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1.
Bovine viral diarrhoea virus infections in piglets born to sows vaccinated against swine fever with contaminated vaccine 总被引：5，自引：0，他引：5
On eight farms a congenital pestivirus infection in piglets was detected which could be traced to vaccination of the dams against swine fever (SF). Viruses isolated from the piglets were not recognised by monoclonal antibodies (MCAs) against swine fever virus (SFV) and were shown to be bovine viral diarrhoea virus (BVDV) or Border disease virus. The expected 'Chinese' strain of SFV could not be demonstrated in the batch of vaccine that had been used on these farms. Instead, a contaminating pestivirus was recovered which was not recognised by the MCAs against SFV. The contaminant had an unexpectedly high virulence for lambs and induced antibodies against BVDV in lambs and pigs. It could, therefore, be characterised as BVDV or Border disease virus. 相似文献
2.
The neutralizing peroxidase-linked assay for detection of antibody against swine fever virus 总被引：7，自引：1，他引：6
The neutralizing peroxidase-linked antibody ( NPLA ) assay was standardized and compared with the micro-plaque reduction test (PRT) on series of sera from pigs infected with different strains of swine fever virus (SFV) and bovine virus diarrhoea virus (BVDV), swine fever reference sera and field sera. The NPLA system was found to be as sensitive as the PRT, it detected SFV antibody in 17 out of 18 pigs 3 weeks after intranasal exposure and differentiated between antibody against SFV and BVDV. With varying concentrations of SFV parallel lines of neutralization with a slope of about 120 degrees were obtained with sera of different origin. The regression coefficient of approximately -1.74 implies that a 10-fold increase in the virus dose will result in an approximate 3.8-fold decrease in the serum titre. The NPLA assay has a high capacity and has been found to be a great asset in large scale surveys for detection of neutralizing antibody against SFV. 相似文献
3.
Limited BVDV transmission and full protection against CSFV transmission in pigs experimentally infected with BVDV type 1b 总被引：1，自引：0，他引：1
Bovine viral diarrhea virus (BVDV) in pigs may interfere with the detection and epidemiology of classical swine fever virus (CSFV). To investigate the importance of BVDV infections in pigs, first we studied the transmission dynamics of a recent BVDV field isolate. Subsequently, the protection of BVD antibodies against transmission and clinical disease of CSF virus was studied. Only limited transmission of BVDV occurred (R = 0.20), while no CSFV transmission occurred in pigs with BVDV antibodies. We concluded that BVDV transmission among pigs is possible, but seems to be limited and thus the virus should disappear from a population if no new introductions occur. Furthermore, the presence of BVD antibodies may completely prevent the transmission of CSFV and therefore could protect pigs against classical swine fever. It was also noticed that double infections with BVDV and CSFV were incorrectly diagnosed using the neutralization peroxidase linked assay (NPLA), which is the golden standard for antibody detection. This might hamper the diagnosis of CSF in herds with a high BVD prevalence. 相似文献
4.
The relationship between vaccine-induced antibody titres against swine fever virus (SFV), as measured by the neutralisation peroxidase-linked assay (NPLA), and protection against virus multiplication, excretion and transmission, disease and death was studied in 46 pigs. The pigs were housed individually and challenged intranasally with 100 pig ID50 of the virulent Brescia strain of SFV. In order to detect virus transmission, a swine fever (SF)-susceptible sentinel pig was placed in contact with the vaccinated animal 2 days after challenge. All 11 pigs with pre-challenge NPLA titres less than 12.5 responded to the challenge with fever, 8 out of 10 showed leucopenia, 7 transmitted virus to their contact and 3 died. Of the 9 animals with titres greater than or equal to 12.5 and less than 25, 8 developed fever, 6 out of 7 had leucopenia, 2 excreted and/or transmitted virus and all survived. Of the 12 pigs with pre-challenge titres greater than or equal to 25 and less than 50, 5 responded with fever, 6 out of 10 had leucopenia, 4 excreted virus and none died. Although all pigs with prechallenge titres greater than or equal to 50 showed a booster response, virus transmission was not observed, indicating that in the case of exposure such animals would not contribute towards the spread of field virus. From an epidemiological point of view, titres less than 32 were found inadequate. 相似文献
5.
