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1.
Tissue section replicates from lymphoid tissues and livers of gnotobiotic swine were examined by immunohistochemistry for the colocalization of porcine circovirus-2 (PCV-2) nucleocapsid and terminal deoxynucleotidyl transferase (TdT)-mediated incorporation of biotinylated nucleotides (UTP) onto the 3'-exposed hydroxyl groups (nick end labeling) nuclear deoxyribonucleic acid (TUNEL), a marker for apoptosis. Single- and dually stained replicates from uninfected controls, subclinically affected PCV-2-infected gnotobiotic pigs, PCV-2-infected piglets immunosuppressed with cyclosporine (Cys), and PCV-2-infected piglets with post-weaning multisystemic wasting syndrome (PMWS) were evaluated. Thymuses were used as positive controls for apoptosis absent PCV-2, tissue sections from dogs given hyperthermic stress were examined as positive controls for induced TUNEL. Tissues from heat-stressed dogs contained TUNEL-positive cell nuclei in both lymphoid tissues and liver, TUNEL was greatest shortly after the delivery of the hyperthermic insult. In uninfected control and subclinically affected PCV-2-infected gnotobiotic pigs, rare hepatocytes and lymphoid cells were TUNEL positive, the frequency of these was similar to that seen in uninfected controls. In PMWS-affected and Cys-treated PCV-2 piglets, the only consistent strongly positive TUNEL signal was contained within the cytoplasm of virus-positive phagocytic mononuclear cells. In phagocytes, some PCV-2 inclusions were TUNEL positive. Collectively, these data indicate that apoptosis is not the primary mechanism of lymphoid depletion and hepatocyte loss in PMWS. Apoptosis associated with systemic viral diseases may be attributable to pyrexia rather than direct or indirect effects of viruses on target cells.  相似文献   

2.
The objective of this study was to compare the induction of humoral and cell-mediated immune responses by four commercially available single-dose porcine circovirus type 2 (PCV-2) vaccines. A total of 50 3-week-old piglets were assigned to five groups (10 pigs per group). Four commercial PCV-2 vaccines were administered according to the manufacturer's instructions and the piglets were observed for 154 days post vaccination (dpv). Inactivated chimeric PCV-1-2 vaccines induced higher levels of PCV-2-specific neutralizing antibodies (NA) and interferon-γ-secreting cells (IFN-γ-SC) in pigs than did the other three commercial PCV-2 vaccines. The proportions of CD4+ cells were significantly higher in animals vaccinated with inactivated chimeric PCV-1-2 and PCV-2 vaccines than in animals vaccinated with the two subunit vaccines. To our knowledge, this is the first comparison of humoral and cell-mediated immunity induced by four commercial single-dose PCV-2 vaccines under the same conditions. The results of this study demonstrated quantitative differences in the induction of humoral and cell-mediated immunity following vaccination.  相似文献   

3.
试验旨在探明饲粮添加不同水平叶酸(FA)对圆环病毒-2(PCV-2)攻击下断奶仔猪增重和组织病变的影响。选用45头PCV-2阴性、初重8.44kg的健康去势、28d断奶DLY仔猪,饲喂添加不同水平FA(0、0.3、15mg/kg)的饲粮7 d后,进行PCV-2攻毒,继续饲喂相应饲粮28 d。第1、7(攻毒前)、21天和第35天采集组织样品;测定体重、腹泻指数、组织病变、血清PCV-2特异抗体、猪瘟抗体和细胞因子水平。结果表明:无PCV-2攻击,断奶应激导致仔猪免疫组织损伤,饲粮添加15 mg/kg FA可明显改善淋巴组织病变;PCV-2攻击导致免疫抑制与组织损伤,仔猪体重极显著降低(P<0.01);饲粮不添加FA仔猪免疫抑制和组织病变最严重,添加0.3 mg/kg FA缓解了免疫抑制而组织病变减轻,添加15 mg/kg FA则不利于组织修复。  相似文献   

