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Updated: Jun 27, 2026

Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization
Published on: August 11, 2018
A role for antimicrobial peptides in intestinal microsporidiosis
1The Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, Florida 32080, USA. leitch@whitney.ufl.edu
Summary:
Clinical isolates from 3 microsporidia species, Encephalitozoon intestinalis and Encephalitozoon hellem, and the insect parasite Anncaliia (Brachiola, Nosema) algerae, were used in spore germination and enterocyte-like (C2Bbe1) cell infection assays to determine the effect of a panel of antimicrobial peptides. Spores were incubated with lactoferrin (Lf), lysozyme (Lz), and human beta defensin 2 (HBD2), human alpha defensin 5 (HD5), and human alpha defensin 1 (HNP1), alone and in combination with Lz, prior to germination. Of the Encephalitozoon species only E. hellem spore germination was inhibited by HNP1, while A. algerae spore germination was inhibited by Lf, HBD2, HD5 and HNP1, although HBD2 and HD5 inhibition required the presence of Lz. The effects of HBD2 and HD5 on microsporidia enterocyte infection paralleled their effects on spore germination. Lysozyme alone only inhibited infection with A. algerae, while Lf inhibited infection by E. intestinalis and A. algerae. HNP1 significantly reduced enterocyte infection by all 3 parasite species and a combination of Lf, Lz and HNP1 caused a further reduced infection with A. algerae. These data suggest that intestinal antimicrobial peptides contribute to the defence of the intestine against infection by luminal microsporidia spores and may partially determine which parasite species infects the intestine.
Insights
Intestinal antimicrobial peptides like HNP1, lactoferrin, and lysozyme inhibit microsporidia spore germination and enterocyte infection. These findings suggest a role for these peptides in defending the gut against microsporidia parasites.
Area of Science:
- Microbiology
- Immunology
- Parasitology
Background:
- Microsporidia are opportunistic pathogens causing intestinal infections.
- The role of innate immune components, specifically antimicrobial peptides, in controlling microsporidia infections is not fully understood.
Purpose of the Study:
- To investigate the in vitro effects of key intestinal antimicrobial peptides on spore germination and enterocyte infection by three microsporidia species.
- To determine the potential contribution of lactoferrin, lysozyme, and defensins to intestinal defense against microsporidia.
Main Methods:
- Spore germination assays were performed using Encephalitozoon intestinalis, Encephalitozoon hellem, and Anncaliia algerae.
- Enterocyte-like (C2Bbe1) cell infection assays were conducted.
- Antimicrobial peptides tested included lactoferrin (Lf), lysozyme (Lz), human beta defensin 2 (HBD2), human alpha defensin 5 (HD5), and human alpha defensin 1 (HNP1), alone and in combination.
Main Results:
- HNP1 inhibited E. hellem spore germination, while Lf, HBD2, HD5, and HNP1 inhibited A. algerae germination.
- HBD2 and HD5 required lysozyme for significant inhibition of A. algerae germination.
- HNP1 significantly reduced enterocyte infection by all three species, and a combination of Lf, Lz, and HNP1 further reduced A. algerae infection.
Conclusions:
- Intestinal antimicrobial peptides play a role in defending the gut against luminal microsporidia.
- The efficacy of these peptides varies among microsporidia species, potentially influencing host-parasite interactions.
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