J T Van Oirschot 《Veterinary microbiology》1983,8(1):97-103
In order to determine the effect of infections with low-virulent swine fever virus (SFV) on antibody responses, pigs were administered lipopolysaccharide (LPS) or sheep red blood cells (SRBC), 2 days after infection. Infected pigs showed an enhanced primary response to LPS late during infection. The secondary response to LPS seemed to be unaffected. Both the primary and secondary antibody response to SRBC appeared to be enhanced rather than depressed in infected pigs. These in vivo findings suggest that pigs infected with low-virulent SFV do not develop a depression of B lymphocyte function. 相似文献
6.
Production of monoclonal antibodies against swine fever virus and their use in laboratory diagnosis 总被引：21，自引：1，他引：20
G Wensvoort C Terpstra J Boonstra M Bloemraad D Van Zaane 《Veterinary microbiology》1986,12(2):101-108
Thirteen hybridoma cell lines which secrete monoclonal antibodies (MCAs) against swine fever virus (SFV) strain Brescia were produced. The hybrid cells resulted from fusion of P3X63-Ag8.653 myeloma cells with splenocytes of Balb/c mice which had been immunized with purified SFV. Screening of supernatant fluids was performed by an indirect enzyme-linked immunosorbent assay (ELISA) and an immunoperoxidase monolayer assay (IPMA). The IPMA, and an immunoperoxidase test (IPT) performed on cryostat sections, were used to characterize these MCAs on several pestivirus strains. All MCAs reacted to a varying degree with all but one of the SFV strains tested. None of the MCAs reacted with the bovine viral diarrhoea virus (BVDV) strains. Two MCAs are now used routinely in the differential diagnosis between infections with field strains of SFV, and the Chinese vaccine strain and BVDV strains. 相似文献
7.
Pigs exposed to a low-virulent strain of swine fever virus (SFV) developed an inapparent infection. At times when a transient leucopenia occurred, the peripheral blood lymphocytes (PBL) were unresponsive to the mitogenic stimulus of anti-immunoglobulin serum (anti-Ig) and protein A.Pigs lethally infected with a virulent SFV showed leucopenia and unresponsiveness of PBL to anti-Ig and protein A from 2 days post infection until death.This suggests a defect in B lymphocyte function in pigs infected with SFV. The unresponsiveness to anti-Ig appeared not to be caused by a reduced ability of lymphocytes to redistribute their receptors into caps, the presence of suppressor cells or absence of surface immunoglobulin bearing lymphocytes in the peripheral blood. A direct action of the virus itself also seemed unlikely.Lymphocytes from spleen reacted as PBL. However, lymph node cells did not lose their capability to respond to anti-Ig.These data suggest that a change in the migration pattern of anti-Ig responsive lymphocytes could account for the observed unresponsiveness of PBL and spleen lymphocytes to anti-Ig. 相似文献
8.
The sustainability, feasibility and desirability of breeding livestock for disease resistance 总被引：6，自引：0，他引：6
The sequence encoding a truncated E2 glycoprotein of the Alfort/187 strain of classical swine fever virus (CSFV) was expressed in Escherichia coli using the pET expression system and the recombinant product purified by Ni-NTA agarose affinity chromatography. The antigenicity of this recombinant protein was demonstrated by immunoblot using anti- CSFV-specific antibodies. A monoclonal antibody was produced against the truncated E2 protein and used as competitor in an ELISA for the detection of antibodies to CSFV. Specific antibodies were demonstrated by competitive ELISA (C-ELISA) as early as 21 days post-infection (dpi) in experimentally infected pigs. Seroconversion was demonstrated by C-ELISA and neutralising peroxidase-linked assay (NPLA) in all infected animals by 4 weeks. No cross-reaction with antibodies to bovine viral diarrhoea virus (BVDV) was seen in the C-ELISA using sera from experimentally infected pigs. The C-ELISA is not intended as a substitute for the NPLA. However, it is expected it will be useful for monitoring and prevalence studies. It will also assist in testing a large number of samples in the event of an outbreak. 相似文献
9.
