• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.350-353
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• 2001

Porcine pneumonia is caused by Pasturella multiocida and Actinobacillus pleuropneumoniae. To identify a potent drug for antipneumonia therapy, several herbal compounds showing antibacterial effects were screened, and it was found that a methanol extract of Coptidis rhizoma root stem exhibited activity against both pneumonia-causing bacteria. Using an activity-guided fragmentation procedure, an isoquinoline alkaloid was isolated which would be responsible for the antibacterial activities against P. multocida and A. pleuropneumoniae.

• Korean Journal of Veterinary Service
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• v.44 no.2
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• pp.103-111
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• 2021

Actinobacillus (A.) pleuropneumoniae is the etiological agent of a porcine pleuropneumonia and have great economic importance to the global swine industry. For recent 5 years, a total of 50 pleuropneumonia cases of 24 pig farms were selected from pig lungs submitted to the College of Veterinary Medicine, Jeju National University using polymerase chain reaction (PCR) analysis. Collected lungs were fixed in 10% neutral phosphate-buffered formalin and processed for histological examination. Serotypes of A. pleuropneumoniae in pneumonic lesions were analyzed by PCR methods. And the antimicrobial susceptibility of A. pleuropneumoniae isolates was determined by a disc diffusion test. Grossly, unilateral distribution of hemorrhagic or necrotic pneumonic lesions was more common than bilateral distribution in lungs. In peracute or acute cases, histopathologic changes were characterized by necrosis, hemorrhage, neutrophils infiltration, vascular thrombosis, widespread edema and fibrinous exudates. Following the acute response, macrophage infiltration, marked fibrosis around zonal necrotic areas, and marked fibrous pleuritis were characteristic in chronic cases. A total of 50 pleuropneumonia were associated with A. pleuropneumoniae serotype 5 in 46 cases (92%), serotype 2 in 3 cases (6%), and both 2 and 5 in 1 case (2%). More than 90% of collected isolates showed high sensitivity to ceftiofur, amoxicillin, and colistin. However, ampicillin, penicillin, and tylosin showed low susceptibility. The results of this study demonstrated that A. pleuropneumoniae serotype 5 was predominant at porcine pleuropneumonia cases in Jeju.

• Korean Journal of Veterinary Service
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• v.20 no.1
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• pp.103-125
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• 1997

An epidemiologic study on pleuropneumonia in the slaughter pigs(Chonan and Asan area, Chungnam province, Korea) during the period of January 1994 through December 1995 was conducted. Isolation of A pleuropneumoniae was attempted in 425 pigs with pneumonic lesions. Biochemical properties, antimicrobial susceptibility, serotypes and pathogenicity of isolated A pleuropneumoniae were investigated. In addition, outer membrane protein(OMP) of the Isolates were extracted to determine its properties and immunogenicity in both mice and piglets The results obtained through this study were summarized as followed ; 1. Of 3, 395 slaughter pigs, pleuropneumonia was observed in 425 pigs(10.6%). A pleuropneumoniae was isolated from 22 pigs(5.2%) out of 425 pigs with pneumonic lesions. The biochemical properties of all isolates were same as those of reference A pleuropneumoniae strain. Among 22 isolates, 9, 1 and 12 isolates were serovar 2, 3 and 5, respectively. 2. The results of antimicrobial susceptibility test revealed that the isolates showed high susceptibility to ciprofloxacin and cephalothin, moderate susceptibility to amikacin, gentamicin, kanamycin and streptomycin, and low susceptibility to erythromycin, tylosin and sulfadimethoxin. 3. The isolates were varied in pathogenicity to mice. Median lethal dose of LE9402(serovar 2) and LE9511(serovar 5) were $9.2{\times}10^7$ CFU and $2.8{\times}10^7$%CFU, respectively. Specific pneumonic lesions were observed from the infected mice with clinical signs. Bacteria recovery rate was high in the lung, but low In heart blood and tracheas. 4. Serovar 2 was found to be more pathogenic than serovar 5 in guinea pig. Mortality on guinea pigs inoculated with serovar 2($5.4{\times}10^8-5.4{\times}10^6$CFU) and serovar 5($2.8{\times}10^8-2.8{\times}10^6$ CFU) was 20~40% and 40~80%, respectively. A severe hemorrhagic lesions and focal pneumonic lesions were observed from dead guinea pigs. Bacteria recovery rate was relatively higher in the lung than that of other organs. 5. In the SDS-PAGE analysis, OMP-enriched fractions of both isolates and reference strains contain common peptide bands equivalent to molecular weight of 17, 27, 42, 52 and 95Kd. In addition to common peptide bands, the bands which are specific to each isolate were also observed. The profiles of Sephadex G25 fractions showed 3 major peaks. The common peptide bands which were observed by SDS-PAGE of the crude OMPs were found in the peaks 1 and 2. 6. The OMPs extracted from serovar 2(LE9402) and serovar 5(LE9511) provided high level of protection in mice(70~80%) and pigs(100%). All animals inoculated with OMPs were seroconverted, showing micro-agglutination titer of 640 to 1280.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.362-366
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• 2005

