江西地区啮齿动物中温州病毒的检及病毒基因特征分析

目的 了解温州病毒在江西地区啮齿动物中感染的情况及病毒基因特征。方法 收集2021年江西省高安市、安义县两地啮齿动物鼠肺组织样本,提取样本核酸,采用温州病毒特异性引物进行巢式PCR扩增,PCR产物进行序列测定。采用Ion GeneStudio S5 二代测序平台(NGS)对1株核酸阳性样本进行病毒基因组测序,采用CLC软件对基因序列进行分析。结果 共收集高安市、安义县啮齿动物肺组织标本164份,通过巢式PCR检出温州病毒3份,均来自高安地区的黄毛鼠。3株病毒部分L基因序列同源性93.66%~98.50%,氨基酸序列同源性95.21%~100%。选取1株病毒(JXGAW45/2021)进行二代测序,获得全基因组序列,其中S、L基因分别含3 429、7 145个核苷酸。基因组比对分析发现JXGAW45/2021与其他温州病毒核苷酸序列同源性为82.58%~85.75%,氨基酸同源性为88.76%~96.83%,在S、L基因系统进化树中均独立分支,为温州病毒新的变异株。结论 首次在江西地区啮齿动物中发现温州病毒。     

珠海市不同时期新型冠状病毒基因组测序及溯源分析

目的 对珠海市4例不同时期新型冠状肺炎确证病例的呼吸道标本进行三代测序,获得新型冠状病毒全基因组序列,分析基因组突变及分子溯源情况。方法 采用nanopore 三代高通量测序技术对呼吸道标本中的新型冠状病毒基因组测序,基于artic流程组装病毒基因组序列,运用生物信息学软件分析病毒全基因组序列与参考序列的一致性与进化情况。结果 4份样本均可获得28 298~29 819 bp长度的基因组序列数,基因组覆盖度94.6%~99.7%,共检出46个碱基位点突变、涉及27处氨基酸变异,非同义突变占比58.7%(27/46),非同义突变中以ORF1ab 基因占比最高44.44%(12/27)。系统发育树显示,4份样本分属于B(Zhuhai/ZQ202001/2020)、B.1.36(Zhuhai/YZQ202011/2020)、B.1.1.63(Zhuhai/ZHG9671/2020和Zhuhai/P0717001/2020)进化分支,Zhuhai/ZQ202001/2020与武汉早期输入密切相关,Zhuhai/YZQ202011/2020、Zhuhai/P0717001/2020、Zhuhai/ZHG9671/2020与同时期香港新冠肺炎病例基因组序列相似性最高,与其流行病学调查结果一致。结论 4例珠海市新型冠状肺炎确证病例均为输入病例,不存在本地感染,核苷酸位点变异存在多态性。三代测序技术可有效用于原始样本中新型冠状病毒基因组序列的溯源分析,在地市级疾控应用前景较好。     

2018-2020年上海市登革1型病毒全基因组序列特征研究

目的 研究2018-2020年上海市本地感染及输入性来源登革1型病毒(Dengue Serotype 1 virus, DENV-1)分离株全基因组序列特征。方法 收集登革热疑似病例血清样本,对DENV-1阳性样本进行病毒分离、全基因组扩增与测序,进一步通过构建进化树对全基因组序列进行同源性分析、核苷酸序列及氨基酸序列相似性分析、编码蛋白氨基酸位点差异分析。结果 从88份DENV-1阳性样本中获得31株分离株的全基因组核苷酸序列,其中3株为本地感染病例来源,28株为输入病例来源。进化分析显示,28株分离株的基因型为G-I型,与G-I型参考序列的核苷酸(氨基酸)相似性均值为96.47%~97.37%(98.78%~99.16%);3株分离株的基因型为G-IV型,与G-IV型参考序列的核苷酸(氨基酸)相似性均值为96.66%~96.86%(99.01%~99.26%);3株本地感染病例来源分离株均为G-I型,根据同源性分析,存在输入性病例引起本地感染可能。分离株与对照株比较各结构蛋白与非结构蛋白氨基酸位点均存在差异,其中E蛋白的495个氨基酸位点中,有31个位点存在差异。结论 2018-2020年上海市DENV-1包含G-I与G-IV两种基因型,以G-I型为主;首次分离得到3株上海市本地感染病例来源DENV-1,为G-I型,存在输入性病例引起本地感染可能。     