Leukopenia and thrombocytopenia in pigs after infection with bovine viral diarrhoea virus-2 (BVDV-2)
Makoschey B Liebler-Tenorio EM Biermann YM Goovaerts D Pohlenz JF 《DTW. Deutsche tier?rztliche Wochenschrift》2002,109(5):225-230
The aim of this study was to investigate whether bovine viral diarrhoea virus-2 (BVDV-2) is pathogenic for pigs, which organs become infected and whether or to which extent the virus is excreted into the environment. Ten pigs were observed for clinical reactions after infection with a BVDV-2 strain, that has been shown to be pathogenic in calves under experimental conditions. Samples were taken to monitor thrombocyte and leukocyte counts as well as antibody development. Post mortem examinations were performed at 7, 11 and 27 days after infection. Tissue samples were collected for virus isolation, histological and immunohistological examination. All ten pigs became infected and BVDV could be re-isolated from the lymphocytes, the plasma and different lymphatic organs. The infection passed clinically inapparent, apart from a slight increase in body temperature in some animals. Some animals developed a slight leukopenia and/or thrombocytopenia. There were no macroscopic or histological lesions observed that could specifically be related to the inoculation of BVDV-2. With respect to all parameters studied, the infection and the consequences thereof were clearly less pronounced in pigs as compared to cattle, the natural host. Our results indicate, that pigs infected with BVDV-2 might develop antibodies that cross-react in tests for antibodies against classical swine fever virus. 相似文献
10.
Vaccinology of classical swine fever: from lab to field 总被引：12，自引：0，他引：12
van Oirschot JT 《Veterinary microbiology》2003,96(4):367-384
There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The E2 subunit vaccine induces immunity from approximately 10-14 days after a single vaccination. The immunity may persist for more than a year, but is then not complete. The Chinese strain vaccine may establish a strong herd immunity 1-2 weeks earlier than the E2 vaccine. The ability of the Chinese vaccine strain to prevent congenital infection has not been reported, but the E2 subunit vaccine does not induce complete protection against congenital infection. Immunological mechanisms that underlie the protective immunity are still to be elucidated. Both types of vaccine are considered to be safe. A great advantage of the E2 subunit vaccine is that it allows differentiation of infected pigs from vaccinated pigs and is referred to as a DIVA vaccine. However, the companion diagnostic E(rns) ELISA to actually make that differentiation should be improved. Many approaches to develop novel vaccines have been described, but none of these is likely to result in a new DIVA vaccine reaching the market in the next 5-10 years. Countries where classical swine fever is endemic can best control the infection by systematic vaccination campaigns, accompanied by the normal diagnostic procedures and control measures. Oral vaccination of wild boar may contribute to lowering the incidence of classical swine fever, and consequently diminishing the threat of virus introduction into domestic pigs. Free countries should not vaccinate and should be highly alert to rapidly diagnose any new outbreak. Once a new introduction of classical swine fever virus in dense pig areas has been confirmed, an emergency vaccination programme should be immediately instituted, for maximum benefit. The question is whether the time is ripe to seriously consider global eradication of classical swine fever virus. 相似文献
11.
P H Walz J C Baker T P Mullaney J B Kaneene R K Maes 《Canadian journal of veterinary research》1999,63(2):119-123
Some isolates of type II bovine viral diarrhea virus (BVDV) are capable of causing severe clinical disease in cattle. Bovine viral diarrhea virus infection has been reported in pigs, but the ability of these more virulent isolates of type II BVDV to induce severe clinical disease in pigs is unknown. It was our objective to compare clinical, virologic, and pathologic findings between type I and type II BVDV infection in pigs. Noninfected control and BVDV-infected 2-month-old pigs were used. A noncytopathic type I and a noncytopathic type II BVDV isolate were chosen for evaluation in feeder age swine based upon preliminary in vitro and in vivo experiments. A dose titration study was performed using 4 groups of 4 pigs for each viral isolate. The groups were inoculated intranasally with either sham (control), 10(3), 10(5), or 10(7) TCID50 of virus. The pigs were examined daily and clinical findings were recorded. Antemortem and postmortem samples were collected for virus isolation. Neither the type I nor type II BVDV isolates resulted in clinical signs of disease in pigs. Bovine viral diarrhea virus was isolated from antemortem and postmortem samples from groups of pigs receiving the 10(5) and the 10(7) TCID50 dose of the type I BVDV isolate. In contrast, BVDV was only isolated from postmortem samples in the group of pigs receiving the 10(7) TCID50 dose of the type II BVDV isolate. Type I BVDV was able to establish infection in pigs at lower doses by intranasal instillation than type II BVDV. Infection of pigs with a type II isolate of BVDV known to cause severe disease in calves did not result in clinically apparent disease in pigs. 相似文献
12.
