Passive immunization does not provide protection against experimental infection with Mycoplasma haemofelis

Sugiarto, Sarah; Spiri, Andrea M.; Riond, Barbara; Novacco, Marilisa; Oestmann, Angelina; de Miranda, Luisa H. Monteiro; Meli, Marina L.; Boretti, Felicitas S.; Hofmann-Lehmann, Regina; Willi, Barbara

The present study used an experimental set-up to address the protective role of passively transferred antibodies in Mhf infection. Experimental infection studies do have some inherent limitations when results are generalized to natural infections. However, to mirror the natural transmission of hemoplasmas most accurately, a published low-dose infection model was applied in this study [22] . The inoculated dose contained only 1000 copies of Mhf, which corresponds to approximately 0.05 μL of infectious blood from a naturally infected cat [22] . This small blood volume can easily be transmitted by bloodsucking arthropods or via aggressive interaction between cats-both of the latter transmission routes are assumed to be natural ways of transmission for feline hemoplasmas [17] [18] [19] . Therefore, the infectious dose applied to the cats should not be the reason for the lack of protection in the passively immunized cats.