HIV and Liver Diseases

Coinfection with hepatitis B virus (HBV) and HIV is common, with 70-90% of HIV-infected individuals in the United States having evidence of past or active infection with HBV. Factors affecting the prevalence of chronic HBV include age at time of infection and mode of acquisition, which vary geographically. In the United States and Western Europe, HBV often is acquired in adolescence or adulthood via sexual contact or injection drug use. Although spontaneous clearance of HBV acquired in adulthood occurs in >90% of immunocompetent individuals, HIV-infected persons are half as likely as HIV-uninfected persons to spontaneously clear HBV. Therefore, chronic HBV infection occurs in 5-10% of HIV-infected individuals who are exposed to HBV, a rate 10 times higher than that for the general population. In the United States, HIV/HBV coinfection rates are highest among men who have sex with men (MSM) and injection drug users. In contrast, in Asia and sub-Saharan Africa, where vertical and early childhood exposure are the most common modes of transmission, respectively, and overall HBV prevalence is higher, the prevalence of HBV among HIV-infected individuals also is higher, at an estimated 20-30%. HBV is a DNA virus that forms stable circular covalently closed (ccc) DNA that can persist in the liver indefinitely. Individuals with evidence of past infection (core antibody positivity) are at risk of HBV reactivation, particularly in the setting of severe immunocompromise, prolonged steroid use, or chemotherapy. There are 8 genotypes of HBV. Genotype G may be predictive of more severe fibrosis in HIV-coinfected patients, and genotypes C and D may be more responsive to interferon. However, in general, knowledge of the HBV genotype is not consistently associated with a response to nucleoside therapy and therefore is not particularly useful in clinical care of HIV/HBV coinfection, as nucleosides are the mainstays of HBV treatment.