Characterization of the MIB-MIP system of different Mollicutes using an engineered Mycoplasma feriruminatoris

Abstract

Abstract The Mycoplasma Immunoglobulin Binding/Protease (MIB-MIP) system is a candidate virulence factor present in multiple pathogenic species of the Mollicutes, including the fast-growing species Mycoplasma feriruminatoris. The MIB-MIP system cleaves the heavy chain of host immunoglobulins, hence affecting antigen-antibody interactions and potentially facilitating immune evasion. In this work we analyzed the distribution and genetic relatedness between MIB-MIP systems of different Mollicutes species. Using -omics technologies, we show that the four copies of the M. feriruminatoris MIB-MIP system have different expression levels, are transcribed as operons controlled by four different promotors. Individual MIB-MIP gene pairs of M. feriruminatoris and other Mollicutes were introduced in an engineered M. feriruminatoris strain devoid of MIB-MIP genes and were tested for their functionality using oriC-based plasmids. The two proteins were functionally expressed at the surface of M. feriruminatoris, which confirms the possibility to display large functional heterologous surface proteins in M. ferirumintoris. Functional expression of heterologous MIB-MIP systems introduced in this engineered strain from phylogenetically distant porcine Mollicutes like Mesomycoplasma hyorhinis or Mesomycoplasma hyopneumoniae could not be achieved. Finally, since M. feriruminatoris is a candidate for biomedical applications such as drug delivery, we confirmed its safety in vivo in domestic goats, which are the closest livestock relatives to its native host the Alpine ibex.