2019年云南省景洪市哨兵动物多种虫媒病毒的分离鉴定

本研究旨在了解云南省景洪市虫媒病毒的流行情况。2019年在景洪市勐罕镇设立了3头哨兵动物牛,定期采血进行虫媒病毒的分离与鉴定,共获得7株病毒分离物。经病毒核酸的RT-PCR鉴定,分离到2株血清型分别为6型和7型流行性出血热病毒（epizootic haemorrhagic disease virus,EHDV）,2株血清型分别为4型和5型的蓝舌病病毒（bluetongue virus,BTV）,1株帕利亚血清群病毒（palyam serogroup virus,PALV）中的D’Aguilar virus（DAV）血清型病毒和2株未鉴定出的环状病毒。经病毒Seg-2、Seg-3序列ORF区的比对和进化分析显示,7株病毒的地域型均为Eastern型,与日本、澳大利亚和印度毒株具有最近的亲缘关系。3头哨兵动物的血液和血清,经病毒核酸及血清中和试验检测,证明3头动物均被相应的病毒感染。动物感染病毒后,血清中的特异性抗体迅速上升,3~4周后达最高点并能够在该水平维持较长时间,而血液中病毒核酸含量2~4周到达最高点后则呈迅速下降趋势。本研究报道了景洪虫媒病毒的分离、毒株序列特征以及在动物上的感染特性,研究结果为进一步了解当地的牛虫媒病毒提供数据支撑,同时3头牛分离获得7株病毒,提示当地可能还存在更多种类的虫媒病毒。     

云南省蓝舌病病毒血清7型毒株的分离与基因组序列分析

2014年,我国广东省的哨兵牛上分离出蓝舌病病毒血清7型（BTV-7）毒株,但该血清型病毒在我国的流行情况尚不清楚,本研究旨在分离我国流行的BTV-7型毒株并掌握其遗传特征。作者在云南省景洪市勐罕镇设立哨兵牛,每周定时采血,并接种C6/36、BHK-21细胞分离虫媒病毒,通过病毒蚀斑试验与增殖曲线分析病毒在细胞上的感染特性,采用高通量测序获取分离毒株的全基因组序列,通过qRT-PCR与血清中和试验对哨兵牛血液中的病毒核酸与中和抗体变化进行回溯分析。结果表明：2020年5月,分离到1株能引起BHK-21细胞发生细胞病变的病毒（毒株号V303/YNJH/2020）,经鉴定为BTV-7型。分离毒株的基因组全长19 154 bp （GenBank收录号MW046280至MW046289）,与广东省2014年分离的BTV-7型GDST008毒株具有最近的亲缘关系,基因节段1至6,基因节段9与10的核酸与编码蛋白氨基酸序列（nt/aa）相似度分别大于98%、99%;V303/YNJH/2020毒株的基因的节段7和基因节段8属Western地域型,与广东GDST008毒株对应基因节段的nt/aa序列相似度仅为71.5%/81.6%、79.6/%84.4%。病毒蚀斑与增殖曲线比较显示,V303/YNJH/2020在BHK-21细胞的增殖能力明显强于GDST008。回溯分析显示,感染V303/YNJH/2020的哨兵牛未出现临床症状,血液中的病毒核酸持续存在长达12周;在病毒感染后第4~9周,血液中的中和抗体滴度水平维持在1∶256。云南省2020年分离的BTV-7型V303/YNJH/2020毒株与广东省分离的BTV-7型GDST008毒株具有最近的亲缘关系,在BHK-21细胞上的增殖能力强于GDST008毒株;V303/YNJH/2020虽未引起感染动物的临床症状,但病毒核酸与中和抗体在感染动物血液中长时间存在。研究结果为开展BTV-7型在我国的演化规律、病毒变异以及致病性等方面的研究奠定了基础。     

