In vivo down regulation of HIV replication after hepatitis C superinfection.

There are increasing molecular and clinical evidences that the effects of human immunodeficiency virus (HIV) infection can be modified by coinfection with other viruses. The objective was to investigate the viral interaction between HIV and hepatitis C virus (HCV) after HCV superinfection. A 16 year-old pregnant woman was evaluated because of icteric acute hepatitis. Admission laboratory tests showed the following results: ALT 877 IU/L; AST 1822 IU/L; bilirubin 6.79 mg/dl. Diagnosis of acute HCV was based on detection of serum HCV RNA by PCR and anti-HCV seroconversion. ELISA for anti HIV testing was positive and confirmed by western blot. Serum markers for other viruses were negative. The patient was followed during 19 months; serum samples were taken monthly during this period for detection of plasma HIV and HCV RNA. Levels of plasma HIV-RNA were positive in all samples tested before and after the onset of acute hepatitis C. Six months later and a for two month period, and 13 months later for a period of one month HIV viremia was undetectable; then HIV-RNA in plasma was detectable again. In conclusion, HCV superinfection may have temporarily interfered with HIV replication in our patient. The following observations support our hypothesis: it has been demonstrated that HIV-1 replication is suppressed by HCV core protein which has transcriptional regulation properties of several viral and cellular promoters. Clinical implications of this event are not generally known and the interaction between these two viruses in dual infections is worth considering.