种猪场猪生殖和呼吸系统综合征血清抗体检测

应用ELISA试剂诊断盒对青海省几个主要种猪场的103份血清进行了PRRS的血清抗体检测，共检出阳性血清6份，阳性率为5．83％，表明青海省几个主要种猪场存在PRRS。     

应用酶联免疫吸附试验检测猪生殖与呼吸综合征血清抗体的研究

建立的检测猛增生殖与呼吸综合征（PRRS）酶联免疫吸附试验（ELISA），其抗原包被浓度为24μ／mL，血清稀释度为1∶100，酶标二抗的工作浓度为1∶500。应用该方法对陕西省9个地区采集的有疑似PRRS征候的250份猪血清进行检测，检出阳性血清32份，阳性率为12．8％，从而证实陕西省存在PRRS，也为该病的大面积血清学普查提供了一种简易、快速、准确的检测方法。     

不同进口蓝耳病病原抗体ELISA检测试剂盒比较及应用浅析

为比较4种PRRS抗体ELISA试剂盒检测效果的差异,将PRRS标准阳性血清和免疫过PRRS疫苗的猪血清分别以100、10-1、10-2、10-3、10-4、10-5、10-6、10-7倍比稀释， 同时分别用4种不同的ELISA试剂盒 （I、J、B、L） 进行检测。结果显示,I厂家的试剂盒敏感度最好，J、B 2家的次之，L厂家的敏感度最低。检测结果表明不同商品化试剂盒的灵敏度存在一定的差异。本研究可为蓝耳病免疫程序制定以及净化检测提供参考。     

猪繁殖与呼吸综合征免疫抗体检测与分析

为了解北疆地区的猪繁殖与呼吸综合征（PRRS）的免疫抗体水平,以便及时发现问题,及时淘汰病猪和做好PRRS的补免工作,本试验从北疆地区的19个现代规模猪场采集血液样品1027份,采用ELISA抗体检测试剂盒对样品进行检测,结果发现有965份免疫抗体阳性血清,阳性率为93.96%;样品KQ平均值为80.25,变异系数平均值为0.36;免疫抗体阳性率超过90%的猪场有17个,占89.47%;有6个猪场的PRRS免疫抗体阳性率超过95%。本试验研究结果发现：北疆地区猪群的PRRS免疫抗体整体水平较高;不同构成成分的试验猪群间PRRS免疫抗体水平存在差异,种公猪的免疫抗体水平最高;虽然仔猪的整体PRRS免疫抗体水平较高,但免疫抗体水平有随日龄的增长而下降的趋势。希望本试验的研究成果对养猪企业的生产有所帮助,并为猪病研究的组织机构提供有价值的参考。     

河北省部分猪场送检样品的猪蓝耳病抗体水平分析

为了解河北省规模猪场猪蓝耳病(PRRS)感染及免疫情况,选取2016—2017年河北省7个地区不同规模猪场送检的1 182份血样进行PRRS EILSA抗体检测,并对结果进行汇总分析。结果显示:7个地区不同规模猪场送检血样的阳性率均在80%以上,尤其是大型规模化猪场,抗体阳性率更高;地区间阳性率差异不大,均在75%~92%之间;散养和断奶仔猪群阳性率相对偏低。结果表明,河北省规模猪场的PRRS免疫效果较好;散养猪群和断奶仔猪群是发生PRRS的高风险猪群。结果提示,规范科学的PRRS免疫程序可以获得较好的免疫效果;应注重对散养和断奶仔猪群的免疫,根据抗体检测情况合理采取免疫措施。     