4.
One-day-old gnotobiotic piglets were inoculated intranasally with in vitro passaged porcine circovirus 1 (PCV-1), PCV-2, and porcine parvovirus (PPV) alone or in combination (PCV-1/PCV-2, PCV-1/PPV, and PCV-2/PPV). Piglets were evaluated for 1) the development of porcine postweaning multisystemic wasting syndrome (PMWS), 2) distribution of viral antigens by immunochemistry, and 3) viremia and the presence of viral DNA in nasal and ocular secretions and feces. All single agent-infected piglets and piglets infected with PCV-1/PCV-2 or PCV-1/PPV were clinically asymptomatic. They were transiently viremic and seroconverted to homologous virus(es). At termination of the study on postinfection day (PID) 35, microscopic lesions were restricted to focal inflammatory cell infiltrates in livers and myocardia. One piglet given PCV-1/PPV was PPV viremic for 2 weeks after infection and had lymphangiectasia of the spiral and descending colon associated with granulomatous inflammation. All four PCV-2/PPV-inoculated piglets developed PMWS, characterized by sudden onset of depression and anorexia, icterus, and submucosal edema. One piglet became moribund on PID 27, and the remaining three piglets were euthanatized between PID 27 and PID 30 because of severe disease. Lymph nodes were small and the livers were mottled. Disseminated angiocentric granulomatous inflammation was present in all tissues examined except the brain. Multiple lightly basophilic intracytoplasmic inclusion bodies were identified in macrophages and histiocytes. PCV-2 antigen was widely distributed within macrophages; PPV antigen was sparse. Hepatocellular necrosis and bile retention were prominent. PCV-2 DNA was identified in ocular, fecal, and nasal secretions. Terminal sera contained antibodies to PPV (4/4) and PCV-2 (3/ 4). Production of PMWS in gnotobiotic swine appears to require PCV-2 and additional infectious agents such as PPV for full disease expression in gnotobiotic piglets.  相似文献   

5.
Porcine circovirus (PCV)-2, a newly described single-stranded circular DNA virus pathogen of swine is the cause of postweaning multisystemic wasting syndrome (PMWS). In gnotobiotic piglets, PCV-2 infection alone produces asymptomatic infection without evidence of overt PMWS. Gnotobiotic piglets infected with PCV-2 were injected with keyhole limpet hemocyanin in incomplete Freund's adjuvant (KLH/ICFA), and the effects on virus production and development of PMWS were determined. In the first experiment, piglets were injected subcutaneously on the left hip and shoulder, and viral burden was assessed in regional lymph nodes draining the injection sites and in contralateral lymph nodes 13-14 days after infection. Immune activation increased the number of virus antigen-positive cells in draining lymph nodes and increased the amount of infectious virus recovered by 1-4 log10. In a second experiment, the effects of injections of KLH/ICFA with or without concurrent stimulation of peritoneal macrophages by intraperitoneal injections of thioglycollate broth on induction of PMWS was assessed. All immunized piglets developed moderate to severe PMWS, whereas none of the piglets infected with PCV-2 alone developed PMWS. In PMWS-affected piglets, extensive replication of PCV-2 was documented by both immunocytochemistry and quantitative viral titrations. Thus, immune activation is a key component of the pathogenesis of PCV-2-associated PMWS in swine.  相似文献   

