EFFECTIVENESS OF BIFIDOBACTERIUM-BIFIDUM IN MEDIATING THE CLINICAL COURSE OF MURINE ROTAVIRUS DIARRHEAL

Human Bifidobacterium sp strain bifidum (B. bifidum) was administered to BALB/c lactating mice (n = 58) and their litters (n = 327 pups) to evaluate the ingested strain's adherent properties and ability to inhi bit murine rotavirus (MRV) infection. ELISA and anaerobic bacteriologi c techniques were used to measure MRV shedding and colonization of Bif idobacterium in the small intestine. At 13-16 d gestation, pregnant da ms (and their expected litters) were randomly assigned to one of four experimental groups: 1) normal controls; 2) B. bifidum-treated only; 3 ) MRV-infected only; and 4) B. bifidum-treated + MRV-infected dams and litters. During the acute phase of diarrhea, 80% of small-intestine c ultures in B. bifidum-treated litters were positive for the ingested B . bifidum strain compared with 24% of fecal cultures. Examination of t issue cross sections under electron microscopy revealed the ingested B . bifidum strain survived passage through the upper gastrointestinal t ract and adhered to the small-intestine epithelium. After the administ ration of the high dose of virus, diarrhea developed in all pups, but onset was significantly delayed in B. bifidum-treated + MRV-infected l itters compared with litters infected with MRV only (p < 0.02). B. bif idum-treated + MRV-infected pups demonstrated a significant reduction in MRV shedding compared with litters challenged with MRV only at d 2 to 10 after inoculation (p < 0.009). More direct studies are needed to assess mechanisms by which this anaerobe can alter the course of MRV infection at the level of gut epithelium.