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1.
The early cytokines interferon-alpha (IFN-alpha), tumour necrosis factor-alpha (TNF-alpha), interleukin-1, -6 and -8 (IL-1, -6, -8) are produced during the most early stage of an infection. The activities of these cytokines have been studied extensively in vitro and in rodents, but in vivo studies on the role of these cytokines in infectious diseases of food animals are few. This review concentrates on in vivo studies of cytokine involvement in infectious respiratory diseases of swine, with an emphasis on viral infections. First evidence for the role of early cytokines in pneumonia in swine came from experimental infections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. The role of TNF-alpha and IL-1 in the symptoms and pathology of porcine pleuropneumonia has recently been proven by use of an adenovirus vector expressing the anti-inflammatory IL-10. In the authors' laboratory, studies were undertaken to investigate the relationship between viral respiratory disease and bioactive lung lavage levels of IFN-alpha, TNF-alpha, IL-1 and IL-6. Out of three respiratory viruses-porcine respiratory coronavirus (PRCV), porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV)-only SIV induced acute respiratory disease and severe lung damage by itself. Disease and lung pathology were tightly associated with the simultaneous production of IFN-alpha, TNF-alpha, IL-1 and IL-6. In challenge studies of SIV-vaccinated pigs, levels of IFN-alpha, TNF-alpha and IL-6, but not IL-1 were correlated with clinical and virological protection. Multifactorial respiratory disease was reproduced by combined inoculations with PRCV or PRRSV followed by LPS from Escherichia coli. In comparison with the respective single inoculations, which were subclinical, there was a true potentiation of disease and production of TNF-alpha, IL-1 and IL-6. TNF-alpha and IL-6 were best correlated with disease. In further studies, we will use more specific strategies to dissect the role of cytokines during viral infections. 相似文献
2.
The acute stages of infection with swine influenza virus (SIV), porcine respiratory coronavirus (PRCV) and porcine reproductive-respiratory syndrome virus (PRRSV) were shown to differ in terms of clinical and lung inflammatory effects and proinflammatory cytokine profiles in bronchoalveolar lavage (BAL) fluids. Caesarian-derived colostrum-deprived pigs were inoculated intratracheally with one of the three viruses. SIV infection was followed within 1 day post inoculation (d PI) by characteristic respiratory and general signs, and excessive lung epithelial desquamation and neutrophil infiltration (38 to 56 per cent of BAL cells at 1 d PI vs 0 to 1 per cent in controls). High concentrations of bioactive interferon-alpha (IFN -alpha), tumour necrosis factor-alpha (TNF -alpha) and interleukin-1 (IL -1) coincided with peak symptoms and neutrophil infiltration. PRCV infection was asymptomatic and produced a mild bronchointerstitial pneumonitis and neutrophil infiltration (13 to 22 per cent of BAL cells at 4 d PI). IFN -alpha titres parallelled those found during SIV infection, TNF -alpha was negligible and IL -1 undetectable. PRRSV infection induced anorexia and lethargy between 3 and 5 d PI. There was marked infiltration with mononuclear cells in alveolar septa and BAL fluids between 7 and 10 d PI, while neutrophils remained at less than 11 per cent of BAL cells at any time. IL -1 was produced from three throughout 10 d PI, while IFN -alpha production was minimal and TNF -alpha undetectable. These data strongly suggest that proinflammatory cytokines can be important mediators of viral respiratory disease. 相似文献
3.
