Little is known about how co-infections and genotype dynamics affect Mycoplasma hyopneumoniae infection in fattening pigs. This study was aimed at assessing the role of co-infections in M. hyopneumoniae outbreaks, their influence on the presence of M. hyopneumoniae genotypes and their impact on consequent lung lesions. Tracheobronchial swabs (TBS) from 300 finishers were collected from 10 farms at the onset of enzootic pneumonia outbreaks and 1 month later, sampling of 3 groups per farm: Group A showed clinical signs first, Group B was housed near Group A, and Group C was located in a different building. Pigs\' lungs were scored at the slaughterhouse. TBS were tested for the main pathogens involved in respiratory diseases, and samples positive for M. hyopneumoniae were genotyped by multiple-locus variable-number tandem repeat analysis (MLVA). Pigs in Group A showed the highest prevalence and load of M. hyopneumoniae. A positive association was detected between M. hyopneumoniae and Mycoplasma hyorhinis, whereas Actinobacillus pleuropneumoniae was more frequent when the M. hyopneumoniae load was higher. Nevertheless, co-infection had no effect on lung lesion scores. The presence of multiple MLVA types (mixed infections) increased in time only in pigs from Group C and was positively associated with porcine reproductive and respiratory syndrome virus infection. Lung lesions were more severe in pigs with at least one TBS positive for M. hyopneumoniae and in pigs with a history of mixed infections. The central role of M. hyopneumoniae and relevance of mixed infections suggest that increased biosecurity might be beneficial for lung lesion sequelae.

Mycoplasma (M.) hyopneumoniae is the initiator agent of the porcine respiratory disease complex (PRDC) and the etiological agent of enzootic pneumonia. M. hyorhinis and M. flocculare are also found in extensive gross pneumonia-like lesions, but their role is not known. We investigated the pathogenicity of M. hyorhinis and M. flocculare in specific-pathogen-free pigs pre-infected or not with M. hyopneumoniae. Mono-inoculated pigs with M. flocculare showed no clinical signs, hematological changes or macroscopic lesions upon necropsy. Mono-inoculated pigs with M. hyorhinis showed, overall seven days after inoculation, an increase in mean temperature with increases in white blood cell (monocyte) counts and in concentrations of pig major acute phase protein, whereas the average daily weight gain (ADWG) decreased compared with non-infected animals. M. hyorhinis was detected in serous membranes (polyserositis) but not in bronchi. Co-infected pigs with M. hyopneumoniae and M. hyorhinis or M. flocculare showed lower ADWG during the third week of the experiment and higher haptoglobin concentrations in contrast to pigs only mono-infected with M. hyopneumoniae. In pigs co-infected with M. hyopneumoniae and M. hyorhinis, it was interesting to observe that (i) M. hyorhinis was detected in bronchi of six pigs, (ii) M. hyopneumoniae was detected in polyserositis and (iii) there was a slight delay in the production of anti-M. hyopneumoniae IgG. The extent of pneumonia was not statistically different between groups. These results suggest that mycoplasmal associations appear to induce an additive effect and increase the inflammatory status in pigs, probably involving in the impairment of the immune system.

The present study compares the safety and efficacy of a needle-free, intradermal Mycoplasma hyopneumoniae vaccine to an intramuscular one. 420 piglets (21+3 days of age) were randomly assigned to two vaccination groups (intradermal vaccination V1 (n=138), intramuscular vaccination V2 (n=144)) and one unvaccinated control group (CG, n=138). As safety parameters clinical observations, local injection site reactions (ISR) and rectal temperatures were assessed. Average daily weight gain (ADWG) and pneumonic lung lesions (LL) were measured as efficacy parameters. ISRs were minor in V1. After both vaccinations, no adverse impact on appetite was observed and mean rectal temperatures remained within physiological range. ADWG during the fattening period was significantly higher in vaccinated groups (V1: 913.4 g, V2: 924.5 g) compared with CG (875.6 g). No differences in ADWG were observed between V1 and V2. Vaccinated pigs had a significantly reduced mean extent of LL compared with CG. V1 was superior in reducing the extent and prevalence of LL compared with V2. These results reveal that a needle-free intradermal vaccination is safe and efficacious in reducing both the prevalence and extent of lung lesions, as well as in improving performance parameters, in a farrow-to-finish farm with a late onset of M hyopneumoniae infection.

