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.

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.

Objective-To evaluate the efficacy of an orally administered vaccine of Mycoplasma hyopneumoniae that was prepared by spray drying or solvent evaporation. Animals-Thirty 6-week-old, crossbred, specificpathogen- free (SPF) pigs. Procedure-Pigs were randomly allocated into 5 groups and housed in an SPF facility. Pigs in 2 groups (groups AQ and CAP) were fed M hyopneumoniae enteric-coated vaccine on days 0, 10, and 20. A third group (group IM) received an IM injection of M hyopneumoniae vaccine with aluminium hydroxide as an adjuvant on days 0, 10, and 20. The last 2 groups (nonvaccinated- challenged [NV-C] and nonchallenged [NC]) were fed a sham treatment. All 24 pigs in groups AQ, CAP, IM, and NV-C were challenge exposed with 5 ml of a 10% pneumonic lung suspension administered on day 40 via intubation of the trachea. All pigs were slaughtered and the lungs removed and examined for lesions on day 68. Results-In vitro studies indicated that these 2 microencapsulation techniques formed an effective shell and protected mycoplasmal antigen from gastric acid. Results of inoculation and challenge tests indicated that microencapsulated M hyopneumoniae were sufficiently potent to induce an immune response and provide good protection. Conclusions and Clinical Relevance-Orally administered microencapsulated M hyopneumoniae vaccines induced an immune response and reduced the severity of lung lesions in challengeexposed pigs. Results suggest that this novel method can be applied to other antigens, because the spray-drying process yielded an orally administered M hyopneumoniae vaccine that induced a good immune response.

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.

Cell surface hydrophobicity of Mycoplasma hyopneumoniae was evaluated by phase partitioning in a hydro-carbon-aqueous mixture, by hydrophobic interaction chromatography, and by salting out with ammonium sulfate. Results obtained by use of these techniques gave evidence that the cell surface of M hyopneumoniae is weakly hydrophobic, compared with strongly hydrophobic Staphylococcus aureus Cowan I and hydrophilic Klebsiella pneumoniae. After treatment of the organisms with trypsin, M hyopneumoniae became less hydrophobic as measured by hydrophobic interaction chromatography. Significant changes in hydrophobicity were not seen after periodate treatment. Electron microscopy of M hyopneumoniae treated with polycationic ferritin revealed an intermediate, compact, unlabeled layer between the cytoplasmic membrane and an external, heavily labeled layer. Electron microscopy of ferritin-labeled M hyopneumoniae after treatment with trypsin or periodate revealed the intermediate layer to be composed of a trypsin-sensitive protein(s). The outer layer was made of periodate-sensitive carbohydrate(s). Therefore, it appears that proteins in the intermediate layer confer at least part of the total hydrophobicity of the mycoplasmal cell and may contribute to adherence of M hyopneumoniae to target respiratory cells by hydrophobic interactions.

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.

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.

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 objective of this study was to compare the efficacy of 2 different commercial Mycoplasma hyopneumoniae vaccines and porcine reproductive and respiratory syndrome virus (PRRSV) vaccines in regard to growth performance, microbiological and immunological analyses, and pathological observation from wean to finish (175 d of age). Pigs were administered M. hyopneumoniae and PRRSV vaccines at 7 and 21 d of age, respectively, or both at 21 d old and then challenged with both M. hyopneumoniae and PRRSV at 49 d old. Significant (P < 0.05) differences were observed between the 2 vaccinated challenged groups in average daily weight gain, nasal shedding of M. hyopneumoniae, M. hyopneumoniae-specific interferon-γ secreting cells, and macroscopic and microscopic lung lesions. Induction of interleukin-10 following PRRSV vaccination does not interfere with the immune responses induced by M. hyopneumoniae vaccine. The present study demonstrated that the single-dose vaccination regimen for M. hyopneumoniae and PRRSV vaccine is efficacious for controlling coinfection with M. hyopneumoniae and PRRSV based on clinical, microbiological, immunological, and pathological evaluation.