新疆昌吉地区部分规模化猪场PRRSV抗体监测和免疫效果分析

为了查明昌吉地区地区部分规模化猪场猪PRRSV的抗体阳性率及免疫合格率,分别采集了昌吉地区4个免疫了弱毒苗的规模化猪场,和3个免疫了灭活苗的规模化猪场血清共1 036份,采用间接ELISA方法检测其抗体.经检测,4个免疫PRRS弱毒苗规模化猪场总阳性率为79.05％（468/592）,平均KQ为49.63,标准差为39.41.3个免疫PRRS灭活苗规模化猪场总阳性率为62.61％ （278/444）,平均KQ为45.88,标准差为31.22.结果表明,在规模化养猪场使用灭活苗免疫预防PRRS感染作用不如弱毒苗,因此,建议临床应用中应选择弱毒苗为宜,结合检测结果、临床生产数据及猪场已采用猪PRRS免疫程序,建议商品猪在仔猪断奶后初免.在高致病性猪蓝耳病流行地区,可根据实际情况在初免后1个月加强免疫一次,种母猪70日龄前免疫程序同商品猪,以后每次配种前加强免疫一次,种公猪70日龄前免疫程序同商品猪,以后每隔4～6个月加强免疫一次.     

猪繁殖和呼吸综合征的诊断及血清学调查

对临床疑似猪繁殖和呼吸综合征(PRRS)的病例进行了病理组织学观察和PCR检验，证实了PRRS在本地区的存在。流行病学资料显示：该地区流行的PRRS以仔猪感染为主，发病率46．8％～96．2％，病死率73．5％～100％，而母猪的繁殖障碍表现较轻。对来自某些规模化猪场的270份血清样品进行血清学检测，结果PRRS抗体阳性率平均为43．7％。     

广西猪繁殖与呼吸综合症的流行病学调查

为从病原学上准确了解PRRS在广西的流行情况，笔者于2004年从广西25个出现可疑PRRS症状的猪场共采集病料156份，应用RT-PCR技术进行分子流行病学调查。检出阳性病料62份，阳性率达40．7％(62／156)；阳性场14个，猪场阳性率为56％(14／56)，现将结果报告如下：     

猪蓝耳病与猪瘟、O型口蹄疫免疫抗体监测结果分析

通过对不同饲养期、同一份血清中高致病性猪蓝耳病（PRRS）、猪瘟（CSF）、猪O型口蹄疫（FMD）三种疫病的免疫抗体监测分析,仔绪、育肥猪、种猪免疫抗体的保护率及阳性率分别为：PRRS阳性率分别为34．4％、49％、63．6％,CSF保护率分别为73.6％、91．9％、81.8％,FMD保护率分别为29％、51.5％、81．8％。     

粤西地区某规模化猪场紧急接种猪繁殖与呼吸综合征基因缺失苗的抗体监测

为了解广东湛江地区某规模化猪场紧急接种猪繁殖与呼吸综合征(PRRS)基因缺失苗免疫效果,笔者对该场紧急接种后的猪群进行了PRRS免疫抗体的监测。共采集样品血清52份,采用ELISA的方法进行PRRS免疫抗体检测。结果显示,紧急接种前和紧急接种后21 d、28 d、35 d和42 d的抗体阻断率平均值分别为1.938 5、2.305 6、2.050 2、1.641 7和1.301 0。抗体阻断率先升高,随后匀速下降,说明PRRS基因缺失苗起到了有效的干预作用,使得PRRS抗体产生了明显变化。抗体离散度分别是99.83%、66.20%、57.00%、78.90%和86.59%。抗体离散度先下降再上升,说明PRRS基因缺失苗起到了有效的干预作用,可见该猪场这次紧急接种PRRS基因缺失苗起到了紧急接种的作用,达到了预期效果。     

潍坊市猪繁殖与呼吸综合征的流行病学调查

猪繁殖与呼吸综合征是由猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus,PRRSV）引起的一种严重危害养猪业的传染病,主要引起妊振母猪的流产、死产、木乃伊胎、弱仔等繁殖障碍和仔猪的呼吸道疾病。本次调查采用RT-PCR对山东省潍坊市7个县20家猪场的送检样品进行PRRSV检测。结果显示,7个县猪场均检出PRRSV阳性,阳性检出率为35%~82%,平均阳性率为67.9%。流行病学调查结果表明,PRRSV感染已在潍坊市猪群中普遍存在,PRRS已成为危害当地养猪业的重要疫病。但各县市之间PRRSV感染率差异较大,在拥有较多小规模猪场的县市阳性率较高;不同日龄猪之间PRRSV感染率及死亡率差异较大,30~60日龄最高;不同品种猪群对该病毒的易感性和感染阳性率差别不大。     

Elevated serum haptoglobin in pigs infected with porcine reproductive and respiratory syndrome virus.