This study assessed the efficacy of two different Mycoplasma hyopneumoniae vaccination programmes in relation to the time of weaning. Eight hundred and twenty-eight piglets were randomly divided into three groups: group V1 was vaccinated three days before weaning, group V2 at weaning (21 days of age) and group NV was left non-vaccinated. Vaccinations were performed using Ingelvac MycoFLEX. After the nursery period, 306 pigs were allocated to fattening unit (F1) and 501 pigs to a second unit (F2). Efficacy was evaluated using performance parameters and pneumonia lesions at slaughter. Statistically significant differences were obtained in F2 where group V1 had a higher average daily weight gain compared to groups V2 and NV for the entire study period (17 and 18 g/day, respectively) and the fattening period (26 and 36 g/day, respectively) (P<0.05). Considering respiratory disease scores for both fattening units, group V1 was the only group where coughing severity did not increase significantly between placement and the end of the fattening period (P>0.05). Between groups, there were no statistically significant differences for the average lung lesion scores (V1=3.44; V2=4.61; NV=4.55, P>0.05) and the prevalence of pneumonia (V1=35.0 per cent; V2=38.0 per cent; NV=41.4 per cent, P>0.05). Overall, vaccination against M hyopneumoniae before weaning provided numerically better performance than vaccination at weaning, but did not reach statistical significance. An influenza outbreak in F1 and the presence of coexisting mixed respiratory infections in both F1 and F2 could have possibly influenced the performance of both vaccinated groups across all measured parameters.

BACKGROUND: Mycoplasma hyopneumoniae (M. hyo) and Porcine Circovirus Type 2 (PCV2) are major pathogens that cause significant health problems in swine worldwide. Maternal derived immunity (MDI) has been suggested as a significant immediate defence factor for newborn piglets and may interfere with piglet\'s vaccination-induced immunity. The study aimed to assess the efficacy of a novel combination vaccine (consisting of PCV2 subunits and inactivated M. hyo strain J), against PCV2 and M. hyo natural infection [Porcilis® PCV M Hyo (MSD Animal Health, Boxmeer, the Netherlands)], in the presence of strong maternally derived PCV2 immunity (antibody titre averaged 11.08 log2), under field conditions. The study was performed according to a controlled, randomized and blinded design in a Greek swine unit with Enzootic Pneumonia (EP) and subclinical PCV2 infection. In total, 600 healthy three-week-old suckling piglets were allocated randomly, either to treatment (vaccinated with the test product) or control group (injected with sterile buffered saline).
RESULTS: Vaccination significantly reduced the severity of lung lesions at slaughter (lesions of cranio-ventral pulmonary consolidation) (P < 0.001). The overall mean lung lesion score (LLS) was 9.6 in the vaccinated group and 12.2 in controls. The level of PCV2 viraemia was significantly reduced in vaccinated pigs. Furthermore, 25 g higher average daily weight gain (ADWG) was observed during the finishing phase (P < 0.001) and 18 g greater ADWG overall (P < 0.001).
CONCLUSIONS: Results of LLS, PCV2 viremia and ADWG support the test product\'s efficacy in the face of strong maternally derived PCV2 immunity.

Enzootic pneumonia (EP) caused by Mycoplasma hyopneumoniae has a significant economic impact on domestic pig production. A control program carried out from 1999 to 2003 successfully reduced disease occurrence in domestic pigs in Switzerland, but recurrent outbreaks suggested a potential role of free-ranging wild boar (Sus scrofa) as a source of re-infection. Since little is known on the epidemiology of EP in wild boar populations, our aims were: (1) to estimate the prevalence of M. hyopneumoniae infections in wild boar in Switzerland; (2) to identify risk factors for infection in wild boar; and (3) to assess whether infection in wild boar is associated with the same gross and microscopic lesions typical of EP in domestic pigs. Nasal swabs, bronchial swabs and lung samples were collected from 978 wild boar from five study areas in Switzerland between October 2011 and May 2013. Swabs were analyzed by qualitative real time PCR and a histopathological study was conducted on lung tissues. Risk factor analysis was performed using multivariable logistic regression modeling. Overall prevalence in nasal swabs was 26.2% (95% CI 23.3-29.3%) but significant geographical differences were observed. Wild boar density, occurrence of EP outbreaks in domestic pigs and young age were identified as risk factors for infection. There was a significant association between infection and lesions consistent with EP in domestic pigs. We have concluded that M. hyopneumoniae is widespread in the Swiss wild boar population, that the same risk factors for infection of domestic pigs also act as risk factors for infection of wild boar, and that infected wild boar develop lesions similar to those found in domestic pigs. However, based on our data and the outbreak pattern in domestic pigs, we propose that spillover from domestic pigs to wild boar is more likely than transmission from wild boar to pigs.

