Fetal Infection with Porcine Parvovirus in Herds with Reproductive Failure

During a 20 months period in 1978 and 1979 aborted, macerated and mummified fetuses as well as stillborn piglets from herds with reproductive failure were examined for evidence of infection with porcine parvovirus (PPV). A total of 602 cases were examined and evidence of infection with PPV was found in 269 (45 %). In 52 % of these antibody to PPV was found. Infective PPV as well as antibody to PPV were found in 41 %, whereas infective PPV alone was found in 7 %. When abortions were excluded from the results a high prevalence of infection with PPV (73–90 %) was found among fetuses of all sizes with the exception of fetuses dead late in gestation or at term.     

用ELISA检测猪细小病毒(PPV)血清抗体

采用差速离心、透析、聚乙二醇(PEG)浓缩方法纯化猪细小病毒(PPVDK7113)制备抗原。用纯化的PPV抗原包被聚苯乙烯微量反应板，建立了检测PPV血清抗体的间接ELISA。抗原最佳包被浓度为6．3μg/ml，被检血清最佳稀释度为1：200。用建立的ELISA检测山东、东北、广东等地的426份血清，结果阳性率为36．2％。与华中农大病毒室提供的猪细小病毒乳胶凝集试验试剂盒相比，其结果符合率为98．6％。通过阻断试验、交叉试验，说明本方法在特异性上达到了较为满意的结果，且易于操作，适用于血清学定性诊断、检疫和大规模的血清流行病学调查。     

引起母猪腿病的原因及应对措施

母猪腿病是引起母猪淘汰的第二大原因,仅次于繁殖性能不佳,其造成母猪的提前淘汰给养猪业带来严重的经济损失,也是动物福利关注的重要问题。母猪腿病可以通过饲养管理、猪场设施设备和营养等方面预防。文章分别从产生原因、临床检查、治疗、预防与管理4个方面对母猪腿病展开综述。     

Factors Associated with Mastitis in Ontario Dairy Herds: A Case Control Study

Data from Ontario dairy cattle herds which had had a high average milk gel index for 1978 (cases) and from other herds which had had a low average during the same period (controls) were collected and analyzed using case control techniques. The purpose of the study was to contrast factors of husbandry and management between the two groups and to determine the relative contribution of each of these factors on mastitis (as determined indirectly by the milk gel index) at the herd level.

Control herds had higher average production levels than did case herds, shipping 1807 litres more milk per cow per year. Milk from control herds averaged 0.06 percentage points higher in butterfat, 0.19 percentage points higher in lactose and 0.05 percentage points lower in total protein. However, many factors can influence production, therefore these latter differences, in both shipped milk and composition, can not be attributed solely to differences in the prevalence of mastitis between the two groups.

Control herds were more likely to use teat dip, receive regular veterinary service, use dry cow antibiotic preparations and have knowledge concerning subclinical mastitis than were case herds. Control herds also tended to raise more of their own replacements, have a higher culling rate for reasons of low production and have a more modernized dairy operation. Case herds, on the other hand, were more likely to scrutinize foremilk, use more milking units per operator and wait longer between the start of stimulation and attachment of the milking unit.

The study confirms, under natural field conditions, the importance of integrated mastitis control practices and also reaffirms the relative importance of practices such as the use of teat dips and dry cow antibiotic preparations.

     

Management Factors Associated with Sow Reproductive Performance After Weaning

To achieve optimal reproductive performance in pig herds, sows need to become pregnant as soon as possible after weaning. The aim of this study was to investigate herd and management factors associated with reproductive performance of sows after weaning. A questionnaire pertaining to sow management at weaning and herd reproductive data were collected from 76 randomly selected commercial pig herds in Belgium. Associations between the herd factors and two reproductive parameters after weaning (weaning‐to‐oestrous interval: WEI and percentage of repeat breeders: RB) were analysed using general linear mixed models. A separated feeding strategy of breeding gilts from 60 kg onwards was significantly associated with a shorter WEI (5.54 vs 7.28 days; p = 0.040). Factors significantly associated with a lower percentage of RB were housing the newly weaned sows separated from the gestating sows (7% vs 12%; p = 0.003), using semen < 4 days after collection (7–9 vs 14%; p = 0.014) and stimulating oestrus twice a day (8 vs 11%; p = 0.025). In conclusion, some management practices, such as feeding strategy of breeding gilts, housing conditions of sows, method of oestrous stimulation and storage duration of semen, have an influence on the outcome of reproductive parameters such as weaning‐to‐oestrous interval and percentage of repeat breeders. These practices can be implemented rather easily by pig producers and may consequently lead to improvements of reproductive performance of sows after weaning.     

