河南省猪传染性胃肠炎血清流行病学调查分析

正为了解河南省猪传染性胃肠炎的流行情况和流行规律,采用酶联免疫吸附试验(ELISA)对河南省36个规模化养猪场的2536份血清样本进行传染性胃肠炎抗体水平检测。结果表明,河南省猪传染性胃肠炎抗体总阳性率为1.5%,成年猪抗体阳性率为1.1%,仔猪抗体阳性率为0.4%,无效血清52份,其余2447份血清为阴性。猪传染性胃肠炎抗体阳性率较低,但病毒仍然在猪场存在,因此仍应该重视对该病的防治。     

上海等4省市动物冠状病毒的流行病学调查

对上海、浙江、安徽和湖北4个地区感染鸡、鸭、猪、牛和犬的5种冠状病毒,即禽传染性支气管炎病毒(IBV)、猪传染性胃肠炎病毒(TEGV)、猪呼吸道冠状病毒(PRCV)、牛冠状病毒(BCV)和犬冠状病毒(CCV)进行病原学和血清学抽查,共完成测试样品2 368份,包括566份拭子样品和1 802份血清样品。检出IBV抗原阳性4份。在血清学调查中,发现IBV抗体的阳性率为86.4%(鸡)和0.7%(鸭);猪TGEV阳性率为6.8%,PRCV阳性率为18.7%;牛BCV阳性率为5.4%;犬冠状病毒的阳性率为50%。     

常州地区猪传染性胃肠炎和呼吸道冠状病毒病血清学调查

为了解本地区猪传染性胃肠炎病毒（TGEV）和呼吸道冠状病毒（PRCV）感染情况,采集生猪规模养殖场、散养户和不同来源的（本地和省外）屠宰场血清样品共308份,用TGEV和PRCV抗体鉴别诊断ELISA试剂盒进行检测。检测结果显示,TGEV抗体阳性率为2.92%,阳性样品都来自一个规模猪场,并与疫苗免疫有关;PRCV抗体总阳性率为27.92%,其中规模场阳性率11.93%,散养户阳性率35.96%,本地来源的屠宰场样品阳性率28%,省外来源的屠宰场样品阳性率45%。     

3种致猪腹泻病毒的多重RT-PCR检测

试验建立了用于检测猪流行性腹泻病毒(PEDV)、猪传染性胃肠炎病毒(TGEV)与猪轮状病毒(PRV)的三重RT-PCR方法,以调查猪群中腹泻病毒感染情况.通过该方法对采自广东省规模化猪场的95份临床疑似病毒性腹泻病料进行了检测,结果表明,猪流行性性腹泻病毒阳性率为33.7%,猪传染性胃肠炎病毒阳性率为4.2%,猪轮状病毒阳性率为20%;猪流行性性腹泻病毒和猪轮状病毒混合感染率为8.4%,猪流行性腹泻病毒和猪传染性胃肠炎病毒混合感染率为2.1%.     

应用ELISA间接法检测猪流行性腹泻抗体的研究

应用猪流行性腹泻病毒(PEDV)吉(J)毒株猪胎肠单层细胞培养物,以冻融法制备抗原,建立了酶联免疫吸附试验(ELISA)间接法检测PED抗体的方法。对30头份经直接免疫荧光技术证实的PED病猪群血清测定,97％为阳性;检测32头份无PED猪场猪血清,93％为阴性。对1份PED“华毒株”,1份“川毒株”以及3头份“吉毒株”PED免疫血清测定,均为阳性。对猪传染性胃肠炎血清、猪轮状病毒病血清、疑似猪血球凝集性脑脊髓炎血清、鸡传染性支气管炎血清及猪梭菌性肠炎血清共16头份检测均为阴性,证明PEDV不与TGEV等其它3种冠状病毒血清发生交叉反应。89头份疫区猪血清的区域性试验阳性率为75％(67/89);对82头份屠宰猪血清测定,53％阳性。抗原包被板保存期试验表明,包被板在-20℃可保存2个月。     

用固定细胞阻断酶联免疫吸附试验鉴别诊断猪传染性胃肠炎病毒和…

用固定细胞阻断酶联免疫吸附试验对来自丹麦猪的１８０份血清进行了猪传染性胃肠炎病毒和猪呼吸道冠状病毒感染的鉴别诊断，共检出了ＰＲＣＶ抗体阳性血清１０７份，ＴＧＥＶ抗体阳性血清０份。同时也检测了一些来自国内不同ＴＧＥＶ感染类型的猪场血清。     

