Phenotypic analysis of peripheral leukocytes in piglets infected with classical swine fever virus.

The phenotypic changes in circulating leukocytes in swine fever influenced by classical swine fever virus (CSFV) infection with different strain virulence was studied in piglets. The phenotypic differences were measured by monoclonal antibodies specific for porcine differentiation antigens. The pattern of phenotypic change varied with the virulence of CSFV. Infection with virulent, but not the attenuated strain of CSFV resulted in the dramatic early loss of CD8-bearing T lymphocytes from the circulation. A similar trend was also seen in the gammadelta T-cell compartment following infection with the highly virulent strain, Washington. The loss of circulating B-lymphocytes was consistent with the failure to generate neutralising antibody. These observations contrasted the finding that the number of leukocytes expressing the CD4 surface antigen increased in piglets infected with CSFV. These data provide preliminary information on the potential range of leukocyte changes produced in piglets following infection with CSFV.     

猪瘟病毒FJFQ-39株的毒力鉴定

为探索一种相对客观、稳定的方法鉴定猪瘟病毒(CSFV)FJFQ-39株的毒力.本研究采用2×103TCID50的FJFQ-39株分别肌肉接种6头敏感猪,通过RT-nPCR 检测扁桃体和血液监测动物感染情况,对动物临床症状和病理变化进行系统评分,结合体温分析,判定病毒毒力.同时用相同剂量的石门株接种4头敏感猪作对照.FJFQ-39和石门接种猪的扁桃体和血液均检测到CSFV核酸;FJFQ-39接种猪的最大临床症状评分(CS)平均值为3.53.5±1.0、病理评分(PS)平均值为3.3±0.9(低于5),平均最高体温为39.3±0.2℃(低于40℃);石门接种猪的最大CS平均值为25.5±2.1、PS平均值为29.5±2.4(大于15),平均最高体温为41.8±0.2℃(高于41.0℃).实验结果表明:猪瘟病毒FJFQ-39株和石门株均成功感染了动物;评分系统结合体温测定评价CSFV毒力是可行的;FJFQ-39 属于低毒力株,而石门属于强毒株.     

新生长白仔猪尾尖成纤维细胞的分离培养及其对猪瘟病毒的易感性分析

以出生2日龄的正常长白仔猪尾尖组织为材料,通过组织消化法培养获得原代尾尖成纤维细胞.并通过间接免疫荧光法,梯度10倍倍比稀释猪瘟病毒石门株(105.2 TCID50/mL)感染在猪尾尖成纤维细胞,确定尾尖成纤维细胞最佳病毒感染滴度.结果显示,运用组织块消化法能够获得生长状态的原代猪尾尖成纤维细胞,并且细胞对10-3稀释倍数的猪瘟病毒石门株具有适中的感染力.     

A histopathologic,immunohistochemical, and ultrastructural study of the intestine in pigs inoculated with classical swine fever virus

The aim of this study was to report on the lesions occurring in the intestine during experimental classical swine fever (CSF) and to clarify the nature of infected cells and the distribution of viral antigen. Thirty-two pigs were inoculated with the virulent CSF virus (CSFV) isolate Alfort 187 and slaughtered from 2 to 15 postinoculation days; four animals of similar background served as a control group. Immunohistochemistry, electron microscopy, and the transferase-mediated deoxyuridine triphosphate nick-end labeling method were used to detect viral antigens and apoptosis. The results showed progressive lymphoid depletion and mucosal necrosis. The lymphoid depletion could have been caused by apoptosis of lymphocytes but could not be directly attributed to the effect of CSFV on these cells. Vascular changes, pathogenic bacteria, and viral infection of epithelial cells were ruled out as causes of necrotic lesions. However, large virally infected monocytes-macrophages with ultrastructural changes indicative of activation were observed in the intestine. This suggests that monocytes-macrophages play an important role in the pathogenesis of intestinal lesions. An understanding of the function of these cells will require additional study.     

Genetic typing of classical swine fever virus

Three regions of the classical swine fever virus (CSFV) genome that have been widely sequenced were compared with respect to their ability to discriminate between isolates and to segregate viruses into genetic groups. Sequence data-sets were assembled for 55 CSFVs comprising 150 nucleotides of the 5' non-translated region, 190 nucleotides of the E2 envelope glycoprotein gene and 409 nucleotides of the NS5B polymerase gene. Phylogenetic analysis of each data-set revealed similar groups and subgroups. For closely related viruses, the more variable or larger data-sets gave better discrimination, and the most reliable classification was obtained with sequence data from the NS5B region. No evidence was found for intertypic recombination between CSFVs. A larger data-set was also analysed comprising 190 nucleotides of E2 sequence from 100 CSFVs from different parts of the world, in order to assess the extent and global distribution of CSFV diversity. Additional groups of CSFV are evident from Asia and the nomenclature of Lowings et al. (1996) [Lowings, P., Ibata, G., Needham, J., Paton, D., 1996. J. Gen. Virol. 77, 1311-1321] needs to be updated to accommodate these. A tentative assignment, adapting rather than overturning the previous nomenclature divides CSF viruses into three groups with three or four subgroups: 1.1, 1.2, 1.3; 2.1, 2.2, 2.3; 3.1, 3.2, 3.3, 3.4. The expanding data-base of CSFV sequences should improve the prospects of disease tracing in the future, and provide a basis for a standardised approach to ensure that results from different laboratories are comparable.     

