REDUCTION OF VIRUS SHEDDING BY B-BIFIDUM IN EXPERIMENTALLY-INDUCED MRV INFECTION - STATISTICAL APPLICATION FOR ELISA

The protective effect of a human strain of Bifidobacterium bifidum (B. bifidum) against murine group A rotavirus (MRV) was examined in the i ntestines of BALB/c infected mice. In experiments designed to determin e whether B. bifidum mediated MRV shedding during diarrheal disease, p regnant dams (and their expected litters) were randomly assigned to th e following groups: (1) mice infected with MRV alone; (2) B. bifidum-t reated + MRV-infected mice; (3) B. bifidum-treated controls; and (4) s aline control animals. An enzyme-linked immunosorbent assay (ELISA) fo r the detection of group A rotavirus was used to measure virus protein . The sensitivity of the MRV antigen detector ELISA was determined by serially diluting the rotavirus antigen in test samples. Antigen was d etected in dilution ranges of 1:256-1:4096 during the acute phase and 1:16-1:512 in the recovery phase of MRV clinical disease, in the sampl es tested. Treatment with B. bifidum significantly reduced shedding of MRV antigen (P < 0.009) on days 2-10 postinoculation. The reduction i n shedding of virus protein corresponded well with delayed onset of ac ute diarrhea (P < 0.02). Closer examination of tissue cross sections u nder electron microscopy revealed that the B. bifidium-ingested strain adhered to the epithelium of the small intestine. These results sugge st that priming the intestine with B. bifidum is effective against exp erimental MRV challenge and confirmed the potential usefulness of this detector ELISA for studying the kinetics of group A rotavirus infecti on in animals and humans.