We examined the two acute phase proteins, alpha (alpha)-1 acid glycoprotein (AGP) and haptoglobin (HP), in serum of pigs following experimental porcine reproductive and respiratory syndrome (PRRS) virus infection. Increased levels of serum HP, but not AGP, were observed from 7 to 21 days post-inoculation in the infected pigs. Furthermore, serum IL-6 increased in the infected pigs, but TNF-alpha did not. The increase of serum IL-6 in pigs following PRRS virus infection may induce production of HP. Also, in the field investigation, serum HP in pigs was dramatically increased after exposure to the PRRS virus.     

Prevalence of porcine reproductive and respiratory syndrome virus detection in aborted fetuses,mummified fetuses and stillborn piglets using quantitative polymerase chain reaction

The objective of the present study was to investigate the prevalence of porcine reproductive and respiratory syndrome (PRRS) virus detection in aborted fetuses (n=32), mummified fetuses (n=30) and stillborn piglets (n=27) from 10 swine herds in Thailand using quantitative polymerase chain reaction (qPCR). Pooled organs and umbilical cord from each fetus/piglet were homogenized and subjected to RNA extraction and cDNA synthesis. The qPCR was carried out on the ORF7 of the PRRS viral genome using fluorogenic probes for amplified product detection. The results revealed that 67.4% (60/89) of the specimens contained PRRS virus. The virus was found in 65.6% (21/32) of aborted fetuses, 63.3% (19/30) of mummified fetuses and 74.1% (20/27) of stillborn piglets (P=0.664). Genotype 1, genotype 2 and mixed genotypes of PRRS virus were detected in 19.1% (17/89), 25.8% (23/89) and 22.5% (20/89) of the specimens, respectively (P=0.316). PRRS virus antigen was retrieved from both non-PRRS-vaccinated herds (68.2%, 45/66) and PRRS-vaccinated herds (65.2%, 15/23) (P=0.794). These findings indicated that these specimens are important sources of the PRRS viral load and the viral shedding within the herd. Thus, intensive care on the routine management of dead fetuses and stillborn piglets in PRRS virus-positive herds should be emphasized.     

Effect of formalin fixation on the immunohistochemical detection of PRRS virus antigen in experimentally and naturally infected pigs.

The purpose of this study was to determine the effect of formalin fixation on the immunohistochemical detection of porcine reproductive and respiratory syndrome (PRRS) viral antigen in lungs of experimentally and naturally infected pigs. In separate trials, five 24-day-old pigs and six 10-day-old pigs were housed as separate groups in isolation and inoculated intranasally with 10(5.5) TCID50 of an isolate of PRRS virus (PRRSV; P129). The older and younger pigs were euthanatized at 7 and 10 days post inoculation (dpi), respectively. At necropsy, all pigs had gross and microscopic lung lesions typical of PRRS, and PRRSV was isolated from all pigs. To insure uniform fixation, lungs from each pig were cut into 1-cm-thick slices and immersed into 10% neutral-buffered formalin. After fixation in formalin for 8 hours or 1, 2, 3, 5, 6, 8, 10, and 15 days, 3 lung sections from some or all pigs were processed for histological examination using routine methods. Immunohistochemical staining for PRRSV antigen was positive at the following times (days unless otherwise stated) after fixation (percentage of pigs staining positive for PRRSV in parentheses): 8 hours (100); 1 (100); 2 (100); 3 (80); 5 (33); and 6, 8, 10, and 15 (0-all negative). To further evaluate the effects of formalin fixation on PRRSV immunodetection, 31 field cases of PRRS were selected for immunohistochemistry (IHC). Over a 3-month period, submitted cases were selected from the Purdue University Animal Disease Diagnostic Laboratory, W. Lafayette, Indiana, for IHC if 1) the clinical history included respiratory disease, 2) PRRSV was isolated from lung and/or serum from the submitted pigs or tissues, 3) at least 1 section of lung fixed in 10% neutral-buffered formalin was submitted for IHC, and 4) the duration of fixation could be accurately determined from the case history. Of the 31 PRRSV-infected pig cases meeting the selection criteria, 23 were fixed in formalin for 4 days or less. Twenty-one of these 23 (91%) were positive by IHC. Two of 8 cases fixed for greater than 4 days (25%) were positive by IHC. In practical terms, 1-day shipping of fixed samples to a laboratory followed by routine tissue processing within a laboratory should not adversely affect immunohistochemical detection of PRRS viral antigen. But a delay in shipping or processing of more than 2 days could reduce or prevent the detection of PRRS viral antigen by IHC.     

