云南首次从患者体内分离到基孔肯雅病毒

本文报告1987年从云南西双版纳地区97份急性发热期病人血中分离到一株基孔肯雅病毒,并在分离到病毒患者恢复期血清中查到中和抗体,指数为316。首次证实云南有基孔肯雅轻型病例及自然疫源地存在。     

基孔肯雅热

基孔肯雅（Chikungunya。cHIK）热是由基孔肯雅病毒（Chikungunya virus,CHIKV）引起,经蚊虫吸血传播的一种自然疫源性疾病。“基孔肯雅”是坦桑尼亚南部土语“chikungunya”译音,意即身体弯曲,是由于病人出现关节炎症状,最后弯腰曲背,故本病可意译为“屈曲病”,其主要临床表现为发热、关节剧烈疼痛和皮疹。     

基孔肯雅病毒小鼠感染模型研究进展

基孔肯雅病毒(Chikungunya virus, CHIKV)感染引发的基孔肯雅热是一种主要经伊蚊叮咬而传播的虫媒传染病,近些年已在100多个国家流行或暴发,成为严重威胁全球公共卫生安全的虫媒病毒性传染病。CHIKV感染后可以引起急性发热、皮疹、肌肉疼痛以及慢性关节炎、腱鞘炎等临床症状,严重者可发生病毒性脑炎。小鼠模型作为CHIKV最常用的动物感染模型,在病毒感染机理、宿主抗感染免疫机制以及相关疫苗或药物研发等方面应用广泛。本文拟就国内外关于基孔肯雅病毒小鼠感染模型的最新研究进展作一综述。     

中国首例输入性基孔肯雅热临床分析

目的 了解2008年我国首例输入性基孔肯雅热病例的流行病学、临床、病原学特点及预后转归.方法 对1例成年男性患者流行病学及临床资料进行回顾性分析,并采用ELISA和胶体合法检测患者血清基孔肯雅病毒IgM(CHIKV-IgM)抗体,实时荧光PCR法检测基孔肯雅病毒核酸(CHIKV RNA).结果 该患者临床表现为发热起病,有头痛、全身肌肉及关节酸痛,全身充血性斑丘疹,WBC及PLT减少.发病第9天CHIKV-IgM阳性;第3、5,7、9天CHIKV RNA阳性;RT-PCR扩增产物为575个核苷酸碱基片段,经序列测序结果与基孔肯雅病毒核酸序列同源性高达99%.患者经对症支持等治疗痊愈出院.结论 该患者为我国首例输入性基孔肯雅热确诊病例,本病临床表现与登革热相似.     

白纹伊蚊经实验感染后涎腺中基孔肯雅病毒和乙型脑炎病毒抗原检测

用基孔肯雅和乙型脑炎病毒经口感染白纹伊蚊，采用免疫荧光试验对雌蚊涎腺作病毒抗原检查，结果于感染后第８￣１４天基孔肯雅的阳性为５０％￣９１．６７％，乙型脑炎为７０％￣８０％。试验认为，白纹伊蚊在感染后第６￣８天即可传播基孔肯雅和乙型脑炎病毒。     

云南基孔肯雅病毒血凝特性的研究

城ＰＨ５．７５－６．４的条件下，云南基孔肯雅病毒及国外原型株能与鸽、鹅、鸡、、绵羊和Ｏ型红细胞发生凝集，尤以鸽、鹅红细胞为佳，凝集最适ＰＨ为５．７５。在４℃、室温和３７℃ 血弟反应无明显差别 。     

基孔肯雅病研究进展

基孔肯雅病（Chikungunya）是一种由节肢动物传播的病毒性疾病，主要在非洲与东南亚地区流行。在灵长类与人类中传播的媒介主要是伊蚊。虽然病毒感染人类后呈现低活性，但由于其可导致世界范围的广泛传播流行，且本身具有潜在危险性Ⅲ，故应当引起足够重视。     

树Qu实验感染后血清中抗基孔肯雅病毒IgM和IgG抗体检查

成年树Ｑｕ经人工感染基孔肯雅病毒后，能产生２－６天的病毒血症。感染后第６天能产生特异性ＩｇＭ抗体，第１４－２１天为高峰，以后逐渐下降，感染后第１２天，ＩｇＧ抗体开始出现，３０－６０天为高峰，并持续不降，表明树Ｑｕ对基孔肯雅病毒敏感。     

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。     

Dengue,chikungunya and Zika virus infections among Dutch travellers to Suriname: a prospective study during the introduction of chikungunya and Zika virus, 2014 to 2017

