马动脉炎病毒实时RT-PCR检测方法的建立

选取马动脉炎病毒基因组中高度保守的开放阅读框7序列,设计了特异性引物和TaqMan探针,利用一步法的实时定量RT-PCR来定量检测马动脉炎病毒.分别使用马动脉炎病毒的总RNA和含有选定检测序列的克隆标准品做扩增曲线,两曲线斜率之差小于0.1,证明两者的扩增效率相同,可用选定检测序列的克隆标准品对马动脉炎病毒进行定量检测.该方法敏感,快速,准确,且无交叉污染,能满足海关及检疫部门对马动脉炎病毒快速、准确的检测要求.     

实时定量RT-PCR检测马动脉炎病毒

选取马动脉炎病毒(EAV)基因组中高度保守的开放阅读框7(ORF7)序列，设计了特异性引物和TaqMan探针，利用一步法的实时定量RT-PCR来定量检测EAV。使用含有选定检测序列的克隆标准品做标准曲线，证明该方法可以检测出含有5(4．77)个RNA分子，即可从组织培养液(TCF)中检出一般含有5PFU／μL病毒拷贝。对猪生殖呼吸道综合征病毒、马疱疹病毒无交叉反应，特异性好。用疫苗用种毒(Bucyrus标准株)肌肉注射于马驹后，定量RT-PCR比病毒分离试验更能灵敏地检出呼吸道排出的病毒。对456份临床鼻腔分泌物样品检测，定量RT—PCR检出6份阳性，而病毒分离只检出2份阳性。一步法实时定量RT—PCR检测样品中的EAV，在快捷、准确、方便和高通量方面优于细胞培养病毒分离的检测方法，可以作为检测马病毒性动脉炎(EVA)病毒的快速方法。     

西方马脑炎病毒TaqMan MGB荧光定量RT-PCR检测方法的建立

通过RT-PCR从西方马脑炎病毒(WEEV)中扩增得到1 317bp特异的保守序列,将其克隆到pMD-20T载体中,进行体外转录,制备标准品cRNA。以10倍比稀释的cRNA为模板,进行TaqMan MGB荧光定量RT-PCR扩增并制作标准曲线,建立了WEEV荧光定量RT-PCR检测方法。对建立的方法进行了特异性和敏感性试验。结果表明,建立的荧光定量RT-PCR方法最低可检测10拷贝的cRNA;且与马鼻肺炎病毒(EHV-1)、马动脉炎病毒(EAV)、马流感病毒(EIV,H3N8)、西尼罗病毒(WNV)、东方马脑炎病毒(EEEV)和日本脑炎病毒(JEV)不发生交叉反应。与常规RT-PCR相比,该方法更加快速,特异性和敏感性更高,灵敏度为常规RT-PCR方法的100倍。     

实时荧光定量RT-PCR检测禽白血病病毒方法的建立与应用

建立了TaqMan实时荧光定量RT-PCR方法检测禽白血病病毒(ALV)。选取ALV病毒的LTR序列设计引物和探针,以梯度稀释的含有ALV目的扩增片段的质粒作为标准品,进行定量PCR反应以确定检测灵敏度。阳性标准品在3.0×102~3.0×107个拷贝共6个数量级的范围内,定量PCR反应有"S"型扩增曲线,检测灵敏度最低为30个拷贝。根据病毒拷贝数与定量反应Ct值的关系,绘制了标准曲线。该方法具有特异性,对新城疫病毒、禽流感病毒、传染性支气管炎病毒、传染性囊病病毒、鸡传染性贫血病毒和马立克病病毒核酸都没有扩增反应。实时定量PCR检测ALV的方法,灵敏度高,特异性好,可以进行定量分析,在禽病的快速检测上具有重要意义。     

东方马脑脊髓炎病毒TaqMan MGB荧光定量RT-PCR检测方法的建立

本试验通过RT-PCR从东方马脑脊髓炎病毒(EEEV)中扩增得到128bp的特异性保守序列,将其克隆到pMD20-T载体中,并进行体外转录,制备标准品cRNA。以10倍系列稀释的cRNA为模板,进行TaqMan MGB荧光定量RT-PCR扩增并制作标准曲线,建立了EEEV TaqMan MGB荧光定量RT-PCR的检测方法。进一步对建立的方法进行了特异性和敏感性试验。结果表明,建立的TaqMan MGB荧光定量RT-PCR最低可检测10拷贝/μL的cRNA;且与阴性对照及马鼻肺炎病毒(EHV-1)、马动脉炎病毒(EAV)、马流感病毒(EIV,H3N8)、西尼罗病毒(WNV)、西方马脑脊髓炎病毒(WEEV)和日本马脑炎病毒(JEV)均不发生交叉反应。所制作的标准曲线在1.0×101~1.0×106拷贝/μL浓度范围内有极好的线性关系,相关系数为0.998,标准曲线方程式为y=40-3.35logx;与常规RT-PCR相比,该方法更加快速,特异性和敏感性更高,灵敏度为常规RT-PCR方法的100倍。试验结果表明,建立了一种快速、高效、特异、敏感的EEEV TaqMan MGB荧光定量RT-PCR检测方法。     

