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J H van Eck 《The Veterinary quarterly》1982,4(3):117-123
Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus. 相似文献
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J. H. H. van Eck 《The Veterinary quarterly》2013,33(3):117-124
Summary Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) litres to BC14 virus and increasing numbers of birds with HI litres were observed from 3 weeks to 15 weeks of age. Sixty‐one per cent of the hens and 77 per cent of the cocks had 2log HI BC14 virus litres exceeding 4 at an age of 15 weeks. Some birds which had been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the result of a production drop in the hens showing seroconversion at 27 or 28 weeks of age. In the group of fowl vertically infected with EDS'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus. 相似文献
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Dewulf J Koenen F Ribbens S Haegeman A Laevens H De Kruif A 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2005,52(9):367-371
It has been demonstrated that pigs that have been double vaccinated with an E2 sub-unit marker vaccine and that are infected with classical swine fever virus (CSFV) through a natural contact infection may react positive in a CSFV detecting RT-nPCR test, whereas no virus could be isolated by using the conventional virus isolation (VI) technique. To evaluate whether these vaccinated and infected pigs may spread the virus, three experiments were set up. In the first, susceptible pigs were inoculated with serum originating from vaccinated RT-nPCR positive pigs. In the second, vaccinated RT-nPCR positive pigs were brought into contact with sentinel animals. In the third, vertical transmission was evaluated in RT-nPCR positive vaccinated pregnant gilts. In the first two experiments, no proof of virus transmission was found, whereas in the third vertical transmission was observed. The conclusion is that in vaccinated pigs that are positive in RT-nPCR but negative in VI, the level of circulating virus is probably not high enough for horizontal transmission, whereas vertical transmission of the virus is possible. 相似文献
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J. Dewulf F. Koenen S. Ribbens A. Haegeman H. Laevens A. De Kruif 《Zoonoses and public health》2005,52(9):367-371
It has been demonstrated that pigs that have been double vaccinated with an E2 sub‐unit marker vaccine and that are infected with classical swine fever virus (CSFV) through a natural contact infection may react positive in a CSFV detecting RT‐nPCR test, whereas no virus could be isolated by using the conventional virus isolation (VI) technique. To evaluate whether these vaccinated and infected pigs may spread the virus, three experiments were set up. In the first, susceptible pigs were inoculated with serum originating from vaccinated RT‐nPCR positive pigs. In the second, vaccinated RT‐nPCR positive pigs were brought into contact with sentinel animals. In the third, vertical transmission was evaluated in RT‐nPCR positive vaccinated pregnant gilts. In the first two experiments, no proof of virus transmission was found, whereas in the third vertical transmission was observed. The conclusion is that in vaccinated pigs that are positive in RT‐nPCR but negative in VI, the level of circulating virus is probably not high enough for horizontal transmission, whereas vertical transmission of the virus is possible. 相似文献
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Detection and quantification of classical swine fever virus in air samples originating from infected pigs and experimentally produced aerosols 总被引：3，自引：0，他引：3
During epidemics of classical swine fever (CSF), neighbourhood infections occurred where none of the 'traditional' routes of transmission like direct animal contact, swill feeding, transport contact or transmission by people could be identified. A hypothesized route of virus introduction for these herds was airborne transmission. In order to better understand this possible transmission route, we developed a method to detect and quantify classical swine fever virus (CSFV) in air samples using gelatine filters. The air samples were collected from CSFV-infected pigs after experimental aerosolization of the virus. Furthermore, we studied the viability of the virus with time in aerosolized state. Three strains of CSFV were aerosolized in an empty isolator and air samples were taken at different time intervals. The virus remained infective in aerosolized state for at least 30 min with half-life time values ranging from 4.5 to 15 min. During animal experiments, concentrations of 10(0.3)-10(1.6)TCID(50)/m(3) CSFV were detected in air samples originating from the air of the pig cages and 10(0.4)-10(4.0)TCID(50)/m(3) from the expired air of infected animals. This is the first study describing the isolation and quantification of CSFV from air samples originating from infected pigs and their cages, supporting previous findings that airborne transmission of CSF is feasible. 相似文献
