title: Efficacy of Mycoplasma hyopneumoniae vaccination before and at weaning against experimental challenge infection in pigs.
abstract: 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.
authors.affiliation: Porcine Health Management Unit, Department of Reproduction, Obstetrics & Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium. Ioannis.Arsenakis@UGent.be.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Arsenakis
authors.affiliation: Porcine Health Management Unit, Department of Reproduction, Obstetrics & Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Luca
authors.initials: L
authors.lastname: Panzavolta
authors.affiliation: Porcine Health Management Unit, Department of Reproduction, Obstetrics & Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Michiels
authors.affiliation: Porcine Health Management Unit, Department of Reproduction, Obstetrics & Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Rubén
authors.initials: R
authors.lastname: Del Pozo Sacristán
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Boyen
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.affiliation: Porcine Health Management Unit, Department of Reproduction, Obstetrics & Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium.
authors.forename: Dominiek
authors.initials: D
authors.lastname: Maes
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000592:standards*; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D045705:Mycoplasma hyopneumoniae; D045729:Pneumonia of Swine, Mycoplasmal / Q000473:pathology* / Q000517:prevention & control*; D034421:Sus scrofa; D013552:Swine; D014611:Vaccination / Q000592:standards / Q000662:veterinary*; D014886:Weaning
chemical_list: D001428:Bacterial Vaccines
keywords: Efficacy; Mycoplasma hyopneumoniae; Strain; Vaccination; Weaning