• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.96-103
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• 1999

The present study was carried out to investigate the prevalence of mycoplasmal pneumonia of slaugter pigs in Youngnam area during the period from 1995 to 1997. The prevalence and pathomorphology of gross lung lesions were studied from 682 slaughter pigs in 8 swine herds. Gross lesions of pneumonia were recorded in the lungs of 442(64.8%), from 367 out of them(83.0%) were diagnosed as mycoplasmal pneumonia. Microbiological examination was performed with 197 lungs with gross lesions of mycoplasmal pneumonia of slaughter pigs from 8 different swine herds. M hyopneumoniae, P multocida, A pleuropneumoniae, Streptococcus spp, Corynebacterium spp, and H parasuis were detected in 24. 4%, 48.2%, 2.5%, 11.2%, 3.6%, and 1.0% of the pneumonic lungs, respectively. A total of 48 strains of M hyopneumoniae was investigated for their in vitro susceptibility to 8 antibiotics. Among the drugs tested, lincomycin, oxytetracycline, tiamulin and tylosin showed the high activity in minimal inhibitory concentration(MIC) of $0.04{\sim}5{\mu}g/ml$ while erythromycin showed low activity in MIC values($1.25{\sim}{\geq}40{\mu}g/ml$).

• Korean Journal of Veterinary Research
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• v.45 no.1
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• pp.55-61
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• 2005

Serum samples of 1,175 pigs from 148 Korean swine farms not using Mycoplasma hyopneumoniae (M. hyo) vaccines were collected for seroepidemiological study of M. hyo infection by indirect ELISA method. Informations of each farm were provided about province where the farm was located and season when blood samples were collected. Then, the selected farms were divided into farm units which had 5 serum samples according to production stages : sow, suckling piglet (<30 days old), nursery pig (30-70 days old), and growing pig (>70 days old). Seroprevalence of M. hyo infection according to production stages, province, and season was investigated by using ELISA-positve rate of the selected samples for each study. This study showed that 85.34% (78.94-91.78%, 95% CI) of farms were positive to M. hyo infection and 34.81% (32.09-37.53%, 95% CI) among pigs were sero-positive to M. hyo infection in Korean swine farms. In the study of seroprevalence by production stage, most farms had sows and growing pigs which were sero-positive to M. hyo infection (sow: 83.05%, growing pigs: 87.72%) and most pigs seemed to be naturally infected by M. hyo at 8-10 weeks of age. Also, M. hyo infection showed seasonal pattern that most pigs were infected in late fall to early winter. However, in the study of seroprevalence by province, there was no significant correlation between province and M. hyo sero-positive rate.

• Korean Journal of Veterinary Research
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• v.49 no.3
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• pp.185-193
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• 2009

In the present study, ten herbal extracts, Citrus unshiu Markovich, root and stem of Berberis koreana, Morus alba, Dendrobium moniliforme, Aster gramineus, A. scabar, Alisma canaliculatum, Fallopia japonica and Origanum (O.) vulgare were determined to examine anti-mycoplasmal activity. Among them, O. vulgare extract (OVE) showed strong anti-mycoplasmal activity and was analyzed by gaschromatography/ mass spectrometry (GC/MS). As the results, OVE was consisted of carvacrol (68.78%), o-cymene (9.80%), terpinene (7.61%) and thymol (4.03%) as main ingredients. To investigate inflammatory activity by intact pathogenic Mycoplasma hyopneumoniae (M. hyo) at 30 $\mu$g/ml, we examined induced transcription of proinflammatory cytokines such as cyclooxygenase-2, tumor necrosis factor-a, interleukin (IL)-1, IL-6 and inducible nitric oxide synthase in RAW 264.7 cells. With the above results, we further investigated whether OVE could reduce inflammation induced by M. hyo at minimal inhibitory concentration. The result showed that 32 $\mu$g/ml of OVE inhibited nitric oxide production by 60%. This study also evaluated the combination of OVE with antibacterials against M. hyo for application. Based on these results, it could be concluded that M. hyo induces inflammation in RAW 264.7 cells and OVE protects this inflammation, indicating that OVE may be useful for industrial animals.

