Antigenic and genetic characterization of lipoprotein LppQ from Mycoplasmamycoides subsp mycoides SC

Lipoprotein LppQ, a predominant 48-kDa antigen, and its corresponding gene, lppQ, were characterized in Mycoplasma mycoides subsp. mycoides SC, the et iological agent of contagious bovine pleuropneumonia. The lppQ gene is spec ific to M. mycoides subsp. mycoides SC and was found in the type strain and in field strains isolated in Europe, Africa, and Australia, as well as in vaccinal strains, LppQ is encoded as a precursor with a consensus sequence for prokaryotic signal peptidase II and a lipid attachment site. The leader sequence shows significant prominent transmembrane helix structure with a predicted outside-to-inside helix formation capacity, The N-terminal domain of the mature LppQ was shown to be surface exposed, It induced a strong, s pecific, early, and persistent immune response in naturally and experimenta lly infected animals, The C-terminal domain of LppQ possesses an integral m embrane structure built up of repeated units, rich in hydrophobic and aroma tic amino acids, which have a pore formation potential. A recombinant pepti de representing the N-terminal domain of LppQ was obtained by site-directed mutagenesis of nine Mycoplasma-specific TGA (Trp) codons into universal TG G (Trp) codons and expression in Escherichia coli hosts. It was used for se ro-detection of cattle infected with M. mycoides subsp. mycoides SC, in whi ch it was detected postinfection for significantly longer than conventional serological test reactions.