Disease relevance of inlA

• Select Listeria monocytogenes subtypes commonly found in foods carry distinct nonsense mutations in inlA, leading to expression of truncated and secreted internalin A, and are associated with a reduced invasion phenotype for human intestinal epithelial cells [1].
• Here, we show that strains of the human pathogen Streptococcus agalactiae express a protein, designated Blr, which together with Slr defines a family of internalin A-related streptococcal LRR proteins [2].
• Bacterial LRR proteins include the recently described Slr protein of Streptococcus pyogenes, which is related to internalin A of Listeria monocytogenes [2].
• When crude E. coli cell lysates were subjected to immunoblot analysis, it was demonstrated that the mAb bound specifically to the heterologously expressed recombinant InlA protein, thus confirming the specificity of the mAb [3].

High impact information on inlA

• The inlA region was localized by transposon mutagenesis, cloned, and sequenced. inlA was introduced into Listeria innocua and shown to confer on this normally noninvasive species the ability to enter cells [4].
• In addition, InlC is strongly transcribed in the cytoplasm of phagocytic J774 cells whereas inlA is poorly transcribed under these conditions, suggesting that internalin C may play a role in a late stage of L. monocytogenes infection rather than in the uptake of L. monocytogenes by non-professional phagocytic cells [5].
• This uptake is independent of listerial adhesion factors internalin A and internalin B but requires cytoskeletal motion and factors present in human plasma [6].
• Incubation of macrophages and wild-type L. monocytogenes in the presence of rInlA or pretreatment of Listeria with anti-InlA antibodies specifically inhibited, by at least 50%, the phagocytosis of Listeria by both of these cells [7].
• Internalin A can mediate phagocytosis of Listeria monocytogenes by mouse macrophage cell lines [7].

Biological context of inlA

• Our data show that specific L. monocytogenes subtypes which are common among U.S. food isolates but rare among human listeriosis isolates carry inlA mutations that are associated with, and possibly at least partially responsible for, an attenuated invasion phenotype [1].
• The results of this study indicate that differential expression levels of inlA and inlB possibly play a role in the virulence capacities of L. monocytogenes strains [8].
• Analysis of sequence data for 120 L. monocytogenes isolates revealed evidence of clustering between isolates from the same source, based on the phylogenies inferred from actA and inlA (P = 0.02 and P = 0.07, respectively; SourceCluster test) [9].
• Assessment of environmental factors on Listeria monocytogenes Scott A inlA gene expression by relative quantitative Taqman real-time reverse transcriptase PCR [10].
• We tested the QEXT assay using five SNPs in the Listeria monocytogenes inlA gene as a model system [11].

Anatomical context of inlA

• Invasion assays with an isogenic PMSC mutant further supported the observation that inlA PMSCs lead to reduced invasion of Caco-2 cells [1].
• Differential inlA and inlB expression and interaction with human intestinal and liver cells by Listeria monocytogenes strains of different origins [8].
• This observation led us to study the mRNA expression levels of inlA, inlB, and ami, important virulence genes mediating adhesion and invasion of eukaryotic cells, by real-time reverse transcription-PCR for 27 clinical and 37 nonclinical L. monocytogenes strains [8].
• Expression of the Listeria monocytogenes EGD inlA and inlB genes, whose products mediate bacterial entry into tissue culture cell lines, by PrfA-dependent and -independent mechanisms [12].
• We show that L. monocytogenes invades human umbilical vein endothelial cells independently of internalin A, internalin B, internalin C, and ActA [13].

Associations of inlA with chemical compounds

• Moreover, spectroscopic features characteristic of the parallel beta helix topology in the pectate lyases are present in the circular dichroic spectrum of internalin A [14].

Analytical, diagnostic and therapeutic context of inlA

• Searches of the Pathogen Tracker database, which contains subtype and source information for more than 5,000 L. monocytogenes isolates, revealed that the six ribotypes shown to contain isolates with inlA PMSCs were overall more commonly isolated from foods than from human listeriosis cases [1].
• Western immunoblotting showed that all three inlA PMSCs result in the production of truncated and secreted InlA [1].
• As evidenced by Southern blot analysis, inlA is part of a gene family [4].

References