无锡市新型冠状病毒感染不同流行时期病例的全基因组特征分析

目的了解无锡市不同流行时期新型冠状病毒(SARS-CoV-2)全基因组序列特征及其突起蛋白的变异情况。方法对无锡市2020年1月至2月的6例新型冠状病毒感染(COVID-19)本土病例和2021年3月至9月的13例COVID-19输入病例的鼻咽拭子样本提取病毒核酸, 扩增全基因组序列, 构建测序文库, 并采用二代测序仪上机测序。以NC₀45512.2为参考株, 使用CLC Genomics Workbench(21版)软件分析下机数据。采用MEGA 7.0软件构建系统进化树, 采用Nextstrain分型法和系统发育归类命名全球暴发分支(Pangolin)分型法鉴定型别。结果 19例COVID-19患者中, Nextstrain分型有5种亚型, Pangolin分型有7种亚型。与参照株NC₀45512.2相比, 核苷酸突变位点范围为0～42个, 中位数为29个;核苷酸突变造成氨基酸突变位点范围为0～34个, 中位数为20个。6例本土病例与13例输入病例无共有的核苷酸突变位点, 处于不同的进化分支。6例本土病例属于大流行早期病例, 其病毒序列与...     

一起由空肠弯曲菌所致食源性疾病暴发事件的流行病学及病原学溯源分析

目的 对一起空肠弯曲菌所致的食源性疾病暴发事件进行流行病学及溯源分析。方法 对突发事件进行现场流行病学调查,采集粪便样本、环境涂抹样本、食品样本等进行快速PCR检测和病原菌分离。对分离菌株进行PFGE分子分型和全基因组测序分析,并进行药敏试验。结果 从7份病例样本和2份环境涂抹样本中分离出空肠弯曲菌。PFGE分析和cgMLST聚类结果表明其中3份病例样本和环境涂抹样本(蒸柜容器把手涂抹)分离的菌株克隆聚集成簇,ST型别为ST11105;另2份病例样本和环境涂抹样本(刀具砧板涂抹)分离的菌株属同一克隆株,ST型别为ST2031。还有2份病例样本分离的菌株ST型为 ST11106和ST7533。药敏结果表明,分离株对四环素类和喹诺酮类耐药率较高,分别为77.8%、55.6%。基因组测序结果发现最多的耐药基因为bla_OXA-193,gyrA、tet(O),其中gyrA基因86位点发生T-I突变。分离株共获得168个毒力基因,涉及多种致病机理。结论 采用快速PCR法、PFGE 分子分型技术、全基因组测序技术等可对突发事件进行快速、准确的溯源分析。     

2016年福建省B型流感病毒基因特征分析

目的 分析2016年福建省B型流感病毒(Influenza Virus)血凝素(Hemagglutinin,HA)和神经氨酸酶(Neuramidinase,NA)的基因变异。方法 从中国疾病预防控制信息系统采集日期2016.1.1至2016.12.31的福建省流感监测数据。毒株来源2016年福建省流感网络监测流感样病例,提取病毒(犬肾传代细胞或鸡胚培养分离)核酸进行RT-PCR扩增HA和NA基因片段并测序,MEGA5.0分析基因特征。结果 测序51株B型流感病毒HA、NA片段,与疫苗株核苷酸同源性在97.8%~100%。 研究发现2株重配株(BY-NA/BV-NA)、耐药株1株、Victoria系HA片段新增一个糖基化位点(197),酶活性中心和周围的相关位点氨基酸仍保持高度保守。结论 2016年福建省B型流感毒株少数发生变异与疫苗株不匹配。     

