Mycoplasma gallisepticum (HS strain) surface lipoprotein pMGA interacts with host apolipoprotein A-I during infection in chicken

The adhesin protein from Mycoplasma gallisepticum (HS strain), namely pMGA1.2, is required for M. gallisepticum (MG) infection in chicken. However, the host factor(s) that interact with pMGA1.2 is not known. In this study, we prepared the membrane fraction of trachea epithelial cells from chicken embryos. Using an improved virus overlay protein blot assay (VOPBA) and glutathione S-transferase (GST) pull-down assay, we found that pMGA1.2 specifically bound to a ∼30 kDa host protein. This host protein was further identified by mass spectrometry as chicken apolipoprotein A-I (ApoA-I). We expressed and purified the recombinant ApoA-I protein in Escherichia coli and confirmed that it bound to the purified pMGA1.2 protein in vitro. Transiently expressed pMGA1.2 and ApoA-I were colocalized in HeLa cells. Finally, we designed small interfering RNA (siRNA) molecules to knock down the expression of either ApoA-I or pMGA1.2, which inhibited the MG-induced cell cycle disruption in cells of chicken embryo fibroblast cell line (DF-1). Similarly, knockdown of ApoA-I inhibited the cilia loss and damage in chicken trachea cells in MG infection. In summary, ApoA-I may be an essential host factor in MG infection through interacting with pMGA1.2.