AUTHOR=Samba-Louaka Ascel , Robino Etienne , Cochard Thierry , Branger Maxime , Delafont Vincent , Aucher Willy , Wambeke Wilfrid , Bannantine John P. , Biet Franck , Héchard Yann 

TITLE=Environmental Mycobacterium avium subsp. paratuberculosis Hosted by Free-Living Amoebae

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=8

YEAR=2018

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2018.00028

DOI=10.3389/fcimb.2018.00028

ISSN=2235-2988

ABSTRACT=<p><italic>Mycobacterium avium</italic> subsp. <italic>paratuberculosis</italic> is responsible for paratuberculosis in animals. This disease, leading to an inflammation of the gastrointestinal tract, has a high impact on animal health and an important economic burden. The environmental life cycle of <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic> is poorly understood and several studies suggest that free-living amoebae (FLA) might be a potential environmental host. FLA are protozoa found in water and soil that are described as reservoirs of pathogenic and non-pathogenic bacteria in the environment. Indeed, bacteria able to survive within these amoebae would survive phagocytosis from immune cells. In this study, we assessed the <italic>in vitro</italic> interactions between several strains of <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic> and <italic>Acanthamoeba castellanii</italic>. The results indicate that the bacteria were able to grow within the amoeba and that they can survive for several days within their host. To explore the presence of <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic> in environmental amoebae, we sampled water from farms positive for paratuberculosis. A <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic> strain was detected within an environmental amoeba identified as related to the poorly described <italic>Rosculus</italic> genus. The bacterial strain was genotyped, showing that it was similar to previous infectious strains isolated from cattle. In conclusion, we described that various <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic> strains were able to grow within amoebae and that these bacteria could be found on farm within amoebae isolated from the cattle environment. It validates that infected amoebae might be a reservoir and vector for the transmission of <italic>M. avium</italic> subsp. <italic>paratuberculosis</italic>.</p>