含马动脉炎病毒N基因的病毒样颗粒的制备

为了构建易于纯化且耐RNase酶的含有马动脉炎病毒N基因的病毒样颗粒,通过RT-RCR扩增马病毒性动脉炎病毒的N基因,将其克隆至含有组氨酸标签的pNH-MS2his载体中,构建重组原核表达载体pNH-MS2his-N。将重组质粒pNH-MS2his-N转化表达菌株大肠杆菌BL21(DE3),1 mmol/L IPTG诱导表达、纯化。对病毒样颗粒进行鉴定及稳定性实验。结果表明该病毒样颗粒含马病毒性动脉炎病毒N基因,并且稳定性良好,构建的病毒样颗粒可以作为RNA病毒检测时的标准品和质控品使用。     

实时荧光定量PCR检测鸡传染性贫血病毒方法的建立

建立了Taqman实时荧光定量PCR方法检测鸡传染性贫血病毒(CAV)。选取CAV病毒的序列设计引物和探针。以梯度稀释的含有CAV目的扩增片段的质粒作为标准品,进行定量PCR反应以确定检测灵敏度。2.0×105～2.0×102个拷贝,4个数量级的范围内定量PCR有"S"型扩增曲线,检测灵敏度为200个拷贝。根据病毒拷贝数与定量反应Ct值的关系,绘制了标准曲线。该方法具有特异性,对传染性支气管炎病毒、传染性法氏囊病毒、禽白血病病毒和马立克病毒核酸都没有扩增反应。采用实时荧光定量PCR方法检测试验感染鸡的肝脏、脾脏、肾脏、胸腺、法氏囊、泄殖腔棉拭子等样品,所有检测样品都有"S"型扩增曲线,且荧光信号值高。实时定量PCR检测CAV的方法,灵敏度高,特异性好,可以进行定量分析,在禽病的快速检测上具有重要意义。     

Ⅰ群4型禽腺病毒特异性SYBR Green Ⅰ荧光定量PCR检测方法的建立与应用

为建立Ⅰ群4型禽腺病毒特异性SYBR GreenⅠ荧光定量PCR检测方法,参考Gen Bank中已发布的禽腺病毒的六邻体基因(Hexon)序列设计两对引物,通过PCR扩增出Hexon基因的954 bp目的片段,克隆至p MD-19T载体,提取阳性质粒测定浓度,10倍系列稀释作为荧光定量PCR的标准品模板,制备标准曲线。结果显示,荧光定量PCR熔解曲线峰值单一,产蛋下降综合症病毒(EDSV)、传染性喉气管炎病毒(ILTV)、禽白血病病毒(ALV)等外源病毒均无扩增曲线出现,对标准品模板最低检出值为1.2×101拷贝/μL。对7份Ⅰ群4型禽腺病毒的细胞培养物的检出率为100%,表明建立的实时荧光定量PCR检测方法准确可行。     

A型猪流感病毒实时荧光定量PCR检测方法的建立及应用

根据WHO推荐的检测A型猪流感病毒的引物和探针序列,建立了A型猪流感病毒实时荧光定量PCR检测方法。使用含有选定检测序列的重组质粒标准品绘制标准曲线,检测结果表明,该方法的敏感性可达100拷贝/25μL反应体系,显示出良好的敏感性和重复性,临床上已用于实验室鼻拭子样品的检测,并成为一种快速定量检测A型猪流感病毒的方法。     

马动脉炎病毒进化分析及DNA条形码的确定

从GenBank数据库下载马动脉炎病毒所有基因组全序列和同属的其他病毒基因组序列,对其进行多重比对,绘制系统进化树,并根据序列比对筛选保守序列作为马动脉炎病毒的DNA条形码。结界发现马动脉炎病毒分为两个分枝,即欧洲型和美洲型,两者同源性在85%以上,而与同属其他病毒同源性低于40%,亲缘关系较远;对马动脉炎病毒基因组序列进行分析,筛选出9条基因序列作为马动脉炎病毒的DNA条形码,可用于马动脉炎病毒的鉴别诊断。     

H3N8亚型马流感病毒单克隆抗体的制备及鉴定

以灭活马流感病毒(EIV)A/Equine/Jilin/1/1989(H3N8)为免疫原,免疫Balb/c小鼠,经常规细胞融合后,用血凝抑制试验(H1)和间接ELISA方法筛选获得3株(3C2、5G10和5A10)能稳定分泌H3N8亚型马流感病毒单克隆抗体(mAb)的杂交瘤细胞株.其中3C2和5G10为IgG2α,5A...     