1株库蠓源版纳病毒的分离与全基因组序列分析

为分析云南省虫媒病毒的种类与遗传特征,在云南省师宗县采集库蠓进行病毒的分离与鉴定;通过全长cDNA扩增与高通量测序技术获取病毒全基因组序列,进行序列比对与系统发生树构建。结果显示,从采集的库蠓样本中分离出1株可在C6/36细胞上引起细胞病变的毒株（YNSZ043）,病毒基因组为分节段双链RNA,琼脂糖凝胶电泳呈"2-4-3"的带型特征;电镜观察可见直径为70~80 nm,呈"指环状",表面具有纤维突起的病毒粒子。全基因组测序结果显示,YNSZ043毒株为版纳病毒（Banna virus,BAV）,基因组大小为20 683 bp,由Seg-1（3 762 bp）至Seg-12（861 bp）12个基因节段组成,与中国BAV毒株各基因节段的核苷酸序列相似性在64.8%~99.6%之间,氨基酸序列相似性在58.8%~100%之间,在系统发生树上YNSZ043毒株与中国分离的BAV聚为一簇,形成独立的中国进化支系。对决定BAV基因型的Seg-12分析结果显示,YNSZ043毒株属于A2基因型,该毒株的Seg-5/VP5与越南分离BAV毒株的核苷酸和氨基酸序列相似性高达97.1%和97.6%,表明该毒株的Seg-5基因节段很可能与越南毒株之间发生了基因重配。研究结果丰富了中国BAV的基因组序列,为开展云南省BAV的流行病学研究提供了参考。     

云南边境地区帕利亚姆血清群中山病病毒的分离与鉴定

【目的】了解西南边境地区牛感染中山病病毒(Chuzan virus, CHUV)的情况。【方法】应用BHK21细胞对云南景洪、江城采集的312份健康黄牛血液样品盲传分离病毒,对出现细胞病变的毒株进行形态学、基因组带型和分子生物学鉴定,对分离到的病毒进行S7、S2基因序列测定和比对分析。【结果】4份血液样品可致BHK21细胞病变,电镜观察病毒颗粒呈球形,直径约50 nm;琼脂糖凝胶电泳发现,4株分离毒株基因组为10节段,带型为“3-3-4”,与2012年云南师宗分离的CHUV SZ187毒株相似;4株病毒S7、S2基因核苷酸序列相似性分别为98.7%～99.7%和97.9%～99.1%;S2基因片段核苷酸和氨基酸序列与中国本土分离的SZ187、GHN-GS-16等毒株相似性最高;S7基因片段核苷酸和氨基酸序列与日本分离的ON-1/E/18、ON-3/E/17及中国本土的SZ187、GHN-GS-16等毒株的相似性最高。S7、S2基因遗传进化分析结果显示,4株新分离毒株亲缘关系最近;4株毒株的S7基因序列与中国本土和日本分离的已知帕利亚姆血清群病毒(Palyam serogroup vir...     

帕利亚姆血清群病毒一步法RT-PCR检测技术的建立

帕利亚姆血清群病毒(PALV)在我国广泛流行,给我国牛羊养殖业健康发展构成了严重威胁,目前国内尚无PALV核酸检测方法的报道。本研究根据流行于我国的中山病毒(CHUV)、Bunyip Creek virus(BCV)和D’Aguilar virus(DAV)3种血清型PALV的Seg-7保守基因序列,设计针对PALV的群特异性RT-PCR扩增引物,通过反应条件优化,建立了PALV的一步法RT-PCR检测方法,其最佳引物浓度为0.8μmol/L;最佳退火温度为56℃。对该方法进行特异性试验,结果显示该方法可特异性的检测出CHUV、BCV和DAV核酸,而对环状病毒属的蓝舌病病毒、流行性出血病病毒、非洲马瘟病毒和广西环状病毒的检测结果均为阴性;敏感性试验结果显示,该方法对RNA标准品的最低检测限为6.9×10~1拷贝/μL。利用该方法检测血液样品,结果显示该方法检测结果与病毒分离结果基本一致。本研究建立的PALV一步法RT-PCR方法具有特异性强、敏感度高等优点,为开展PALV感染疫病诊断与流行病学研究提供了技术保障。     

