The objective of this study was to compare clinical, microbiologic, immunologic, and pathologic parameters in pigs each concurrently administered porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae, and porcine circovirus type 2 (PCV2) vaccine from 1 of 2 commercial sources at 21 days of age and challenged with field strains of each of the 3 pathogens. Pigs were challenged with PRRSV and M. hyopneumoniae at 42 days of age (-14 days post-challenge, dpc) followed by a challenge with PCV2 at 56 days of age (0 dpc). Significant differences were observed between vaccinated challenged and unvaccinated challenged groups in clinical (average daily gain and clinical signs), microbiologic (viremia and nasal shedding), immunologic (antibodies and interferon-γ secreting cells), and pathologic (lesions) outcomes. Significant differences were observed among the 3 vaccinated challenged groups in microbiologic (nasal shedding of M. hyopneumoniae and viremia of PCV2) and immunologic (M. hyopneumoniae- and PCV2-specific interferon-γ secreting cells) outcomes. The vaccination regimen for PRRSV vaccine, M. hyopneumoniae vaccine, and PCV2 vaccine is efficacious for controlling triple challenge with PRRSV, M. hyopneumoniae, and PCV2 from weaning to finishing period.

The objective of this study was to evaluate the efficacy of a new Mycoplasma hyopneumoniae bacterin against a Korean M. hyopneumoniae challenge under experimental conditions. Fifteen pigs were allocated randomly into 3 groups (5 pigs per group) that were designated in 1 of 3 ways: vaccinated-challenged, unvaccinated-challenged, or unvaccinated-unchallenged. The pigs in the vaccinated-challenged group were immunized with an M. hyopneumoniae whole-cell bacterin at a 1.0 mL dose-level at 21 d old. At 42 d old (0 d post-challenge), the pigs in the vaccinated-challenged and unvaccinated-challenged groups were inoculated intranasally with a strain of Korean M. hyopneumoniae. Vaccinated-challenged pigs elicited a strong cell-mediated immunity as measured by M. hyopneumoniae-specific interferon-γ secreting cells when compared with unvaccinated-challenged pigs. Vaccination of pigs with this new M. hyopneumoniae bacterin reduced nasal shedding and lung lesions. The evaluated vaccine was therefore considered effective in controlling M. hyopneumoniae infection.

The aim of this study was to assess the genetic variability of Mycoplasma hyopneumoniae within various swine production flows. Four M. hyopneumoniae positive production flows, composed of 4 production stages, were selected for this study. Laryngeal and/or bronchial swabs were collected from each production stage within a flow, for a period of 4 months up to 3 years. A multiple-locus variable-number tandem repeat analysis was performed to assess the genetic variation of M. hyopneumoniae within and across production flows through the identification of variable-number tandem repeat (VNTR) types. A maximum of 6 M. hyopneumoniae VNTR types were identified in a single flow, in which VNTR types appeared to be flow specific. An identical VNTR type was detected across several production stages for up to 3 years. In this study, minimal M. hyopneumoniae genetic variation was evidenced within and across production flows.

In the present study, ten herbal extracts, Citirus unchiu Markovich, root and stem of Berberis koreana, Morus alba, Dendrobium moniliforme, Aster gramineus, A. scabar, Alisma canaliculatum, Fallopia japonica and Origamum (O.) vulgare were determined to examine anti-mycoplasmal activity. Among them, O. vulgare extract (OVE) showed strong anti-mycoplasmal activity and was analyzed by gas-chromatography/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 hyoneumoniae (M. hyo) at 30 ㎍/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 ㎍/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.

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.

Pathogens causing significant respiratory disease in growing pigs include Porcine reproductive and respiratory syndrome virus, Porcine circovirus 2, swine influenza virus, porcine respiratory coronavirus, Mycoplasma hyopneumoniae, and Bordetella bronchiseptica. The objective of this research was to characterize the respiratory excretion of these pathogens by acutely infected pigs. Pigs were inoculated under experimental conditions with 1 pathogen. Samples were collected from the upper respiratory tract and exhaled air. All pathogens were detected in swabs of the upper respiratory tract, but only M. hyopneumoniae and B. bronchiseptica were detected in expired air from individually sampled, acutely infected pigs. These findings suggest either that the acutely infected pigs did not aerosolize the viruses or that the quantity of virus excreted was below the detection threshold of current sampling or assay systems, or both, at the individual-pig level.

