Microbiota-Derived Extracellular Vesicles as a Postbiotic Strategy to Alleviate Diarrhea and Enhance Immunity in Rotavirus-Infected Neonatal Rats

Rotavirus (RV) infection is a major cause of acute gastroenteritis in children under 5 years old, resulting in elevated mortality rates in low-income countries. The efficacy of anti-RV vaccines is limited in underdeveloped countries, emphasizing the need for novel strategies to boost immunity and alleviate RV-induced diarrhea. This study explores the effectiveness of interventions involving extracellular vesicles (EVs) from probiotic and commensal E. coli in mitigating diarrhea and enhancing immunity in a preclinical model of RV infection in suckling rats. On days 8 and 16 of life, variables related to humoral and cellular immunity and intestinal function/architecture were assessed. Both interventions enhanced humoral (serum immunoglobulins) and cellular (splenic natural killer (NK), cytotoxic T (Tc) and positive T-cell receptor gamma delta (TCR gamma delta) cells) immunity against viral infections and downregulated the intestinal serotonin receptor-3 (HTR3). However, certain effects were strain-specific. EcoR12 EVs activated intestinal CD68, TLR2 and IL-12 expression, whereas EcN EVs improved intestinal maturation, barrier properties (goblet cell numbers/mucin 2 expression) and absorptive function (villus length). In conclusion, interventions involving probiotic/microbiota EVs may serve as a safe postbiotic strategy to improve clinical symptoms and immune responses during RV infection in the neonatal period. Furthermore, they could be used as adjuvants to enhance the immunogenicity and efficacy of anti-RV vaccines.