New infection with heterotypic hepatitis C virus in a patient with long-term hepatitis C virus eradication

BACKGROUND: Experimental hepatitis C virus infection in chimpanzees has shown that natural hepatitis C virus infection does not induce protective immunity and reinfection can occur in seroconverted animals. AIM: To study the clinical, virological and histological outcome of a new infection sustained by a different hepatitis C virus strain after a primary infection with eradication of the original virus. PATIENTS AND METHODS: A young Italian man with chronic hepatitis C virus type 4 hepatitis was treated with Interferon therapy and achieved a sustained biochemical and virological response. After long follow-up, an asymptomatic flare-up of alanine transaminase occurred. This alanine transaminase increase was associated with serum hepatitis C virus RNA positivity and a low viral load, and the infecting hepatitis C virus genotype was type 3. The clinical and virological course of this new infection is described. RESULTS AND CONCLUSIONS: This report shows that there is no protective immunity against hepatitis C virus type 3 after infection by hepatitis C virus type 4 strain.