This paper reviews in vivo studies on the interaction between porcine reproductive and respiratory syndrome virus (PRRSV) and LPS performed in the authors' laboratory. The main aim was to develop a reproducible model to study the pathogenesis of PRRSV-induced multifactorial respiratory disease. The central hypothesis was that respiratory disease results from an overproduction of proinflammatory cytokines in the lungs. In a first series of studies, PRRSV was shown to be a poor inducer of TNF-alpha and IFN-alpha in the lungs, whereas IL-1 and the anti-inflammatory cytokine IL-10 were produced consistently during infection. We then set up a dual inoculation model in which pigs were inoculated intratracheally with PRRSV and 3-14 days later with LPS. PRRSV-infected pigs developed acute respiratory signs for 12-24h upon intratracheal LPS inoculation, in contrast to pigs inoculated with PRRSV or LPS only. Moreover, peak TNF-alpha, IL-1 and IL-6 titers were 10-100 times higher in PRRSV-LPS inoculated pigs than in the singly inoculated pigs and the cytokine overproduction was associated with disease. To further prove the role of proinflammatory cytokines, we studied the effect of pentoxifylline, a known inhibitor of TNF-alpha and IL-1, on PRRSV-LPS induced cytokine production and disease. The clinical effects of two non-steroidal anti-inflammatory drugs (NSAIDs), meloxicam and flunixin meglumine, were also examined. Pentoxifylline, but not the NSAIDs, significantly reduced fever and respiratory signs from 2 to 6h after LPS. The levels of TNF-alpha and IL-1 in the lungs of pentoxifylline-treated pigs were moderately reduced, but were still 26 and 3.5-fold higher than in pigs inoculated with PRRSV or LPS only. This indicates that pathways other than inhibition of cytokine production contributed to the clinical improvement. Finally, we studied a mechanism by which PRRSV may sensitize the lungs for LPS. We hypothesized that PRRSV would increase the amount of LPS receptor complex in the lungs leading to LPS sensitisation. Both CD14 and LPS-binding protein, two components of this complex, increased significantly during infection and the amount of CD14 in particular was correlated with LPS sensitisation. The increase of CD14 was mainly due to infiltration of strongly CD14-positive monocytes in the lungs. The PRRSV-LPS combination proved to be a simple and reproducible experimental model for multifactorial respiratory disease in pigs. To what extent the interaction between PRRSV and LPS contributes to the development of complex respiratory disease is still a matter of debate. 相似文献
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5.
Combinations of porcine respiratory coronavirus (PRCV) and either of two swine influenza viruses (H1N1 or H3N2) were administered intranasally and by aerosol to six- to eight-week-old specific pathogen-free pigs. The clinical responses, gross respiratory lesions and growth performances of these pigs were studied and compared with those of single (PRCV, H1N1 or H3N2) and mock-infected animals. PRCV infection caused fever, growth retardation and lung lesions, but no respiratory symptoms. Infection with swine influenza viruses caused rather similar, mild symptoms of disease, with H1N1 infection being the least severe. Combined infections with influenza viruses and PRCV did not appear to enhance the pathogenicity of these viruses. Furthermore, viruses were isolated more frequently from tissues and nasal swabs taken from 'single' than 'dual' infected animals, suggesting a possible in vivo interference between replication of PRCV and swine influenza virus. 相似文献
6.
Pathogenesis of porcine Actinobacillus pleuropneumonia, part II: roles of proinflammatory cytokines. 
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下载免费PDF全文 H Huang A A Potter M Campos F A Leighton P J Willson D M Haines W D Yates 《Canadian journal of veterinary research》1999,63(1):69-78
The in vitro production of proinflammatory cytokines after stimulation with Actinobacillus pleuropneumoniae and the relation of these cytokines in vivo with the disease caused by A. pleuropneumoniae were investigated. Within 24 h, in vitro stimulation by A. pleuropneumoniae (serotype 1) preparations, including killed bacteria, bacterial culture supernatant, lipopolysaccharide, and bacterial extracts, porcine pulmonary alveolar macrophages (PAM) produced significant (P < 0.05) amounts of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) as measured by bioassays. The supernatants containing interleukin-8 from PAM after stimulation by bacterial preparations showed significant neutrophil chemotaxis, while bacterial preparations alone did not. After in vivo infection with A. pleuropneumoniae, the mean levels of TNF-alpha and IL-1 in serum, as measured by bioassays, were elevated 37- to 27836-fold for TNF-alpha and 11- to 5941-fold higher for IL-1 within 4 d post-infection, depending on the treatments, and remained elevated up to Day 7. Both cytokines were also detected in porcine lungs by bioassays and immunocytochemistry. The results indicated that both secreted and surface components of A. pleuropneumoniae can stimulate PAM to produce proinflammatory mediators. Neutrophil chemoattractants rather than bacterial components are the major factor causing acute lung inflammation. The elevation of TNF-alpha and IL-1 in pigs occurred coincident with the onset of acute clinical disease. 相似文献
7.
