Assessment of treatment efficacy in HBV infection and disease.

In patients co-infected with HIV and HBV viral load monitoring allows comparison of the efficacy of different antiviral drugs and determination of the initial response to therapy. Usually, the decline in viral load is associated with an improvement in ALT levels and liver histology scores, but some patients show transient elevations in ALT levels due to the restoration of the specific anti-HBV immune response. Analysis of liver histology is useful to determine the improvement of the inflammatory activity of the disease and liver fibrosis, and to make an accurate diagnosis when drug hepatotoxicity is suspected. HBe seroconversion and HBs loss have been described in some patients during anti-HBV therapy with lamivudine, adefovir or tenofovir, indicating that the control of viral replication by these agents may lead to a dramatic suppression of viral load. HBV drug resistant mutants can be diagnosed at an early stage with the monitoring of viral load. Future research directions include the determination of predictive factors of response, the effect of anti-HBV therapy on liver disease severity, the impact of long-term treatment on HBsAg clearance and intrahepatic cccDNA, the impact of HBV drug resistance on the liver disease, the role of cross-resistance testing of HBV strains in patients with HBV treatment failure.