Study of 25 Mycoplasma hyopneumoniae, Mycoplasma hyorhinis or Mycoplasma flocculare strains by Next-generation sequencing

The objective of this work was to study the virulence of three mycoplasmal species in pig: Mycoplasma hyopneumoniae (MHP), Mycoplasma hyorhinis (MHR) and Mycoplasma flocculare (MF) cohabiting in the porcine respiratory tract. MHP causes the porcine enzootic pneumonia, while MF is a commensal bacterium. MHR is present in cases of pneumonia, polyserositis and arthritis. Comparative analyses demonstrated high similarity between these species. The genomic resemblance among these three mycoplasmal species combined with their different levels of pathogenicity is an indication that they have mechanisms of virulence and differential expression, as for most mycoplasmas.Recently, an exploratory investigation was carried out in lung samples from slaughtered pigs in order to study the relationships between the severity of pneumonia and the detection of the three mycoplasmal species, alone or in association (Fourour et al. 2018, doi: 10.1111/jam.13770). The multidimensional analysis revealed three main groups of associations between variables describing the score of gross pneumonia-like lesions and the PCR status of the lungs for the three mycoplasmal species. A first group was characterized by lungs without or with low gross pneumonia-like lesion scores (score=2) and lung samples PCR-negative for all three mycoplasmal species or PCR-positive only for MF. A second group consisted of lung samples with moderate to high gross pneumonia-like lesion scores (score = 3) and lung samples PCR-positive for MHP. The third group comprised lung samples with high gross pneumonia-like lesion scores (score>10) and lung samples PCR-positive for several mycoplasmal species.The 25 strains sequenced in this BioProject were isolated in these three epidemiological groups: 6 strains of group 1 (4 MF, 1 MHP, 1 MHR), 8 strains of group 2 (5 MHP, 3 MHR) and 11 isolates of group 3 (3 MF, 3 MHP, 5 MHR). Whole-genome sequencing was performed on Illumina MiSeq platform.