Effect of the deletion of lprG and p55 genes in the K10 strain of mycobacterium avium subspecies paratuberculosis

Abstract

The lprG-p55 operon of Mycobacterium tuberculosis, M. bovis and M. avium strain D4ER has been identified as avirulence factor involved in the transport of toxic compounds. LprG is a lipoprotein that modulates the hostimmune response against mycobacteria, whereas P55 is an efflux pump that provides resistance to several drugs.In the present study we search for, and characterize, lprg and p55, putative virulence genes in Mycobacteriumavium subsp. paratuberculosis (MAP) to generate a live-attenuated strain of MAP that may be useful in the futureas live-attenuated vaccine. For this purpose, we generated and evaluated two mutants of MAP strain K10: onemutant lacking the lprG gene (ΔlprG) and the other lacking both genes lprG and p55 (ΔlprG?p55). None of themutant strains showed altered susceptibility to first-line and second-line antituberculosis drugs or ethidiumbromide, only the double mutant had two-fold increase in clarithromycin susceptibility compared with the wildtypestrain. The deletion of lprG and of lprG-p55 reduced the replication of MAP in bovine macrophages; however,only the mutant in lprG-p55 grew faster in liquid media and showed reduced viability in macrophages andin a mouse model. Considering that the deletion of both genes lprG-p55, but not that of lprG alone, showed areduced replication in vivo, we can speculate that p55 contributes to the survival of MAP in this animal model.