virus. Additionally, we identified two more risk factors influencing astrovirus shedding. First, the detection rate of astroviruses was higher at the beginning of the rainy compared to the dry season. Second, there was a trend that individuals with a poor body condition had a higher probability of shedding astroviruses in their feces. The identification of risk factors for increased viral shedding that may potentially result in increased interspecies transmission is important to prevent viral spillovers from bats to other animals, including humans.     

Is There Still Room for Novel Viral Pathogens in Pediatric Respiratory Tract Infections?

Viruses are the most frequent cause of respiratory disease in children. However, despite the advanced diagnostic methods currently in use, in 20 to 50% of respiratory samples a specific pathogen cannot be detected. In this work, we used a metagenomic approach and deep sequencing to examine respiratory samples from children with lower and upper respiratory tract infections that had been previously found negative for 6 bacteria and 15 respiratory viruses by PCR. Nasal washings from 25 children (out of 250) hospitalized with a diagnosis of pneumonia and nasopharyngeal swabs from 46 outpatient children (out of 526) were studied. DNA reads for at least one virus commonly associated to respiratory infections was found in 20 of 25 hospitalized patients, while reads for pathogenic respiratory bacteria were detected in the remaining 5 children. For outpatients, all the samples were pooled into 25 DNA libraries for sequencing. In this case, in 22 of the 25 sequenced libraries at least one respiratory virus was identified, while in all other, but one, pathogenic bacteria were detected. In both patient groups reads for respiratory syncytial virus, coronavirus-OC43, and rhinovirus were identified. In addition, viruses less frequently associated to respiratory infections were also found. Saffold virus was detected in outpatient but not in hospitalized children. Anellovirus, rotavirus, and astrovirus, as well as several animal and plant viruses were detected in both groups. No novel viruses were identified. Adding up the deep sequencing results to the PCR data, 79.2% of 250 hospitalized and 76.6% of 526 ambulatory patients were positive for viruses, and all other children, but one, had pathogenic respiratory bacteria identified. These results suggest that at least in the type of populations studied and with the sampling methods used the odds of finding novel, clinically relevant viruses, in pediatric respiratory infections are low.