6.
The objective of this study was to evaluate the prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) through a longitudinal study in an integrated swine production system (7 farms) experiencing postweaning multisystemic wasting syndrome (PMWS). Risk factors for PCV-2 infection and for PCV-2 and PRRSV coinfection were also evaluated. Fifteen sows from each herd and 4 non-cross-fostered piglets from each sow were randomly selected at farrowing and ear-tagged at birth. Serum samples were analyzed for antibodies to PCV-2 and for detection of the PCV-2 and PRRSV genomes. Statistical analyses involved 2 approaches. The 1st approach characterized the dynamics of PCV-2 infection and their relationship with PRRSV infection. The 2nd approach analyzed the probability of being infected by PCV-2 or by both PCV-2 and PRRSV through a generalized linear mixed model incorporating sow and farm characteristics. At the 1st sampling time (1 wk of age), there was a significant relationship between sow PCV-2 infection and piglet PCV-2 infection (P < 0.0001). The risk of PCV-2 and PRRSV coinfection was 1.85 times greater in piglets from a sow with low titers of PCV-2 antibodies than in piglets from sows with medium to high titers (P = 0.03) and was 2.54, 2.40, and 2.02 times greater, respectively, in piglets from primiparous sows, PCV-2-infected sows, and farms in an area of high pig density than in piglets from sows of higher parity (P = 0.004), noninfected sows (P = 0.04), and farms in a low-density area (P = 0.09).  相似文献   

7.
Postweaning wasting is a major worldwide problem in pig production, particularly with respect to the disease termed postweaning multisystemic wasting syndrome (PMWS). In addition to wasting, PMWS symptoms include respiratory distress, diarrhoea, pallor and occasional cases of jaundice. The causative agent is porcine circovirus type 2 (PCV-2). The objective of the present study was to determine the significance of PMWS and similar conditions in Switzerland. A total of 72 weaned piglets from 26 farms showing wasting were examined for the presence of PCV-2 by immunohistochemical and histological analysis and 57 piglets from 21 farms were examined serologically. Possible causes for wasting other than PCV-2 were investigated by macroscopic, histological and bacteriological methods. PCV-2 antigen was identified immunohistochemically in the lymphatic organs in 11 of these 72 piglets. However, only 4 animals showed histological changes typical of PMWS. PCV-2 antibodies were found in 70% of the piglets. Piglets with wasting syndrome not associated with PCV-2 infection suffered from conditions including porcine proliferative enteropathy, gastric ulcers, polyserositis and polyarthritis. The most frequent condition was chronic enteritis not associated to circovirus infection. The results from the serological analyses indicate a wide distribution of PCV-2 in the Swiss pig population. However, confirmed cases of PMWS were rare in the investigated piglets.  相似文献   

8.
A total of 100 liver samples from pigs with postweaning multisystemic wasting syndrome (PMWS) were studied. All livers were evaluated microscopically and were staged based on the severity and localization of lesions. Presence of porcine circovirus type 2 (PCV-2) was evaluated using an in situ hybridization technique. Eighty-eight of 100 livers (88%) had a variable degree of lymphohistiocytic hepatitis, with apoptotic bodies, disorganization of hepatic plates, and/or perilobular fibrosis. Twelve pigs did not have microscopic liver lesions. Four stages of hepatic damage were established based on intensity and distribution of the lesions. Viral nucleic acid was detected in 70 of 100 livers (70%). Target cells for PCV-2 infection included Kupffer cells, hepatocytes, and inflammatory infiltrates. According to distribution of PCV-2 nucleic acid, four basic labeling patterns were identified. This study shows that liver damage is a frequent microscopic finding in cases of PMWS and hepatocytes are a target cell for PCV-2 infection and replication. Therefore, PCV-2 should be considered a new hepatitis-inducing viral agent in pigs.  相似文献   

9.
为分离鉴定流行于重庆某猪场的猪圆环病毒2型,本研究从断奶仔猪多系统衰竭综合征猪的淋巴结病料中进行病毒学检测,病毒利用PK-15细胞增殖,其基因组序列经克隆、测序、拼接获得,并完成对全序列的生物信息学分析鉴定。结果获得了1株猪圆环病毒2型(命名PCV-2CQ1),该毒株的全序列大小为1 767bp,同源性分析发现该病毒与国内公布的PCV-2毒株同源性超过了90%,尤其与广西分离株同源性达100%;系统进化分析本分离病毒与浙江株(EU257511)、黑龙江株(HM038032)聚类到一起,形成一个进化分支,同属于PCV-2b型;对编码的衣壳蛋白分析发现,PCV-2CQ1Cap氨基酸发生了较大变异,与强毒株同源性较高,考虑到本病毒源自PMWS病猪,推测该毒株属于强毒株。  相似文献   