云南边境地区流行性出血热病毒血清学监测及血清型鉴定

为了解近几年云南边境地区牛、羊流行性出血热病毒（EHDV）的感染和流行情况,本研究从2014年起连续3年在与老挝、越南接壤的江城县设置EHDV监测点,每年选择投放EHDV抗体阴性的10头牛和5只山羊作为哨兵动物进行跟踪监测。每年5~10月份对哨兵动物采血,每周1次,11、12月每月采集一次,进行EHDV抗体、抗原监测和病毒分离。针对致细胞病变的样品,采用EHDV群特异性S7基因片段引物进行RT-PCR方法检测,同时利用EHDV-1、-5、-6、-7、-10标准阳性血清对分离到的病毒进行中和试验鉴定。结果显示,2014－2016年江城县牛EHDV抗体阳性率分别为41.9%、58.6%和75.4%;3年期间共监测到15头EHDV抗体阳性黄牛,并从中分离到20个可致细胞病变样品,经RT-PCR确认为EHDV,遗传进化分析发现有11个毒株与1997和2003年日本分离的EHDV毒株亲缘关系较近,9个毒株与1977和1981年澳大利亚分离的EHDV毒株亲缘关系较近,5个毒株与2015年广西分离株的亲缘关系较近;3年期间在山羊体内未检测出抗体,未发现抗原阳性动物;经中和试验血清型鉴定,确定20株毒株包括EHDV-5、-6、-7、-10型4种血清型,感染时间均在5~9月之间。本研究发现,江城县长期存在多种血清型EHDV同时流行,2014－2016年EHDV抗体阳性率逐年增加,亟需加强对EHDV感染情况及活动规律的持续研究,提高流行性出血热的防控效率。     

蓝舌病病毒群特异性RT-LAMP检测方法的建立与初步应用

本研究旨在建立针对中国流行蓝舌病病毒（bluetongue virus,BTV）的逆转录-环介导等温扩增（RT-LAMP）检测方法。根据我国分离BTV毒株Seg-5基因序列的高度保守区域,设计特异性引物,优化反应条件及反应体系,进行特异性及灵敏度验证,建立BTV RT-LAMP检测方法;对46株中国分离的12种血清型BTV（BTV-1、-2、-3、-4、-5、-7、-9、-12、-15、-16、-21与-24）代表毒株进行检测,进一步对120份BTV核酸阳性血液样品及60份2020年采集自监控动物的临床血液样品进行BTV的RT-LAMP及qRT-PCR检测,验证建立的RT-LAMP检测方法的准确性和可靠性。试验结果表明,本研究建立的RT-LAMP方法最佳反应条件为64℃,扩增45 min;反应体系中外引物：内引物：环引物的最佳浓度及比例为0.2 μmol·L^-1：0.6 μmol·L^-1：0.4 μmol·L^-1。该方法可特异性检测中国流行的12种血清型BTV核酸,与动物流行性出血病病毒（EHDV）、中山病毒（CHUV）、阿卡斑病毒（AKAV）、口蹄疫病毒（FMDV）及非洲马瘟病毒（AHSV）核酸均无交叉扩增现象;最低可检测4.5拷贝·μL^-1的BTV核酸。对46株分属12种血清型的BTV代表毒株的检测结果均为阳性;120份BTV核酸阳性血液样品的检测结果与qRT-PCR检测结果无显著差别（McNemar检验P>0.05）,符合率为95.0%;60份临床血液样品的检测结果与qRT-PCR结果完全一致,以上结果表明本研究建立的RT-LAMP方法准确可靠,对中国分离的BTV毒株及临床血液样品均具有良好的检测效果。本研究建立的BTV RT-LAMP检测方法具有反应快速、结果可视化、特异性强和敏感度高等优点,为我国开展BTV检测诊断与流行病学研究提供了技术支持,具有较好的应用前景。     