云南省1株基孔肯雅毒株全基因组序列测定及特征分析

目的 对1例缅甸输入基孔肯雅热病例血清标本进行病毒分离及全基因组测序,分析其基因特征。方法 采用real-time RT-PCR方法对标本进行检测,分离培养后获得毒株,对病毒核酸扩增后的产物进行全基因组测序,使用DNAStar 7.1软件对测序结果进行拼接,Mega5.0软件对序列进行比对和系统发生树构建。结果 病例血清标本核酸检测显示CHIKV阳性,经分离培养获得CHIKV毒株(YN0627株),全基因组测序得到其序列,YN0627全长为11 586 nt,其基因结构符合CHIKV的基因特征。系统进化分析显示,YN0627与东中南非洲遗传谱系(East, Central and South African Lineage, ECSA)的其他流行株聚集在一起,属于ECSA谱系。YN0627的编码区与参考序列相比,核苷酸同源性为85.24%~99.96%,氨基酸同源性为95.34%~99.97%,结构蛋白编码区域有28个氨基酸变异位点。结论 云南省输入性CHIKV-YN0627属于ECSA谱系,且观察到多个氨基酸位点突变,提示云南省应当加强对CHIKV的监测和研究。     

2017-2019北京地区犬钩端螺旋体病流行病学调查

目的 了解北京地区犬钩端螺旋体的感染情况。方法 采用快速实时荧光快速聚合酶链式反应(Rapid real-time fluorescence quantitative polymerase chain reaction, qPCR)对2017年1月至2019年2月从宠物医院、犬舍、流浪动物基地收集到的1 600份血液和尿液样本进行分子学检测,以及风险因素分析。并对qPCR阳性病例样本进行血清学和PCR鉴定。结果 qPCR检出阳性样本17份,检出率为1.01%(95%CI 0.6- 1.7)。其中尿液阳性检出率2.00%(16/800)显著高于血液检出率0.13%(1/800)(χ²=11.653,P<0.01)。地区(χ²=17.828,P<0.05)、季节(χ²=10.916,P<0.05)、样本来源(χ²=9.432,P<0.01)是犬钩体感染的风险因素,但不同年龄(χ²=1.103, P=0.613)、性别(χ²=1.124, P=0.223)、品种(χ²=0.427, P=0.448)的犬感染钩体的差异无统计学意义。显微凝集试验显示12份qPCR阳性病犬血清样本存在澳洲群和拜伦群抗体;菌株经PCR鉴定均为问号钩端螺旋体。结论 北京部分地区存在犬钩体病的流行,应加强疾病监测和宠物犬定期疫苗接种以降低其向人类传播的风险。     

2019-2020年海南省A(H1N1)pdm09流感病毒基因特性分析

目的 分析海南省A(H1N1)pdm09亚型流感病毒的抗原性和基因特性,了解病毒的变异情况,为海南省A(H1N1)pdm09亚型流感病毒的防控提供依据。方法 选取14株2019-2020年海南省流感监测网络实验室分离到的A(H1N1)pdm09亚型流感病毒进行基因序列测定,测序结果用MEGA 10.1.8和DNASTAR7.0.1软件进行基因特性分析。结果 2019-2020年海南省A(H1N1)pdm09亚型流感病毒与国际疫苗株A/Brisbane/02/2018的血凝素基因(Hemagglutinin HA)和神经氨酸酶基因(Neuraminidase NA)均在核苷酸进化树6B.1分支上。海南分离株与疫苗株A/Brisbane/02/2018 HA基因核苷酸和氨基酸同源性范围分别为98.5%~99.1%和97.7%~99.1%,对神经氨酸酶抑制剂敏感,HA基因在Sa抗原决定簇NQT162-164有共同变异位点,N162位点的变异增加了1个潜在糖基化位点。Sb抗原决定簇K156位点发生变异的分离株为参考血清A/Brisbane/02/2018的低反应株,其余分离株均为疫苗株A/Brisbane/02/2018的类似株。结论 2019-2020年海南省A(H1N1)pdm09亚型流感病毒与WHO推荐的北半球疫苗组分匹配。     

3种新型冠状病毒核酸检测试剂对120份样本检测结果的比较与分析

目的 对市售的3种国产新型冠状病毒核酸检测试剂(实时荧光RT-PCR法)的检测结果进行比较和分析,以供检测机构参考。方法 采用3种核酸检测试剂(实时荧光RT-PCR法)对120份新冠肺炎病人和密切接触者的咽拭子、尿液、唾液和粪便样本进行平行检测,运用SPSS20软件采用卡方检验对检测结果进行分析。结果 120份样本中,3种试剂阳性率分别为42.50%(51/120)、39.17%(47/120)和41.67%(50/120),阳性检出率无统计学差异(χ²=0.298,P>0.05),对4种样本检测阳性检出率,差异无统计学意义(P>0.05)。3种试剂检测结果一致的有89份。检测结果一致性从高到低为:A试剂和C试剂>B试剂和C试剂>A试剂和B试剂。结论 由于不同厂家试剂灵敏度和准确性不同导致检测结果和检测一致性存在差异,提示试剂厂家需进一步优化性能,提高检测灵敏度和准确性,同时各检测机构应采取多种质控方法以确保新冠病毒核酸检测准确性,以便更好地为疫情防控、病人救治提供科学依据。     

