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1.
Various vaccine adjuvant candidates were assessed with the modified-live porcine reproductive and respiratory syndrome virus (MLV PRRSV) (Ingelvac PRRS MLV) vaccine. Their influence on humoral-mediated immune (HMI) and cell-mediated immune (CMI) responses as well as protection from virulent PRRSV challenge (MN-184) was evaluated. Ninety seronegative pigs were randomly divided into nine groups of 10 pigs. One group received MLV vaccine alone. Five groups received MLV vaccine with either bacterial endotoxin-derived adjuvant (ET), mixed open reading frame 5 (ORF5) peptides derived from various PRRSV isolates, porcine interferon alpha (IFNalpha), polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (poly-ICLC), or porcine interleukin-12 (IL-12). One group did not receive MLV vaccine but was immunized with ORF5 peptides conjugated with cholera toxin (ORF5 peptide/CT). Two groups served as challenged and unchallenged non-vaccinated controls. Four-color flow cytometry was utilized to simultaneously identify three major porcine T-cell surface markers (CD4, CD8, and gammadelta TCR) and detect activation marker CD25 (alpha chain of IL-2 receptor) or intracellular IFNgamma. The MLV PRRSV vaccine alone successfully primed CD4(-)CD8(+)gammadelta- T-cells as demonstrated by a significant increase in %IFNgamma+ cells when live PRRSV was used as a recall antigen. Booster immunizations of mixed ORF5 peptides and co-administration of IL-12 with MLV PRRSV vaccine significantly enhanced IFNgamma expression by some T-cell subsets (CD4(-)CD8(+)gammadelta+ and CD4(-)CD8(-)gammadelta+ for mixed ORF5 peptides and CD4(+)CD8(+)gammadelta- and CD4(-)CD8(+)gammadelta+ for IL-12). All groups receiving MLV-vaccine with or without adjuvants had reduced lung lesions after challenge. The group immunized with only ORF5 peptide/CT did not have significant T-cell recall responses and was not protected from challenge. Expression of IFNgamma by several T-cell subsets correlated with reduced lung lesions and viremia, whereas expression of CD25 did not. Expression of surface CD25 did not correlate with IFNgamma production. PRRSV ELISA s/p ratio prior to challenge also correlated with reduced lung lesions and viremia. In conclusion, booster immunizations of the mixed ORF5 peptides and co-administration of IL-12 effectively enhanced the CMI response to MLV vaccine. However, neither adjuvant significantly contributed to reducing clinical effects when compared to MLV alone.  相似文献   

2.
No information is currently available on porcine reproductive and respiratory syndrome virus (PRRSV) infection in wild boars (Sus scrofa) in Korea. In this study, the status of PRRS in wild boars was investigated. Blood samples were collected from 267 wild boars from eight provinces in Korea. Four of the samples tested (1.5%) were positive for PRRSV antibodies and eight (3.0%) were positive for antigens. Of the virus-positive samples, three and five samples were typed as containing European (EU, type 1) or North American (NA, type 2) viruses, respectively. Two amplicons (one from type 1 and one from type 2) were used to analyze the PRRSV open reading frame 7 (ORF7) sequence. The nucleotide sequences of type 1 PRRSV ORF7 had identities between 96.1% and 98.4% with PRRSVs from domestic pigs in Korea. The sequences of type 2 PRRSV ORF7 had identities of 100% with the PRRSV strain VR-2332, which was prototypic North American strain. These results show that PRRSVs are present in wild boars in Korea, and effective PRRSV surveillance of the wild boar population might therefore be useful for disease control.  相似文献   

