Reactivation of a Vaccine Escape Hepatitis B Virus Mutant in a Cambodian Patient During Anti-Hepatitis C Virus Therapy.

A 76-year-old Cambodian man co-infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) 6c-1 presented for care. HBV DNA was intermittently detectable despite anti-HBs levels being above the protective threshold. During treatment for HCV, HBV DNA levels increased. Sequencing revealed multiple mutations including vaccine escape mutation and mutations predicted to enhance fitness. This case represents exacerbation of an HBV vaccine escape mutant during a direct-acting antiviral therapy.