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R. Vrancken A. Haegeman J. Dewulf J. Paeshuyse G. Puerstinger M. Tignon M.-F. Le Potier J. Neyts F. Koenen 《Veterinary microbiology》2009,139(3-4):365-368
5-[(4-Bromophenyl)methyl]-2-phenyl-5H-imidazo[4,5-c]pyridine (BPIP) is a representative molecule of a novel class of highly active in vitro inhibitors of the replication of Classical swine fever virus (CSFV). We recently demonstrated in a proof of concept study that the molecule has a marked effect on viral replication in CSFV-infected pigs. Here, the effect of antiviral treatment on virus transmission to untreated sentinel pigs was studied. Therefore, BPIP-treated pigs (n = 4), intra-muscularly infected with CSFV, were placed into contact with untreated sentinel pigs (n = 4). Efficient transmission of CSFV from four untreated seeder pigs to four untreated sentinels was observed. In contrast, only two out of four sentinel animals in contact with BPIP-treated seeder animals developed a short transient infection, of which one was likely the result of sentinel to sentinel transmission. A significant lower viral genome load was measured in tonsils of sentinels in contact with BPIP-treated seeder animals compared to the positive control group (p = 0.015). Although no significant difference (p = 0.126) in the time of onset of viraemia could be detected between the groups of contact animals, a tendency towards the reduction of virus transmission was observed. Since sentinel animals were left untreated in this exploratory trial, the study can be regarded as a worst case scenario and gives therefore an underestimation of the potential efficacy of the activity of BPIP on virus transmission. 相似文献
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Ribbens S Dewulf J Koenen F Laevens H Mintiens K de Kruif A 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2004,51(10):438-442
An experiment was set up to investigate the role of excretions and secretions in the indirect transmission of classical swine fever virus (CSFV). In five small pens, 10 weaner pigs (two pigs per pen) were housed and inoculated with CSFV. Experimental infection was successful in all pigs. The infected pigs were kept in the pens for a period of 15 days after which the pens were depopulated and pigs were killed. At the moment of depopulation, all inoculated pigs were visibly clinically diseased and had high fever. Ten hours later the same pens were repopulated with five pairs of susceptible pigs. From inoculation onwards and especially between depopulation and restocking, the pens were neither cleaned nor disinfected. Four days post-repopulation, three of the susceptible pigs were detected positive on virus isolation. A fourth pig was detected positive 2 days later. Later on, the remaining pigs also became infected, most probably due to contact and between pen infections. It can be concluded that transmission of the virus via excretions and secretions succeeded in four of 10 pigs. This result indicates that transmission of CSFV via excretions and secretions can be of importance in a late, clinical stage of disease. 相似文献
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In this paper we describe a study of the use of the white blood cell count (wbcc) as a parameter for detecting outbreaks of Classical Swine Fever (CSF). Meta-analysis of the results of challenge experiments revealed that oronasal infection of SPF-pigs with the virulent CSF virus (CSFV) strains Brescia or NL9201 resulted in a significant decrease in the average white blood cell count during the first week after inoculation of the virus. Challenge of conventional finishing pigs and sows with the moderately virulent strain Paderborn also resulted in a significant decrease in the average wbcc. However, this decrease was not observed after inoculation of SPF pigs with the mildly virulent CSFV strains Henken, Zoelen, or Bergen. The usefulness of clinical inspection in combination with