Differential immunity in pigs with high and low responses to porcine reproductive and respiratory syndrome virus infection

One hundred Hampshire x Duroc cross-bred pigs (HD) and 100 NE Index line (I) pigs were infected with porcine reproductive and respiratory syndrome (PRRS) virus and evaluated for resistance/susceptibility. Controls (100/line) were uninfected littermates to the infected pigs. Viremia, change in weight (WTdelta), and rectal temperature at 0, 4, 7, and 14 d postinfection were recorded. Lung, bronchial lymph node (BLN), and blood tissue were collected at necropsy (14 d postinfection). The first principal component from principal component analyses of all variables was used to rank the pigs for phenotypic response to PRRS virus. Low responders (low PRRS burden) had high WTdelta, low viremia, and few lung lesions; high responders (high PRRS burden) had low WTdelta, high viremia, and many lesions. The RNA was extracted from lung and BLN tissue of the 7 highest and 7 lowest responders per line and from each of their littermates. Expression of 11 innate and T helper 1 immune markers was evaluated with cDNA in a 2 x 2 x 2 factorial design. Significant upregulation in lung, lymph, or both of infected pigs relative to controls occurred for all but one gene. Expression differences were greater in HD than I pigs. Significant downregulation for certain immune genes in low pigs, relative to littermate controls, was detected in lung and BLN, particularly in line I. Serum levels of the immune cytokines affirmed the gene expression differences. High preinfection serum levels of IL 8 were significantly associated with PRRS virus-resistant, low pigs. After infection, low expression of interferon gamma in cDNA and in serum was also correlated with PRRS virus resistance. Important genetic associations were revealed for fine mapping of candidate genes for PRRS virus resistance and determining the causative alleles.     

三明市某规模化猪场几种疫病的检测情况与分析

通过对三明市某大型猪场进行猪瘟、普通蓝耳病、高致病性蓝耳病、伪狂犬病的病原学和血清学检测,以更好地了解这些疫病在猪场的流行情况,为猪场这几种疫病的防控和净化奠定基础。本次调查分别检测45份后备母猪血清、92份生产母猪血清、13份生产公猪血清,共计150份血清,150份扁桃体样品。通过ELISA方法分别检测了猪瘟、普通蓝耳病、伪狂犬病gE和伪狂犬病gB。荧光定量PCR方法检测了猪瘟、高致病性蓝耳病。结果猪瘟和高致病性蓝耳病病原学阳性率分别为8%和5.3%。一个月后对病原学检测阳性猪采样复查,结果猪瘟阳性率4.6%,高致病性蓝耳病阳性率2.6%。猪瘟免疫抗体合格率93.3%,普通蓝耳病免疫抗体合格率96%,伪狂犬病gB免疫抗体合格率100%,伪狂犬病gE感染抗体2%。生产母猪胎次越多,猪瘟和普通蓝耳病的免疫抗体水平越高。     

Pathogenesis of porcine reproductive and respiratory syndrome virus infection in mid-gestation sows and fetuses.