猪流行性腹泻病毒重组N蛋白间接ELISA检测方法的建立

为建立检测猪流行性腹泻病毒(PEDV)血清抗体的间接ELISA方法,本研究以原核表达的重组N蛋白作为检测抗原,优化ELISA反应条件,建立了PEDV间接ELISA抗体检测方法。该方法仅对PEDV血清检测为阳性,对猪传染性胃肠炎、猪轮状病毒感染猪的阳性血清检测结果均为阴性;其批内和批间重复性试验的变异系数均小于10%。采用建立的ELISA方法检测了130份临床样品,其中78份血清样品为PEDV抗体阳性。表明建立的以重组N蛋白为包被抗原检测PEDV血清抗体的方法可以用于检测PEDV感染及相关的流行病学调查。     

某规模化猪场主要猪繁殖障碍性传染病抗体检测及分析

为了解某规模化猪场猪瘟病毒(CSFV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪伪狂犬病病毒(PRV)的抗体水平以及猪伪狂犬病野毒感染情况,研究应用ELISA检测技术对该场307份血清进行了CSFV、PRRSV抗体检测,63份血清进行了PRV-gB、PRV-gE蛋白抗体检测,猪群总体CSFV抗体阳性率为81.11%;PRRSV抗体阳性率为90.23%;PRV-gB蛋白抗体阳性率为95.24%;PRV-gE蛋白抗体阳性率为69.84%,并对不同类别猪群的抗体水平做出具体分析。该结果为了解该猪场3种常见传染病的整体免疫水平,进一步制定合理的免疫程序和防治措施提供参考。     

陕西省部分猪场5种疫病抗体及病原的检测

为调查2019年陕西省规模化猪场中口蹄疫(FMD)、猪繁殖与呼吸综合征(PRRS)、猪瘟(CSF)、猪圆环病毒2型(PCV2)和猪伪狂犬病(PR)的免疫状况及病原感染情况,采用间接ELISA对送检的20 233份血清样品进行抗体检测,采用PCR/RT-PCR方法对送检的1 633份病料样品进行病原检测。结果表明,检测口蹄疫抗体的5 154份血清样品中(4 089份免疫血清,1 065份未免疫血清),免疫抗体阳性率为76.69%,感染率为42.25%;检测猪繁殖与呼吸综合征抗体的6 259份血清样品中(5 516份免疫血清,743份未免疫血清),免疫抗体阳性率为85.06%,感染率为28.26%;检测猪瘟抗体的5 165份血清样品中(4 881份免疫血清,284份未免疫血清),免疫抗体阳性率为88.10%,感染率为47.89%;检测伪狂犬病病毒gB抗体的3 142份血清样品中(2 810份免疫血清,332份未免疫血清),免疫抗体阳性率为84.23%,感染率为21.69%;检测猪圆环病毒2型抗体的513份血清样品中(420份免疫血清,93份未免疫血清),免疫抗体阳性率为95%,感染率为88.17%。检测猪瘟病毒的328份病料中,阳性率为9.45%;检测猪圆环病毒2型的218份病料中,阳性率为14.23%;检测猪繁殖与呼吸综合征病毒的654份病料中,阳性率为10.86%;检测伪狂犬病病毒的144份病料中,阳性率为2.78%;检测口蹄疫病毒的226份病料中,阳性率为0.44%。通过对5种常见病原和抗体的检测,为陕西省猪场常见疫病的防控提供了基础资料。     

应用ELISA(双抗体夹心法)检测猪流行性腹泻病猪粪便中的病毒抗原

应用猪流行性腹泻(PED)—ELISA直接法(双抗体夹心法)对120头健康猪和5头猪传染性胃肠炎(TGE)病猪粪便标本进行检测,均不出现交叉反应;对15头PED病毒实验感染仔猪粪便标本检测,全部呈阳性;将对3(?)份ELISA阳性粪便标本和3份阴性标本的检测结果与电镜观察结果比较,其阳性符合率为97.37％,阴性符合率为100％;对在PED发病季节从不同地区采集的腹泻病猪粪便标本112份检测结果,阳性率为60.71％,而阴性反应的标本,绝大多数是在病愈后15～20d采集的。     

Prevalence of coronavirus antibodies in Iowa swine.

Three hundred and forty-seven serum samples from 22 Iowa swine herds were screened for TGEV/PRCV neutralizing antibody. Ninety-one percent of the sera and all 22 herds were positive. These sera were then tested by the blocking ELISA test to distinguish TGEV and PRCV antibody. The ELISA test confirmed the high percentage of TGEV/PRCV positive sera. By the blocking ELISA test, 12 herds were PRCV positive, 6 herds were TGEV positive and 4 herds were mixed with sera either positive for TGEV or PRCV antibody. The results suggest a recent increase in TGEV/PRCV seroprevalence in Iowa swine most likely due to subclinical PRCV infections.     

