In silico characterization of a putative ORF-MAP1138c of Mycobacterium avium subspecies paratuberculosis(MAP) with its implications in virulence

Abstract

Background Johne’s disease is a chronic mycobacterial infection of the small intestine affecting ruminants worldwide. It is estimated that over 50% of the European Union (EU) dairy holdings is infected [1]. The causal agent is Mycobacterium avium subspecies paratuberculosis (MAP), a slow-growing, acid-fast bacterium. It is a part of the Mycobacterium avium complex (MAC), which also comprises of opportunistic pathogens of humans, as well as innocuous, environmental bacteria [2]. MAP generally interacts with macrophages via different types of receptors, including Toll-like receptors (TLRs) [3,4]. It has been demonstrated of late that H37Rv1411c (LprG) enhances the recognition of triacylated Mycobacterium tuberculosis glycolipids by TLR2 and thereby restraining the expression of MHC-II molecules and processing of antigen and presentation of MHC restricted antigens by macrophages in a TLR2dependent manner [5,6]. However, little is known about how M. paratuberculosis evades and resists this active CD4 T-cell response and survives and infects other macrophages, a hallmark of mycobacterial infections. In this context, the identification of antigenic proteins is useful in understanding the immune evasion mechanism of MAP within host macrophages.