Chang HW Jeng CR Liu JJ Lin TL Chang CC Chia MY Tsai YC Pang VF 《Veterinary microbiology》2005,108(3-4):167-177
Two common viral pathogens of swine, namely, porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV), were investigated in regard to their effects on monolayer cultures of swine alveolar macrophages (AMs). The purpose was to identify selected cellular changes and responses potentially associated with the clinical reactions of pigs infected with either or both of these viruses. Measurements included the (1) absolute and relative numbers of infected, viable, and apoptotic cells; (2) distribution of viral antigens; (3) levels of interferon-alpha (IFN-alpha) and tumor necrosis factor-alpha (TNF-alpha) produced and their association with the extent of virus-induced cytopathology. Four groups of AMs were studied, including mock-infected, PCV2 alone-infected (PCV2-A), PRRSV alone-infected (PRRSV-A), and PCV2 and PRRSV dually infected (PCV2/PRRSV) groups. The AMs of PCV2-A group had high antigen-containing rate without cell death. There was a marked increase in cell death and apoptosis in PRRSV-A group. However, a lower PRRSV-induced infectious rate, cell death, and apoptosis were seen in PCV2/PRRSV group. High levels of IFN-alpha production were detected in PCV2-infected groups, but not in mock-infected and PRRSV-A groups. The PRRSV-induced cytopathic effect (CPE) on MARC-145 cells or swine AMs was markedly reduced by pre-incubation of the cells with UV-treated or non-UV-treated supernatants of PCV2-infected AMs. In addition, the reduction in CPE was abolished when the supernatants of PCV2-infected AMs were pre-treated with a mouse anti-recombinant porcine IFN-alpha antibody. The results suggest that swine AMs were an important reservoir of PCV2; PCV2 infection reduced PRRSV infection and PRRSV-associated CPE in PCV2/PRRSV AMs; the reduction of PRRSV infection in AMs was mediated by IFN-alpha generated by PCV2 infection. The reduced PRRSV-associated CPE in AMs and increased pro-inflammatory cytokine production may lead to a more severe pneumonic lesion in those dually infected pigs. 相似文献
8.
The effect of a bacterial infection on interferon-alpha (IFN-alpha) and interleukin-6 (IL-6) production by porcine cells was studied in specific pathogen-free (SPF) pigs, infected intranasally with Actinobacillus pleuropneumoniae serotype 2. Three experimental groups of five pigs were used: infected non-treated pigs, infected pigs that were treated with enrofloxacin at disease onset, and non-infected, non-treated control pigs. Blood samples were collected from all pigs on the day of infection and on days 1, 4, 7, 13 and 17 post-infection. Sera were analysed for presence of antibodies to A. pleuropneumoniae and for the cytokines IL-6 and IFN-alpha. Ability to produce these cytokines was tested in vitro using whole blood cultures stimulated with inactivated virus (Aujeszky's disease virus infected porcine kidney cells (ADV/PK-15)), inactivated bacteria (A. pleuropneumoniae) or bacterial plasmid (pcDNA3). All cytokine inducers were used neat or pre-incubated with the transfectious agent lipofectin. IL-6 appeared in the serum of all infected non-treated animals but no IFN-alpha was found in the serum of any of the experimental pigs. Accordingly, the bacteria induced a substantial IL-6 but hardly any IFN-alpha production when tested in vitro. However, following incubation with lipofectin, the inactivated bacteria as well as pcDNA3 became efficient inducers of IFN-alpha in whole blood cultures. The increased IFN-alpha production, previously recorded in vitro during the acute phase of infection with A. pleuropneumoniae, was confirmed using lipofected plasmid DNA and it was indicated that leukocytes obtained from infected but apparently cured animals also exhibited an increased production of IFN-alpha. Thus, even mild/sub-clinical bacterial infections may affect cytokine production in pigs. 相似文献
9.
