Humane endpoints in the efficacy testing of swine erysipelas vaccines.
For licensing the efficacy of vaccines for veterinary use has to be demonstrated by well-controlled laboratory experiments in which vaccinated and untreated animals of the target species are challenged. Erysipelas challenge tests cause extreme suffering of the unprotected animals with high fever, apathy, large skin lesions, and even death. This paper describes a standardised procedure for the vaccination challenge test and gives due consideration to the welfare of the animals. By monitoring and using clinical signs observed during the test it is possible to minimise animal pain and distress, thus preventing unnecessary animal suffering. (+info)
Detection of cytokine activated chondrocytes in arthritic joints from pigs infected with Erysipelothrix rhusiopathiae.
Chronic polyarthritis was induced in pigs by injection of Erysipelothrix rhusiopathiae and the in vivo activation of chondrocytes by cytokines was then investigated in the affected joints by immunocytochemistry. A polyclonal antiserum which recognises surface markers on in vitro interleukin 1 activated porcine chondrocytes was used to detect activated chondrocytes in all zones of the cartilage from diseased joints. In contrast, cartilage removed from an unaffected joint in the same animal showed no chondrocyte activation. Inflammatory synovial tissue removed from diseased joints and cocultured with cartilage from the unaffected joint induced activation of adjacent chondrocytes. The presence of interleukin 1 in the inflammatory cells of the synovium was confirmed and major histocompatibility complex (MHC) class II antigens were detected as a marker of synovial activation. Chondrocytes were found not to express class II antigens in cartilage from either the diseased or the unaffected joint. These observations show that the porcine erysipelas model of arthritis will be useful in facilitating a novel approach to monitoring the behaviour of individual chondrocytes under pathophysiological conditions. (+info)
Enzyme-linked immunosorbent assay employing a recombinant antigen for detection of protective antibody against swine erysipelas.
The specificities and sensitivities of five recombinant proteins of the surface protective antigen (SpaA) of Erysipelothrix rhusiopathiae were examined by indirect enzyme-linked immunosorbent assay (ELISA) with the aim of developing a reliable serological test for the detection of protective antibody against E. rhusiopathiae. Fully mature protein and the N-terminal 416 amino acids (SpaA416) showed sufficient antigenicities, and further examination was done with SpaA416 because of its higher yield. The antibody titers of pigs experimentally immunized with commercial live vaccine and two types of inactivated vaccines clearly increased after immunization, and all pigs were completely protected against challenge with virulent strains. On the other hand, the antibody titers of nonimmunized control pigs remained very low until they were challenged, and all showed severe symptoms or subsequently died. Interference with the production of antibody against live vaccine by maternal antibody or porcine respiratory and reproductive syndrome virus infection 1 week after vaccination was also clearly detected. Because the ELISA titer correlated well with the protection results, the specificity and sensitivity of the ELISA were further evaluated with sera collected from pigs reared on 1 farm on which animals had acute septicemia, 2 farms on which the animals were infected or free from infection, and 10 farms on which the animals were vaccinated with live vaccine, among others. The ELISA titers clearly revealed the conditions of the herds. These results indicate that the SpaA416 ELISA is an effective method not only for evaluating pigs for the presence of protective antibody levels resulting from vaccination or maternal antibody but also for detecting antibody produced by natural infection. This test has important potential for the effective control of swine erysipelas. (+info)
Erysipelothrix rhusiopathiae: genetic characterization of midwest US isolates and live commercial vaccines using pulsed-field gel electrophoresis.
This is the first report of molecular characterization of US erysipelas field isolates and vaccine strains of Erysipelothrix rhusiopathiae by pulsed-field gel electrophoresis (PFGE). Erysipelas in pigs is mainly caused by E. rhusiopathiae serotypes 1a, 1b, and 2. In 2001, erysipelas reemerged as a clinical problem in pigs in the midwestern United States. In this work 90 erysipelas isolates (58 recent and 28 archived field isolates as well as 4 live-vaccine strains) were genetically characterized. Because of the limited availability of antiserum, 74/90 isolates (44/58 recent isolates) were serotyped. The serotype of the majority (79.6%) of the 44 recent isolates tested was determined to be 1a, 13.6% were serotype 1b, and 6.8% of recent isolates were serologically untypeable. Among all 90 isolates, 23 different PFGE patterns were identified. There were 43 isolates identified as serotype 1a with 4 genetic patterns: 38/43, 1A(I); 3/43, 1A(III); 1/43, 1B(V); and 1/43, 3B. Sixteen serotype 1b isolates had 11 unique genetic patterns: 4/16 were genotype 1B(III), 2/16 were genotype 3A(I), and 1/16 was in genotype groups 1A(V), 1A(VI), 1A(VII), 1B(I), 1B(IV), 1B(VII), 2, 4, and 5. Six genetic patterns were distinguished among the 10 serotype 2 isolates: 1A(IV) (1/10), 1A(V) (1/10), 1B(VI) (1/10), 2 (4/10), 7 (1/10), and 8 (2/8). Erysipelas vaccine strains (modified live) were similar to each other but different from current field strains, sharing 78.6% identity with the most prevalent genotype 1A(I) based on the PFGE-SmaI pattern. Compared with serotyping, PFGE genotyping is a more distinguishing technique, easy to perform and not dependent on the limited availability of antiserum. (+info)
Serotyping of 800 strains of Erysipelothrix isolated from pigs affected with erysipelas and discrimination of attenuated live vaccine strain by genotyping.