3.
Genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) has been based on ORF5/GP5 and ORF7/N protein variations. Complete viral genome studies are limited and focused on a single or a few set of strains. Moreover, there is a general tendency to extrapolate results obtained from a single isolate to the overall PRRSV population. In the present study, six genotype-I isolates of PRRSV were sequenced from ORF1a to ORF7. Phylogenetic comparisons and the variability degree of known linear B-epitopes were done considering other available full-length genotype-I sequences. Cytokine induction of all strains was also evaluated in different cellular systems. Non structural protein 2 (nsp2) was the most variable part of the virus with 2 out of 6 strains harboring a 74 aa deletion. Deletions were also found in ORF3 and ORF4. Phylogenetic analyses showed that isolates could be grouped differently depending on the ORF examined and the highest similarity with the full genome cluster was found for the nsp9. Interestingly, most of predicted linear B-epitopes in the literature, particularly in nsp2 and GP4 regions, were found deleted or varied in some of our isolates. Moreover, 4 strains, those with deletions in nsp2, induced TNF-α and 3 induced IL-10. These results underline the high genetic diversity of PRRSV mainly in nsp1, nsp2 and ORFs 3 and 4. This variability also affects most of the known linear B-epitopes of the virus. Accordingly, different PRRSV strains might have substantially different immunobiological properties. These data can contribute to the understanding of PRRSV complexity.  相似文献   

4.
Porcine reproductive and respiratory syndrome virus (PRRSV) is an emerging pathogen causing significant economic losses in the swine industry worldwide. Two novel gene-deleted viruses were constructed and evaluated as vaccine candidates. Using the full-length infectious cDNA clone of North American PRRS isolate P129, the ORF2 and ORF4 genes (which encoded minor structural glycoproteins GP2a/2b and GP4, respectively) were individually deleted from the viral genome. Both deletion mutants were non-viable in MARC-145 cells and porcine alveolar macrophages, indicating that both genes are essential for virus replication. To rescue the replication-defective PRRSV, two complementing cell lines, MARC-2000 and MARC-400, were established to stably express the PRRSV GP2 and GP4 proteins, respectively. These cells were able to complement the deleted gene function of PRRSV in trans and supported production of the replication-defective DeltaORF2-PRRSV and DeltaORF4-PRRSV viruses. Both DeltaORF2-PRRSV and DeltaORF4-PRRSV viruses were propagated for 40-50 generations in the corresponding complementing cells and remained replication-defective in MARC-145 cells. To examine the immunogenic potential of the replication-defective PRRSV as vaccine candidates, four groups of pigs, 20 pigs per group, were immunized twice with DeltaORF2-PRRSV or DeltaORF4-PRRSV and challenged with the homologous virulent virus at 3 weeks post-immunization. In spite of the fact one group showed significant reduction in virus load, we could not demonstrate improvement from clinical diseases in this vaccination/challenge study. However, we did show that the cDNA clone of PRRSV can be a useful tool to genetically engineer PRRSV vaccine candidates and to study pathogenesis and viral gene functions.  相似文献   

5.
Experiments were designed to determine if porcine reproductive and respiratory syndrome virus (PRRSV) or Bordetella bronchiseptica could be transmitted through indirect airborne contact. Three principal pigs were infected with PRRSV, B. bronchiseptica or both. Five days after the principal pigs were challenged, the three principal pigs and one direct-contact pig were placed into one isolation tent together, and three indirect-contact pigs were placed into another isolation tent which received its air supply from the first isolation tent. Airborne transmission of B. bronchiseptica occurred in 5/5 trials where B. bronchiseptica was the only agent used, and in 3/5 trials where the principal pigs were coinfected with both agents. Airborne transmission of PRRSV occurred in 4/5 trials where PRRSV was the only agent used, and in 2/5 trials where the principal pigs were coinfected with both agents. Thus, airborne transmission of both agents over short distances, such as within a barn, is probable.  相似文献   

