Molecular and Immunological Analyses of the Mycobacterium avium Homolog of the Immunodominant Mycobacterium leprae 35-Kilodalton Protein

Abstract

The analysis of host immunity to mycobacteria and the development of discriminatory diagnostic reagents relies on the characterization of conserved and species-specific mycobacterial antigens. In this report, we have characterized the Mycobacterium avium homolog of the highly immunogenic M. leprae 35-kDa protein. The genes encoding these two proteins were well conserved, having 82% DNA identity and 90% identity at the amino acid level. Moreover both proteins, purified from the fast-growing host M. smegmatis, formed multimeric complexes of around 1000 kDa in size and were antigenically related as assessed through their recognition by antibodies and T cells from M. leprae-infected individuals. The 35-kDa protein exhibited significant sequence identity with proteins from Streptomyces griseus and the cyanobacterium Synechoccocus sp. strain PCC 7942 that are up-regulated under conditions of nutrient deprivation. The 67% amino acid identity between the M. avium 35-kDa protein and SrpI of Synechoccocus was spread across the sequences of both proteins, while the homologous regions of the 35-kDa protein and the P3 sporulation protein of S. griseus were interrupted in the P3 protein by a divergent central region. Assessment by PCR demonstrated that the gene encoding the M. avium35-kDa protein was present in all 30 M. avium clinical isolates tested but absent from M. intracellulare,M. tuberculosis, or M. bovis BCG. Mice infected with M. avium, but not M. bovis BCG, developed specific immunoglobulin G antibodies to the 35-kDa protein, consistent with the observation that tuberculosis patients do not recognize the antigen. Strong delayed-type hypersensitivity was elicited by the protein in guinea pigs sensitized with M. avium.

Identification and characterization of a gene encoding a 35-kDa protein from Mycobacterium avium subspecies paratuberculosis

“…These results are in line with earlier reports on the 35-kDa protein [12]. The presence of the 35-kDa protein gene in M. leprae and M. avium was earlier reported [12,17]. Our study extends the list by identifying a homologue of the 35-kDa protein encoding gene in M. paratuberculosis.…”

“…The 35-kDa protein is a major membranous antigenic component of M. leprae and M. avium eliciting T-cell immune response [12,17]. The genes encoding the protein are well conserved among the two species.…”

“…The proposed mature protein was 307 amino acids in length with an estimated molecular mass of 33 670.31 Da. Alignment of the nucleotide sequence of the MPL35 gene of M. a. paratuberculosis with that of the 35-kDa gene of M. leprae [12] and M. avium [17] showed 82.79% and 95.67% homology, respectively. The deduced amino acid sequence had 90.3% and 95.1% similarities, respectively ( Fig.…”

“…This PCR-based strategy simpli¢es the search for analogous genes in related organisms. This gene is reported to be absent in the Mycobacterium tuberculosis complex group and also in some serovars of M. intracellulare [17].…”

Reactive oxygen species‐mediated endoplasmic reticulum stress response induces apoptosis ofMycobacterium avium‐infected macrophages by activating regulated IRE1‐dependent decay pathway

“…The incidence of NTM lung disease is increasing worldwide (Arend, van Soolingen, & Ottenhoff, 2009). Mycobacterium avium complex, an NTM, is an important pathogen in pulmonary disease and in patients with acquired immunodeficiency syndrome (Lagrange, Wargnier, & Herrmann, 2000;Triccas et al, 1998).…”