Fablet C Marois-Créhan C Simon G Grasland B Jestin A Kobisch M Madec F Rose N 《Veterinary microbiology》2012,157(1-2):152-163
A study was carried out in 125 farrow-to-finish pig herds to assess the relationships between pathogens involved in respiratory disorders and to relate these findings to clinical signs of respiratory diseases and pneumonia and pleuritis at slaughter. Clinical examination and sampling were carried out on four different batches in each herd (pigs aged 4, 10, 16 and 22 weeks). Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, swine influenza viruses (SIV), porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) were detected by serological or PCR tests. Pneumonia-like gross lesions and pleuritis were scored at the slaughterhouse. The results indicate that the percentage of pigs PCR-positive for PCV2 at 4, 10 and 16 weeks old was associated with the percentage of pigs PCR-positive for M. hyopneumoniae at these ages. On the other hand, the percentage of pigs with antibodies against PRRSV at 10, 16 and 22 weeks was positively correlated with the percentage of pigs seropositive for M. hyopneumoniae at 22 weeks, with the percentage of pigs with antibodies against SIV H1N1 and SIV H1N2 and the percentage of pigs sero-positive for A. pleuropneumoniae serotype 2. The findings also indicate that, within the five studied pathogens, M. hyopneumoniae, PRRSV and SIV H1N1 are the major pathogens involved in pneumonia-like gross lesions even though PCV2 may play a role. A. pleuropneumoniae serotype 2, in association with PRRSV, is significantly associated with extensive pleuritis. Respiratory diseases could be significantly reduced by implementing measures including appropriate management practices to control these pathogens. 相似文献
10.
The role of swine torque teno sus viruses (TTSuVs) as co-factors in disease syndromes involving porcine circovirus strain 2 (PCV2) and porcine reproductive and respiratory disease syndrome virus (PRRSV) has been a debatable subject. In this study, the prevalence of TTSuVs in Iowa, the leading pork producing state in the U.S., was estimated by a duplex PCR. The PCR is capable of simultaneously detecting both teno sus viruses 1 and 2 (TTSuV1 and 2). Based on an analysis of 300 random samples representing six major geographical regions of the state, the overall prevalence rates for TTSuV1 and 2 were 47.34% and 24.67% respectively while the combined prevalence rate was 52.33%. The epidemiological association of TTSuV1 and 2 with the common etiological agents of the porcine respiratory disease complex (PRDC) namely porcine PRRSV, PCV2, Mycoplasma hyopneumoniae and swine influenza virus (SIV) was estimated in lung tissue derived from 45 pigs showing clinical signs of PRDC. Notably, 86.67% of the PRDC-suspect samples were positive for TTSuV1 in comparison to the baseline population prevalence rate of 47.34%. However, the prevalence of TTSuV2 (26.67%) was not significantly different. TTSuV1 was detected in 80.00%, 81.81%, 75.00% and 77.78% of the PRRSV, SIV, M. hyopneumoniae and PCV2 positive PRDC-suspect samples respectively. Our results indicate that TTSuV1 is strongly associated with clinical PRDC and support the hypothesis that TTSuVs might function as co-factors in PRDC. Further studies to define their possible role in the pathogenesis of swine respiratory diseases are warranted. 相似文献
11.
Xue Q Zhao YG Zhou YJ Qiu HJ Wang YF Wu DL Tian ZJ Tong GZ 《Veterinary immunology and immunopathology》2004,102(3):291-298
In the present study, five eukaryotic double-gene expression plasmids containing porcine reproductive and respiratory syndrome virus (PRRSV) ORF5 and ORF7 genes combined with cDNAs encoding porcine IFNgamma and IL-2 were constructed for evaluation as PRRSV vaccine candidates. After immunization and viral challenge, two of three pigs immunized with pIRESorf5/IFNgamma, one of three pigs immunized with pIRESorf5/IL-2 and one of three pigs immunized with pIRESorf7/IL-2 were protected from lung lesions that were present in other vaccinated and control animals. Virus replication was reduced but not completely prevented in organs of the DNA-vaccinated animals as compared to controls. Therefore, the porcine cytokines IFNgamma and IL-2, delivered in combination with ORF5 or ORF7, may improve the immune efficacy of DNA vaccines against PRRSV. 相似文献
12.