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 (less than 30 days old), nursery pig (30-70 days old), and growing pig (greater than 70 days old).

To differentiate Mycoplasma hyopneumoniae, the cause of mycoplasmal pneumonia in pigs, from M flocculare and M hyorbinis, an assay, using the polymerase chain reaction to amplify a segment of the 16S rRNA gene sequence, was developed. The assay was found to be useful for identification of field isolates, as well as for identification of laboratory-adapted strains. Amplification of DNA from M hyopneumoniae and M flocculare resulted in products of 200 and 400 base pairs, respectively. The DNA from M hyorbinis was not amplified. The assay was sensitive enough to detect as little as 1,000 genome equivalents of M hyopneumoniae and M flocculare DNA. Sensitivity was increased 100-fold by increasing the concentration of magnesium ion in the reaction buffer from 2 to 4 mM; however, DNA from M hyorbinis was also amplified under these conditions. The DNA from several walled bacteria and from other mycoplasmas was also tested, but none of these DNA samples was amplified, suggesting that the assay was specific for porcine mycoplasmas.

Aerosol vaccination is used effectively to immunize poultry against Newcastle disease, but to the authors' knowledge, this vaccination procedure is not well studied in other species. The efficacy of IM and aerosol vaccination of pigs against Mycoplasma hyopneumoniae infection was evaluated. Twenty-one pigs from a Mycoplasma-free herd were randomly allotted by litter and body weight into 3 groups. One group was given aerosolized phosphate-buffered saline solution (PBSS) by inhalation. The second group (AERO) was given aerosolized M hyopneumoniae vaccine by inhalation. The third group (IM) was given the same vaccine by IM injection. Vaccination by IM administration was repeated once, and aerosol vaccination was repeated twice at 2-week intervals. Two weeks after the last vaccination, all pigs were intratracheally challenge-exposed with 3 ml of broth culture containing 10(7) color-changing units (CCU) of a low-passage strain of virulent M hyopneumoniae. Pigs were observed daily for coughing. Four weeks after challenge exposure, all pigs were necropsied. Percentage of lung affected by gross pneumonia was measured, bronchioalveolar lavage fluid (BALF) cells were counted, and quantitative culture for mycoplasmas was performed on lung sections. Additionally, M hyopneumoniae-specific antibodies were measured in prevaccination, postvaccination, and postchallenge-exposure serum and BALF by use of indirect ELISA. Mean prevalence of persistent coughing in pigs of the AERO group (4.6 d/pig) was not different from that in pigs of the PBSS group (3.7 d/pig). Prevalence of coughing in IM vaccinated pigs (1.0 d/ pig) was lower (P < 0.05) than that in pigs of the PBSS group. Mean gross lung lesion scores and BALF cell counts were not different between the AERO (15% pneumonia, 5,233 cells/microliter) and PBSS (11% pneumonia, 3,022 cells/microliter) groups, but were lower (P < 0.05) in the IM group (1.5% pneumonia, 400 cells/microliter) than in the PBSS group. Mean lung mycoplasmal counts were not significantly (P < 0.05) different among the PBSS (10(5.6) CCU/g), AERO (10(5.3) CCU/g), and IM (10(3.3) CCU/g) groups. Postvaccination M hyopneumoniae-specific IgG or IgA was not detectable in BALF after either vaccination procedure. Postvaccination M hyopneumoniae-specific serum IgG concentration was not different among the 3 groups. Postchallenge exposure M hyopneumoniae-specific IgG and IgA were detectable in BALF of all pigs, but were not different among the 3 treatment groups. Postchallenge exposure-specific serum IgG concentration was not different between the PBSS (mean OD, 0.739) and AERO (mean OD, 0.672) groups, but was higher (P < 0.05) in the IM group (mean OD, 1.185) than in the PBSS group. Aerosol vaccination failed to induce local and systemic antibody responses detectable by ELISA, and failed to protect pigs against mycoplasmal pneumonia. Intramuscular vaccination failed to induce local and systemic antibody responses detectable by ELISA, but substantially reduced the clinical signs and lesions caused by challenge exposure to virulent M hyopneumoniae.