Actinobacillus pleuropneumoniae is an important pig pathogen, which is responsible for swine pleuropneumonia, a highly contagious respiratory infection. To develop subunit vaccines for A. pleuropneumoniae infection, the Apx toxin genes, apxI and apxII, which are thought to be important for protective immunity, were expressed in Saccharomyces cerevisiae, and the induction of immune responses in mice was examined. The apxI and apxII genes were placed under the control of a yeast hybrid ADH2-GPD promoter (AG), consisting of alcohol dehydrogenase II (ADH2) and the GPD promoter. Western blot analysis confirmed that both toxins were successfully expressed in the yeast. The ApxIA and ApxIIA-specific IgG antibody response assays showed dose dependent increases in the antigen-specific IgG antibody titers. The challenge test revealed that ninety percent of the mice immunized with ApxIIA or a mixture of ApxIA and ApxIIA, and sixty percent of mice immunized with ApxIA survived, while none of those in the control groups survived longer than 36 h. These results suggest that vaccination of the yeast ex­pressing the ApxI and ApxII antigens is effective for the induction of protective immune responses against A. pleuropneumoniae infections in mice.

• Korean Journal of Veterinary Research
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• v.60 no.4
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• pp.225-228
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• 2020

Apx toxins are a virulent factor of Actinobacillus pleuropneumoniae (App). At least four genes, apxC, apxA, apxB, and apxD, are involved in the release of Apx toxins from App. apxA encodes Apx toxins, whereas apxB and apxD encode exporters. Some serotypes of App such as serotype 2 retain apxIBD, apxIICA, and apxIIICABD. Although the specificity of the ApxIB/ApxID exporter to ApxII has been established in those serotypes, that to ApxIII is under-studied. We constructed an apxIB- and apxID-lacking mutant strain of the App serotype 2 to study whether the ApxIB/ApxID exporter is capable of secreting both ApxII and ApxIII toxins.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.181-186
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• 2013

This study was conducted to isolate the Actinobacillus pleuropneumoniae (APP) and to find out the distribution of 15 serovars mainly in southern Gyeonggi province, Korea. From July 2011 to Nov. 2012, a total of 2,204 slaughter pigs (110 herds) were inspected for evaluation of APP like pneumonic lesions. 48 (33.8%) APP strains were isolated from the 142 lungs and identified using PCR assays (cps, apx/omlA, biovar). Consequently, the serotype ratio were as in the following; type2 41.7% (n=20), type5 33.3% (n=16), type12 10.4% (n=5), type1 6.2% (n=3), type4 and 7 2.1% (n=1) and unknown 4.2% (n=2). Also serological test was implemented for 452 (83 herds) serum samples randomly collected from above slaughter pigs using commercial ELISA kits. The positive ratio of each serotype for tested pigs were 19.1% (77/404) on [2], 7.1% (32/452) on [3, 6, 8], 6.9% (28/404) on [5a, 5b], 6.2% (28/452) on [4, 7], 2.8% (9/320) on [12], 2.0% (9/452) on [1, 9, 11] and 0.0% (0/452) on [10]. And 49.3% (223/452) of pigs were positive on apxIV antibody. On the basis of latter screening test, the infected farm ratio accounted for 71.1% (59/83) and that was much higher than previously reported data.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1037-1043
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• 2020