Dorr PM Baker RB Almond GW Wayne SR Gebreyes WA 《Journal of the American Veterinary Medical Association》2007,230(2):244-250
OBJECTIVE: To identify important pathogens and characterize their serologic and pathologic effects in porcine circovirus type 2 (PCV2)-infected pigs in relation to pig age and type of swine production system. DESIGN: Cross-sectional study. ANIMALS: 583 conventionally reared pigs. PROCEDURES: 3- (n = 157), 9- (149), 16- (152), and 24-week-old (125) pigs from 41 different 1-, 2-, and 3-site production systems (5 pigs/age group/farm) were euthanized and necropsied. Pigs with and without PCV2 infection were identified (via PCR assay); infection with and serologic responses to other pathogens and pathologic changes in various tissues (including lungs) were assessed. Logistic regression models were constructed for effects overall and within each age group and type of production system. RESULTS: Compared with PCV2-negative pigs, PCV2-positive pigs were more likely to have swine influenza virus (SIV) type A and Mycoplasma hyopneumoniae infections and sample-to-positive (S:P) ratios for SIV H1N1 from 0.50 to 0.99; also, PCV2-positive pigs had higher serum anti-porcine reproductive and respiratory syndrome virus (PRRSV) antibody titers and more severe lung tissue damage. Infection with SIV (but lower SIV H1N1 S:P ratio) was more likely in 3-week-old PCV2-positive pigs and evidence of systemic disease was greater in 16-week-old PCV2-positive pigs than in their PCV2-negative counterparts. By site type, associations of coinfections and disease effects between PCV2-positive and -negative pigs were greatest in 3-site production systems. CONCLUSIONS AND CLINICAL RELEVANCE: In PCV2-positive pigs, coinfections with SIV, M. hyopneumoniae, and PRRSV are important, having the greatest effect in the early to late nursery phase and in 3-site production systems. 相似文献
13.
Gutiérrez-Martín CB Rodríguez-Delgado O Alvarez-Nistal D De La Puente-Redondo VA García-Rioja F Martín-Vicente J Rodríguez Ferri EF 《Research in veterinary science》2000,68(1):9-13
A total of 198 pigs with tachypnoea and temperature >/= 40 degrees C were selected on a Spanish finishing unit, and their sera were examined for antibodies to Actinobacillus pleuropneumoniae (App), porcine reproductive and respiratory syndrome virus (PRRSV), Aujeszky' disease virus (ADV), and swine influenza virus (SIV). Eighty-nine point nine per cent of the pigs were seropositive to App, 88.6 per cent to PRRS, 73.0 per cent to ADV, and 30.6 per cent to SIV. Thirty-one pigs (15.6 per cent) were seropositive for App, PRRSV, ADV and SIV, and only one (0.5 per cent) was seronegative for all. Statistical association was assessed for dual infections but it was not found in any case (P > 0.05). Other parameters (dyspnoea, nasal discharge and coughing) were also recorded, and no significant associations between them and the presence of antibodies against any of the four infections was found. 相似文献
14.
Jamie R. V. Sookhoo Arianne Brown-Jordan Lemar Blake Ridley B. Holder Sharon M. Brookes Stephen Essen Christine V. F. Carrington Ian H. Brown Christopher A. L. Oura 《Tropical animal health and production》2017,49(6):1117-1124
The objective of this study was to evaluate the seroprevalence and identify the strains of swine influenza virus (SwIV), as well as the seroprevalence of porcine parvovirus (PPV), transmissible gastroenteritis virus (TGEV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine respiratory coronavirus (PRCV), porcine circovirus type 2 (PCV-2), and classical swine fever virus (CSFV) in pigs in Trinidad and Tobago (T&T). Blood samples (309) were randomly collected from pigs at farms throughout T&T. Serum samples were tested for the presence of antibodies to the aforementioned viruses using commercial ELISA kits, and the circulating strains of SwIV were identified by the hemagglutination inhibition test (HIT). Antibodies against SwIV were detected in 114 out of the 309 samples (37%). Out of a total of 26 farms, 14 tested positive for SwIV antibodies. HI testing revealed high titers against the A/sw/Minnesota/593/99 H3N2 strain and the pH1N1 2009 pandemic strain. Antibodies against PPV were detected in 87 out of the 309 samples (28%), with 11 out of 26 farms testing positive for PPV antibodies. Antibodies against PCV-2 were detected in 205 out of the 309 samples tested (66%), with 25 out of the 26 farms testing positive for PCV-2 antibodies. No antibodies were detected in any of the tested pigs to PRRSV, TGEV, PRCV, or CSFV. 相似文献
15.
