Identification ofMycobacterium aviumpathogenicity island important for macrophage and amoeba infection

Abstract

The ability to infect macrophages is a common characteristic shared among many mycobacterial species. Mycobacterium avium, Mycobacterium tuberculosis, and Mycobacterium kansasii enter macrophages, using the complement receptors CR1, CR3, CR4, and the mannose receptor. To identify M. avium genes and host cell pathways involved in the bacterial uptake by macrophages, we screened a M. avium transposon mutant library for the inability to enter macrophages. Uptake-impaired clones were selected. Sequence of six M. avium clones identified one gene involved in glycopeptidolipid biosynthesis, one gene encoding the conserved membrane protein homologue to the M. avium subsp. paratuberculosis MAP2446c gene and four others belonging to the same region of the chromosome. Analysis of the chromosome region revealed a pathogenicity island inserted between two tRNA sequences with 58% of G؉C content versus 69% in the M. avium genome. The region is unique for M. avium and is not present in M. tuberculosis or M. paratuberculosis. Although the mutants did not differ from the WT bacterium regarding the binding to macrophage cell membrane, analysis of macrophage proteins after 1 h infection revealed a deficiency in the mutant to phosphorylate certain proteins on uptake. To understand M. avium interaction with two evolutionarily distinct hosts, the mutants were evaluated for Acanthamoeba castellanii invasion. The defect in the ability of the mutants to invade both cells was highly similar, suggesting that M. avium might have evolved mechanisms that are used to enter amoebas and human macrophages. uptake M ycobacterium avium complex is an intracellular pathogen that can infect a variety of host cells (1-4). M. avium, like the majority of pathogenic mycobacteria, infects and replicates within macrophages (5, 6), which are the phagocytic cells where M. avium establishes a long-term infection (7).A number of studies in vitro have determined that M. avium, in a manner similar to Mycobacterium tuberculosis, is taken up by macrophages using the complement receptors CR3, CR4, and CR1 (8-10), and/or the mannose receptor (8, 11). M. tuberculosis has been found to bind to the CD11b chain of the ␤-integrin of the CR3 and CR4 receptors, which happened without participation of the serum complement proteins (10). Other studies demonstrated that the mannose capped lipoarabinomannan antigen of virulent M. tuberculosis cell wall is capable to recognize and bind to the mannose receptors on the macrophage membrane (11).It has been hypothesized that virulent mycobacteria bind to many receptors because pathogenic mycobacteria would use several different receptors on the macrophage membrane to be internalized, as a strategy to guarantee phagocytosis, even when a sitespecific macrophage would not contain one or more membrane receptors. In addition, this property would address the possibility that mycobacteria may not express all of the ligands during all phases of infection. Most mycobacteria evolved to survive inside phagocytic cells, although they can enter ...

Cooccurrence of Free-Living Amoebae and Nontuberculous Mycobacteria in Hospital Water Networks, and Preferential Growth of Mycobacterium avium in Acanthamoeba lenticulata

“…than the collection strain M. avium 104 (P Ͻ 0.05). This might be due to attenuated virulence of the laboratory strain since virulence correlates with the ability of M. avium strains to invade FLA (39). We believe that proliferation of M. avium in A. lenticulata may significantly impact the epidemiology of this pathogenic NTM in drinking water networks.…”

Surface Proteome of “Mycobacterium avium subsp. hominissuis” during the Early Stages of Macrophage Infection

“…Capable of surviving within a hijacked phagosome, M. avium subsp. hominissuis replicates within host macrophages (15). Like other pathogenic mycobacteria, M. avium subsp.…”

Species of Environmental Mycobacteria Differ in Their Abilities To Grow in Human, Mouse, and Carp Macrophages and with Regard to the Presence of Mycobacterial Virulence Genes, as Observed by DNA Microarray Hybridization

“…Many of the genes selected for the microarray were identified by a number of genome-or proteome-wide screens designed to detect M. avium or M. tuberculosis genes or proteins upregulated in human macrophages (7,13,16,25). Over 50 of these gene products have no known or predicted function, including the ORFs in a 3-kb PI identified in our laboratory, that is important in virulence (14). Little is known about how the genes contained in the open reading frames in the PI may function in virulence, but it has been shown to allow for the infection of amoeba.…”

“…These 181 genes encode proteins with predicted or characterized roles in the virulence of mycobacteria, along with representative genes of various metabolic pathways. Additionally, the array probes included 15 sequences from a recently identified pathogenicity island (PI) in M. avium (14). MAC104 gene sequences were compared to those of M. tuberculosis and M. smegmatis and other mycobacterial sequences when homologues were present.…”