Study of the Ability of Bifidobacteria of Human Origin to Prevent and Treat Rotavirus Infection Using Colonic Cell and Mouse Models

<div><p>Rotavirus is the leading cause of severe acute gastroenteritis among children worldwide. Despite effective vaccines, inexpensive alternatives such as probiotics are needed. The aim of this study was to assess the ability of probiotic candidate <i>Bifidobacterium thermophilum</i> RBL67 to inhibit rotavirus infection. Bacterial adhesion to intestinal cells and interference with viral attachment were evaluated <i>in vitro</i>. <i>B</i>. <i>thermophilum</i> RBL67 displayed adhesion indexes of 625 ± 84 and 1958 ± 318 on Caco-2 and HT-29 cells respectively and was comparable or superior to four other bifidobacteria, including <i>B</i>. <i>longum</i> ATCC 15707 and <i>B</i>. <i>pseudolongum</i> ATCC 25526 strains. Incubation of <i>B</i>. <i>thermophilum</i> RBL67 for 30 min before (exclusion) and simultaneously (competition) with human rotavirus strain Wa decreased virus attachment by 2.0 ± 0.1 and 1.5 ± 0.1 log₁₀ (by 99.0% and 96.8% respectively). Displacement of virus already present was negligible. In CD-1 suckling mice fed <i>B</i>. <i>thermophilum</i> RBL67 challenged with simian rotavirus SA-11, pre-infection feeding with RBL 67 was more effective than post-infection feeding, reducing the duration of diarrhea, limiting epithelial lesions, reducing viral replication in the intestine, accelerating recovery, and stimulating the humoral specific IgG and IgM response, without inducing any adverse effect. <i>B</i>. <i>thermophilum</i> RBL67 had little effect on intestinal IgA titer. These results suggest that humoral immunoglobulin might provide protection against the virus and that <i>B</i>. <i>thermophilum</i> RBL67 has potential as a probiotic able to inhibit rotavirus infection and ultimately reduce its spread.</p>