AUTHOR=Keshavarz Maryam , Zanchi Caroline , Rolff Jens 

TITLE=The effect of combined knockdowns of Attacins on survival and bacterial load in Tenebrio molitor

JOURNAL=Frontiers in Immunology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1140627

DOI=10.3389/fimmu.2023.1140627

ISSN=1664-3224

ABSTRACT=<sec><title>Introduction</title><p>Upon infection, insect hosts simultaneously express a cocktail of antimicrobial peptides (AMPs) which can impede pathogen colonization and increase host fitness. It has been proposed that such a cocktail might be adaptive if the effects of co-expressed AMPs are greater than the sum of individual activities. This could potentially prevent the evolution of bacterial resistance. However, <italic>in vivo</italic> studies on AMPs in combination are scarce. Attacins are one of the relatively large AMP families, which show anti-Gram-negative activity <italic>in vitro</italic>.</p></sec><sec><title>Material and methods</title><p>Here, we used RNA interference (RNAi) to silence three members of the Attacin family genes in the mealworm beetle, <italic>Tenebrio molitor</italic>: (<italic>TmAttacin1a</italic> (<italic>TmAtt1a</italic>), <italic>TmAttacin1b</italic> (<italic>TmAtt1b</italic>), and <italic>TmAttacin</italic>2 (<italic>TmAtt2</italic>) both individually and in combination. We then infected <italic>T. molitor</italic> with the Gram negative entomopathogen <italic>Pseudomonas entomophila</italic>.</p></sec><sec><title>Results</title><p>We found that survival of the beetles was only affected by the knockdown of <italic>TmAttacin1b</italic>, <italic>TmAttacin2</italic> and the knockdown of all three Attacins together. Triple knockdown, rather than individual or double knockdowns of AMPs, changes the temporal dynamics of their efficiency in controlling the colonization of <italic>P. entomophila</italic> in the insect body.</p></sec><sec><title>Discussion</title><p>More precisely, AMP gene expression influences <italic>P. entomophila</italic> load early in the infection process, resulting in differences in host survival. Our results highlight the importance of studying AMP-interactions <italic>in vivo</italic>.</p></sec>