猪细小病毒结构蛋白VP2及其疫苗的研究进展

猪细小病毒(porcine parvovirus,PPV)是引起母猪繁殖障碍性疾病的主要病原之一,该病毒在世界范围内广泛存在并呈地方性流行, 给生猪的繁殖、发展带来了巨大的经济损失,故防制猪细小病毒病非常重要。PPV VP2蛋白是病毒粒子的主要衣壳蛋白,在体外能自我装配成病毒样颗粒,并能刺激机体产生抗PPV中和抗体,且可作为抗原转运载体,所以研究VP2对PPV新型疫苗研制至关重要。文章综述了猪细小病毒结构蛋白VP2及其疫苗的研究进展。     

猪细小病毒VP2的原核表达与多克隆抗体制备

克隆猪细小病毒(PPV)VP2基因全长1 740bp,构建其原核表达载体后进行蛋白的表达与纯化,接种家兔制备多克隆抗体。用PCR方法扩增PPV VP2全长基因,扩增产物克隆至表达载体pET-32a并转化至E.coli BL21(DE3)感受态中。分别用不同诱导时间、IPTG浓度、温度诱导表达VP2重组蛋白,经SDS-PAGE电泳切胶回收纯化目的蛋白。对家兔进行3次免疫后,采集血清制备抗体。PCR扩增得到1 740bp的VP2基因片段;构建原核表达载体pET-32a-VP2,经37℃,IPTG浓度1.0mmol/L诱导表达4h可得分子质量大小约为82ku目的蛋白;间接ELISA检测抗体效价可达1∶12 800;Western blot证明所制备的抗体能够有效的应用于PPV VP2抗原的检测。本研究成功构建了表达PPV VP2基因的原核载体,获得了VP2蛋白,制备了兔抗多克隆抗体,为建立检测PPV VP2蛋白ELISA方法奠定了基础。     

Clinical Bovine Mycoplasmal Mastitis: An Epidemiologic Study of Factors Associated with Problem Herds

The California Dairy Herd Improvement Association records of 29 California dairies which experienced clinical mycoplasmal mastitis between January 1975 and December 1977 were examined and compared to the records of selected control herds. A 15-fold greater risk of clinical mycoplasmal mastitis was found among large herds as compared to small herds. On average, herds with clinical mycoplasmal mastitis culled 5 % more cows than did control herds (33 % vs 28 %). No difference was found in average milk production. These findings compare closely with the findings of a previous report where infected herds were identified by the presence of pathogenic mycoplasma in bulk tank milk. The similarity of results support the use of frequent bacteriologic culture of bulk tank milk as a routine surveillance strategy for mycoplasmal mastitis in endemic areas. The similarity of results also supports the use of routine clinical diagnostic data in the study of the epidemiology of diseases of veterinary importance.     

猪细小病毒病的诊治

作者对某猪场的病死猪进行临床症状观察、病理剖检及实验室诊断,通过病毒的分离培养及鉴定,确诊病死猪为猪细小病毒感染。鉴于养殖场中该病的存在及对养猪业的危害,建议加强对猪细小病毒的诊断及监控。     

猪细小病毒的分离与鉴定

本试验从福建省某猪场疑似猪细小病毒病死胎的淋巴结、肝脏中分离到1 株病毒。病料接种PK-15细胞36 h后出现了圆缩、集聚、脱落等细胞病变,猪细小病毒阳性血清能特异性地中和该分离病毒。根据已发表的细小病毒(PPV) VP2基因的序列设计并合成了一对引物,采用PCR方法可扩增531 bp DNA片段。测序结果表明,分离株VP2基因与NCBI公布的NADL-2株的同源性高达99.2％,证实分离的病毒株为猪细小病毒。为进一步开展该病毒致病机理、流行病学、诊断研究与疫苗免疫等奠定了基础。     