Evaluation of the baculovirus-expressed S glycoprotein of transmissible gastroenteritis virus (TGEV) as antigen in a competition ELISA to differentiate porcine respiratory coronavirus from TGEV antibodies in pigs.

The spike (S) glycoprotein of the Miller strain of transmissible gastroenteritis virus (TGEV) was recently cloned and expressed in baculovirus. The recombinant S protein was used as the coating antigen in a competition (blocking) enzyme-linked immunosorbent assay (ELISA) in combination with monoclonal antibodies to the S protein epitope A (conserved on TGEV and porcine respiratory coronavirus [PRCV]) or epitope D (present on TGEV only) to differentiate PRCV- from TGEV-induced antibodies. One set (set A) of 125 serum samples were collected at different times after inoculation of caesarean-derived, colostrum-deprived (n = 52) and conventional young pigs (n = 73) with 1 of the 2 porcine coronaviruses or uninoculated negative controls (TGEV/PRCV/negative = 75/30/20). A second set (set B) of 63 serum samples originated from adult sows inoculated with PRCV and the recombinant TGEV S protein or with mock-protein control and then exposed to virulent TGEV after challenge of their litters. Sera from set A were used to assess the accuracy indicators (sensitivity, specificity, accuracy) of the fixed-cell blocking ELISA, which uses swine testicular cells infected with the M6 strain of TGEV as the antigen source (ELISA 1) and the newly developed ELISA based on the recombinant S protein as antigen (ELISA 2). The sera from set B (adults) were tested for comparison. The plaque reduction virus neutralization test was used as a confirmatory test for the presence of antibodies to TGEV/PRCV in the test sera. The accuracy indicators for both ELISAs suggest that differential diagnosis can be of practical use at least 3 weeks after inoculation by testing the dual (acute/convalescent) samples from each individual in conjunction with another confirmatory (virus neutralization) antibody assay to provide valid and complete differentiation information. Moreover, whereas ELISA 1 had 10-20% false positive results to epitope D for PRCV-infected pigs (set A samples), no false-positive results to epitope D occurred using ELISA 2, indicating its greater specificity. The progression of seroresponses to the TGEV S protein epitopes A or D, as measured by the 2 ELISAs, was similar for both sets (A and B) of samples. Differentiation between TGEV and PRCV antibodies (based on seroresponses to epitope D) was consistently measured after the third week of inoculation.     

Seroprevalence of economically important viral pathogens in swine populations of Trinidad and Tobago,West Indies

The objective of this study was to evaluate the seroprevalence and identify the strains of swine influenza virus (SwIV), as well as the seroprevalence of porcine parvovirus (PPV), transmissible gastroenteritis virus (TGEV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine respiratory coronavirus (PRCV), porcine circovirus type 2 (PCV-2), and classical swine fever virus (CSFV) in pigs in Trinidad and Tobago (T&T). Blood samples (309) were randomly collected from pigs at farms throughout T&T. Serum samples were tested for the presence of antibodies to the aforementioned viruses using commercial ELISA kits, and the circulating strains of SwIV were identified by the hemagglutination inhibition test (HIT). Antibodies against SwIV were detected in 114 out of the 309 samples (37%). Out of a total of 26 farms, 14 tested positive for SwIV antibodies. HI testing revealed high titers against the A/sw/Minnesota/593/99 H3N2 strain and the pH1N1 2009 pandemic strain. Antibodies against PPV were detected in 87 out of the 309 samples (28%), with 11 out of 26 farms testing positive for PPV antibodies. Antibodies against PCV-2 were detected in 205 out of the 309 samples tested (66%), with 25 out of the 26 farms testing positive for PCV-2 antibodies. No antibodies were detected in any of the tested pigs to PRRSV, TGEV, PRCV, or CSFV.     

Virological and serological studies of porcine respiratory coronavirus infection on a Japanese farm

We detected transmissible gastroenteritis virus (TGEV) antibodies in pig farms in Tochigi prefecture, although the farms had no past record of TGEV vaccination or TGE. Among the farms, Farm A showed a high antibody incidence. We could not confirm if either TGEV or porcine respiratory coronavirus (PRCV) induced the antibodies, since conventional tests failed to discriminate PRCV from TGEV. Therefore, we conducted virological and serological examinations of this farm for 4 years to establish the etiology - TGEV or PRCV. Although no TGEV was detected, PRCVs were isolated from the nasal samples of pigs. Using a commercial ELISA kit, it was found that the antibodies detected in pigs of all the raising stages and sows were raised against PRCV but not TGEV. The phylogenetic analysis of the nucleotide sequences of the isolates showed that they were closely related to each other, and formed a separate cluster apart from the U.S.A. and European strains. In Cesarean-derived, colostrums-deprived piglets inoculated with a PRCV isolate, no clinical signs were seen, and the viruses were mainly isolated from the nasal samples. Moreover, viral genes were detected from the nasal sample of the contact pig. The result suggested that PRCV infection was located in the nasal cavity of pigs, and horizontal transmission easily occurs. From these results, PRCVs with different origins from the exotic PRCVs might be prevalent in pig farms in Japan.     

