A 61-year-old man with chronic hepatitis B was treated with interferon (IFN
)-alpha for flare-up after the emergence of a lamivudine-induced YMDD motif
mutant. The YMDD mutant emerged 13 months after the initiation of lamivudi
ne therapy. Despite this, lamivudine therapy was continued. Acute exacerbat
ion occurred 25 months after the emergence of the YMDD mutant. Treatment wi
th IFN-alpha resulted in rapid loss of hepatitis, B virus DNA, resolution o
f hepatitis, and clinical recovery.