10.
The viral distribution and lesions in Kunming mice experimentally infected with porcine circovirus type 2b (PCV-2b) were investigated. Seventy special pathogen free mice were divided into 2 groups with 35 mice in each group. The test group (TG) was infected with PCV-2b, the control group (CG) was inoculated with sterile cell cultures. Five mice in each group were sacrificed at 3, 7, 14, 21, 28, 35 and 42 dpi (day post infection), respectively. Necropsies were performed on all mice and tissues were collected for testing by histopathology, immunohistochemistry, transmission electron microscope (TEM) and polymerase chain reaction (PCR). Apoptosis and necrosis in lymphoid organs were observed in virus-infected mice, and became severe from 14 to 28 dpi. The proportion of PCV-2b antigen-positive cells was moderate in lung, heart, thymus, liver or kidney, and low in brain from TG. In spleen and cervical lymph node, the proportions of PCV-2b antigen-positive cells were low to high from 7 to 28 dpi, and moderate from 35 to 42 dpi. PCV-2b DNA was detected in all tissues examined in TG from 7 to 42 dpi. Viral inclusion bodies presented in the cytoplasm of lymphocytes, macrophages, hepatocytes, podocytes, neurocytes, spermatids and uterine epithelial cells in TG. In CG, no viruses and viral lesions were detected. PCV-2b could replicate in mice, and PCV-2b associated lesions in mice were similar to those observed in pigs. The present results indicate that it is possible to use Kunming mouse as an animal model for PMWS research.  相似文献   

11.
An outbreak of exudative epidermitis (EE) among piglets in a Swedish SPF-herd initiated a survey for indications as to the cause of disease.The herd was established by caesarean section and has been closed to all new animal material, with the exception of semen for artificial insemination (AI). The study comprised serum samples from the SPF-herd over a 10-year period (n=109) and a close monitoring of animals in the herd during the period after the EE outbreak. Serum samples from conventional boars at the AI-station servicing the herd were also included (n=9). All serum samples were tested for antibodies to porcine circovirus-2 (PCV-2). In addition, 3-week-old piglets from three litters (n=24) farrowed close after the initial EE outbreak were closely monitored for clinical signs of skin disease, sampled for Staphylococcus hyicus, tested for antibodies to porcine parvovirus and in sequentially collected serum samples tested for interferon-alpha (IFN-alpha) and interleukin-6.The PVC-2 serology showed that animals in the herd were sero-negative at least until 2 months prior to the EE outbreak. During the period close after the EE outbreak the animals showed varying levels of antibodies to PCV-2 but all the tested animals had sero-converted 4 months later. The AI boars were also sero-positive to PCV-2 at the time of the EE outbreak. Animals in the SPF-herd remained sero-positive to PCV-2 during the following 7 years. In the monitored litters, one piglet had clinical EE and 15 piglets displayed defined erythemas on the abdomen. Fourteen of the piglets also had IFN-alpha in serum on one or more occasions during the study, indicating viral activity among the animals. S. hyicus was isolated from all of the piglets from the earliest sampling point (3 days of age) and onwards, irrespective of clinical signs. PCV-2 was isolated from lymph node tissue collected from one of the EE affected pigs.Further, increases in the number of stillborn piglets, small litters (<6 piglets) and repeat breeders could be correlated to the time of PCV-2 sero-conversion. Coincidence of active viral infection and sero-conversion to PCV-2 points to the virus as the cause of the EE outbreak and reproductive disturbances.  相似文献   