Assessment of Viral Targeted Sequence Capture Using Nanopore Sequencing Directly from Clinical Samples

Shotgun metagenomic sequencing (SMg) enables the simultaneous detection and characterization of viruses in human, animal and environmental samples. However, lack of sensitivity still poses a challenge and may lead to poor detection and data acquisition for detailed analysis. To improve sensitivity, we assessed a broad scope targeted sequence capture (TSC) panel (ViroCap) in both human and animal samples. Moreover, we adjusted TSC for the Oxford Nanopore MinION and compared the performance to an SMg approach. TSC on the Illumina NextSeq served as the gold standard. Overall, TSC increased the viral read count significantly in challenging human samples, with the highest genome coverage achieved using the TSC on the MinION. TSC also improved the genome coverage and sequencing depth in clinically relevant viruses in the animal samples, such as influenza A virus. However, SMg was shown to be adequate for characterizing a highly diverse animal virome. TSC on the MinION was comparable to the NextSeq and can provide a valuable alternative, offering longer reads, portability and lower initial cost. Developing new viral enrichment approaches to detect and characterize significant human and animal viruses is essential for the One Health Initiative.     

Detection and Genome Sequencing of SARS-CoV-2 in a Domestic Cat with Respiratory Signs in Switzerland

Since the emergence of coronavirus disease (COVID-19) in late 2019, domestic cats have been demonstrated to be susceptible to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) under natural and experimental conditions. As pet cats often live in very close contact with their owners, it is essential to investigate SARS-CoV-2 infections in cats in a One-Health context. This study reports the first SARS-CoV-2 infection in a cat in a COVID-19-affected household in Switzerland. The cat (Cat 1) demonstrated signs of an upper respiratory tract infection, including sneezing, inappetence, and apathy, while the cohabiting cat (Cat 2) remained asymptomatic. Nasal, oral, fecal, fur, and environmental swab samples were collected twice from both cats and analyzed by RT-qPCR for the presence of SARS-CoV-2 viral RNA. Both nasal swabs from Cat 1 tested positive. In addition, the first oral swab from Cat 2 and fur and bedding swabs from both cats were RT-qPCR positive. The fecal swabs tested negative. The infection of Cat 1 was confirmed by positive SARS-CoV-2 S1 receptor binding domain (RBD) antibody testing and neutralizing activity in a surrogate assay. The viral genome sequence from Cat 1, obtained by next generation sequencing, showed the closest relation to a human sequence from the B.1.1.39 lineage, with one single nucleotide polymorphism (SNP) difference. This study demonstrates not only SARS-CoV-2 infection of a cat from a COVID-19-affected household but also contamination of the cats’ fur and bed with viral RNA. Our results are important to create awareness that SARS-CoV-2 infected people should observe hygienic measures to avoid infection and contamination of animal cohabitants.     

Multiple Early Introductions of SARS-CoV-2 to Cape Town,South Africa

Cape Town was the first city in South Africa to experience the full impact of the coronavirus disease 2019 (COVID-19) pandemic. We acquired samples from all suspected cases and their contacts during the first month of the pandemic from Tygerberg Hospital. Nanopore sequencing generated SARS-CoV-2 whole genomes. Phylogenetic inference with maximum likelihood and Bayesian methods were used to determine lineages that seeded the local epidemic. Three patients were known to have travelled internationally and an outbreak was detected in a nearby supermarket. Sequencing of 50 samples produced 46 high-quality genomes. The sequences were classified as lineages: B, B.1, B.1.1.1, B.1.1.161, B.1.1.29, B.1.8, B.39, and B.40. All the sequences from persons under investigation (PUIs) in the supermarket outbreak (lineage B.1.8) fall within a clade from the Netherlands with good support (p > 0.9). In addition, a new mutation, 5209A>G, emerged within the Cape Town cluster. The molecular clock analysis suggests that this occurred around 13 March 2020 (95% confidence interval: 9–17 March). The phylogenetic reconstruction suggests at least nine early introductions of SARS-CoV-2 into Cape Town and an early localized transmission in a shopping environment. Genomic surveillance was successfully used to investigate and track the spread of early introductions of SARS-CoV-2 in Cape Town.     