BackgroundSuriname, a country endemic for dengue virus (DENV), is a popular destination for Dutch travellers visiting friends and relatives and tourist travellers. Chikungunya and Zika virus (CHIKV, ZIKV) were introduced in 2014 and 2015, respectively. Data on infection risks among travellers are limited.AimWe aimed to prospectively study incidence rate (IR) and determinants for DENV, ZIKV and CHIKV infection in adult travellers to Suriname from 2014 through 2017.MethodsParticipants kept a travel diary and were tested for anti-DENV, anti-ZIKV and anti-CHIKV IgG antibodies (Euroimmun). Selected samples were subjected to an in-house DENV and ZIKV PRNT50. The IR (infections/1,000 person-months of travel) and IR ratio and determinants for infection were calculated.ResultsTravel-acquired infections were found in 21 of 481 participants: 18 DENV, four ZIKV and two CHIKV, yielding an IR_DENV of 47.0 (95% CI: 29.6–74.6), IR_ZIKV of 11.6 (95% CI: 4.4–31.0) and IR_CHIKV of 5.6 (95% CI: 1.4–22.2)/1,000 person-months. In nine DENV and three ZIKV infected participants, infections were PRNT50-confirmed, yielding a lower IR_DENV of 23.3 (95% CI: 12.1–44.8) and an IR_ZIKV of 8.4 (95% CI: 2.7–26.1) per 1,000 person-months. Tourist travel was associated with DENV infection. ZIKV and CHIKV infections occurred soon after their reported introductions.ConclusionsDespite an overestimation of serologically confirmed infections, Dutch travellers to Suriname, especially tourists, are at substantial risk of DENV infection. As expected, the risk of contracting ZIKV and CHIKV was highest during outbreaks. Cross-reaction and potential cross-protection of anti-DENV and -ZIKV antibodies should be further explored.     

Structural basis of Chikungunya virus inhibition by monoclonal antibodies

Chikungunya virus (CHIKV) is an emerging viral pathogen that causes both acute and chronic debilitating arthritis. Here, we describe the functional and structural basis as to how two anti-CHIKV monoclonal antibodies, CHK-124 and CHK-263, potently inhibit CHIKV infection in vitro and in vivo. Our in vitro studies show that CHK-124 and CHK-263 block CHIKV at multiple stages of viral infection. CHK-124 aggregates virus particles and blocks attachment. Also, due to antibody-induced virus aggregation, fusion with endosomes and egress are inhibited. CHK-263 neutralizes CHIKV infection mainly by blocking virus attachment and fusion. To determine the structural basis of neutralization, we generated cryogenic electron microscopy reconstructions of Fab:CHIKV complexes at 4- to 5-Å resolution. CHK-124 binds to the E2 domain B and overlaps with the Mxra8 receptor-binding site. CHK-263 blocks fusion by binding an epitope that spans across E1 and E2 and locks the heterodimer together, likely preventing structural rearrangements required for fusion. These results provide structural insight as to how neutralizing antibody engagement of CHIKV inhibits different stages of the viral life cycle, which could inform vaccine and therapeutic design.

Chikungunya virus (CHIKV), a single-stranded positive-sense RNA envelope virus, is an emerging alphavirus transmitted to humans by Aedes species mosquitoes (1, 2). CHIKV consists of three related genotypes: Asian, East/Central/South African (ECSA), and West African (3). According to the Centers for Disease Control and Prevention, there have been millions of cases reported in approximately 100 countries. CHIKV infection causes an acute febrile illness accompanied by musculoskeletal disease (4, 5). A subset of cases (∼30%) showed that chronic arthritis can develop and persist for months to years (6, 7).The 12-kb positive-sense RNA genome is packaged within an icosahedral nuclear capsid core composed of 240 copies of capsid proteins, which is surrounded by a host-derived lipid bilayer. The surface of the mature CHIKV particle (diameter ∼700 Å) has 80 trimeric envelope E1-E2 heterodimer protein spikes anchored on the lipid bilayer membrane (SI Appendix, Fig. S1A) arranged in T = 4 icosahedral symmetry. E1 and E2 protein ectodomains each consist of three domains: E1-DI; E1-DII and E1-DIII; and E2-DA, E2-DB, and E2-DC (SI Appendix, Fig. S1B). The fusion loop on the distal end of E1-DII mediates endosomal membrane fusion. The groove formed by E2-DA and E2-DB shields the fusion loop of E1 protein from premature membrane fusion at neutral pH (8). Multiple attachment factors have been implicated in CHIKV entry of cells (9), and E2-DB reportedly contains receptor-binding sites (10, 11). Mxra8, a recently identified alphavirus receptor (12), recognizes an epitope spanning both the E1 and E2 proteins (13, 14).The virus infection cycle starts with the E1-E2 proteins binding to the cell-surface receptors (12). The virion is then internalized into the endosome (15, 16). The acidic condition of the endosome causes E1-E2 heterodimers to undergo conformational changes, exposure of the E1 fusion loop for insertion into the endosomal membrane, and subsequent reorganization of the E1 protein into E1 trimers to allow endosomal membrane fusion (17, 18). After fusion, the capsid and RNA genome are released into the cytoplasm (19) to allow translation and replication of the viral genome. The newly synthesized virus buds at the plasma membrane (20).Currently, there exist no licensed CHIKV vaccine or therapeutics. Neutralizing antibodies have been shown to confer both prophylactic and therapeutic protection in animal models (21–28). Here we show the potencies of two CHIKV antibodies, CHK-124 and CHK-263, in vivo and demonstrate that they inhibit multiple steps in the virus infection cycle in vitro. We also determined the cryogenic electron microscopy (cryo-EM) structures of their Fab fragments complexed with CHIKV to 4- to 5-Å resolution. For CHK-124, the predominant neutralization mechanisms are aggregation of virus particles and inhibition of receptor binding. For CHK-263, the mechanism is the inhibition of fusion by locking E1 and E2 proteins together. Altogether, our study provides a structural understanding as to how potent antibodies block CHIKV infection.     