12.
All 37 fetuses of 3 laparotomized pregnant sows at 86, 92, and 93 days of gestation were inoculated intramuscularly through the uterine wall with porcine circovirus type 2 (PCV-2). The sows were allowed to farrow, and blood and tissue samples were collected from their piglets before and after suckling colostrum. Thirteen fetuses from 2 sows at 90 and 103 days of gestation were used as controls. Of the 37 PCV-2 inoculated fetuses, 24 were grossly normal and 13 were mummified, stillborn, or weak-born at farrowing. Infection with PCV-2 was demonstrated in various tissues of grossly normal and abnormal fetuses by virus isolation, polymerase chain reaction, and immunohistochemical methods. Antibodies specific to PCV-2 were also detected from the sera or thoracic fluids of abnormal fetuses and unsuckled normal pigs. No evidence of PCV-2 infection was found in any control fetuses. The present results confirm previous findings that PCV-2 can infect late-term swine fetuses and may cause reproductive abnormalities.  相似文献   

13.
Multiplex PCR was established to detect porcine circovirus type 2 (PCV-2), porcine parvovirus (PPV) and porcine pseudorabies virus (PRV) and applied to samples from 137 piglets exhibiting clinical signs of postweaning multisystemic wasting syndrome (PMWS). PCV-2 DNA was detected from all samples. Moreover, 43 samples were positive for PPV but negative for PRV; 11 samples were positive for PRV but negative for PPV; and 35 samples were positive both for PPV and PRV. These results suggests that PCV-2 co-infection with PRV and PPV may play an important role in PMWS. Also, multiplex PCR is an appropriate candidate method for diagnosis of PCV-2, PRV and PPV simultaneously in field cases.  相似文献   

14.
参考GenBank中发表的猪圆环病毒2型(PCV-2)全基因序列,设计一对PCR引物,从病料中扩增获得4株PCV-2的全基因组序列,分别命名为SDNY-PCV-2、ShD-PCV-2、HBbd-PCV-2、GSLN-PCV-2,经测序确定长度均为1 767 bp。应用DNA Star序列分析表明,4个PCV-2分离株与国外部分分离株的核苷酸序列同源性达95.5%~99.8%,与PCV-1毒株的序列同源性为76.2%~77.6%。与国内外部分分离毒株序列进化树分析表明,4个PCV-2分离毒株处于不同分支中,存在一定差异。  相似文献   

15.
猪圆环病毒(PCV)分为1型(PCV-1)和2型(PCV-2).PCV-1一般认为无致病性,而PCV-2是断奶仔猪多系统衰竭综合征(PWMS)的主要致病因子;此外,猪皮炎肾病综合征(PDNS)、仔猪先天性震颤(CT)等疾病也与PCV-2有关.在临床上PCV-2常与猪繁殖与呼吸综合征病毒(PRRSV)、猪细小病毒(PPV)、猪流感病毒(SIV)等病毒混合感染,PCV-2相关疾病已经给世界养猪业造成了巨大的经济损失.然而,由于该病常常和上述几种疾病混合感染,且其临床症状十分类似,所以仅仅依靠单一的临床症状或者某一种实验室诊断方法并不能有效的检测该病.因此,将目前诊断PCV-2的各种方法集中起来,分析其优缺点,从而可以根据实验室的具体情况采取合适的方法是诊断该病的关键.论文就目前PCV-2的检测技术做一介绍.  相似文献   

16.
The present study investigated the influence of polyunsaturated fatty acids (PUFA) on the immune system of germ-free piglets. Oil with increased content of omega-3 PUFA was administered to piglets from the experimental group (EG) for four weeks. Piglets from the control group (CG) received identical volumes of saline solution. At the age of 21 days both groups of germ-free piglets were inoculated perorally with Lactobacillus casei subsp. casei at a dose of 2 ml (1x10(8) mli). At the age of 28 days, i.e. after one-week colonisation of germ-free piglets with Lactobacillus casei subsp. casei, significant differences were recorded in phagocytic activity of neutrophils (PANe) and phagocytic activity of potentially phagocytizing cells (PA) (P < 0.05). Between EG and CG there have been observed no significant differences in absolute numbers of CD4+ and CD8+ T lymphocytes and numbers of IgM cells and in additional investigated parameters - number of CD2+ T lymphocytes, index of phagocytic activity of neutrophils (IPANe) and index of phagocytic activity (IPA).The total number of leukocytes (Le) in EG was also higher. Of the parameters determined in blood serum we observed a significant increase in concentration of alpha linolenic, eicosapentaenoic and docosahexaenoic acids and a parallel decrease in the level of arachidonic acid.  相似文献   