Two experiments were undertaken to evaluate whether porcine reproductive and respiratory syndrome (PRRS) virus was able to cross the placenta and infect midgestation fetuses following intranasal inoculation of sows and whether PRRS virus directly infected fetuses following in utero inoculation. In experiment 1, eight sows between 45 and 50 days of gestation were intranasally inoculated with PRRS virus (ATCC VR-2332), and four control sows were inoculated with uninfected cell culture lysate. Virus inoculated sows were viremic on postinoculation (PI) days 1, 3, 5, 7 and 9, shed virus in their feces and nasal secretions, and became leukopenic. Sixty-nine of 71 fetuses from principal sows euthanized on PI day 7, 14 or 21 were alive at necropsy and no virus was isolated from any of the fetuses. Two principal sows that farrowed 65 and 67 days PI delivered 25 live piglets and three stillborn fetuses. The PRRS virus was isolated from two live piglets in one litter. In experiment 2, laparotomies were performed on five sows between 40 and 45 days of gestation and fetuses were inoculated in utero with either PRRS virus alone, PRRS virus plus a swine serum containing PRRS antibodies, or uninfected cell culture lysate. Three sows were euthanized on PI day 4 and two sows on PI day 11. Viral replication occurred in fetuses inoculated with virus alone and was enhanced in fetuses inoculated with virus plus antibody. No virus was isolated from control fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)     

沈阳市及周边地区规模化猪场猪繁殖与呼吸障碍综合征疫苗免疫效果及病原调查

为了解沈阳及周边地区猪繁殖与呼吸障碍综合征病毒感染情况和疫苗免疫效果,应用已建立的猪繁殖与呼吸障碍综合征病毒RT—PCR．检测方法在2011年1月～2013年6月期间,对来自辽宁省沈阳、大连、鞍山等16个市县地区的猪场和屠宰场的送检样品进行检测。结果发现,2011年辽宁省猪繁殖与呼吸障碍综合征病毒的阳性率为9．28％,2012年为27．3％,2013年上半年为0．6％,3年平均阳性率为12．1％;同时选择沈阳市5家规模化养猪场3年采集血清902份进行猪繁殖与呼吸障碍综合征疫苗免疫效果的评价,结果显示,2011年5个猪场猪繁殖与呼吸障碍综合征疫苗免疫抗体合格率为97．3％,2012年为98．8％,2013年上半年为94．8％,3年平均阳性率为97．5％;另外,对沈阳市某猪场免疫母猪所产仔猪的母源抗体进行为期7周的监测,发现,仔猪猪繁殖与呼吸障碍综合征病毒母源抗体在7日龄时达到最大值,直到21日龄维持在较高水平,之后呈现下降趋势。     

Shedding of porcine reproductive and respiratory syndrome virus in mammary gland secretions of sows.

OBJECTIVE: To document shedding of porcine reproductive and respiratory syndrome (PRRS) virus in mammary gland secretions of experimentally inoculated sows, to evaluate effects of vaccination during gestation on virus shedding during the subsequent lactation, and to evaluate shedding of PRRS virus in milk of sows in commercial herds. ANIMALS: 6 sows seronegative for PRRS virus were used for experiment 1, and 2 sows were retained for experiment 2. For experiment 3, 202 sows in commercial herds were used. PROCEDURE: In experiment 1, 2 sows were inoculated with PRRS virus, 2 sows were vaccinated with modified-live PRRS virus vaccine, and 2 sows served as control pigs. Mammary gland secretions were assayed for PRRS virus. In experiment 2, pregnant vaccinated sows from experiment 1 were vaccinated with another modified-live PRRS virus vaccine. Mammary gland secretions were assayed in the same manner as for experiment 1. For experiment 3, milk collected from 202 sows in commercial herds was assayed for PRRS virus. RESULTS: In experiment 1, PRRS virus was detected in mammary gland secretions of both vaccinated and 1 of 2 virus-inoculated sows. In experiment 2, virus was not detected in samples from either vaccinated sow. In experiment 3, all samples yielded negative results. CONCLUSIONS AND CLINICAL RELEVANCE: Na?ve sows inoculated late in gestation shed PRRS virus in mammary secretions. Previous vaccination appeared to prevent shedding during the subsequent lactation. Results for samples obtained from sows in commercial herds suggested that virus shedding in mammary gland secretions of such sows is uncommon.