OBJECTIVE: The objective of the present study was to investigate whether a combined or concurrent application of two vaccines against Mycoplasma hyopneumoniae (M. hyo.) and porcine circovirus type 2 (PCV2) in suckling piglets can be as effective as the single use of both products.
METHODS: A total of 598 piglets were allocated to five groups. In the 1st and 3rd weeks of life the placebo Porcilis® Diluvac forte and the two vaccines Porcilis® M HYO (\"M HYO\") and Porcilis® PCV (\"PCV\") were administered according to the following scheme: group A: placebo/PCV; group B: M HYO/M HYO; group C: placebo/placebo; group D: M HYO/M HYO + PCV (combined single dose); group E: placebo/M HYO + PCV (different injection sites). Lung lesions due to M. hyo. infection were recorded at slaughter, and average daily weight gain, morbidity, mortality, serum PCV2 load and specific humoral immune responses were compared between the groups. Local and systemic side effects were recorded.
RESULTS: Sporadic impairment of the herd health status due to piglet diarrhoea (n = 111) from the 1st to 3rd weeks of life were not associated with M. hyo. or PCV2. A tendency towards a higher average daily weight gain was found in vaccinated pigs compared to the control group. Slight differences between groups in terms of lung lesions, morbidity and mortality were not significant. M. hyo. and PCV2 antibody-titers were significantly higher in vaccinated than in non-vaccinated pigs. One pig from both group A (PCV2) and group C (placebo) displayed local reactions at the vaccination site.
CONCLUSIONS: A positive effect on animal health can be achieved by vaccination against M. hyo. and PCV2 in herds with suboptimal health status. A simultaneous vaccination either by a combined or concurrent application has no negative effect on health status. Simultaneous vaccination yielded the same positive effect on average daily weight gain as single vaccinations. Therefore, a simultaneous vaccination against M. hyo. and PCV2, which reduces workload and is beneficial for animal welfare, can be recommended.

An improved direct fluorescent antibody test was evaluated for specificity and efficacy in diagnosing mycoplasmal pneumonia of swine. A sequential study was carried out in which pigs inoculated with a pneumonic lung suspension containing Mycoplasma hyopneumoniae strain 11 were euthanatized at postinoculation (PI) weeks 2 to 12. Fluorescent coating of M hyopneumoniae was detected primarily on bronchial and bronchiolar epithelial surfaces of lungs with gross lesions of pneumonia. Fluorescence was observed to be most intense at PI weeks 4 to 6, with a tendency to decrease in intensity from PI weeks 8 to 12. This indicated that there may be a decrease in number of M hyopneumoniae cells in the more advanced stages of the disease. The use of a counterstain (chelated azo-dye) provided an excellent color contrast and permitted making unambiguous interpretation of results.

Vaccines against M. hyopneumoniae and PRRSV are often administered at the same time. The administration of the two vaccines mixed in one syringe (simultaneous use) would save labour and increase animal welfare by reducing the number of injections. The aim of this study was to verify under field conditions, if the simultaneous administration of the two vaccines, would be comparable to the administration of the individual vaccines. 1000 piglets were divided into five groups and were either non vaccinated or vaccinated against M. hyopneumoniae and/or PRRSV-EU-type. Body weight, local reactions, morbidity and mortality were measured and clinical examinations were carried out. Blood samples were analysed serologically for the presence of antibodies against PRRSV and M. hyopneumoniae by ELISA. M. hyopneumoniae-induced lung lesion scoring (with a maximum score of 55 points) was performed at the slaughterhouse. In the 1000 pigs included in this study, no clinically relevant local or systemic reactions were observed following vaccination. No significant differences in average daily weight gain (ADWG), mortality, clinical parameters or in the prevalence of pneumonia and pleuritis at the slaughterhouse were detected between the different study groups. Significant differences were observed for the serological results, with M. hyopneumoniae antibody positive pigs in the vaccinated groups being significantly higher than in the non-vaccinated groups. Regarding the severity code of the lung lesions of the affected lungs, the lung scores from the simultaneously vaccinated pigs were significantly lower (0.92) than those from non-vaccinated pigs (1.77). Due to the low infectious pressure of both PRRSV and M. hyopneumoniae on this farm, we have to conclude that efficacy of the vaccines could not adequately be tested.

A longitudinal study was carried out to investigate the diversity and persistence of Mycoplasma hyopneumoniae (M. hyopneumoniae) strains in four infected pig herds. In each herd, 20 pigs were randomly selected and blood and/or bronchoalveolar lavage (BAL) fluid was collected at 6, 10, 14 and 26 weeks of age. In the BAL fluid, quantitative PCR and MLVA (multiple-locus variable number of tandem repeats (VNTR) analysis) testing were performed for detection and typing of M. hyopneumoniae strains, respectively. At 26 weeks of age, the prevalence and severity of lung lesions were recorded at slaughter (minimum 50 pigs belonging to the same batch as the investigated pigs). The percentage of pigs testing positive on qPCR increased from 35% at 6 weeks to 96% at 26 weeks of age. With MLVA testing, positive pigs were found from 14 weeks onwards. Within each herd, only one distinct strain was detected, although clonal variants were identified in two herds. In three of the herds, the strain remained present until slaughter age. The percentage of pigs with Mycoplasma-like lesions ranged from 38% to 98%, and the average pneumonia score ranged from 1.7 to 11.9, respectively. The present field study documented that within a herd, mainly one distinct M. hyopneumoniae strain was present that persisted in the same animals for at least 12 weeks. This implies that the immune response of the animals following infection is not able to rapidly clear the infection from the respiratory tract.