Bovine
mycoplasmosis caused by Mycoplasma bovis
comprises diseases like pneumonia, mastitis, arthritis, otitis or genital
disorders. The lack of efficient
vaccines and medication result in large economic losses in the beef- and dairy
industries. Little is known about the pathogenesis mechanisms of this bacterium
and a better understanding of the host-M.
bovis interactions is necessary to find solutions to limit infections. Recent
studies suggest an intracellular phase of M.
bovis in host cells. To study cell invasion by M. bovis, a cellular assay using primary Embryonic Calf Nasal
Epithelial (ECaNEp) cells was developed. Three different approaches, the
gentamicin protection assay, fluorescence microscopy using differential
staining and transmission electron microscopy were conducted to confirm and
study M. bovis attached to- and
inside ECaNEp cells in vitro. These
methods all confirmed that M. bovis
is able to invade and reside inside ECaNEp cells. Mycoplasmal cell invasion was
further investigated by chemically blocking clathrin- and caveolin-based
endocytosis as well as macropinocytosis. Results demonstrate that M. bovis enters ECaNEp cells via a clathrin-mediated
pathway as well as by macropinocytosis. Overall it can be concluded, that M. bovis is able to invade and persist
inside ECaNEp cells via clathrin-mediated endocytosis and macropinocytosis.