Genomic variability of Mycoplasma hyopneumoniae within pig lung lobes

Matteo Tonni; M Beatrice Boniotti; Sara Gasparrini; Flavia Guarneri; Nicoletta Formenti; Maria Pieters; Paolo Pasquali; Giovanni L Alborali

doi:10.1186/s40813-021-00195-1

Genomic variability of Mycoplasma hyopneumoniae within pig lung lobes

Porcine Health Manag. 2021 Jan 28;7(1):14. doi: 10.1186/s40813-021-00195-1.

Authors

Matteo Tonni¹, M Beatrice Boniotti², Sara Gasparrini², Flavia Guarneri², Nicoletta Formenti², Maria Pieters³, Paolo Pasquali⁴, Giovanni L Alborali²

Affiliations

¹ Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via Bianchi, 9, 25124, Brescia, Italy. matteo.tonni@izsler.it.
² Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via Bianchi, 9, 25124, Brescia, Italy.
³ Department of Veterinary Population Medicine, and Veterinary Diagnostic Laboratory, University of Minnesota, 1365 Gortner Ave, St. Paul, MN, 55108, USA.
⁴ Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità viale, Regina Elena 299, 00161, Rome, Italy.

Abstract

Background: Genotypic variability in M. hyopneumoniae has been reported within and among herds. However, information regarding VNTR types within single lung lobes is lacking. The objective of his study was to analyse M. hyopneumoniae infections and their association with VNTR types and lung lesions at the lobe level. Lungs from 300 pigs from 10 farms experiencing an enzootic pneumonia outbreak were collected and scored. M. hyopneumoniae was detected by real-time PCR and genotyped by MLVA assay in all samples.

Results: The results showed genotypic variability within single pigs and among lung lobes. At the lobe level, infection with one VNTR type (SN infection) was dominant. Lobes with lesion scores > 0 were associated with positive results for real-time PCR. At the lobe level, no relationship was observed between infections with more than one genotype (MX infections) and the proportion of Mycoplasma-like lesions. Lesion-free lobes presented a higher proportion of MX infections than lobes scored > 0. M. hyopneumoniae was detected more frequently in the right lobe of the lung (p < 0.05), with a similar distribution within lobes for SN and MX infections. The anatomic conformation of swine lungs led to a higher prevalence of infections in the right lobe. However, this study showed that this condition did not affect the distribution of infections with multiple VNTR types. Nevertheless, careful consideration of sample selection should be practised for M. hyopneumoniae genotype analyses, including lung lobes with no visible lesions.

Conclusion: The results did not show a significant association between the number of detected genotypes and the severity of the lesions at the lung lobe level, but revealed the unexpected detection of M. hyopneumoniae genotypes in lesion-free lobes. These results imply that a representative sampling of all lobes may lead to an accurate identification of the VNTR-type distribution. Further studies including factors that can affect pathogenetic evolution of this bacterium could shed light on the complexity of the relationship between genotypes and the lung lesions magnitude.

Keywords: Lobe; Lung; MLVA; Mycoplasma hyopneumoniae; Swine; VNTR type; Variability.