A cell-permeable, all-D-amino acid autophagy-inducing peptide based on the retro-inverso sequence of Tat-Beclin1 that is expected to be more resistant to proteolytic degradation than Tat-Beclin1 and is shown to be more potent than Tat-Beclin1 in inducing autophagy in muscle, heart, and pancreas tissues in 6-wk-old GFP-LC3 transgenic mice (20mg/kg i.p.) in vivo. Only the retro-inverso peptide, but not Tat-Beclin1, is effective in reducing autophagy substrate p26 level in the brain tissue of 5-d-old neontal GFP-LC3 mice (20mg/kg i.p.). The retro-inverso peptide treatment is also reported to greatly reduce brain viral titre in neonatal mice subjected to West Nile Virus infection.