Transient classical swine fever virus infection in wild boar piglets partially protected by maternal antibodies

An experimental study was conducted to investigate the clinical course of classical swine fever (CSF) in wild boar piglets partially protected by maternal antibodies. Five healthy wild boar piglets with a low serum titre of colostral antibodies against CSF virus were challenged with virulent CSF virus at the age of three months. Apart of reduced food intake and diarrhoea no major clinical symptoms were noticed after challenge. These signs were seen during the second and third week of infection, afterwards the piglets recovered completely. CSF virus could be re-isolated from blood samples taken on day 12 and day 19 post challenge. From blood samples taken later on and from the organ material taken at post mortem examinations no CSF virus could be isolated anymore. It can be concluded that the presence of maternal antibodies influences the clinical course of CSF in terms that the outcome is rather transient than lethal. Such wild boar could play a crucial role in the spread of CSF virus and might contribute to the maintenance of long lasting epizootics.     

酵母β-葡聚糖对断奶仔猪猪瘟抗体水平的影响

选取28日龄断奶的三元杂交仔猪72头(杜×长大),平均体重(7.32±0.38)kg,按体重和性别随机分为4组,每组设3个重复,每个重复6头仔猪(公母各半),组1至组4在饲喂基础日粮的基础上,酵母β-葡聚糖的添加量分别是0.025%、0.05%、0.1%和0。用正向间接血凝法(IHA)测定猪瘟抗体,以此来研究β-葡聚糖对早期断奶仔猪猪瘟抗体的影响。结果表明:与对照组相比,处理组的猪瘟抗体效价均有不同程度的升高;其中处理组1差异显著(P<0.05);而处理组2和处理组3差异不显著(P>0.05)。     

猪瘟病毒感染致外周免疫器官损伤的病理组织学观察

将10头28日龄健康仔猪随机分成2组,其中感染组8头,对照组2头。感染组按1 mL/头颈部肌注猪瘟病毒(CSFV)石门株血毒(104TCID50/mL)进行人工感染,对照组不做任何处理。2 d后感染组仔猪体温升至40~41.5℃,稽留不退,而对照组体温正常。采集体温升高的仔猪扁桃体,运用RT-PCR方法检测,结果CSFV均为阳性,表明人工感染CSFV成功。分别于感染后4,7 d剖杀感染组和对照组仔猪各1头,剖解后观察各器官大体病变并采集脾脏和淋巴结等外周免疫器官制作石蜡切片,观察病理组织学变化;其余感染组仔猪分别于感染后13,16(2头),19,23,31 d自然死亡,死亡后按剖杀猪方法同样处理。组织学观察显示:随着病情的发展,感染组仔猪的脾脏和淋巴结的淋巴滤泡逐渐发生萎缩、甚至消失,脾脏的动脉周围淋巴鞘、淋巴结的副皮质区细胞亦逐渐减少坏死,即造成了T、B淋巴细胞的渐进性减少,而对照组无异常变化。结果表明:CSFV感染仔猪后,可引起脾脏淋巴结的淋巴细胞渐进性变性与坏死,造成免疫损伤。     

猪瘟病毒感染仔猪接种猪瘟疫苗后抗原的跟踪检测

为了解猪瘟病毒感染仔猪免疫猪瘟疫苗后带毒情况,并比较实验室几种猪瘟抗原检测方法的适用性,采用(CSFV)RT-nPCR、猪瘟兔化弱毒疫苗荧光定量RT-PCR(HCLV-FQ-PCR)和CSFV实时荧光定量RT-PCR(CSFV-FQ-PCR)3种检测方法对田间感染CSFV仔猪疫苗免疫前后带毒情况进行定期跟踪检测.结果显示:本实验室建立的CSFV-FQ-PCR灵敏度高于CSFV-RT-nPCR;猪瘟疫苗免疫48 d后,采用HCLV-FQ-PCR方法检测不到血液中的HCLV;猪瘟病毒感染猪免疫疫苗后仍存在持续带毒现象,因此对猪瘟病毒感染猪必须彻底淘汰.     