6.
抗独特型抗体对猪繁殖与呼吸综合征病毒感染的免疫作用   总被引：1，自引：0，他引：1  
用PRRSV感染SPF猪，血清检测结果显示，机体不仅产生抗PRRSV抗原的各种抗体(Ab1)，而且产生针对这些抗体的抗独特型抗体(Ab2)。根据各种蛋白质的等电点不同，应用IEF技术分离纯化出PRRSV感染猪血清中的不同IgG。分别以纯化的抗PRRSV—GP5蛋白、抗PRRSV-M蛋白的Ab2免疫SPF猪各5头，7d后经鼻腔感染PRRSV，定期采集血样进行病毒分离或鉴定试验。抗PRRSV-GP5蛋白的Ab2免疫的猪，其血样自感染后3～7d均检出PRRSV；3头猪在感染后14～63d未检出PRRSV；2头猪在感染后14～35d检出PRRSV，从42～56d转为阴性，其中1头猪在63d时检出PRRSV。抗PRRSV—M蛋白的Ab2免疫的猪，其血样自感染后3～7d均检出PRRSV；2头猪在感染后14～63d未检出PRRSV；3头猪在感染后14～35d检出PRRSV，从42～56d转为阴性，其中1头猪在63d时检出PRRSV。抗PRRSV—GP5和抗PRRSV—M蛋白的Ab2免疫作用显著，可作为PRRSV-GP5和PRRSV—M蛋白的替代抗原产生具有中和效应的抗体，保护机体免受PRRSV的感染。  相似文献   

7.
Porcine respiratory and reproductive syndrome virus (PRRSV) disease, one of the most economically significant viral diseases in the swine industry, is characterized by miscarriages, premature farrowing, stillborn pigs, and respiratory disease associated with death and chronic poor performance of nursing and weaned pigs. Interleukin-12 (IL-12) is a key component in driving the development of cell-mediated immunity as well as stimulating interferon-gamma (IFN-gamma) production from T cells and natural killer cells. Although some studies have investigated the use of IL-12 as a vaccine adjuvant in swine, little is known about its effectiveness as a treatment against viral diseases in swine. The present study investigated whether recombinant porcine IL-12 (rpIL-12) enhances the immune response and thereby diminishes the effects of PRRSV infection in young pigs. Interestingly, in vitro experiments demonstrated that rpIL-12 is capable of inducing swine pulmonary alveolar macrophages (PAMs), the target cells of PRRSV, to produce IFN-gamma in a dose and time dependent manner. In addition, in vitro studies also revealed that rpIL-12 treatment was capable of significantly reducing PRRSV viral titers in PAMs. In vivo administration of rpIL-12 significantly decreased PRRSV titers in the lungs and blood of infected animals. Furthermore, treatment with rpIL-12 prevented significant growth retardation in PRRSV-infected animals. Finally, in response to viral antigen recall challenge, PAMs isolated from rpIL-12-treated/PRRSV-infected animals produced greater amounts of IFN-gamma and lesser amounts of interleukin-10 than PAMs isolated from non-rpIL-12-treated/PRRSV-infected animals. Taken together our data indicate that treatment with rpIL-12 may provide an effective approach to control or ameliorate PRRSV-induced disease in swine.  相似文献   

8.
Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for significant economic losses in the porcine industry. Currently available commercial vaccines do not allow optimal and safe protection. In this study, replicating but nondisseminating adenovectors (rAdV) were used for the first time in pigs for vaccinal purposes. They were expressing the PRRSV matrix M protein in fusion with either the envelope GP5 wild-type protein (M-GP5) which carries the major neutralizing antibody (NAb)-inducing epitope or a mutant form of GP5 (M-GP5m) developed to theoretically increase the NAb immune response. Three groups of fourteen piglets were immunized both intramuscularly and intranasally at 3-week intervals with rAdV expressing the green fluorescent protein (GFP, used as a negative control), M-GP5 or M-GP5m. Two additional groups of pigs were primed with M-GP5m-expressing rAdV followed by a boost with bacterially-expressed recombinant wild-type GP5 or were immunized twice with a PRRSV inactivated commercial vaccine. The results show that the rAdV expressing the fusion proteins of interest induced systemic and mucosal PRRSV GP5-specific antibody response as determined in an ELISA. Moreover the prime with M-GP5m-expressing rAdV and boost with recombinant GP5 showed the highest antibody response against GP5. Following PRRSV experimental challenge, pigs immunized twice with rAdV expressing either M-GP5 or M-GP5m developed partial protection as shown by a decrease in viremia overtime. The lowest viremia levels and/or percentages of macroscopic lung lesions were obtained in pigs immunized twice with either the rAdV expressing M-GP5m or the PRRSV inactivated commercial vaccine.  相似文献   