Eight hundred Erysipelothrix strains isolated between 1992 and 2002 from swine with erysipelas in Japan were serotyped. Thirty-seven, 47, 73, and 643 strains were isolated from animals with acute septicemia, urticaria, chronic endocarditis, and chronic arthritis, respectively, of which 381, 146, 254, and 19 isolates belonged to serotypes 1a, 1b, and 2b and other serotypes, respectively. All serotype 1a isolates were further examined for acriflavine resistance and their genotypes to discriminate them from the attenuated live vaccine strain, defined as serotype 1a, which is resistant to 0.02% acriflavine and which shows low levels of pathogenicity in mice. Of the serotype 1a isolates, 64.6% were acriflavine resistant, with 98.4% of these acriflavine-resistant strains having been isolated from animals with chronic arthritis. By randomly amplified polymorphic DNA (RAPD) analysis, almost all the acriflavine-resistant serotype 1a strains showed the 253-bp band characteristic of vaccine strains and were easily discriminated from all 113 strains of acriflavine-sensitive serotype 1a strains from animals with acute and subacute swine erysipelas. The incidence of acriflavine-resistant strains of the distinctive RAPD type 1-2 was markedly higher than that of the other RAPD types and serotypes. RAPD type 1-2 strains also included a specific group identifiable by restriction fragment length polymorphism DNA analysis. Furthermore, the pathogenicities of 29 isolates of RAPD type 1-2 for mice were lower than those of the 21 isolates of other RAPD types. Our results indicate that RAPD type 1-2 strains are live vaccine strains and that 37% of the cases of chronic swine erysipelas detected in the past 11 years in Japan have occurred as a side effect of live vaccine use. (+info)
Development and validation of an immunohistochemical method for rapid diagnosis of swine erysipelas in formalin-fixed, paraffin-embedded tissue samples.
The objective of the study was to develop an immunohistochemical (IHC) assay for rapid detection of Erysipelothrix rhusiopathiae. Serotypes 1a, 1b, and 2 are most frequently associated with clinical disease in pigs. Antiserum against serotypes 1a, 1b, and 2 was produced in rabbits, pooled, and applied to formalin-fixed, paraffin-embedded tissue sections of pigs (lungs, heart, spleen, and skin). The results obtained with the IHC assay were compared with direct culture on tissue samples from experimentally inoculated pigs either treated (n = 6) with antibiotics or untreated (n = 8) as well as on samples from field cases (n = 170) submitted to the Veterinary Diagnostic Laboratory at Iowa State University. The agreement between direct culture and IHC staining was found to be substantial. The results of the present study indicate that the IHC assay is highly sensitive and specific in detecting E. rhusiopathiae antigen in formalin-fixed, paraffin-embedded tissues. Results indicated that the IHC is particularly useful in cases in which pigs had been treated with antibiotics prior to submission and in which direct cultures of organs were negative. In addition, the IHC was found to be useful for detection of E. rhusiopathiae antigen in skin lesions, which are often culture negative. (+info)
Characterization of Erysipelothrix species isolates from clinically affected pigs, environmental samples, and vaccine strains from six recent swine erysipelas outbreaks in the United States.
Erysipelothrix spp. genotypes, serotypes, and surface protective antigen types associated with abattoir condemnations.
The objective of the current study was to investigate characteristics of Erysipelothrix spp. from slaughter condemnations. Specimens from 70 carcasses with lesions suspect for swine erysipelas were collected at an abattoir in Iowa from October 2007 to February 2009. Erysipelothrix spp. were isolated from 59 of 70 carcasses (84.3%). Abattoir inspectors classified lesions as acute, subacute, or chronic; 8 of 8 (100%) were acute cases, 31 of 32 (96.9%) were subacute cases, and 20 of 30 (66.6%) were chronic cases that were isolation positive. The following serotypes were identified: 1a (40.7%; 24/59), 2 (49.2%; 29/59), 7 (1/59), 10 (1/59), 11 (1/59), and untypeable (5.1%; 3/59). Serotypes 1a and 2 were identified in pigs with acute, subacute, or chronic clinical manifestations, whereas serotypes 7, 10, and 11 were only present in chronic cases. Fifty-seven of the 59 isolates were determined to belong to E. rhusiopathiae, and 2 of 59 of the isolates were determined to be E. tonsillarum by multiplex real-time polymerase chain reaction. Surface protective antigen (spa) A was detected in all E. rhusiopathiae isolates but not in E. tonsillarum serotypes 7 and 10. The results of the present study indicate that E. rhusiopathiae serotypes 1a and 2 continue to be commonly isolated from condemned pig carcasses and that spaA is the exclusive spa type in U.S. abattoir isolates. Interestingly, E. tonsillarum, thought to be avirulent for swine, was isolated from systemic sites from 3.4% of the carcasses that were negative for E. rhusiopathiae, indicating the potential importance of this genotype in erysipelas pathogenesis. (+info)