Sequencing and mutations analysis of the first recorded SARS-CoV-2 Omicron variant during the fourth wave of pandemic in Iraq

Despite vaccine development and vaccination programs underway around the globe, the coronavirus disease 2019 (COVID-19) pandemic has not been controlled as the SARS-CoV-2 virus is evolving and new variants are emerging. This study was conducted to sequence and molecularly characterize the representing samples from the early fourth SARS-CoV-2 wave in Iraq. Here, we have performed next-generation sequencing of whole-genome sequencing of two representing samples from the country's early beginning of the fourth pandemic wave. The samples were sequenced using Illumina Miseq system, and the reference sequences were retrieved from GISAID database. Phylogenetic analysis was performed through Mega software. This study provides an initial sequence analysis and molecular characterization of the first Omicron variant cases recorded in the country. Our analysis revealed many mutations on the spike glycoprotein, especially on the receptor binding domain, with potential impact on immune escape and infectivity. The study findings suggest considering the highly mutated immunogenic epitope of the Omicron variant as a reference for developing a new vaccine for combating the ongoing pandemic.     

Exploring the hepatitis C virus genome using single molecule realtime sequencing

Single molecular real-time(SMRT) sequencing, also called third-generation sequencing, is a novel sequencing technique capable of generating extremely long contiguous sequence reads. While conventional short-read sequencing cannot evaluate the linkage of nucleotide substitutions distant from one another, SMRT sequencing can directly demonstrate linkage of nucleotide changes over a span of more than 20 kbp, and thus can be applied to directly examine the haplotypes of viruses or bacteria whose genome structures are changing in real time. In addition, an error correction method(circular consensus sequencing) has been established and repeated sequencing of a single-molecule DNA template can result in extremely high accuracy. The advantages of long read sequencing enable accurate determination of the haplotypes of individual viral clones. SMRT sequencing has been applied in various studies of viral genomes including determination of the full-length contiguous genome sequence of hepatitis C virus(HCV), targeted deep sequencing of the HCV NS5 A gene, and assessment of heterogeneity among viral populations. Recently, the emergence of multi-drug resistant HCV viruses has become a significant clinical issue and has been also demonstrated using SMRT sequencing. In this review, we introduce the novel third-generation PacBio RSII/Sequel systems, compare them with conventional next-generation sequencers, and summarize previous studies in which SMRT sequencing technology has been applied for HCV genome analysis. We also refer to another long-read sequencing platform, nanopore sequencing technology, and discuss the advantages, limitations and future perspectives in using these thirdgeneration sequencers for HCV genome analysis.     

Direct RNA Sequencing Reveals SARS-CoV-2 m6A Sites and Possible Differential DRACH Motif Methylation among Variants

The causative agent of COVID-19 pandemic, SARS-CoV-2, has a 29,903 bases positive-sense single-stranded RNA genome. RNAs exhibit about 150 modified bases that are essential for proper function. Among internal modified bases, the N⁶-methyladenosine, or m6A, is the most frequent, and is implicated in SARS-CoV-2 immune response evasion. Although the SARS-CoV-2 genome is RNA, almost all genomes sequenced thus far are, in fact, reverse transcribed complementary DNAs. This process reduces the true complexity of these viral genomes because the incorporation of dNTPs hides RNA base modifications. Here, we present an initial exploration of Nanopore direct RNA sequencing to assess the m6A residues in the SARS-CoV-2 sequences of ORF3a, E, M, ORF6, ORF7a, ORF7b, ORF8, N, ORF10 and the 3′-untranslated region. We identified fifteen m6A methylated positions, of which, six are in ORF N. Additionally, because m6A is associated with the DRACH motif, we compared its distribution in major SARS-CoV-2 variants. Although DRACH is highly conserved among variants, we show that variants Beta and Eta have a fourth position C > U change in DRACH at 28,884b that could affect methylation. This is the first report of direct RNA sequencing of a Brazilian SARS-CoV-2 sample coupled with the identification of modified bases.     