用ＥＬＩＳＡ检测了接种猪瘟疫苗猪的血清抗体。共计４８６份猪血样,检测到血清抗体阳性者４４１份,阳性率为９０．７４％。同时对其中的１１１份血清进行了自然强毒血清抗体的检测,检测到强毒抗体阳性４份,阳性率为３．６０％。结果表明青海省猪瘟疫苗注射密度较高,但也反映出在青海省猪群中可能存在猪瘟自然强毒感染。 相似文献
13.
Peripheral blood and spleen lymphocytes from pigs infected with a low-virulent strain of swine fever virus (SFV) were transiently hyporesponsive to the mitogenic action of PHA, PWM and Con A. The mitogenic reactivity of lymphocytes from lymph nodes from such pigs appeared to be enhanced rather than depressed at that time. In addition, hyperresponsiveness of peripheral blood lymphocytes (PBL) to these mitogens occurred in some pigs.PBL from pigs lethally infected with virulent SFV showed a persistent depression of the response to these mitogens, whereas lymphocytes from lymph nodes had a high responding capacity.A lymphocyte response to SFV antigens could not be demonstrated in infected pigs.These SFV infections did not markedly affect the percentage of lymphocytes in the blood and most lymphoid organs rosetting with sheep red blood cells. On the other hand, surface immunoglobulin-bearing lymphocytes were markedly increased in lymph nodes from pigs exposed to virulent SFV. The sum of both lymphocyte subpopulations in the lymph nodes from these pigs often considerably exceeded the 100% value, which strongly suggests the presence of cells bearing both surface immunoglobulin and receptors for dextran-treated sheep red blood cells.Possible correlations between these findings are discussed. The results suggest that infections with SFV induce systemic alterations in the process of lymphocyte recirculation in the pig. 相似文献
14.
牛病毒性腹泻病毒感染对猪瘟免疫的影响 总被引：2，自引：0，他引：2
猪瘟病毒（CSFV）与同属的牛病毒性腹泻病病毒（BVDV）同源性较高,抗原性上有交叉。本次调查对368份猪瘟免疫猪血清样本进行BVDV抗原检测,其中7份呈阳性,阳性率1.90%。对7份BVDV阳性血清采用ELISA和IHA两种方法检测猪瘟（CSFV）抗体水平,抗体合格率偏低,两者的结果符合率为71%。研究表明：BVDV在一定程度上干扰了猪瘟疫苗的免疫效果,影响抗体水平。 相似文献
15.
T D Parsons P M Pitcher C Johnstone 《Journal of the American Veterinary Medical Association》1990,197(2):188-191
The economic impact of pseudorabies was examined in a commercial swine herd. At the onset of clinical signs, a modified-live virus vaccine was administered to the sow herd and repeated at 3-month intervals. According to production data from the 320-sow farrow-to-feeder unit, preweaning mortality increased twofold, and subsequently, the number of pigs weaned per litter decreased by 19% (P less than 0.005) during the 5-week epizootic. Also, the number of pigs born alive decreased by 6% during the epizootic (P less than 0.05). No significant differences in production were observed between the 6-month periods before and after the epizootic. Actual cash flow analysis for the farm under isomarket conditions revealed a decreased net return of $2.40/inventoried sow/week, which was attributed to the disease during the epizootic, and a $0.46 decrease in net return/inventoried sow/week in the postepizootic period. Most seropositive herds have clinical signs less severe than those described in this herd, and the cost of eradication of the virus from a swine herd can be in excess of $200/inventoried sow. Thus, we believe that sufficient financial incentives are not available to all swine producers to ensure their enthusiastic cooperation in the effort to eradicate pseudorabies from the US swine population. 相似文献
16.
