Fluorescence <i>In Vivo</i> Hybridization (FIVH) for Detection of <i>Helicobacter pylori</i> Infection in a C57BL/6 Mouse Model

<div><p>Introduction</p><p>In this study, we applied fluorescence <i>in vivo</i> hybridization (FIVH) using locked nucleic acid (LNA) probes targeting the bacterial rRNA gene for in vivo detection of H. pylori infecting the C57BL/6 mouse model. A previously designed Cy3_HP_LNA/2OMe_PS probe, complementary to a sequence of the <i>H</i>. <i>pylori</i> 16S rRNA gene, was used. First, the potential cytotoxicity and genotoxicity of the probe was assessed by commercial assays. Further, the performance of the probe for detecting <i>H</i>. <i>pylori</i> at different pH conditions was tested <i>in vitro</i>, using fluorescence <i>in situ</i> hybridization (FISH). Finally, the efficiency of FIVH to detect <i>H</i>. <i>pylori</i> SS1 strain in C57BL/6 infected mice was evaluated <i>ex vivo</i> in mucus samples, in cryosections and paraffin-embedded sections by epifluorescence and confocal microscopy.</p><p>Results</p><p><i>H</i>. <i>pylori SS1</i> strain infecting C57BL/6 mice was successfully detected by the Cy3_HP_LNA/2OMe_PS probe in the mucus, attached to gastric epithelial cells and colonizing the gastric pits. The specificity of the probe for <i>H</i>. <i>pylori</i> was confirmed by microscopy.</p><p>Conclusions</p><p>In the future this methodology can be used in combination with a confocal laser endomicroscope for <i>in vivo</i> diagnosis of <i>H</i>. <i>pylori</i> infection using fluorescent LNA probes, which would be helpful to obtain an immediate diagnosis. Our results proved for the first time that FIVH method is applicable inside the body of a higher-order animal.</p>