9.
The present study characterized the homologous and heterologous immune response in type-I porcine reproductive and respiratory syndrome virus (PRRSV) infection. Two experiments were conducted: in experiment 1, eight pigs were inoculated with PRRSV strain 3262 and 84 days post-inoculation (dpi) they were challenged with either strain 3262 or strain 3267 and followed for the next 14 days (98 dpi). In experiment 2, eight pigs were inoculated with strain 3267 and challenged at 84 dpi as above. Clinical course, viremia, humoral response (neutralizing and non-neutralizing antibodies, NA) and virus-specific IFN-γ responses (ELISPOT) were evaluated all throughout the study. Serum levels of IL-1, IL-6, IL-8, TNF-α and TGF-β were determined (ELISA) after the second challenge. In experiment 1 primo-inoculation with strain 3262 induced viremia of ≤ 28 days, low titres of homologous NA but strong IFN-γ responses. In contrast, strain 3267 induced longer viremias (up to 56 days), higher NA titres (≤ 6 log2) and lower IFN-γ responses. Inoculation with 3267 produced higher serum IL-8 levels. After the re-challenge at 84 dpi, pigs in experiment 1 developed mostly a one week viremia regardless of the strain used. In experiment 2, neither the homologous nor the heterologous challenge resulted in detectable viremia although PRRSV was present in tonsils of some animals. Homologous re-inoculation with 3267 produced elevated TGF-β levels in serum for 7–14 days but this did not occur with the heterologous re-inoculation. In conclusion, inoculation with different PRRSV strains result in different virological and immunological outcomes and in different degrees of homologous and heterologous protection.  相似文献   

10.
A study was performed to evaluate the presence of porcine reproductive and respiratory syndrome virus (PRRSV) in pig meat collected at slaughterhouses and its potential transmission to pigs via pig meat. A total of 1039 blood samples were collected from pigs upon their arrival at the abattoir. The following day, meat samples (n = 1027) were collected from the carcasses of these same pigs. Samples originated from 2 Canadian slaughterhouses, 1 situated in the province of Quebec and the other situated in the province of Manitoba. Serum samples were tested for antibodies to PRRSV and both serum and meat samples were also tested for PRRSV nucleic acid by polymerase chain reaction (PCR). Seropositivity to PRRSV for all serum samples was 74.3%. Furthermore 45 (4.3%) of the total serum samples and 19 (1.9%) of the 1027 meat samples were positive for PRRSV by PCR. Sequence analysis of open reading frame (ORF) 5 performed on 15 of the 19 PRRSV strains identified in pig meat indicated that 9 were field strains and 6 were vaccine-like (98% to 99.7% nucleotide homology with the Ingelvac RespPRRS/Repro vaccine). One of these 6 strains presented an intermediate 2-6-2 restriction fragment length polymorphism (RFLP) cut pattern and the others showed the characteristic 2-5-2 RFLP pattern of the vaccine strain. All strains sequenced were determined to be North American strains. In only 1 of the 19 PRRSV-positive meat samples could PRRSV be isolated. To test the potential infectivity of meat samples containing residual PRRSV, 11 of the PCR-positive meat samples (weighing 1.05 to 1.8 kg) were each used in feeding experiments of 2 PRRSV antibody-negative specific pathogen-free pigs of 9 wk of age. Samples were cut into several pieces and fed to each pair of pigs on 2 consecutive days. Each pig pair was housed in a separate cubicle and serum samples were collected at -7, 0, 7, 14, and 20 to 21 days post exposure. Seven pig pairs were found to be infected by PRRSV following ingestion of meat samples, including meat samples containing vaccine-like virus, as judged by the demonstration of PRRSV antibodies and/or PRRSV nucleic acid in the serum. In summary, the present study indicated that low residual quantities of PRRSV may be found in a small percentage of pig meat collected at slaugtherhouses. Furthermore, when this meat was fed raw to pigs in the experimental setting designed, pigs could be infected by PRRSV.  相似文献   

