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The transactivator protein Tax of human T-cell leukemia virus type I plays an important role in the development of adult T-cell leukemia probably through modulation of growth regulatory molecules including p16INK4a . The molecular mechanism of leukemogenesis induced by Tax has yet to be elucidated. We analyzed Tax

RNA interference (RNAi) can be used to inhibit viral replication in mammalian cells and therefore could be a powerful new antiviral therapy. Small interfering RNA (siRNA) may be effective for RNAi, but there are some technical problems that must be solved in each case, for example, predicting the effective siRNA target site and targeting heterogeneous sequences in a virus population. We show here that diced siRNA generated from long double-stranded RNA (dsRNA) is highly effective for inducing RNAi in HuH-7 cells harboring hepatitis C virus (HCV) replicons and can overcome variations in the HCV genotype. However, in mammalian cells, long dsRNA induced an interferon response and caused cell death. Here we describe an improvement of this method, U6 promoter-driven expression of long hairpin-RNA with multiple point mutations in the sense strand. This can efficiently silence HCV RNA replication and HCV protein expression without triggering the interferon response or cell death normally caused by dsRNA. In conclusion, intracellular-diced dsRNA efficiently induces RNAi, and, despite the high rate of mutation in HCV, it should be a feasible therapeutic strategy for silencing HCV RNA.

The effect of isomalto-oligosaccharides on human fecal flora was studied. Bifidobacteria and the Bacteroides fragilis group from human intestine could utilize isomalto-oligosaccharides but Escherichia coli and other bacteria could not. After the administration of isomaltooligosaccharides (13.5 g daily for 2 weeks) to healthy adult men and senile persons, the numbers of bifidobacteria in the feces increased. The consistency of feces was improved. These studies may support the usefulness of isomalto-oligosaccharides as components of new healthy foodstuffs for the improvement of the intestinal flora.

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