Simultaneous vaccination of piglets against foot-and-mouth disease and classical swine fever

Six-week-old piglets, born of unvaccinated sows, were vaccinated against foot-and-mouth disease (FMD) with a trivalent, inactivated vaccine containing an adjuvant or vaccinated against classical swine fever (CSF) with a live attenuated vaccine or against both diseases simultaneously at two different sites. The antibody response to the FMD vaccine was not significantly influenced by the simultaneous vaccination against CSF. FMD vaccine administered simultaneously with the CSF vaccine produced a significantly higher antibody response to CSF than occurred with CSF vaccination only.     

Survival and inactivation of classical swine fever virus

Classical swine fever virus, like many enveloped viruses, may be regarded as moderately fragile. It shows a short but variable survival time in the environment, depending on physical conditions, but may remain viable for prolonged periods in favourable circumstances as found, for example, in stored meat. Published information is reviewed on the survival time of the virus under a variety of physical and chemical conditions, including the variable influence of environmental factors. The principles of virus inactivation by heat, pH or chemicals are discussed, with a consideration of the principles of containment for laboratories working with the virus.     

Ultrastructural glomerular changes in experimental infection with the classical swine fever virus

Ultrastructural studies of glomerular changes were performed on 16 pigs experimentally infected with a highly virulent strain of the classical swine fever virus. Our observations revealed the thickening of glomerular basement membranes, swelling of endothelial cells and cytoplasmic vacuolization within podocytes containing abundant viral particles. An early viral infection of podocytes was suggested as the cause of selective swelling of the foot processes of these cells with the consequent obliteration of the glomerular urinary spaces. To our knowledge this is the first report of ultrastructural evidence of classical swine fever virions infecting glomerular podocytes.     

用RT-PCR技术检测盐渍猪肠衣中猪瘟病毒的研究

参考GenBank中发表的猪瘟病毒（CSFV）序列，设计一对CSFV特异性PCR引物；从CSFV感染猪盐渍小肠中提取总RNA，经逆转录后进行PCR扩增，在盐渍小肠中成功扩增出与预期大小（168bp）一致的特异性条带，而正常猪和感染猪伪狂犬病病毒的猪小肠扩增结果均为阴性。用本方法对20例不同稀释浓度的盐渍猪肠衣样本进行检测，结果显示比经典抗原检测方法（抗原捕获ELISA法）具有更高的敏感性。实验表明，本RT—PCR技术能应用于盐渍猪肠衣的CSFV检测，为快速、准确检测盐渍猪肠衣中CSFV提供了一条新途径。     

Emergence of classical swine fever virus in Israel in 2009

Classical swine fever (CSF) re-emerged in Israel in February 2009 after an absence of 62 years. The outbreak occurred on a domestic pig farm in northern Israel and affected domestic pigs and wild boar. On the basis of phylogenetic analysis of a 190 base pair fragment of the E2 glycoprotein gene, the Israeli CSF virus strain belonged to genotype 2.1 and was genetically most similar to a Chinese CSF virus strain.     

Prevalence of African swine fever virus and classical swine fever virus antibodies in pigs in Benue State,Nigeria

Tropical Animal Health and Production - This study investigated the prevalence of African swine fever virus (ASFV) and classical swine fever virus (CSFV) antibodies in pigs in Benue State, Nigeria....     

Role of birds in transmission of classical swine fever virus

Active transmission of classical swine fever virus (CSFV) was studied in six birds (five ravens, one hooded crow) and two laying hens. Cloacal swabs, blood and organs of birds and hens as well as blood and organ samples of pigs which had been fed with faeces derived from CSFV infected birds or which had come in contact with faeces of infected hens were negative for CSFV. None of the animals seroconverted during the study. This result demonstrates that active virus transmission by these animals is unlikely. Dissemination of CSFV from wild boar to domestic pigs is discussed.     

用荧光定量RT-PCR方法检测猪瘟病毒

为了建立能特异检测不同基因型猪瘟病毒(Classical swine fever virus,CSFV),同时又能区分其他瘟病毒的基因检测方法,本实验针对CSFV基因组5′端非编码区设计并合成了简并引物和TaqMan探针,在优化反应条件的基础上,成功地建立了特异检测CSFV的荧光定量RT-PCR检测方法。再以已知滴度的CSFV石门株血毒总RNA反转录产物建立标准品,该标准品可以用于定量临床样品中的CSFV滴度,所建立的荧光定量PCR方法可以灵敏地检测出10~(-0.82)个TCID_(50)病毒含量。最后用建立的方法对108份临床样品进行检测并同时进行病毒分离,荧光定量PCR方法检测出73份阳性样品且与病毒分离的符合率为100%,而常规RT-PCR只检测出54份阳性样品,表明本荧光定量RT-PCR法在检测猪瘟病料上具有潜在的应用价值。