RESUMO
This was a retrospective, unmatched case control, laboratory-based study, investigating the impact of human immunodeficiency virus (HIV) infection on the outcome of routine laboratory detection of HBsAg and prevalence of active HBV infection in 295 samples from 167 HIV-positive and 128 HIV-negative patients. The samples were tested for HBV (HBsAg, anti-HBc, anti-HBs, HBeAg and anti-HBe) and anti-HIV 1 and 2 (Axsym assays, Abbott Laboratories), as part of routine diagnosis. A nested PCR assay, with detection limit of 800 copies/ml and employing independent sets of primers to core and surface genes, was used to investigate HBV DNA. Quantification of HBV DNA was determined with the Cobas Amplicor HBV Monitor assay (Roche Diagnostics). Of the 295 samples, the frequency of anti-HBc was almost similar; 82% for the HIV-negatives and 85% for the HIV-positives, indicating that both groups were equally exposed to HBV infection. The HIV-positives had a higher rate of anti-HBs (76.0% versus 47.7%) and a lower rate of HBsAg carriage (16.2% versus 35.2%), suggesting that HIV-positive individuals are less likely to experience chronic HBV infection. However, analysis of HBV DNA indicated that many of the anti-HBs positives (20.5% versus 8.2%) and HBsAg-negatives (22.1% versus 2.4%) had active HBV infection in the HIV-positive group. There was a statistically significant difference in the prevalence of HBV DNA in the HBsAg-negatives between the two groups (Odds ratio: 11.52; chi-square: p=0.00006). Additionally, 33.3% (5/15) of sera with "anti-HBc alone" serological pattern were HBV viremic in the HIV-positive group, compared to 0% (n=31) in the HIV-negatives. Quantification of HBV DNA from HBsAg-negative/HIV-positive patients demonstrated low level HBV viremia (below 10,000 copies/ml). In conclusion, these findings strongly support that HIV infection is a risk factor for occult HBV infections.