wbcc to detect CSF outbreaks in the field was examined using the results of 214 EDTA blood specimens collected from 22 infected herds and 7250 EDTA blood specimens collected from 1450 non-infected herds. Half of the infected herds had been infected with the moderately virulent CSFV strain Venhorst (closely related to strain Paderborn) during the 1997-98 epidemic in the Netherlands. The other half had been infected with the moderately virulent CSFV strain Loraine. Using these data as a starting point, 1000 samples of one to ten specimens were generated by Monte Carlo simulation. These simulated samples and the samples of the non-infected herds were analysed by use of Receiver Operating Characteristic curves. On the basis of that analysis, the optimal number of animals whose wbcc needed to be determined to detect a CSF outbreak was five. With this number of animals, in conjunction with the threshold of 8000 white blood cells per mm3 (meaning that a herd is designated as CSF suspect if one or more of the five specimens has a white blood cell count of 8000 leukocytes/mm3 or less), the test procedure had a herd sensitivity (HSE) of 94.5% and a herd specificity (HSP) of 97.2%). The HSE is defined as the percentage of samples of infected herds with a positive result of the test procedure; HSP is defined as the percentage of uninfected herds with a negative result of the test procedure. We conclude that the wbcc can help the veterinary practitioner to detect outbreaks of CSF caused by (moderately) virulent CSFV strains. However, for the detection of outbreaks caused by mildly virulent CSFV strains, the contribution of the wbcc is doubtful. Development of additional tools that can improve the clinical diagnosis of the veterinary practitioner remains desirable. 相似文献
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Sara Mu?oz-González Marta Perez-Simó Marta Mu?oz José Alejandro Bohorquez Rosa Rosell Artur Summerfield Mariano Domingo Nicolas Ruggli Llilianne Ganges 《Veterinary research》2015,46(1)
Classical swine fever (CSF) causes major losses in pig farming, with various degrees of disease severity. Efficient live attenuated vaccines against classical swine fever virus (CSFV) are used routinely in endemic countries. However, despite intensive vaccination programs in these areas for more than 20 years, CSF has not been eradicated. Molecular epidemiology studies in these regions suggests that the virus circulating in the field has evolved under the positive selection pressure exerted by the immune response to the vaccine, leading to new attenuated viral variants. Recent work by our group demonstrated that a high proportion of persistently infected piglets can be generated by early postnatal infection with low and moderately virulent CSFV strains. Here, we studied the immune response to a hog cholera lapinised virus vaccine (HCLV), C-strain, in six-week-old persistently infected pigs following post-natal infection. CSFV-negative pigs were vaccinated as controls. The humoral and interferon gamma responses as well as the CSFV RNA loads were monitored for 21 days post-vaccination. No vaccine viral RNA was detected in the serum samples and tonsils from CSFV postnatally persistently infected pigs for 21 days post-vaccination. Furthermore, no E2-specific antibody response or neutralising antibody titres were shown in CSFV persistently infected vaccinated animals. Likewise, no of IFN-gamma producing cell response against CSFV or PHA was observed. To our knowledge, this is the first report demonstrating the absence of a response to vaccination in CSFV persistently infected pigs. 相似文献
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Oral immunisation of swine with a classical swine fever vaccine (Chinese strain) and transmission studies in rabbits and sheep 总被引：6，自引：0，他引：6
Chenut G Saintilan AF Burger C Rosenthal F Crucière C Picard M Bruyère V Albina E 《Veterinary microbiology》1999,64(4):265-276
