OBJECTIVETo investigate and analyze the differential prevalence, as well as the risk factors and clinical features, of occult hepatitis B virus (HBV) infection in the human immunodeficiency virus (HIV)-infected population without antiretroviral therapy (ART) as compared to the general (non-HIV-infected) population.

METHODSTwo-hundred-and-forty-eight individuals with confirmed HIV infection but ART naive (males: 220, females: 28; 15-82 years old) were enrolled in the study, along with 121 healthy individuals (confirmed HIV antibody-negative; males: 53, females: 68; 20-88 years old). HBV markers (hepatitis B surface antigen (HBsAg); hepatitis B e antigen (HBeAg); anti-HBs, anti-HBe and anti-hepatitis B core (HBc) antibodies) were detected by microparticle enzyme-linked immunosorbent assay (AxSYM immunology analyzer manufactured by Abbott Laboratories); all cases and controls were confirmed negative for hepatitis B surface antigen (HBsAg). Then, the HBV DNA level in serum was detected using nucleic acid amplification assay (COBAS AmpliPrep/COBAS TaqMan HBV test, version 2.0 manufactured by Roche). CD4+ T lymphocytes were measured by flow cytometry, and alanine aminotransferase (ALT, marker of liver function) was measured by enzymatic assay.

RESULTSTwenty-four of the HIV cases (9.7%) and four of the healthy controls (3.3%) tested positive for HBV DNA; the amount of individuals with HBV DNA-positivity was significantly higher in the HIV-infected group (P = 0.035). Among the 24 cases of HBV DNA(+) HIV-infected individuals, the lowest HBV DNA load was < 20 IU/ml and the highest was 3.22 x 10s IU/ml; nine of the individuals (37.5%) had HBV DNA load > 100 IU/ml, four (16.7%) had 20-99 IU/ ml, and 11 (45.8%) had < 20 IU/ml. Among the total HIV-infected cases with HBV DNA-positivity, 7.3% (8/110) were anti-HBc(+)/anti-HBs(+), 20.8% (11/53) were anti-HBc(+)/anti-HBs(-), 14.3% (3/21) were anti-HBc(-)/anti-HBs(+), and 3.1% (2/64) were anti-HBc(-)/anti-HBs(-). The amount of individuals with HBV DNA-positivity in the anti-HBc(+)/anti-HBs(-) group was significantly different from those in the anti-HBc(+)/anti-HBs(+) group (P = 0.018) and the anti-HBc(-)/anti-HBs(-) group (P = 0.003). However, multiple comparison of HBV DNA loads detected between the four groups of HBV marker status revealed no significant difference (P = 0.805). Furthermore, statistical analysis provided no evidence to support that occult hepatitis B infection in HIV-infected individuals had any impact on CD4+ T lymphocytes count (Z = 1.902, P = 0.059) or ALT levels (Z =1.401, P = 0.161).

CONCLUSIONHIV-infected individuals who are ART naive and HBsAg(-) have a higher incidence of HBV DNA-positivity than individuals in the general (non-HIV-infected) population. In addition, the highest rate of occult hepatitis B among the HIV-infected cases occurred among individuals who were anti-HBc(+)/anti-HBs(-).