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. Author manuscript; available in PMC: 2016 Jul 1.
Published in final edited form as: Trends Parasitol. 2015 Apr 27;31(7):315–323. doi: 10.1016/j.pt.2015.03.010

Figure 2. Changes in the microbial composition and the consequent immune responses in the tick gut.

Figure 2

Alterations in the gut microbiome associated with feeding, development and infection could modulate the following immune response pathways in ticks: A. Toll pathway. Microbiota-induced activation of Spatzle, enabling Spatzle-Toll interaction and initiation of the signaling cascade resulting in the production of antimicrobial peptides (AMPs). B. Immunodeficiency (IMD) pathway. Sensing of Gram-negative peptidoglycan (Peptidoglycan) by the peptidoglycan recognition protein (PGRP-LC) to activate the signaling cascade leading to AMP production. C. Janus kinase/Signal transducer and activator of transcription JAK-STAT pathway. Microbiota and pathogen-induced activation of Dual oxidase (DUOX) results in the reactive oxygen species (ROS) production to control bacteria. ROS-mediated collateral damage to the gut epithelial cells initiates the release of cytokine-like molecule Unpaired 3 Upd that engages with its receptor, DOME, a signal transducing transmembrane protein receptor, to activate the JAK-STAT signaling pathway. STAT transcriptionally regulates pathways leading to immune responses, epithelial regeneration and repair, and peritrophic membrane integrity. AMPs and immune responses generated by Toll, IMD and JAK-STAT pathways influence pathogen survival, and also facilitate bacterial homeostasis (Based on citations 58, 87, 88 and 89).