Seven experiments including a total of 47 pigs, 11 wild boars, 26 rabbits, 10 hares and 16 sheep were carried out to assess the efficacy, safety and transmission of the Chinese vaccine strain of the classical swine fever virus (CSFV) administrated by the oral route. Within 3 weeks after oral vaccination, a clear seroconversion occurred in the pigs. Six weeks after vaccination, vaccinated pigs were fully protected against a virulent challenge. The C-strain was not isolated from tonsils, spleen, lymph nodes, thymus, saliva, urine and faeces of pigs within 4 days after oral vaccination. In one experiment, susceptible pigs were placed in direct contact with vaccinated pigs. None of these contact-exposed pigs became serologically positive for CSFV antibodies. It is concluded that the C-strain induces protection in pigs when administrated by the oral route and is not shed by vaccinated pigs. Serum anti-CSFV antibodies developed in seven out of eight wild boars vaccinated by the oral route. No vaccine virus was detected in the spleen and tonsils of these animals. The results in wild boar were in accordance with those obtained in domestic pigs. Sheep did not show any clinical signs after oral vaccination while rabbits had moderate hyperthermia and growth retardation. No clinical response to oral immunisation in hares was detected. At the end of the experiment, no sheep had detectable serum antibodies against CSFV, whereas a few vaccinated rabbits and hares became seropositive. None of the contact-exposed rabbits and hares seroconverted. These data indicate that the C-strain is safe for sheep and as expected, moderately or not pathogenic for rabbits and hares. These efficacy and safety studies on oral vaccination with the C-strain under experimental conditions provide essential information for further studies in wild boars under experimental and field conditions, including assays with baits to control a CSF epidemic. 相似文献
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为初步探讨猪瘟病毒的致病机理及机体的免疫应答机制,进行了猪瘟病毒感染试验,利用流式细胞术、阻断ELISA、白细胞计数和剖检观察对猪的体液免疫、细胞免疫、白细胞数量及病理损伤进行了研究。结果表明,感染猪的CD3＋和CD4＋T细胞亚群的数量在感染过程中均出现了明显的降低;CD8＋T细胞亚群在感染初期变化幅度不大,后期明显升高;猪瘟抗体于第7天开始产生,呈上升趋势。白细胞数量在感染期间呈下降趋势。病理学观察可知感染猪的肺脏、肾脏、扁桃体等出现了不同程度的损伤。猪瘟病毒感染对机体的免疫系统造成了较大的损伤,抑制了机体的免疫应答。 相似文献
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Development of a classical swine fever subunit marker vaccine and companion diagnostic test 总被引：12，自引：0，他引：12
The development of a classical swine fever (CSF) subunit marker vaccine, based on viral envelope glycoprotein E2, and a companion diagnostic test, based on a second viral envelope glycoprotein E(RNS), will be described. Important properties of the vaccine, such as onset and duration of immunity, and prevention of horizontal and vertical transmission of virus were evaluated. A single dose of the vaccine protected pigs against clinical signs of CSF, following intranasal challenge with 100LD(50) of virulent classical swine fever virus (CSFV) at 2 weeks after vaccination. However, challenge virus transmission to unvaccinated sentinels was not always completely inhibited at this time point. From 3 weeks up to 6 months after vaccination, pigs were protected against clinical signs of CSF, and no longer transmitted challenge virus to unvaccinated sentinels. In contrast, unvaccinated control pigs died within 2 weeks after challenge. We also evaluated transmission of challenge virus in a setup enabling determination of the reproduction ratio (R value) of the virus. In such an experiment, transmission of challenge virus is determined in a fully vaccinated population at different time points after vaccination. Pigs challenged at 1 week after immunization died of CSF, whereas the vaccinated sentinels became infected, seroconverted for E(RNS) antibodies, but survived. At 2 weeks after vaccination, the challenged pigs seroconverted for E(RNS) antibodies, but none of the vaccinated sentinels did. Thus, at 1 week after vaccination, R1, and at 2 weeks, R=0, implying no control or control of an outbreak, respectively. Vertical transmission of CSFV to the immune-incompetent fetus may lead to the birth of highly viraemic, persistently infected piglets which are one of the major sources of virus spread. Protection against transplacental transmission of CSFV in vaccinated sows was, therefore, tested in once and twice vaccinated sows. Only one out of nine once-vaccinated sows transmitted challenge virus to the fetus, whereas none of the nine twice-vaccinated sows did. Finally, our data show that the E(RNS) test detects CSFV-specific antibodies in vaccinated or unvaccinated pigs as early as 14 days after infection with a virulent CSF strain. This indicates that the E2 vaccine and companion test fully comply with the marker vaccine concept. This concept implies the possibility of detecting infected animals within a vaccinated population. 相似文献
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利用套式反转录聚合酶链式反应(RT-PCR)技术,对实验性感染猪瘟病毒猪的福尔马林固定石蜡包埋组织标本中的病毒RNA进行检测,将所扩增产物点样于尼龙膜上进行Dot-blotting鉴定,扩增结果与各器官的病理组织学变化进行了比较。从攻毒对照组猪的肝脏、脾脏、肾脏、淋巴结和扁桃体中检出了猪瘟病毒RNA,未从免疫攻毒猪只的脏器中检出猪瘟病毒RNA;所有扩增产物经Dot-blotting鉴定均得到了阳性信号;病毒基因的检出率与猪瘟病毒导致的病理组织学变化程度相一致。本试验成功建立了套式RT-PCR技术检测石蜡包埋组织中的猪瘟病毒RNA方法,为猪瘟病毒的诊断和回顾性分析提供了技术手段。 相似文献
