{Reference Type}: Journal Article {Title}: Functional surface expression of immunoglobulin cleavage systems in a candidate Mycoplasma vaccine chassis. {Author}: Torres-Puig S;Crespo-Pomar S;Akarsu H;Yimthin T;CippĂ  V;DĂ©moulins T;Posthaus H;Ruggli N;Kuhnert P;Labroussaa F;Jores J; {Journal}: Commun Biol {Volume}: 7 {Issue}: 1 {Year}: 2024 Jun 28 {Factor}: 6.548 {DOI}: 10.1038/s42003-024-06497-8 {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, using -omics technologies and 5'RACE, we show that the four copies of the M. feriruminatoris MIB-MIP system have different expression levels and are transcribed as operons controlled by four different promoters. 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 newly developed oriC-based plasmids. The two proteins are functionally expressed at the surface of M. feriruminatoris, which confirms the possibility to display large membrane-associated proteins in this bacterium. However, 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.