• Korean Journal of Veterinary Service
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• v.31 no.3
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• pp.291-303
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• 2008

This study was performed to evaluate the effect of commercial swine mycoplasma vaccine (M+$Pac^{(R)}$, Schering-Plough Animal HealthCo.) at different vaccination time points. Total 139 piglets were moved to experimental farm after weaning and were randomly allocated to 3 treatment groups and 1 control group. Piglets of 3 treatment groups (A, B and C) were vaccinated twice at 1 and 3 weeks (A group), 3 and 5 weeks (B), and 6 and 8 weeks (C), respectively. All vaccinates showed higher antibody titers compared with nonvaccinates, and maintained to finish (P<0.001). Performance and RBC/WBC count showed no significant difference between groups. Vaccinates at 6-8 weeks showed better effect on decrease of clinical sign compared with vaccinates at 1-3 weeks and 3-5 weeks and nonvaccinates. Also, lung lesion assessment showed significant difference between vaccinates at 3-5 weeks and 6-8 weeks, and nonvaccinates and vaccinates at 1-3 weeks (P<0.05). Vaccinates at 3-5 score in comparison with other groups. In conclusion, these results suggested that vaccination at 3-5 weeks or later may be more effective than earlier vaccination.

• Korean Journal of Veterinary Research
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• v.56 no.2
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• pp.109-111
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• 2016

The present study was conducted to determine the antibiotic susceptibilities of local Mycoplasma hyopneumoniae (Mhp) and Mycoplasma hyorhinis (Mhr) filed isolates. Minimum inhibitory concentrations (MICs) of Mhp and Mhr field isolates (twelve each) obtained from enzootic pneumonia-like lung lesions during 2009-2011 from Korea were determined using the broth microdilution method. Tylvalosin showed the highest activity against Mhp and Mhr field isolates, with $MIC_{90}$ values of $0.06{\mu}g/mL$ and $0.12{\mu}g/mL$, respectively. Therefore, Korean Mhp and Mhr isolates are highly susceptible to tylvalosin.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.267-274
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• 2008

This study was to evaluate the efficacy of single dose Mycoplasma hyopneumoniae (M. hyo)-vaccination in the swine farms which had different serological patterns of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2). A minimum of 240 pigs from each farm was applied, allocating M. hyo vaccinated and control groups. The PRRSV and PCV2 infections were analyzed by serological method (commercial ELISA kit). After administrating pigs a single dose of M. hyo vaccine or control saline at 3 weeks of age, serum antibodies to M. hyo, PRRSV and PCV2 were monitored at 4, 10, 16 and 22 weeks of age. Mortality, weight changes, feed conversion ratio (FCR) and lung score were also evaluated. A single-dose vaccination of M. hyo bacterin was efficacious to reduce mycoplasmal lung lesions and induce good humoral immune response. However, FCR was improved only in one of the three farms where showed seronegative status to both PRRSV and PCV2 in the period from 4 to 16 weeks of age. These results might imply that M. hyo vaccine alone could not overcome the PRRSV and PCV2 infection-associated wasting in the field condition. Therefore, the control of PRRSV and PCV2 should be considered to obtain the better effects of M. hyo vaccination.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1438-1445
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• 2004

The objective of this study was to determine the effects of dietary Zn level on performance, serum Zn concentrations, alkaline phosphatase activity (ALP), and immune response of pigs inoculated with Porcine Reproductive and Respiratory Syndrome virus (PRRSv) and Mycoplasma hyopneumoniae. A $2{\times}4$ factorial arrangement of treatments was used in a randomized design. Factors included; 1) PRRSv and M. hyopneumoniae inoculation (n=36 pigs) or sham inoculation (n=36 pigs) with media when pigs entered the grower facility (d 0) at 9 weeks of age and 2) 10, 50, 150 ppm supplemental Zn sulfate (${ZnSO}_4$) from weaning until the completion of the study, or 2,000 ppm supplemental ${ZnSO}_4$for two weeks in the nursery and then supplementation with 150 ppm ${ZnSO}_4$for the remainder of the trial. The basal diet contained 34 ppm Zn. Pigs were weighed on d 0, 10, 17, 24 and 31 and blood samples were collected on d 0, 7, 14, 21 and 28. Pigs inoculated with PRRSv were serologically positive at d 28 and control pigs remained negative to PRRSv. In contrast, the M hyopneumoniae inoculation was inconsistent with 33.3% and 52.8% of pigs serologically positive at d 28 in the control and infected groups, respectively. A febrile response was observed for approximately one week after inoculation with PRRSv. Feed intake (p<0.01) and gain (p<0.1) were less in PRRSv infected pigs than control pigs for the 31 d study. However, performance did not differ among pigs in the four levels of ${ZnSO}_4$. Assessments of immune responses failed to provide unequivocal influence of either PRRSv inoculation or ${ZnSO}_4$level. These data suggest that PRRSv and M. hyopneumoniae act to produce some performance deficits and the influence of Zn supplementation of nursery age pigs does not have clear effect in grower pigs affected with disease.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.587-591
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• 2004