Actinobacillus pleuropneumoniae (APP) is a causative agent of porcine pleuropneumonia. Therefore, the development of an effective vaccine for APP is necessary. Here, we optimized the culture medium and conditions to enhance the production yields of Apx toxins in APP serotype 1, 2, and 5 cultures. The use of Mycoplasma Broth Base (PPLO) medium improved both the quantity and quality of the harvested Apx toxins compared with Columbia Broth medium. Calcium chloride (CaCl₂) was first demonstrated as a stimulation factor for the production of Apx toxins in APP serotype 2 cultures. Cultivation of APP serotype 2 in PPLO medium supplemented with 10 ㎍/ml of nicotinamide adenine dinucleotide (NAD) and 20 mM CaCl₂ yielded the highest levels of Apx toxins. These findings suggest that the optimization of the culture medium and conditions increases the concentration of Apx toxins in the supernatants of APP serotype 1, 2, and 5 cultures and may be applied for the development of vaccines against APP infection.

• Korean Journal of Veterinary Service
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• v.23 no.3
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• pp.289-299
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• 2000

The study was performed to investigate the distributions of swine pleuropneumonia in Kyongbuk western area by the enzyme-linked immunosorbent assay (ELISA). Sera collected from 400 slaughtered pigs in 3 slaughter houses during the period from May 1999 to october 1999 were tested to detect antibodies against A pleuropneumonie serotype 2 and 5. The optimal dilution of CBE antigen, conjugate and serum for this ELISA were determined 1 : 400, 1 : 20,000, 1 100, respectively. The optimal dilution of OW antigen, conjugate and serum for this ELISA were determined 1 : In, 1 : 20,000, 1 : 200, respectively. Cut-off value in this ELISA was determined by mean absorbance (at 492 nm) of negative control sera added with the triple value of the standard deviation. Cut-off value in ELISA by CBE and OMP antigen were 1.134 and 1.217, respectively. By the ELISA, positive reaction rates to A pleuropneumoniae serotype 2 and 5 for CBE antigen were 38.8% and 18.8%, and for OMP antigen were 42.8% and 23.5% of the 400 samples, respectively.

• Korean Journal of Veterinary Research
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• v.36 no.1
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• pp.131-142
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• 1996

The effect of relative humidity in swine house on swin pleuropneumonia was examined in piglets experimentally infected with Actinobacillus pleuropneumoniae serotype 5. A total of 20 piglet were grown under 30~40%, 41~50%, 51~64% and 65~80% relative humidity chambers after intratracheal inoculation of A pleuropneumoniae. Characteristic fibrinous pleuropneumonia was observed in the pigs grown at the low relative humidity groups. The detailed results were as follows : 1. Growth performance and environment conditions were lower than high relative humidity groups. 2. Characteristic histopathological findings were fibrinous pleuritis and pneumonia accompanied congestion, hemorrhage, thrombosis and edematous change. 3. Antigenic distribution of inoculated bacterium was found mainly in alveolar macrophages or accumulated foci of macrophages adjacent to necrotic area. 4. Characteristic electron microscopic findings were proliferation of type II pneumocyte with increased lamella bodies and activated alveolar macrophages with pseudopods and widening of interstitium.

• Journal of Veterinary Science
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• v.21 no.2
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• pp.20.1-20.13
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• 2020

Actinobacillus pleuropneumoniae (APP) causes a form of porcine pleuropneumonia that leads to significant economic losses in the swine industry worldwide. The apxIBD gene is responsible for the secretion of the ApxI and ApxII toxins and the pnp gene is responsible for the adaptation of bacteria to cold temperature and a virulence factor. The apxIBD and pnp genes were deleted successfully from APP serotype 1 and 5 by transconjugation and sucrose counter-selection. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants lost hemolytic activity and could not secrete ApxI and ApxII toxins outside the bacteria because both mutants lost the ApxI- and ApxII-secreting proteins by deletion of the apxIBD gene. Besides, the growth of these mutants was defective at low temperatures resulting from the deletion of pnp. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants were significantly attenuated compared with wild-type ones. However, mice vaccinated intraperitoneally with APP5ΔapxIBDΔpnp did not provide any protection when challenged with a 10-times 50% lethal dose of virulent homologous (APP5) and heterologous (APP1) bacterial strains, while mice vaccinated with APP1ΔapxIBDΔpnp offered 75% protection against a homologous challenge. The ΔapxIBDΔpnp mutants were significantly attenuated and gave different protection rate against homologous virulent wild-type APP challenging.