Decreased rotavirus infection of MA104 cells via probiotic extract binding to Hsc70 and ß3 integrin receptors

Probiotic bacteria are microorganisms beneficial to human health, useful to improving biological conditions. Thanks to probiotic bacteria the symptoms of viral infections can be alleviated. Different mechanisms whereby probiotic bacteria exert they antiviral effect have been proposed. The aim of this study was to determine whether probiotic bacteria extracts bind to receptors of host cells susceptible of rotavirus (RV) infection. To accomplish this objective, four probiotic bacterial strains of Lactobacillus spp. and Bifidobacterium spp. were tested. Probiotic extracts were obtained after bacterial growth, cell lysis and centrifugation. Obtained probiotic extracts were used in assays to interfere with adhesion and penetration of a RV strain in the mammal cell line MA104. Furthermore, the interaction between probiotic extracts and MA104 cell receptors was evaluated by co-immunoprecipitation assays using anti-ß3-integrins and anti-Hsc70 antibodies. All four probiotic, protein-rich, extracts reduced RV infections in MA104 cells, suggesting a successful antiviral activity mediated by these probiotic extracts. All probiotic extracts significantly exerted thir antiviral activity by interfering with RV adhesion on MA104 cell receptors, with proteins in probiotic extracts competitively interacting with cell surface receptors necessary to RV infection. Co-immunoprecipitation assay results showed that proteins in probiotic extracts were able to bind to ß3-integrinsand Hsc70, which are two cellular receptors required to viral infection. The most significant contribution of this study is an insight into the mechanisms of probiotic antiviral activity, thus expanding current probiotics fundamental knowledge.