Active circulation of bluetongue vaccine virus serotype-2 among unvaccinated cattle in central Italy

Several seroconversions occurring in 2002 among sentinel cattle during the bluetongue-vaccination campaign in Lazio and Tuscany (central Italy) led to the suspicion of vaccine-virus circulation. Therefore in 2003, 17 seroconverting sentinel herds were investigated for the characteristics of the virus involved. From these farms, 91 unvaccinated animals and 57 Culicoides pools were tested for the presence of the bluetongue vaccine virus (serotype-2) or other strains. The presence of vaccine virus serotype-2 was confirmed by PCR followed by restriction analysis in the whole blood of 17 unvaccinated sentinel cattle and 12 pools of Culicoides imicola or C. obsoletus. Of the 17 herds, five were positive only for vaccine virus serotype-2, four were positive for other strains and two for both the vaccine and other strains; the remaining premises were virologicaly negative. The vaccine virus serotype-2 also was detected in areas not included in the vaccination campaign.     

A sentinel herd system for the study of arbovirus infections in Australia and Papua-New Guinea

The establishment, and development between 1969 and 1978, of a system of sentinel cattle in herds located in many areas of Australia and in Papua New Guinea is described. Though the system was established for the study of the epidemiology of a variety of viruses infecting cattle, the study has been limited since 1974 to arboviruses. By means of serology, it was established that bovine ephemeral fever virus was present in Australia in subclinical form between major epidemics but was not detected in Papua-New Guinea. The development of antibody to bovine ephemeral fever virus in individual cattle before they developed clinical signs in epidemics was clearly demonstrated. The sentinel technique was used to demonstrate that subclinical Akabane virus infection in cattle occurred at the time that virus was present in its suspected vector,Culicoides brevitarsis which had been collected nearby. The epidemiology of other Simbu group viruses, D'Aguilar virus, and bluetongue virus, (serotype 20) was also studied. A limited programme of arbovirus isolation in tissue cultures produced 0.8% of isolates from 2090 of the blood clots which accompanied sentinel herd serum samples.The most valuable aspect of the sentinel herd scheme has been the accumulation of a well documented representative set of serum samples for retrospective serology by the use of newly isolated or imported antigens.     

Seroprevalence of five arboviruses in sentinel cattle as part of nationwide surveillance in South Korea, 2009?2012

To investigate the possible circulation of arboviruses in South Korea, nationwide surveillance of five arbovirues was conducted in sentinel calves during 2009−2012. We used serum neutralization tests to investigate the presence of antibodies for the Aino virus, Akabane virus, bovine ephemeral fever virus, Chuzan virus and Ibaraki virus. In 2009, 2011 and 2012, the seropositive rates for these five arboviruses were all less than 14.1%. In 2010, however, the seropositive rates for Aino virus and Akabane virus were 33.2% and 40.2%, respectively. High seropositive rates were also associated with a large-scale outbreak of Akabane viral encephalomyelitis in cattle in southern Korea in 2010. Continued seroprevalence surveillance will be useful for monitoring natural arboviral diseases.     

Detection of carriers of foot-and-mouth disease virus among vaccinated cattle

To investigate and optimise detection of carriers, we vaccinated 15 calves with an inactivated vaccine based on foot-and-mouth disease virus (FMDV) A Turkey strain and challenged them and two further non-vaccinated calves with the homologous virus four weeks later. To determine transmission to a sensitive animal, we put a sentinel calf among the infected cattle from 60 days post-infection until the end of the experiment at 609 days post-infection. Samples were tested for the presence of FMDV, viral genome, specific IgA antibodies, antibodies against FMDV non-structural (NS) proteins or neutralising antibodies. Virus and viral genome was intermittently isolated from probang samples and the number of isolations decreased over time. During the first 100 days significantly more samples were positive by RT-PCR than by virus isolation (VI), whereas, late after infection more samples were positive by virus isolation. All the inoculated cattle developed high titres of neutralising antibodies that remained high during the entire experiment. An IgA antibody response was intermittently detected in the oropharyngeal fluid of 14 of the 17 calves, while all of them developed detectable levels of antibodies to NS proteins of FMDV in serum, which declined slowly beyond 34 days post-infection. Nevertheless, at 609 days after inoculation, 10 cattle (60%) were still positive by NS ELISA. Of the 17 cattle in our experiment, 16 became carriers. Despite frequent reallocation between a different pair of infected cattle no transmission to the sentinel calf occurred. It remained negative in all assays during the entire experiment. The results of this experiment show that the NS ELISA is currently the most sensitive method to detect carriers in a vaccinated cattle population.     