17.
Kim J  Jung K  Chae C 《The Veterinary record》2004,155(16):489-492
A retrospective study of natural cases of abortion, recorded between October 2000 and September 2002, was made to determine the prevalence of abortions associated with porcine circovirus type 2 (PCV-2). The virus was detected by PCR, immunohistochemistry and in situ hybridisation. A total of 46 (13.1 per cent) of 350 aborted fetuses and stillborn piglets were positive for PCV-2 by PCR, and the virus was detected in fetuses at all stages of gestation. Viral antigen was detected in macrophages from the aborted fetuses and stillborn piglets by immunohistochemistry, and viral DNA was detected by in situ hybridisation.  相似文献   

18.
Postweaning multisystemic wasting syndrome (PMWS) is a worldwide emerging disease of weaned piglets. The objective of this review is to summarize the current knowledge regarding PMWS, its causative agent, mode of transmission, diagnostic techniques to detect PCV-2, the possible control measures, and the association of PMWS and PCV-2 with porcine dermatitis and nephropathy syndrome (PDNS). The causative agent of PMWS is porcine circovirus type 2 (PCV-2), however, not all pigs infected with PCV-2 develop the syndrome. PCV-2 is consistently associated with PMWS and PMWS is considered not to occur without it. Both the syndrome and the virus are not regarded as new. Co-factors that could activate PCV-2 to cause PMWS are considered. This enigmatic nature of both the syndrome and the virus is triggering a concern towards uncertainties of the viral transmission, its introduction in to the herd, effective tools of diagnosis, and control strategies.  相似文献   

19.
广东省猪圆环病毒2型感染的血清学调查   总被引：1，自引：0，他引：1  
为了解广东省猪群中猪圆环病毒2型(PCV-2)的感染情况,应用酶联免疫吸附试验(ELISA)对广东部分地区的764份不同年龄段的猪血清进行PCV-2抗体检测,对PCV-2与猪猪繁殖与呼吸综合征病毒(PRRSV)、伪狂犬病病毒(PRV)混合感染情况做了进一步调查.结果表明,PCV-2抗体检测平均阳性率为61.91％(47...  相似文献   

20.
ABSTRACT: Porcine circovirus type 2 (PCV-2) is the causal agent of the post-weaning multisystemic wasting syndrome (PMWS). PCV-2 are small single-stranded circular DNA viruses clustered into two main genogroups: PCV-2a and PCV-2b. Each genogroup present a specific highly-conserved motif of six amino acids (between amino acids 86 and 91) in the PCV-2 capsid protein. The aim of this study was to verify whether the motif located in the capsid protein and specific to each PCV-2 genogroup contributes to virulence. Two parental DNA clones, PCV-2a and PCV-2b, were constructed as well as two mutants DNA clones, PCV-2a/motif 2b and PCV-2b/motif 2a by exchanging the capsid motif of each genogroup. The four DNA clones were characterized in vitro as well as in vivo. Cells transfected by the four DNA clones produced infectious viruses. In specific-pathogen-free piglets transfected by the four infectious DNA clones, PCV-2b/motif 2a virulence was not attenuated while the PCV-2a/motif 2b virulence was drastically reduced compared to their parent virulence. These results suggest that the amino acids between positions 86 and 91 of the capsid protein are determinant for the virulence of isolates. However, the environment of this motif seems also involved.  相似文献   

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