杭州市2019年登革病毒分子流行病学研究

目的 了解2019年杭州市登革病毒分子特征和可能的传播来源.方法 收集登革热患者血清样本,分析登革热流行特征.分别采用ELISA和RT-PCR方法检测登革热抗体、登革病毒核酸及其型别,再对核酸阳性样本进行E基因扩增、序列测定和进化分析.结果 2019年杭州共检测登革热病例212例(输入性病例158例,本地病例54例),...     

Identification of a hepatitis B virus S gene mutant in lamivudine-treated patients experiencing HBsAg seroclearance

BACKGROUND & AIMS: Seroclearance of hepatitis B virus (HBV) surface antigen (HBsAg) is a rare event in chronic hepatitis B patients receiving lamivudine therapy. It is generally believed to be a benevolent sign, implicating clearance of viremia. The aim of this study is to examine the authenticity of this dogma. METHODS: In a 5-year period, 11 patients treated with lamivudine experienced seroclearance of HBsAg. The clinical data were examined. The HBV S gene sequences derived from the patient's serum samples before and after seroclearance of HBsAg were analyzed. RESULTS: Serum HBV-DNA could be detected by nested polymerase chain reaction (PCR) in all 11 patients, by 1-step PCR in 8, and by Cobas Amplicor HBV-DNA test (>200 copies/mL) in 5. A mutation hot spot, P120A in the S gene, was identified in 6 of the 11 patients. Site-directed mutagenesis experiments indicated that the Ausria-II RIA test failed to detect this mutant. Decreased sensitivity of detection was also observed when other monoclonal antibodies were applied. CONCLUSIONS: Seroclearance of HBsAg during lamivudine therapy may not indicate viral clearance. Specifically, it may be caused by a point mutation in the S gene, which results in detection failure. In such patients, further verification and follow-up using a sensitive HBV-DNA test are advised.     

感染登革病毒后抗体产生规律及应用于暴发疫情的血清学诊断

目的了解感染登革病毒后特异性抗体产生规律,指导基层实验室应用血清抗体检测方法对暴发疫情的早期病例作出正确诊断,为控制暴发提供实验室依据。方法采集福建省1次暴发登革热疫情中的发热病人和密切接触者血清标本441份,以及恢复期血清22份,用捕获法ELISA检测登革IgG和IgM抗体,并结合病例的流行病学资料进行分析。结果根据本研究规定的病例判定标准,441例中登革热感染者为228例。其中,IgM抗体检出226例,IgG抗体检出119例。226例IgM抗体阳性标本中,IgG抗体同时阳性的为118份;119例IgG阳性标本中,IgM抗体阴性1例;两者均阴性的标本中用RT-PCR方法检测出1例。22份恢复期血清两类抗体检测均为阳性。绝大部分病例集中在10～70岁,病例的职业分布较广,男女比例为1∶1.53。结论登革病毒感染后特异性IgM抗体在发病早期即可检出,并可维持至少一个半月,但个别病例发病早期IgM可能为阴性;IgG抗体随病程的延长,其检出率逐步增高,至发病后50 d,其检出率可达95%左右。本研究结果抗体产生规律同以往研究结果一致,可为基层实验室开展登革热血清学检测和病例诊断提供参考。     

Occult hepatitis B virus infection: diagnosis, implications and management?

Abstract   Occult hepatitis B virus (HBV) infection is generally defined as the detection of HBV-DNA in the serum or liver tissue of patients who test negative for hepatitis B surface antigen. In most cases, occult HBV infection is related to low level HBV infection with subdetectable levels of HBsAg and not infection with HBV variants that cannot express S proteins or produce S proteins with aberrant epitopes that are not detected by conventional serological assays. Prevalence of occult HBV infection is related to the overall prevalence of HBV infection in that country, being more common in persons with prior exposure to HBV. Occult HBV infection has been found in a substantial proportion of patients with cirrhosis and hepatocellular carcinoma but other causes of liver disease are frequently present. Future studies should focus on delineating the pathogenic role of occult HBV infection and the basis for failure to detect circulating hepatitis B surface antigen.     

致病梭菌感染的实验室诊断方法的研究进展

致病梭菌指一类可使人或动物致病的梭状芽孢杆菌, 主要包括肉毒梭菌、艰难梭菌、产气荚膜梭菌和破伤风梭菌。致病梭菌感染往往病情严重,病死率高,是重要的一类人兽共患病。鉴定致病梭菌感染的传统方法一般检测周期长,对操作人员的技术要求也高,因此,在常规检测中的应用越来越少。免疫学和分子生物学方法因其快速灵敏的特点而被广泛应用。本文将近年国内外致病梭菌的实验室诊断相关研究综述如下, 以期能够为致病梭菌临床诊断及流行病调查研究提供参考。