牛病毒性腹泻病毒、大肠杆菌和奇异变形杆菌混合感染致犊牛腹泻的研究

为确定甘肃省临夏州某奶牛场犊牛腹泻的病因,并提供合适的治疗方案和防控措施,试验采集该牛场13头腹泻犊牛的粪便和血清,通过胶体金技术、ELISA方法、细菌分离鉴定、Kirby-Bauer法分别进行病毒病原学检测、病毒血清学抗体检测、病原菌鉴定和药物敏感性试验。病毒学检测结果显示,13份粪样中未检测出牛轮状病毒（BRV）、牛冠状病毒（BCV）的抗原,牛病毒性腹泻病毒（BVDV）抗原阳性率为23.08%（3/13）;未检出BRV和BCV的抗体,BVDV血清学抗体阳性率为38.46%（5/13）。病原菌检测结果显示,13份粪便样品中,分离出13株大肠杆菌和7株奇异变形杆菌。药敏试验表明,分离的大肠杆菌和奇异变形杆菌对20种常规药物均产生了不同程度的耐药,且无对两种细菌均有效的药物。此次犊牛腹泻是由BVDV、大肠杆菌、奇异变形杆菌混合感染引起的,且大肠杆菌和奇异变形杆菌的耐药现象严重,本试验结果为该牛场进一步治疗此次的犊牛腹泻病提供了合理有效的依据。     

Epidemiologic study of bluetongue viruses in Central America and the Caribbean: 1986-1988. Regional Bluetongue Team.

Results of a prospective serologic and virologic study of ruminant livestock in Central America and the Caribbean islands revealed bluetongue virus (BTV) to be enzootic in the 9 countries participating in the study. Bluetongue virus serotypes 1, 3, 6, and 12 were isolated from sentinel animals. To the authors' knowledge, these are the first isolations of BTV from the region studied and the first isolations of these serotypes in the Western Hemisphere. Clinical disease attributable to BTV infection was not observed in sentinel animals. The incidence pattern, with respect to age and geographic location, was determined. The need to evaluate the epizootiologic features or arthropod-borne viruses (arboviruses) on a regional ecologic basis is stressed.     

Study of cattle persistently infected with bovine viral diarrhea virus that lack detectable virus in serum

OBJECTIVE: To determine whether cattle persistently infected with bovine viral diarrhea virus (BVDV) that lack virus detectable in serum by use of the immunoperoxidase microtiter assay (IPMA) can transmit the virus to susceptible herdmates and determine prevalence of these cattle. DESIGN: Clinical trial and serologic survey. SAMPLE POPULATION: 2 cattle and 1,952 blood samples. PROCEDURE: A persistently infected cow in which virus could not be detected in serum was housed with a BVDV-seronegative steer. Blood and nasal swab specimens were tested via virus isolation and serum virus neutralization. Parallel WBC preparations and sera from blood samples of 1,952 adult cows were screened for BVDV by use of IPMA. RESULTS: The steer seroconverted to BVDV within 4 weeks of contact with the cow. Virus was detected in sera and WBC of 5 adult cows that were verified as persistently infected by retest 3 weeks later. Cattle persistently infected with BVDV in which virus could not be detected in both serum and WBC by use of IPMA were not found. CONCLUSION AND CLINICAL RELEVANCE: Cattle persistently infected with BVDV in which virus cannot be detected in serum by use of IPMA may serve as virus reservoirs for infecting susceptible cattle. Persistent infection was detected at a prevalence of 0.26%. Screening adult cattle by use of IPMA on serum samples appears to be a reliable means of detecting persistent infection with BVDV. Prevalence of cattle persistently infected with BVDV that have negative results of IPMA on serum is extremely low.     