Equine viral arteritis

Equine viral arteritis is reviewed with specific reference to clinical features, etiology, transmission, diagnosis, epidemiology, and current methods for the control of this disease. There is evidence of variation in pathogenicity among strains of equine arteritis virus. Virus transmission occurs primarily by the respiratory and venereal routes during the acute phase of the infection. The long-term carrier stallion appears to play a major epidemiological role in dissemination and perpetuation of the virus. Unlike the stallion, the carrier state has yet to be demonstrated in the mare or foal. A commercial modifiedlive equine arteritis virus vaccine has been shown to be safe and efficacious for stallions and mares. The disease can be controlled by identification and isolation of carrier stallions, immunization of seronegative stallions, and by restricting the breeding of equine arteritis virus-shedding stallions to equine arteritis virus vaccinated or seropositive mares.     

Equine viral arteritis: A respiratory and reproductive disease of significant economic importance to the equine industry

Equine arteritis virus is the causative agent of equine viral arteritis, a respiratory and reproductive disease that affects the members of the family Equidae. The virus was first isolated from the lung of an aborted fetus after an extensive outbreak of respiratory disease and abortion on a Standardbred breeding farm near Bucyrus, Ohio, in 1953. Since then, periodic outbreaks of equine viral arteritis have been reported in a number of countries around the world. This disease may result in significant economic loss to the equine industry due to the occurrence of abortion in pregnant mares, neonatal mortality, and establishment of the carrier state in stallions. This article provides an extensive review on equine arteritis virus, epidemiology, disease, pathogenesis, and prevention and control measures.     

Equine arteritis virus: an overview.

The causative agent of the respiratory disease equine viral arteritis is a small, single-stranded RNA virus with a genome organization and replication strategy related to that of coronaviruses and toroviruses. Clinical signs of infection in horses vary widely and severe infection can lead to pregnant mares aborting. Infected horses generally make good recoveries but stallions may become semen shedders of equine arteritis virus (EAV). These carrier stallions play an important role in the dissemination and perpetuation of EAV. Laboratory tests exist to detect virus and the equine immune response to infection. However, vaccines are not currently licensed in the UK to combat viral arteritis, the incidence of which may increase due to changes in European legislation.     

The effects of vaccination with tissue culture-derived viral vaccines on detection of antibodies to equine arteritis virus by enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of serum antibodies to equine arteritis virus (EAV). Results from this assay produced a good correlation with results from virus neutralisation tests in horses which had not been regularly vaccinated with commercially available mammalian tissue culture-derived viral vaccines. Vaccination of some horses with tissue culture-derived vaccines induced the formation of antibodies to bovine serum. These antibodies reacted with the bovine protein contaminants in the EAV ELISA antigen, producing false-positive results. Non-viral protein contaminants were found to be closely associated with EAV in that they co-purified with the virus during gradient centrifugation.     

Evidence for absence of equine arteritis virus in the horse population of New Zealand

AIM: To summarise investigation and laboratory data collected between 2001 and 2011 to provide evidence that equine arteritis virus is not present in the horse population of New Zealand.

METHODS: Analysis was carried out on results from laboratory tests carried out at the Ministry for Primary Industries Animal Health Laboratory (AHL) for equine arteritis virus from horses tested prior to being imported or exported, testing of stallions as part of the New Zealand equine viral arteritis (EVA) control scheme and testing as part of transboundary animal disease (TAD) investigations for exclusion of EVA. Horse breeds were categorised as Thoroughbred, Standardbred or other.

RESULTS: A total of 7,157 EVA serological test records (from import and export testing, EVA control scheme testing and TAD investigations) were available for analysis between 2005 and 2011. For the three breed categories a seroprevalence of ≤1.6% at the 95% confidence level was determined for each category. Between 2001 and 2011, as part of the EVA control scheme, the EVA status of 465 stallions was determined to be negative. During 2005–2011 EVA was excluded from 84 TAD investigations.

CONCLUSIONS: There was no evidence of equine arteritis virus being present in the general horse population outside of carrier stallions managed under the EVA control scheme.

CLINICAL RELEVANCE: Equine arteritis virus is absent from the general horse population of New Zealand.     