猪圆环病毒病疫苗免疫母猪的生产现场试验

本文介绍了一系列的试验结果,证实一种新的猪Ⅱ型圆环病毒(PCV-2)疫苗可免疫母猪以减少母猪和新生仔猪潜在的圆环病毒病的排毒,因而可减少仔猪出生后早期的病毒暴露量,并通过母源抗体保护仔猪,以防止PCV-2的早期感染。     

新疆哈密市布鲁氏菌病阳性畜群抗体跟踪监测及影响因素分析

为了解新疆哈密市阳性畜群的布鲁氏菌病检疫净化效果及其主要影响因素,采用竞争ELISA方法,在哈密市131个曾检出布鲁氏菌病阳性的养殖场户中,随机抽检1 699份非免疫牛羊血清样品进行布鲁氏菌抗体检测,并从养殖区域、养殖模式、年龄及性别等方面对检测结果进行统计分析。结果显示：131个布鲁氏菌病阳性养殖场户的牛羊血清样品抗体阳性率为（8.65%,147/1 699）。从养殖区域看,各区县牛布鲁氏菌阳性率差异较小（P＞0.05）,而羊阳性率存在一定的地区差异,其中伊州区（12.38%）显著高于巴里坤县（P＜0.01）;从养殖模式看,全程舍饲、全程放牧、半农半牧、混牧模式下的牛羊布鲁氏菌抗体阳性率依次升高（3.49%~16.72%）,差异显著（P＜0.05）;从年龄看,牛布鲁氏菌抗体阳性率随年龄增加呈上升趋势,而羊则无明显规律性;从性别看,雌性牛羊布鲁氏菌抗体阳性率均高于雄性。结果表明：哈密市阳性畜群的布鲁氏菌病流行率较高,净化效果不佳;养殖区域、养殖模式、年龄和性别等是家畜布鲁氏菌病的潜在影响因素。结果提示,需根据该病的流行特点,制定有针对性的阳性畜群布鲁氏菌病防控策略。本研究可为哈密市及周边地区布鲁氏菌病防控策略的制定与实施提供参考。     

猪细小病毒病诊断研究进展

猪细小病毒(Porcine parvovirus，PPV)是一类小DNA病毒，是引起猪繁殖障碍的主要病原之一，其危害主要表现为受感染的母猪，特别是初产母猪及血清学阴性经产母猪发生流产、不孕、产死胎、畸形胎、木乃伊胎及弱仔等。由于被感染妊娠母猪临床症状不明显，其它猪感染后无明显临床症状。该病毒对理化因素有很强的抵抗力，广泛分布于世界各地并在大多数猪场呈地方性流行，严重地影响着养猪业的发展，该病的严重危害受到了国内外许多学者的关注，对PPV诊断方法及免疫防制的研究成为了热点之一。     

猪细小病毒在兔体内的垂直传播

以猪细小病毒（ＰＰＶ）细胞复壮毒接种于妊娠后１１～１３ｄ的初妊母兔,接毒的初妊母兔均于妊娠后３０～３２ｄ分娩。分娩后立即扑杀接毒母兔及其死产仔兔、对照母兔及其仔兔,分别无菌采集其肝脏和肾脏,按常规方法处理后以银加强胶体金技术进行检测,结果试验兔样本均为阳性,而对照兔样本均为阴性,这表明ＰＰＶ也可在兔体内垂直传播,并引起繁殖障碍。初妊母兔可替代妊娠母猪作为ＰＰＶ人工感染试验的动物模型。     

Some Factors Affecting the Abortion Rate in Dairy Herds with High Incidence of Neospora‐Associated Abortions are Different in Cows and Heifers