猪传染性胃肠炎病毒与猪呼吸道冠状病毒荧光RT-PCR鉴别检测方法建立与应用

本研究根据Genbank登录的猪传染性胃肠炎病毒(TGEV)N基因和S基因保守区序列设计合成了两对引物和探针,通过对荧光定量RT-PCR反应条件的优化,建立了TaqMan荧光定量RT-PCR快速检测TGEV的方法。该方法能有效地鉴别序列密切相关的猪传染性胃肠炎病毒与呼吸道冠状病毒。与常规RT-PCR试验比较表明,所建立的荧光RT-PCR检测技术快速、敏感,检测时限3个小时以内,具有很好的特异性和重复性。通过对39份临床样品进行检测,结果表明所建立的检测方法直接检测样品中猪传染性胃肠炎病毒。     

Porcine respiratory coronavirus in Quebec: Serological studies using a competitive inhibition enzyme-linked immunosorbent assay

Porcine respiratory coronavirus (PRCV) was identified for the first time in Quebec, using a blocking enzyme-linked immunosorbent assay (ELISA). Unlike the virus neutralization test (VNT), this ELISA was able to distinguish transmissible gastroenteritis virus (TGEV) from PRCV. Among the 15 seropositive fattening herds from group A, sera containing PRCV antibodies represented 74.8%, whereas those with TGEV antibodies represented only 7.2%. In group B, which consisted of 15 sow herds, nine herds expressed only PRCV-specific antibodies while the other herds had animals positive for TGEV-specific antibodies.     

Infection with porcine respiratory coronavirus does not fully protect pigs against intestinal transmissible gastroenteritis virus

Eight nine-week-old specific-pathogen-free pigs which had been infected with the transmissible gastroenteritis virus (TGEV)-related porcine respiratory coronavirus (PRCV) and four uninfected littermates were challenged with TGEV. The previous PRCV infection failed to protect them against the enteric TGEV infection. Virus excretion in faeces was detected by an ELISA in all the pigs for three to six consecutive days after inoculation. Although little diarrhoea was observed, the infection extended through much of the small intestine of one of the previously infected pigs four days after inoculation. Challenge with TGEV caused a secondary neutralising antibody response. By using a peroxidase conjugate of a monoclonal antibody which recognises a specific antigenic site on TGEV, antibodies against TGEV could be distinguished from antibodies against PRCV in an ELISA blocking test.     

Serological studies of transmissible gastroenteritis in Great Britain, using a competitive ELISA.

A competitive ELISA which differentiates between transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) was used to detect non-neutralising antibodies to the peplomer protein of TGEV in porcine sera. The test was shown to be TGEV specific, having a relative specificity of 100 per cent, and to have a relative sensitivity of 94.9 per cent when compared with the virus neutralisation test. The prevalence of TGEV in Great Britain is low; only 0.6 per cent of sows sampled in 1990 were seropositive to TGEV. Seroconversion to the virus neutralisation test occurred in a closed herd in 1984, with no apparent spread, but later testing by the ELISA did not detect any blocking antibodies. The possibility of the existence of a less contagious strain of PRCV is discussed. All British isolates of TGEV tested by the indirect fluorescent antibody test were recognised by the monoclonal antibody 1D.B12, the indicator antibody in the ELISA.     

Seroprevalence of porcine respiratory coronavirus in selected Korean pigs

A total of 446 serum samples from 88 herds in Korea were examined for antibody to porcine respiratory coronavirus (PRCV) using blocking enzyme-linked immunosorbent assay (ELISA). All serum samples were collected from 24- to 26-week-old finishing pigs between December 1998 and June 1999. By ELISA, 237 out of 446 sera tested (53.1%) and 54 out of 88 sampled herds (61.3%) were positive against PRCV. Of 446 sera from 88 herd tested, 185 (41.5%) serum samples from 22 (25%) herds were seronegative against PRCV and transmissible gastroenteritis virus infection. Our data suggested that seropositive herds for PRCV are distributed diffusely throughout South Korea.