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Mycoplasma bovis
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The main Mycoplasma bovis subtype in France actually conceals two lineages

A study of Mycoplasma bovis, a bacterium that is pathogenic for cattle, has revealed the presence of two lineages in France, whereas the population of bacteria of the main circulating subtype was previously thought to be homogeneous. This discovery will help improve surveillance of this bacterium. 

The bacterium Mycoplasma bovis is a major cause of respiratory disease in cattle. Scientists from the joint research unit (UMR) on Animal mycoplasmas, which brings together researchers from ANSES's Lyon Laboratory and VetAgro Sup, conducted a study into the evolution of strains of this bacterium present in France between 2000 and 2020. It was the first large-scale study of complete sequenced genomes of this bacterium. It was carried out in collaboration with scientists from the UMR on Epidemiology of animal and zoonotic diseases (INRAE-VetAgro Sup) and was funded by the thematic research network for animal health and welfare in the Auvergne-Rhône-Alpes region (SAARA).

"Thanks to the Vigimyc epidemiological surveillance network for ruminant mycoplasmas, which was set up in 2003, we have a large collection of bacteria", explains Claire Becker, Director of the UMR on Animal mycoplasmas. "The network's partner veterinary laboratories send us bacteria of the genus Mycoplasma from samples taken from sick animals in order to identify the bacterial species. More than 500 strains are collected in this way each year"

Two lineages of bacteria, rather than just one

This strain collection revealed that the evolution of Mycoplasma bovis circulating in France is more complex than previously thought. "Since the early 2000s, a subtype of Mycoplasma bovis, known as subtype 2, has been the dominant one circulating in France. We initially thought that this subtype was homogeneous, but we now realise that there are in fact two distinct lineages", explains Chloé Ambroset, co-author of the study and a scientist at the UMR. These two lineages are very similar genetically, which explains why the usual detection tools were unable to tell them apart. "This discovery will enable us to develop more targeted molecular detection tools to spot the emergence of a new lineage of Mycoplasma bovis". This is because while the lineages currently found in France cause identical symptoms, it is possible that a new lineage could emerge with different transmission capabilities or pathogenicity.

The research has also provided the scientists with insights into the factors influencing the evolution of Mycoplasma bovis. "In 2000, subtype 2 supplanted subtype 1, which was previously present in France, because of its increased resistance to antibiotics", explains Chloé Ambroset. "Our aim was to trace the dynamics of the population's evolution in order to determine the emergence and spread of subtype 2 in France. The dynamics of this population actually show two distinct lineages, which probably appeared due to the introduction of new strains when cattle were imported".

Find out more

Julien Thézé, Chloé Ambroset, Séverine Barry, Sébastien Masseglia, Adélie Colin, et al. Genome-wide phylodynamic approach reveals the epidemic dynamics of the main Mycoplasma bovis subtype circulating in France. Microbial Genomics, 2023, 9 (7), doi: 10.1099/mgen.0.001067. PMID: 37486749; PMCID: PMC10438803.