11.
The effect of dietary Echinacea purpurea on performance, viremia, and ontogeny of the humoral antibody response against porcine reproductive and respiratory syndrome virus (PRRSV) infection was evaluated in weaned pigs. In three replicates, 120 weaned pigs (25 +/- 1 d of age; 8.46 +/- 0.48 kg of BW) from a PRRSV-naive herd were allotted randomly to one of eight pens (diets) in two separate rooms (four pens/room), with each pen containing five pigs. Pigs began one of four dietary treatments (as-fed basis) 1 wk before inoculation with PRRSV: 1) basal diet composed of corn, soybean meal, whey, and essential vitamins and minerals; 2) basal diet plus carbadox (0.055 g/kg of diet; as-fed basis); 3) basal diet plus Echinacea 2% (2% of the total diet); 4) basal diet plus Echinacea 4% (4% of the total diet). The diets were formulated to be isocaloric and isolysinic. Echinacea purpurea was purchased in powder form and determined by chemical analysis to contain 1.35% cichoric acid (as-fed basis). Seven days after starting the diets, all pigs in one room were intranasally inoculated with PRRSV isolate ATCC VR-2332 at a concentration of 10(4) tissue culture infectious dose50/mL. To monitor the effects of Echinacea and PRRSV challenge, BW and blood samples were obtained from all pigs at 7-d intervals. Serum samples were analyzed for the presence of PRRSV and PRRSV-specific antibodies. All challenged pigs became infected with PRRSV, and all unchallenged pigs remained free of infection. No differences (P > 0.10) in ADG, ADFI, or gain:feed (G:F) were observed in PRRSV-challenged compared with unchallenged animals. For PRRSV-challenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, or G:F ratio. Among PRRSV-challenged pigs, dietary Echinacea did not affect (P > 0.10) the rate or level of the ELISA-detectable antibody response from d 7 to 42 or the level and duration of PRRSV in serum. For PRRSV-unchallenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, and G:F ratio. Under the conditions of this study, dietary Echinacea did not enhance growth, exhibit antiviral effects to PRRSV, or show any evidence of immune enhancing properties.  相似文献   

12.
The objectives of this study was to investigate the role of DNA vaccines in the generation of an immune response and that elicited against individually encoded proteins of PRRSV. The genomic regions encoding ORF s 4, 5, 6 and 7 of the PRRS virus vaccine strain were cloned into the mammalian expression vector pc DNA 3.1 (+). Inoculations with the recombinant plasmids resulted in detection of PRRS virus-specific antibodies in 71 per cent of the immunized animals by ELISA, virus neutralization and/or Western blotting assays. In addition, cellular immune responses were detected in 86 per cent of the immunized pigs by interferon gamma assay and/or proliferation assay. Pigs in the control group had no detectable immune response to PRRS virus. The results obtained demonstrated that DNA immunization against PRRS virus results in the production of both humoral and cell mediated immune responses in pigs. The results also indicate that neutralization epitopes for PRRS virus are present on the viral envelope glycoproteins encoded by ORF 4 and ORF 5.  相似文献   