Blood samples from 622 pigs of 44 farms which were sero-positive to Mycoplasma hyopneumoniae (M. hyo) by ELISA method were collected from May 2003 to July 2004. And they were divided into 2 categories : M. hyo-vaccinated group (7 swine farms) and M. hyo-non-vaccinated group (37 swine farms). Then, each swine farm was analysed by sero-positive percentage per weeks of age. It was observed that the sero-positive percentage to M. hyo is directly proportional to weeks of age in the 44 swine farms that were selected. This meant that there has been a chronic infection of M. hyo in Korean swine herds and control of M. hyo infection did not have worked efficiently. In 7 M. hyo-vaccinated swine farms, there were no reliable patterns between sero-positive percentage to M. hyo and weeks of age. Although the swine farms have been used M. hyo vaccine, they had only little sero-positive percentage that was less than 50% at 6 to 11 weeks of age. This means a present vaccination program does not induce sufficiently a seroconversion expected. In 37 M. hyo-non-vaccinated swine farms, it was observed that sero-positive percentage was higher at above 15 weeks of age. This result showed that infection of M. hyo occurred commonly at between 7 and 12 weeks of age, at which pigs moved to the growing house. Because a risk of natural infection is severe at growing stage as well as nursery stage, it suggested that M. hyo vaccination at several weeks prior to the growing stage will give efficient effect to control the enzootic pneumonia.

• Journal of Veterinary Science
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• v.23 no.3
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• pp.49.1-49.13
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• 2022

Background: Porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (MHP) are economically significant pathogens in the pig industry. The use of combined vaccines against PCV2 and MHP is one of the most effective ways of protecting pigs from both diseases, and it has become a part of general management. Objectives: This study evaluated the efficacy of two new bivalent vaccines of PCV2 and MHP (Myco-X and Myco-XD) in SPF pigs. Myco-X and Myco-XD are a combined vaccine of MHP with PCV2b and PCV2d, respectively. Methods: Sixteen pigs were divided into four groups: Myco-X-vaccinated challenged, Myco-XD-vaccinated challenged, unvaccinated challenged, and unvaccinated unchallenged. Two milliliters of Myco-X were administered intramuscularly, and 0.5 mL of Myco-XD was injected intradermally at 3 wk of age. The pigs were challenged with virulent PCV2d via the intramuscular and intranasal route 4 wk post-vaccination. Results: All vaccinated pigs showed effective reduction of the clinical signs, the PCV2d load in the blood and nasal swab samples, as well as lung and lymphoid tissue lesions in the challenge test. Compared to unvaccinated challenged animals, the vaccinated challenged animals showed significantly higher (p < 0.05) levels of anti-PCV2 IgG, PCV2d-specific interferon-γ (IFN-γ), and anti-MHP IgG. Conclusions: Based on clinical, microbiological, serological, and pathological assessments, this study confirmed that both combined vaccines could protect pigs against PCV2 infection caused by PCV2d. On the other hand, further research on the efficacy evaluation of these new vaccines against the MHP challenge and PCV2d/MHP co-challenge is needed.

• Korean Journal of Veterinary Research
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• v.42 no.2
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• pp.225-229
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• 2002

We report that mycoplasma organisms from lung tissues of slaughter pigs were identified to genes fragments with references use of nested-PCR technique(nPCR). Seven strains of mycoplasma species were isolated from 70 lung tissues. The organisms were detected by in vitro amplification of 16S rRNA and 23S rRNA genes. Nucleotide sequences of the spacer between 16S and 23S in the ribosomal RNA operons of mycoplasma were identified by the analysis of products from the nested PCR. Four common PCR primers, MhF1, MhF2 MhR1 and MhR2, were designed by analysis between these sequences by first amplified with F1, R1 and second with F2, R2, respectively. Specific amplification of the spacer region for reference strains of M. hyopneumoniae, M. hyorhinis, M. flocculare were confirmed by first round of PCR in which the traduced fragments of 690bp, 460bp, 630bp. But amplications of second round was changed to 240bp, 210bp, 230bp, respectively. Three different strains (M. hyopneumoniae:4, M. hyorhinis:2, M. flocculare:1) were detected by the nested-PCR technique. The results suggest that the detection of swine mycoplasma by n-PCR can be analyzed the nucleotide sequences between rRNA operons and homology study.