Development of an enzyme-linked immunosorbent assay for the detection of antibody to epizootic hemorrhagic disease of deer virus.

An enzyme-linked immunosorbent assay has been developed to detect antibodies to epizootic hemorrhagic disease of deer virus (EHDV). The assay incorporates a monoclonal antibody to EHDV serotype 2 (EHDV-2) that demonstrates specificity for the viral structural protein, VP7. The assay was evaluated with sequential sera collected from cattle experimentally infected with EHDV serotype 1 (EHDV-1) and EHDV-2, as well as the four serotypes of bluetongue virus (BTV), BTV-10, BTV-11, BTV-13, and BTV-17, that currently circulate in the US. A competitive and a blocking format as well as the use of antigen produced from both EHDV-1- and EHDV-2-infected cells were evaluated. The assay was able to detect specific antibody as early as 7 days after infection and could differentiate animals experimentally infected with EHDV from those experimentally infected with BTV. The diagnostic potential of this assay was demonstrated with field-collected serum samples from cattle, deer, and buffalo.     

1株牛病毒性腹泻病毒分离毒株的基因组特征

旨在从宁夏某奶牛群持续感染牛分离牛源牛病毒性腹泻病毒（BVDV）,并解析其基因组特征,为研究我国不同地区BVDV分离株遗传演化规律提供理论依据。利用BVDV抗原检测试剂盒检测宁夏回族自治区银川市某示范区的240头高产奶牛间隔两周的双份抗凝血,筛选持续感染牛,分离血液淋巴细胞制备裂解液接种牛肾细胞（MDBK）,分离鉴定获得BVDV株,克隆测序获得全基因组序列,比较分析其遗传演化关系。从该示范区高产奶牛筛选获得2头持续感染牛,分离获得1株非致细胞病变型BVDV,命名为NX2019/01。测序获得基因组全序列（12 107 nt）,其中ORF长11 703 nt,编码3 898个氨基酸。在基因组水平,NX2019/01株与我国SD-15、ZM-95、XC、LN-1等1m亚型分离株相似性较高（92.17%~93.84%）,但E^rns、E1以及E2基因存在较大差异。示范区同群牛急性感染BVDV时,毒株E2蛋白N端编码区核苷酸突变可导致第9位或第67位氨基酸变异。重组分析表明,NX2019/01株E2基因179—288位核苷酸区段以及ZM-95株E1基因168位—E2基因332位核苷酸区段存在相似的重组信号,可能由主要亲本SD-15株与次要亲本LN-1株重组形成,表明NX2019/01株、ZM-95株在演化进程中与SD-15株以及LN-1株或早期流行的高度相似毒株存在密切关联。本研究从持续感染高产奶牛分离获得了牛源BVDV-1m亚型毒株,在基因组水平厘清了BVDV-1m亚型毒株的进化关系,并首次发现同亚型BVDV毒株基因同源重组,为进一步研究BVDV在我国的演化规律奠定了基础。     

1株分离自云南省师宗县库蠓的新型西藏环状病毒

西藏环状病毒(Tibet orbivirus,TIBOV)为环状病毒属的新成员,病毒于2009年首次从我国西藏墨脱县采集的圆斑按蚊中分离,目前,对该病毒的认识仍十分有限.本研究对1株分离自我国云南省师宗县库蠓的新型TIBOV毒株YNSZ/V290/2019进行了鉴定,结果表明,病毒可在C6/36与BHK-21细胞上引起...