Choi YK Goyal SM Joo HS 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(9):735-737
Twenty-eight hundred and seventy-two cases of respiratory disease in pigs were analyzed for their etiologic agents. Two or more pathogens were detected from 88.2% of the cases, indicating that porcine reproductive and respiratory syndrome virus (PRRSV) or swine influenza virus (SIV) combined with other bacterial agents was a common cause for porcine respiratory diseases in the mid-western USA. 相似文献
16.
Zelnickova P Leva L Stepanova H Kovaru F Faldyna M 《Veterinary immunology and immunopathology》2008,124(3-4):367-378
The aim of the present study was to determine postnatal ontogeny of proinflammatory cytokines IL-1beta, IL-8 and TNF-alpha production by in vitro stimulated porcine blood leukocytes. Four age categories of pigs were chosen. Cytokine production was determined using intracellular flow cytometry. It was found that IL-8 and TNF-alpha production by blood monocytes significantly increased during the postnatal period while production of IL-1beta remained unchanged. In blood neutrophils, the IL-8 production increased only during the postnatal period, while the levels of TNF-alpha and IL-1beta were undetectable during the whole postnatal period. Generally, the most intensive changes in cytokine production occurred before weaning. The production of low levels of cytokines by monocytes and neutrophils from young pigs was not caused by a delayed cytokine response because the cytokine production after 8-h stimulation was lower than that after 4-h stimulation in all age categories. The ontogenetical changes showed the same trends when two different stimulators (LPS, heat-inactivated E. coli) were used, suggesting that the ontogenetical changes are not caused by a simple defect in one signalling pathway, but it is probably a more complex process. No differences in cytokine production between the whole blood and the isolated cells supplemented with newborn or adult serum were found. Thus the ability of newborn monocytes and neutrophils to produce proinflammatory cytokines was not decreased due to the influence of composition of the microenvironment, where the cells were present. In conclusion, the ability of porcine blood leukocytes to produce cytokines develops during postnatal life. 相似文献
17.
Regula G Lichtensteiger CA Mateus-Pinilla NE Scherba G Miller GY Weigel RM 《Journal of the American Veterinary Medical Association》2000,217(6):888-895
OBJECTIVE: To compare serologic testing with slaughter evaluation in assessing effects of subclinical infection on average daily weight gain (ADG) in pigs. DESIGN: Cohort study. ANIMALS: 18 cohorts (30 to 35 pigs/cohort) of pigs on/farms. PROCEDURE: Blood samples were collected, and pigs were weighed at 8, 16, and 24 weeks of age. Sera were tested for antibodies to porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), transmissible gastroenteritis virus (TGEV), pseudorabies virus, Mycoplasma hyopneumoniae, and Actinobacillus pleuropneumoniae. At slaughter, skin, nasal turbinates, lungs, and liver were examined. Associations between ADG and results of serologic testing and slaughter evaluation were examined by use of multiple linear regression. RESULTS: Pathogens that had a significant effect on any given farm during any given year and the magnitude of that effect varied. However, at 16 and 24 weeks of age, a higher antibody titer was consistently associated with a lower ADG. Mean differences in ADG between seropositive and seronegative pigs were 18 g/d (0.04 lb/d) for SIV, 40 g/d (0.09 lb/d) for PRRSV, 38 g/d (0.08 lb/d) for M hyopneumoniae, and 116 g/d (0.26 lb/d) for TGEV. Of the evaluations performed at slaughter, only detection of lung lesions was consistently associated with a decrease in ADG. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that subclinical infection with any of a variety of pathogens commonly found in swine herds was associated with a decrease in ADG. Serologic testing was more effective than slaughter evaluation in assessing the impact of subclinical infection on ADG in these pigs. 相似文献
18.