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Virus antigen expression and alterations in peripheral blood mononuclear cell subpopulations after classical swine fever virus infection. 总被引：2，自引：0，他引：2
Depletion in the number of lymphocytes and viral persistence are thought to be the most important outcomes of classical swine fever virus (CSFV) infection. To define the change in peripheral blood mononuclear cells (PBMC) and virus replication in leukocytes after CSFV infection, 8-week old pigs were infected with the LPC vaccine strain or virulent CSFV (HCV-YL strain). Changes in the relative number of PBMCs were analyzed by flow cytometry. The results showed a significant increase in the relative percentage of monocytes in PBMCs during acute CSFV infection of naive pigs (p < 0.05). Monocyte frequencies were not changed in LPC-vaccinated pigs and control pigs. There was also a significant decrease in the number of IgM+ cells (p < 0.05) and a slight decrease in the number of CD4+ lymphocytes after 5 days of infection. There was no change in the frequency of CD8+ lymphocytes in PBMCs after infection. To define which subpopulation of PBMCs was the target for CSFV infection, PBMC populations from CSFV infected pigs were separated and stained for virus antigen expression. Alveolar macrophages (AM) were also studied. The results showed that CSFV replicated in all PBMC subpopulations: CD4+, CD8+, and IgM+ lymphocytes, and monocytes as well as AMs. However, virus antigen expression was more intense in monocytes and AMs. The infection of lymphocytes may, therefore, contribute to the depletion in their numbers after infection and lead to defective antibody production during virulent CSFV infection. 相似文献
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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. 相似文献
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Uttenthal A Le Potier MF Romero L De Mia GM Floegel-Niesmann G 《Veterinary microbiology》2001,83(2):85-106
Two commercial marker vaccines against classical swine fever virus (CSFV) and companion diagnostic tests were examined in 160 conventional pigs. To test the vaccines in a "worst case scenario", group of 10 weaners were vaccinated using a single dose of an E2 (gp55) based vaccine at days -21, -14, -10 or -7, and subsequently challenged at day 0. The challenge virus was CSFV 277, originating from a recent outbreak of classical swine fever (CSF) in Germany. In all groups, only 5 out of 10 pigs were challenged; the remaining 5 pigs served as vaccinated contact controls. Also, three control groups, each consisting of 10 non-vaccinated pigs, were challenged in parallel to the vaccinated animals. CSFV could be isolated from all non-vaccinated pigs. Among these pigs 40% displayed a chronic course of the infection (virus positive for more than 10 days). Pigs vaccinated 21 or 14 days before challenge displayed no clinical signs of CSFV after challenge. However, they were still able to replicate CSFV when challenged, as measured by reisolation of CSFV from leukocytes of the directly challenged pigs. CSFV could be isolated from the leucocytes of 25% of the pigs vaccinated 21 days before challenge and 50% of the pigs vaccinated 14 days before challenge. Chronic infection was not observed, but transmission to one vaccinated contact pig occurred. From all pigs vaccinated 10 or 7 days before challenge, CSFV could be reisolated. We observed a chronic course of infection in 5% of pigs vaccinated 10 days before challenge and in 30% of pigs vaccinated 7 days before challenge. The mortality rate was 20% in the pigs vaccinated 10 days before challenge, and varied between 20 and 80% in pigs vaccinated 7 days prior to challenge. The contact animals had lower mortality (0-20%) than directly challenged pigs, probably mirroring the delayed time point of infection. There was thus some protection against clinical illness by both marker vaccines, but not a solid protection against infection and virus shedding. The efficacy of the vaccine was best if used 3 weeks before challenge and a clear correlation between time interval from vaccination to challenge and the level of virus shedding was observed. Each vaccine had its own accompanying discriminatory ELISA, but 18% of the virus positive pigs never seroconverted in these tests. 相似文献
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