Status of equine viral arteritis in Kentucky, 1985

Clinical cases of equine arteritis virus infection have not been diagnosed in Kentucky since 1984, and there has been no indication that any of the horses involved in the 1984 epizootic have since been responsible for spread of the disease to horses in other states or other countries. Cases of abortion caused by naturally acquired infection with this virus have not been confirmed in 1984 or 1985. Neither field nor vaccine strains of equine arteritis virus have been shown to induce teratologic abnormalities or the carrier state in foals born to infected or vaccinated mares. The carrier stallion appears to have played a major epidemiologic role in the dissemination and perpetuation of the virus. A commercial modified live equine viral arteritis vaccine was found to be safe and efficacious for stallions and mares. The disease can be controlled by immunizing the stallion population and by restricting the breeding of equine arteritis virus-shedding stallions to vaccinated or seropositive mares, followed by an appropriate period of isolation from other nonvaccinated Equidae.     

Responses of horses vaccinated with avirulent modified-live equine arteritis virus propagated in the E. Derm (NBL-6) cell line to nasal inoculation with virulent virus

Nineteen horses with no prior experience with equine arteritis virus (EAV) were inoculated IM with an avirulent live-virus vaccine against equine viral arteritis; the vaccinal virus had been passaged serially 131 times in primary cell cultures of equine kidney, 111 times in primary cell cultures of rabbit kidney, and 16 times in an equine dermis cell line (EAV HK-131/RK-111/ED-16). Three or 4 of the vaccinated horses each, along with appropriate nonvaccinated controls, were inoculated nasally with virulent EAV at each of months 3, 6, 9, 12, 18, and 24 after they were vaccinated. The following was concluded: Vaccination did not induce clinical signs of disease in any horse and, thus, seemed safe for use in the field. All vaccinated horses (n = 19) developed serum-neutralizing antibodies to EAV. Fourteen of the vaccinated horses were completely protected from clinical arteritis when exposed to large doses of virulent EAV. Four were partially protected, and one had little or no protection. Six of 13 nonvaccinated horses died of acute arteritis, and the remaining 7 horses experienced severe signs of disease, but survived the infection. All horses (n = 32), whether vaccinated or not, became infected when inoculated nasally with virulent EAV. Virus was recovered from 17 of the 19 vaccinated horses, and all 19 had a secondary humoral immune response. The duration and severity of thermal reaction and persistence of virus were more transitory in vaccinated horses than in the nonvaccinated controls. Protection afforded by this vaccine can persist for at least 24 months, the maximal time after horses were vaccinated that immunity was challenged in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Abortogenic viruses in horses

Viral causes of abortion include equine viral arteritis (EVA) and infection with equine herpesviruses‐1 and ‐4 (EHV‐1 and EHV‐4). Transmission of equine arteritis virus (EAV) occurs through respiratory, venereal or transplacental routes. Horizontal respiratory transmission of EAV results from exposure to infective nasopharyngeal secretions from acutely infected horses. For this transmission to occur, direct and close contact between horses is necessary. Venereal infection is an efficient method of transmission, with seroconversion of 85 to 100% of seronegative mares bred to virus shedding stallions. Asymptomatic carrier stallions are the essential natural reservoir of equine arteritis virus. Equine herpesviruses‐1 and ‐4 infect a susceptible host, replicate and establish a lifelong latent infection without any associated clinical signs. Reactivation of latent infections can result from factors such as stress and intercurrent disease. The control of these diseases is by implementation of appropriate management and hygiene measures, supplemented by vaccination and, in the case of EVA, by the identification of persistently infected stallions, which can be removed from breeding or continue to be bred to if managed under controlled conditions to prevent the risk of an outbreak of the disease.     

Detection of cattle infected with bovine viral diarrhea virus using nucleic acid hybridization.

A ribonucleic acid (RNA) hybridization assay to identify cattle infected by bovine viral diarrhea virus (BVDV) is described. The RNA probe was derived from the coding region at the 3' end of the genome of the NADL strain of BVDV. Total RNA from infected cell cultures or peripheral blood leukocytes from suspect animals was extracted and applied to nylon membranes with a slot blot apparatus. Peripheral blood leukocytes were tested concurrently for BVDV by virus isolation. The results of hybridization and virus isolation were in agreement for 92% of the cases. When compared with virus isolation, hybridization had a sensitivity of detection of 59.5% and a specificity of 95%. Cross-reactivity to RNA extracts of border disease virus-infected cells was noted. No cross-reactivity was detected to other common bovine viruses (bovine herpesvirus-1, bovine respiratory syncytial virus, parainfluenza-3 virus, and bluetongue virus), to viruses classified in related families (equine arteritis virus and Venezuelan equine encephalitis virus), or to viruses having similar genomic organization (dengue virus type 2 and Japanese encephalitis virus).