13.
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14.
Three-week-old cesarean-derived colostrum-deprived (CD/CD) pigs were inoculated with porcine circovirus type 2 (PCV2, n = 19), porcine reproductive and respiratory syndrome virus (PRRSV, n = 13), concurrent PCV2 and PRRSV (PCV2/PRRSV, n = 17), or a sham inoculum (n = 12) to compare the independent and combined effects of these agents. Necropsies were performed at 7, 10, 14, 21, 35, and 49 days postinoculation (dpi) or when pigs became moribund. By 10 dpi, PCV2/PRRSV-inoculated pigs had severe dyspnea, lethargy, and occasional icterus; after 10 dpi, mortality in this group was 10/11 (91%), and all PCV2/ PRRSV-inoculated pigs were dead by 20 dpi. PCV2-inoculated pigs developed lethargy and sporadic icterus, and 8/19 (42%) developed exudative epidermitis; mortality was 5/19 (26%). PRRSV-inoculated pigs developed dyspnea and mild lethargy that resolved by 28 dpi. Microscopic lesions consistent with postweaning multisystemic wasting syndrome (PMWS) were present in both PCV2- and PCV2/PRRSV-inoculated pigs and included lymphoid depletion, necrotizing hepatitis, mild necrotizing bronchiolitis, and infiltrates of macrophages that occasionally contained basophilic intracytoplasmic inclusion bodies in lymphoid and other tissues. PCV2/ PRRSV-inoculated pigs also had severe proliferative interstitial pneumonia and more consistent hepatic lesions. The most severe lesions contained the greatest number of PCV2 antigen-containing cells. PRRSV-inoculated pigs had moderate proliferative interstitial pneumonia but did not develop bronchiolar or hepatic lesions or lymphoid depletion. All groups remained seronegative to porcine parvovirus. The results indicate that 1) PCV2 coinfection increases the severity of PRRSV-induced interstitial pneumonia in CD/CD pigs and 2) PCV2 but not PRRSV induces the lymphoid depletion, granulomatous inflammation, and necrotizing hepatitis characteristic of PMWS.  相似文献   

15.
本试验构建了1株表达猪繁殖与呼吸综合征病毒(Porcine reproductive and respiratory syndrome virus,PRRSV)RF5/ORF6基因的重组鸡痘病毒,并进行了小鼠免疫实验,对其诱导BALB/c小鼠产生体液免疫和细胞免疫反应的能力进行了评价。结果表明,重组鸡痘病毒能够刺激免疫鼠产生特异性PRRSV ELISA抗体,促进特异性T淋巴细胞增殖。对免疫小鼠血清中细胞因子检测结果表明,IFN-γ的分泌显著提高。结果表明,所构建重组鸡痘病毒可以对小鼠起到良好的免疫效果,具有成为抗PRRSV感染新型疫苗的潜力。  相似文献   

16.
Thirty-three pigs affected by porcine dermatitis and nephropathy syndrome, 30 from Spain and three from the USA, were investigated in order to detect porcine circovirus (PCV) in their tissues. A standard in situ hybridisation technique using a specific DNA 317-bp probe based on a well-conserved sequence of PCV (which recognises both PCV-1 and PCV-2) was applied to formalin-fixed, paraffin-embedded tissues. Twenty-eight of the 30 Spanish pigs and all three American pigs had PCV in at least one tissue. Viral nucleic acid was detected mainly in lymphoid organs, and especially the lymph nodes. The viral genome was also found, in order of decreasing quantity, in Peyer's patches, tonsil, lung, spleen, kidney, liver, and skin. Viral nucleic acid was located mainly within the cytoplasm of monocyte/macrophage lineage cells, including follicular dendritic cells, macrophages, histiocytes and Kupffer cells. No viral nucleic acid was found in damaged glomeruli or arteriolar walls. In frozen samples available from three Spanish pigs, the virus was identified as type 2 by using the polymerase chain reaction and restriction fragment length polymorphism. Most of the pigs from which serum was available were seropositive against porcine respiratory and reproductive syndrome virus (PRRSV), and PRRSV antigen was detected in the lung of two of the Spanish pigs. These results suggested that PCV is present in tissues of almost all pigs affected by PDNS, and PCV has to be considered as a possible agent involved in the pathogenesis of the syndrome.  相似文献   