A retrospective study on pig lung tissues from 60 cases of proliferative and necrotizing pneumonia (PNP) was performed to determine the presence of porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), and porcine circovirus type 2 (PCV2) in these lesions. Cases selected included 30 cases diagnosed between 1988 and 1992 and 30 cases diagnosed between 1997 and 2001. In each group of 30 cases, 10 were from suckling piglets, whereas the other 20 were from postweaned animals representing either nursery or grower-finisher pigs. Immunohistochemistry using a monoclonal antibody to influenza virus type A was used to determine the presence of SIV, and in situ hybridization was used for the detection of PRRSV and PCV2 nucleic acids. PRRSV was detected in 55 of the 60 cases examined (92%), PCV2 in 25 cases (42%), and SIV in only 1 case (2%). In 30 cases (50%), PRRSV was the only virus detected, whereas in 25 other cases (42%), a combination of PRRSV and PCV2 could be detected in the lungs with PNP lesions. PCV2 could not be detected in the lungs of suckling pigs with PNP. All PCV2-positive cases were found in postweaned pigs and were always in combination with PRRSV. In this latter age group, PCV2 was detected in 63% of the cases (25/40). Data from our study indicate that SIV is rarely identified in PNP and that PCV2 infection is not essential for the development of PNP lesions. The results of the present study demonstrate that PRRSV is consistently and predominantly associated with PNP and should be considered the key etiologic agent for the condition. 相似文献
19.
Meier WA Husmann RJ Schnitzlein WM Osorio FA Lunney JK Zuckermann FA 《Veterinary immunology and immunopathology》2004,102(3):299-314
Immunization of pigs with a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine initially elicits a weak interferon (IFN)-gamma response. To improve the immune response, an adjuvant consisting of plasmid encoding either porcine interleukin (IL)-12 or IFN-alpha was co-administered during vaccination. In the presence of either adjuvant, at least a three-fold increase in the primary virus-specific IFN-gamma response was observed. While this enhancement was only transient (1 week) when the IL-12 expressing plasmid was used, the effect was not only still apparent at 6 weeks after vaccination in the presence of the IFN-alpha expressing plasmid but even after challenge with a virulent genetically divergent PRRSV. In contrast, no effect of either adjuvant on the production of anti-virus antibodies was noticed throughout the study. Despite the apparent augmentation of a T helper (Th) 1 type response by the inclusion of IFN-alpha or IL-12 during vaccination, this modulation did not necessarily correlate with a reduction in viremia. Since a similar increase in the degree of the IFN-gamma response to the PRRSV vaccine could be achieved by substituting polyinosinic-polycytidylic acid in lieu of either cytokine, exposure to PRRSV in the presence of a variety of Th 1 polarizing molecules can positively influence the development of the cell-mediated immune response of swine to this pathogen. Conceivably, such intervention could be applied to improve the formulation of anti-PRRSV vaccines. 相似文献
20.
Previous studies demonstrated that experimental dual infections of pigs with porcine reproductive and respiratory syndrome virus (PRRSV) followed by H1N1 influenza virus cause more severe disease and growth retardation than the respective single virus infections. Here three experiments were undertaken to better define the clinical impact of combined PRRSV‐H1N1 infections in conventional and caesarean‐derived colostrum‐deprived (CDCD) pigs. Groups of pigs were inoculated by aerosol with PRRSV followed by H1N1 at 3‐, 7‐ or 14‐day intervals. During the post‐H1N1 period, mean body temperatures, respiratory signs and mean weight gains in the PRRSV‐H1N1 inoculated groups were recorded and compared with those in uninoculated controls (experiments 1 and 2) or in singly virus‐inoculated pigs (experiment 3). In a first experiment with conventional pigs, the PRRSV‐3d‐H1N1 and PRRSV‐7d‐H1N1 infections induced mean body temperatures >40.5°C during 8 days (peaks 41.1 and 41.6°C, respectively) and mean growth reductions of 3.4 and 4.8 kg, respectively, during the 2 weeks after H1N1, along with marked depression and respiratory disease. The PRRSV‐14d‐H1N1 infection, on the contrary, was largely subclinical. In a second experiment with conventional pigs, PRRSV‐3d‐H1N1 and PRRSV‐7d‐H1N1 infections were clinically milder, with smaller increases in mean body temperatures (peak 40.5°C in both groups) and growth reductions (1.4 and 1.6 kg, respectively). In both groups, only one pig showed prominent general and respiratory signs. In a final experiment with CDCD pigs, PRRSV‐7d‐H1N1 infection had minimal effects on mean clinical performances and growth and, except for one pig that was severely affected, differences with the single virus inoculations were negligible. Thus, both the time interval between infections and the sanitary status of pigs can affect the clinical outcome of dual PRRSV‐H1N1 infections. However, factors so far unknown seem to cause large variations in the clinical response between individual pigs. 相似文献