Losses over a 2-year period associated with fetal infection with the bovine viral diarrhea virus in a beef cow-calf herd in Saskatchewan. 总被引：1，自引：0，他引：1 
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下载免费PDF全文 L F Taylor E D Janzen J Van Donkersgoed 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(1):23-28
In 1992, significant calf losses occurred between birth and weaning in a 650-cow Saskatchewan beef herd. These losses occurred subsequent to ill-thrift and disease, and every calf necropsied was found to be persistently infected with bovine viral diarrhea virus (BVDV). The objectives of this study were to describe the losses associated with fetal infection with BVDV in this herd and to determine why they occurred. For investigative purposes, blood samples were collected from the entire cow herd and the surviving calves at pregnancy testing in 1992, and tested by virus isolation for BVDV. Between 51 and 71 persistently infected calves were born in 1992. Bovine viral diarrhea virus was only isolated from calves. The only confirmed fetal infections with BVDV were recorded as the birth of persistently infected calves. However, abortions, reduced pregnancy rates, and delayed calvings were also recorded in the cow herd and may have been the result of fetal infections. The herd was monitored again in 1993. Fetal infections with BVDV were recorded as the birth of stunted, deformed, and persistently infected calves. The greatest losses due to fetal infection with BVDV in the 2 years of this study occurred in cows that were 3-years-old at calving (second calves). Bovine viral diarrhea virus appears to have remained endemic in this herd by transmission from persistently infected calves on young 3- and 4-year-old cows to naive calved 2-year-old cows that were mingled with them annually for rebreeding. Significant numbers of the 2-year-old cows remained naive to BVDV, because they were segregated from persistently infected calves at weaning, preventing cross-infection with BVDV. 相似文献
17.
牛病毒性腹泻病毒RT-PCR检测方法的建立及应用 总被引：1，自引：1，他引：0
根据GenBank中登录的牛病毒性腹泻病毒(BVDV)基因序列,设计合成了1对特异性引物,建立了检测BVDV的RT-PCR方法。通过对该方法的特异性、敏感性和重复性进行试验,结果显示,该方法可从BVDV标准毒株Oregon C24V中扩增出471 bp的特异性片段,而对猪瘟病毒、牛传染性鼻气管炎病毒、牛呼吸道合胞体病毒、牛副流感病毒、MDBK正常细胞的扩增结果均为阴性。经对标准毒株的细胞毒进行检测,其敏感度达10-1 TCID50/mL。应用该方法对临床腹泻病牛各脏器样品进行检测,结果比病毒分离方法更为敏感,操作简便。表明建立的RT-PCR方法具有特异、灵敏、高效、快速的特点,可用于BVDV的临床检测及流行病学监测。 相似文献
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肇东市某商品猪场内仔猪大批发病,病猪精神状态极差、发热、食欲下降、拉白色糊状并伴有腥臭味的粪便,有些迅速死亡但死亡率不高。为确诊此批病猪,运用临床分子生物学诊断和病理解剖观察等手段初步判定为大肠杆菌与猪瘟病毒混合感染。根据其剖解现象使用细菌学检测和PCR技术对蓝耳病病毒、猪圆环病毒、猪瘟病毒、大肠杆菌、放线杆菌及链球菌进行检测。SS培养基培养出的菌落形态为圆形半透明的小凸起,革兰氏染色镜检后观察到是革兰氏阴性杆菌。PCR检测结果显示猪瘟病毒为阳性。最终确诊为大肠杆菌和猪瘟病毒混合感染。通过对分离细菌进行药敏试验结果显示该菌对环丙沙、硫酸阿米卡星、恩诺沙星、阿莫西林等药物较为敏感。 相似文献
20.
The biological properties of bovine viral diarrhoea virus (BVDV) strain Oregon C24V were studied after intranasal and subcutaneous infection of pregnant sows. This virus strain is widely used in Hungary for immunising cattle against bovine viral diarrhoea (BVD). Based upon the results of the clinical, gross pathological, histopathological and virological examinations it can be established that the given strain caused asymptomatic infection and serological conversion in sows that were in the second third of gestation. The virus caused clinically apparent disease in some of the piglets born at term, which indicates that it had crossed the placenta. More than half (57%) of the live-born piglets died within 60 days of birth. The sows and their progeny did not shed the virus. BVDV infection has great differential diagnostic importance in pigs, as classical swine fever (CSF) virus strains of reduced virulence cause similar clinical symptoms and gross and histopathological changes. 相似文献