17.
Porcine reproductive and respiratory syndrome (PRRS) is now considered to be one of the most important diseases in countries with intensive swine industries. The two major membrane-associated proteins of porcine reproductive and respiratory syndrome virus (PRRSV), GP5 and M (encoded by ORF5 and ORF6 genes, respectively), are associated as disulfide-linked heterodimers (GP5/M) in the virus particle. In this study, we designed 5 of the small hairpin RNAs (shRNAs) targeting the GP5 and M gene of PRRSV respectively, and investigated their inhibition to the production of PRRSV. The highest activity displayed in shRNAs of the ORF6e sequence (nts 261-279), which the inhibition rate reached was 99.09%. The result suggests that RNAi technology might serve as a potential molecular strategy for PRRSV therapy. Furthermore, the transgenic Marc-145 cell line of piggyBac transposon-derived targeting shRNA interference against PRRS virus was established. It presented stable inhibition to the replication and amplification of PRRS. The work implied that shRNAs targeting the GP5 and M gene of PRRSV may be used as potential RNA vaccines in vivo, and supplied the screening methods of transformed pig embryonic fibroblast which are prerequisite for the disease-resistant transgenic pigs to PRRS.  相似文献   

18.
为了解Nsp2Δ1882-2241缺失后弱化的高致病性PRRSV（TJM株）对宿主免疫学应答的刺激机理,本研究分析了免疫猪血清中的细胞因子及变化规律。将14头4周龄易感仔猪随机分为3组：第1组接种PRRSV TJM-F92株,为免疫组;第2组接种高致病性PRRSV TJ-F5毒株,为攻毒组;第3组不接种疫苗及病毒,为对照组。接种后28d,用TJ-F5毒株攻击试验猪,于不同时间点采集血样,用ELISA法测定血清中的PRRSV抗体、IL-2、IL-10、IL-12p40、TNF-α、IFN-α和IFN-β水平。结果显示：（1）与对照组和攻毒组相比,免疫组猪IL-12p40水平持续上调,于免疫后28d受PRRSV强毒攻击后,其水平开始缓慢降低,但仍高于攻毒后的对照组。（2）免疫组IL-2水平在接种疫苗后的前21d内无明显升高且低于攻毒组,在受到强毒攻击后其IL-2水平却有明显升高。（3）免疫组IL-10水平与对照组无明显差别,并在免疫14d后一直显著低于攻毒组（P〈0.01）。（4）免疫组接种疫苗后的前21d内,TNF-α水平保持稳定,28d明显上调。攻毒组TNF-α水平0～28d一直低于对照组,且在21d达到最低（P〈0.01）。免疫组在28d受强毒攻击后,其TNF-α水平下降且在攻毒7d时最为明显（P〈0.01）,此后恢复到正常水平。（5）免疫组免疫后28d时IFN-α水平升高,在受到强毒攻击后再次显著降低（P〈0.01）。免疫组IFN-β水平一直低于对照组和攻毒组,不因强毒攻击而变化。以上结果提示,IL-12上调在PRRSV免疫保护中起明显作用;另外,上调TNF-α及下调IL-10都是基因缺失疫苗发挥效力的潜在机制。  相似文献   

19.
The objective of this study was to evaluate if spray dried porcine plasma (SDPP) containing porcine circovirus type 2 (PCV2) genome supplemented in feed could transmit PCV2 to pigs challenged with porcine reproductive and respiratory syndrome virus (PRRSV). Twenty-three PRRSV-free pigs, non-viraemic for PCV2, were housed in bio-safety level 3 facilities and assigned to four groups in a 2×2 factorial design consisting of PRRSV challenge and a negative control. The diet contained 0 or 8kg SDPP per 100kg of feed. PRRSV challenge groups were inoculated intranasally with 2mL of a suspension containing 10(6) TCID(50)/mL PRRSV. The SDPP used in the study contained 7.56×10(5) PCV2 genome copies per gram. Dietary treatments were fed from 4days prior to PRRSV inoculation until 28days post-inoculation (PI). All challenged pigs developed PRRSV viraemia by day 3PI and PRRSV antibodies were detected in sera by day 14PI, with no difference between diet treatments. Neither PRRSV viraemia nor seroconversion was observed in non-challenged pigs. PCV2 was not detected in the serum of any pigs throughout the experimental period. SDPP containing the PCV2 genome supplemented in feed did not result in PCV2 transmission to either healthy or PRRSV-infected pigs under these experimental conditions.  相似文献   

20.
The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea.  相似文献   

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