The aim of this study was to determine if the factors affecting the abortion rate in dairy herds with high incidence of Neospora‐associated abortions are different in pregnancies of cows and heifers chronically infected with Neospora caninum. In heifers (n = 229), an increase in the cumulative number of days with a mean relative humidity (RH) lower than 60% during the second trimester of gestation increases the risk of abortion. Yet, the likelihood of abortion was 7.6 times lower for pregnant heifers inseminated with Limousin bull semen, compared with those inseminated with Holstein‐Friesian bull semen. In pregnancies of parous cows (n = 521), an increase in rainfall and in the cumulative number of days with a mean RH lower than 60% during the second trimester of gestation increased the abortion rate. However, in contrast, an increase in the lactation number produced a decrease in the abortion rate, with a likelihood of abortion 4.8 times lower for pregnant cows inseminated with Limousin bull semen, and three times lower for those inseminated with Belgian Blue bull semen, compared with dairy cows inseminated with Holstein‐Friesian bull semen. Finally, the likelihood of abortion was 3.2 times lower for pregnancies of parous cows with low antibody titres against N. caninum (6–30 units) as compared to those with high antibody titres (≥30 units), whereas in heifers this variable had no effect. The practical recommendations of the present study include the control of the cow environment during the second trimester of gestation, the priority of culling for parous cows with higher antibody titres against N. caninum and the insemination of Neospora‐seropositive cows with semen from the Limousin breed.     

一株内源性猪细小病毒的分离与鉴定

本研究从不明病毒污染的ＰＫ１５细胞培养物中分离到了一株猪细小病毒,从形态学、血清学、分子生物学几个方面对其进行了鉴定,同时克隆了该毒株ＶＰ２基因,并测定了其核苷酸序列。将该毒株命名为ＳＹ－９９株。     

四川省PPV与PCV2的病原流行病学调查

从四川省21个规模化猪场采集样品273份,利用PCR方法检测并分析了猪细小病毒和猪圆环病毒的感染及混合感染情况,结果共检出PPV病原阳性样品47份（占17．22％）;PPV阳性猪场8个（占38．1％）;种猪的感染率较高,仔猪感染率相对较低;检出PCV2病原阳性样品143份（占52．38％）,PCV2阳性猪场18个（占85．7％）;PCV2感染随猪年龄的增长而升高;检出PPV和PCV2混合感染样品29份（占10．62％）;同时存在PPV和PCV2的猪场6个（占28．7％）,混合感染主要集中在母猪和保育仔猪阶段。仅有3个猪场未检出PPV和PCV2病原,占14．3％。该结果说明PPV与PCV2及其混合感染在四川省流行广泛,对养殖业构成了较严重的危害。     

猪细小病毒(PPV)SC1株的分离鉴定

猪细小病毒(porcine parvovirus,PPV)为引起母猪繁殖障碍的主要病原之一,可引起胚胎或/和胎儿的感染和死亡,导致母猪发生流产、死胎、木乃伊胎及新生仔猪的死亡。该病最早发生于欧洲一些国家,后发展到北美洲、亚洲、南美洲、非洲及大洋洲[1]。现在世界许多国家和地区均有流行。     

检测猪伪狂犬病病毒和猪细小病毒的二重PCR方法的建立

作者建立了一种同时检测猪细小病毒(PPV)和猪伪狂犬病病毒(PRV)的二重PCR方法。根据GenBank上发表的PPV和PRV基因序列,针对各自保守区各设1对特异性引物,用这2对引物对同一样品中的PPV和PRV进行检测,结果同时扩增出942 bp(PPV)和485 bp(PRV)2条特异性片段。特异性试验表明,对其他几种病原的PCR扩增结果均为阴性。敏感性试验结果表明,该二重PCR能检出PPV 和PRV最低浓度分别为22、11.7 pg/L。该方法的建立对临床上进行这2种疾病的鉴别诊断和混合感染的检测都具有重要意义。     

基于重组NS1蛋白猪细小病毒野毒抗体间接ELISA诊断方法的建立与应用

本研究以原核表达的重组NS1蛋白作为诊断抗原,建立了检测猪细小病毒(PPV)野毒抗体的NS1-ELISA诊断方法。该方法检测猪瘟病毒、猪繁殖与呼吸综合征病毒、猪伪狂犬病病毒、猪圆环病毒2型、猪流行性腹泻病毒5种常见猪病病毒的阳性血清均为阴性;检测灵敏度为1:12800;批内、批间重复性试验的变异系数分别小于5%和10%;与血凝抑制试验(HI)符合率为100%。本研究建立的PPV NS1-ELISA检测方法具有良好的特异性、敏感性和重复性,为PPV的野毒抗体检测及PPV流行病学调查等快速诊断提供了一种技术手段。