In vivo transmission studies of ‘Candidatus Mycoplasma turicensis’ in the domestic cat

The natural transmission routes of the three feline haemotropic mycoplasmas – Mycoplasma haemofelis, ‘Candidatus Mycoplasma haemominutum’, and ‘Candidatus Mycoplasma turicensis’ (CMt) – are largely unknown. Since CMt has been detected in the saliva of infected cats using PCR, we hypothesised that direct transmission via social or aggressive contact may occur. The aim of this study was to evaluate this transmission route. CMt-positive saliva and blood samples were obtained from three prednisolone-treated specific pathogen-free (SPF) cats that were infected intraperitoneally with CMt. Five SPF cats were inoculated with CMt-positive saliva or blood subcutaneously to mimic cat bites, and five cats were inoculated orally with blood or oronasally with saliva to mimic social contact. Blood samples were monitored for CMt infection using quantitative real-time PCR and for seroconversion using a novel western blot assay. Neither oronasal nor subcutaneous inoculation with CMt-positive saliva led to CMt infection in the recipient cats, as determined by PCR, independent of prior prednisolone treatment. However, when blood containing the same CMt dose was given subcutaneously, 4 of the 5 cats became PCR-positive, while none of the 5 cats inoculated orally with up to 500 μL of CMt-positive blood became PCR-positive. Subsequently, the latter cats were successfully subcutaneously infected with blood. All 13 CMt-exposed cats seroconverted. In conclusion, CMt transmission by social contact seems less likely than transmission by aggressive interaction. The latter transmission may occur if the recipient cat is exposed to blood from an infected cat.