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Background: Mycoplasma hyopneumoniae (M. hyopneumoniae) is the primary agent of enzootic pneumonia in pigs. Pigs are often infected with different M. hyopneumoniae strains. This study assessed the efficacy of vaccination against experimental infection with two genetically different M. hyopneumoniae strains in weaned piglets. At 33 days of age (D0), 45 M. hyopneumoniae-free piglets were randomly assigned to three different groups: 1) negative control group (NCG; n = 5): not vaccinated, not infected, 2) positive control group (PCG; n = 20): not vaccinated, infected, and 3) vaccination group (VG; n = 20): single vaccination with an inactivated whole-cell M. hyopneumoniae vaccine (Hyogen®, Ceva) (D1), infected. The PCG and VG were endotracheally inoculated with 7 × 10 7 CCU in 7 ml of the highly virulent M. hyopneumoniae strain F7.2C (D24) and 7 × 10 7 CCU in 7 ml low virulent strain F1.12A (D25). A respiratory disease score (RDS) was assessed from D24 until D53. At D53 (euthanasia), macroscopic lung lesions (MLL) were scored, log copies of M. hyopneumoniae DNA (qPCR) and IL-1 and IL-6-concentrations (ELISA) on bronchoalveolar lavage fluid were determined., Results: The RDS and MLL at euthanasia were respectively 0, 1.20 and 0.55 (P < 0.001) and 0, 7.56 and 0.68 (P < 0.001) for NCG, PCG and VG, respectively. The qPCR results for PCG and VG were 3.99 and 1.78 log copies (P < 0.001), respectively, with a significant difference between PCG and VG. The IL-1 and IL-6 results at euthanasia for NCG, PCG and VG were 17.61, 1283.39 and 53.04 pg/ml (P < 0.001) and 148.10, 493.35 and 259.80 pg/ml (P = 0.004), respectively with a significant difference between PCG and VG., Conclusions: Vaccination with Hyogen® in pigs was efficacious against an experimental challenge with both a low and highly virulent M. hyopneumoniae strain as the vaccinated pigs coughed significantly less, and showed significantly less lung lesions compared to the non-vaccinated challenged pigs: the vaccinated animals showed a 52.9% lower RDS and 91.0% lower MLL compared to the PCG. In the bronchoalveolar lavage fluid collected at the necropsy of the vaccinated pigs, a significantly lower amount of M. hyopneumoniae-DNA and a significantly lower IL-1 and IL-6 concentration was found compared to the pigs of the PCG.

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., (British Veterinary Association.)

Background: Commercial bacterins are widely used at weaning to control Mycoplasma hyopneumoniae infections in pigs. However, it is not known whether the efficacy of vaccinating against M. hyopneumoniae can be influenced by the weaning process when vaccination is applied at the day of weaning. The present study assessed the efficacy of a single M. hyopneumoniae vaccination (Ingelvac MycoFLEX®) three days before weaning (V1) or at weaning (V2) against experimental challenge infection. Four weeks after vaccination, groups V1 and V2 (n = 20 pigs each) and a non-vaccinated, positive control group (PCG) (n = 20) were endotracheally inoculated with a virulent M. hyopneumoniae field strain. Five pigs were used as a negative control group. All pigs were euthanized 5 weeks after challenge. The main parameters investigated included macroscopic and histopathological lung lesions at necropsy, immunofluorescence (IF) staining and quantitative real-time PCR (qPCR) on broncho-alveolar lavage (BAL) fluid for quantifying M. hyopneumoniae., Results: The average macroscopic lung lesion scores in groups V1, V2 and PCG were 0.54, 0.88 and 1.04, respectively (P > 0.05). The average lymphohistiocytic infiltration scores in groups V1, V2 and PCG were 2.95, 3.16 and 3.61, respectively (P < 0.05). The average IF scores were: V1 = 1.13, V2 = 1.19 and PCG = 1.25 (P > 0.05), the qPCR values were: V1 = 10(2.94), V2 = 10(2.76) and PCG = 10(3.23) (P > 0.05). All pigs of the negative control group remained negative throughout the study., Conclusions: Both vaccinated groups had lower numbers of macroscopic and histopathological lung lesions, and lower numbers of M. hyopneumoniae organisms in the BAL fluid compared to the PCG. However, no firm conclusions could be made on whether weaning negatively influences the efficacy of M. hyopneumoniae vaccination, since significant differences between the treatment groups were only obtained for the histopathological lung lesions. This could be attributed to the fact that milder macroscopic lung lesions were produced in the inoculated pigs, when compared to previous trials conducted by the same group. Further research under field conditions is warranted to assess possible differences between the two vaccination strategies.