Prediction of SARS-CoV-2 Variant Lineages Using the S1-Encoding Region Sequence Obtained by PacBio Single-Molecule Real-Time Sequencing

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causal agent of the COVID-19 pandemic that emerged in late 2019. The outbreak of variants with mutations in the region encoding the spike protein S1 sub-unit that can make them more resistant to neutralizing or monoclonal antibodies is the main point of the current monitoring. This study examines the feasibility of predicting the variant lineage and monitoring the appearance of reported mutations by sequencing only the region encoding the S1 domain by Pacific Bioscience Single Molecule Real-Time sequencing (PacBio SMRT). Using the PacBio SMRT system, we successfully sequenced 186 of the 200 samples previously sequenced with the Illumina COVIDSeq (whole genome) system. PacBio SMRT detected mutations in the S1 domain that were missed by the COVIDseq system in 27/186 samples (14.5%), due to amplification failure. These missing positions included mutations that are decisive for lineage assignation, such as G142D (n = 11), N501Y (n = 6), or E484K (n = 2). The lineage of 172/186 (92.5%) samples was accurately determined by analyzing the region encoding the S1 domain with a pipeline that uses key positions in S1. Thus, the PacBio SMRT protocol is appropriate for determining virus lineages and detecting key mutations.     

Nosocomial Outbreak of SARS-CoV-2 in a “Non-COVID-19” Hospital Ward: Virus Genome Sequencing as a Key Tool to Understand Cryptic Transmission

Dissemination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in healthcare institutions affects both patients and health-care workers (HCW), as well as the institutional capacity to provide essential health services. Here, we investigated an outbreak of SARS-CoV-2 in a “non-COVID-19” hospital ward unveiled by massive testing, which challenged the reconstruction of transmission chains. The contacts network during the 15-day period before the screening was investigated, and positive SARS-CoV-2 RNA samples were subjected to virus genome sequencing. Of the 245 tested individuals, 48 (21 patients and 27 HCWs) tested positive for SARS-CoV-2. HCWs were mostly asymptomatic, but the mortality among patients reached 57.1% (12/21). Phylogenetic reconstruction revealed that all cases were part of the same transmission chain. By combining contact tracing and genomic data, including analysis of emerging minor variants, we unveiled a scenario of silent SARS-CoV-2 dissemination, mostly driven by the close contact within the HCWs group and between HCWs and patients. This investigation triggered enhanced prevention and control measures, leading to more timely detection and containment of novel outbreaks. This study shows the benefit of combining genomic and epidemiological data for disclosing complex nosocomial outbreaks, and provides valuable data to prevent transmission of COVID-19 in healthcare facilities.     

Symptomatic SARS-CoV-2 Reinfection in a Healthy Healthcare Worker in Italy Confirmed by Whole-Genome Sequencing

This study describes a case of SARS-CoV-2 reinfection confirmed by whole-genome sequencing in a healthy physician who had been working in a COVID-19 hospital in Italy since the beginning of the pandemic. Nasopharyngeal swabs were obtained from the patient at each presentation as part of routine surveillance. Nucleic acid amplification testing was performed on the two samples to confirm SARS-CoV-2 infection, and serological tests were used to detect SARS-CoV-2 IgG antibodies. Comparative genome analysis with whole-genome sequencing was performed on nasopharyngeal swabs collected during the two episodes of COVID-19. The first COVID-19 episode was in March 2020, and the second was in January 2021. Both SARS-CoV-2 infections presented with mild symptoms, and seroconversion for SARS-CoV-2 IgG was documented. Genomic analysis showed that the viral genome from the first infection belonged to the lineage B.1.1.74, while that from the second infection to the lineage B.1.177. Epidemiological, clinical, serological, and genomic analyses confirmed that the second episode of SARS-CoV-2 infection in the healthcare worker met the qualifications for “best evidence” for reinfection. Further studies are urgently needed to assess the frequency of such a worrisome occurrence, particularly in the light of the recent diffusion of SARS-CoV-2 variants of concern.