Tissue sequestration of 'Candidatus Mycoplasma turicensis'

'Candidatus Mycoplasma turicensis' ('Candidatus M. turicensis') is a hemoplasma species that infects felids. It differs from other feline hemoplasma species due to its particular infection kinetics and phylogenetic similarity to rodent hemoplasma species. The lower and shorter bacteremia produced by 'Candidatus M. turicensis' suggests a possible tissue sequestration of the organism. The aim of this study was to explore this possibility. Five specified-pathogen free cats were subcutaneously inoculated with 'Candidatus M. turicensis' and sacrificed 86 days after inoculation. Thirty-one selected organs were collected upon necropsy, and samples were analyzed by real-time Taqman® PCR. The humoral immune response was monitored by DnaK ELISA. All five cats had detectable 'Candidatus M. turicensis' loads in the majority (52-100%) of the tested tissues. High 'Candidatus M. turicensis' tissue loads (average 3.46 × 104 copies/10 mg) were detected in the samples. The presence of the organisms in the tissues could not be explained by the blood burdens because the blood of four out of five cats tested PCR-negative at the time of necropsy. This is the first study to describe the distribution of 'Candidatus M. turicensis' in various organs; it also demonstrates that, in contrast to other feline hemoplasma species, significant sequestration of 'Candidatus M. turicensis' occurs in many tissues. These results represent an important step toward the understanding of the pathogenesis of 'Candidatus M. turicensis'.