It should be noted that mycoplasma disease could be
demonstrated in the M. hyopneumoniae and M. hyosynoviae
challenge groups, but not the M. hyorhinis and M. flocculare
challenged groups. Our PCR results clearly show that the
mycoplasmas were present in the challenged pigs after
7 days or more, and the serological responses suggest that
infection had occurred as well. Failure to demonstrate
lesions at necropsy in the M. hyorhinis and M. flocculare
challenged pigs is likely due to the clearance of these
infections from the lungs by the time of necropsy 118 days
post challenge or the lack of sensitivity of our assays to
detect them. It should be noted that there are no well
established infection models for M. hyorhinis, M. hyosynoviae
and M. flocculare.