It has been proposed that occult hepatitis B virus (HBV) infection, defined as detectable HBV-DNA in serum with undetectable surface antigen (HBsAg(-)), is associated with raised transaminases in HIV-infected persons. The aim of this study was to determine the prevalence of occult HBV infection in two independent cohorts, and investigate its predictors, association with alanine-aminotransferase (ALT) levels and response to antiretroviral therapy. Sera from HBsAg(-) persons with core antibody (anti-HBc(+)) were tested by real-time PCR. Overall, 5.2% of patients were HBsAg(+) and 39% HBsAg(-)/anti-HBc(+). The prevalence of occult HBV infection was 48/343 (14.0%; 95% CI 10.7-18.1%), and 27/196 (13.8%) and 21/147 (14.3%) in the two cohorts. Median HBV-DNA load was 342 (51-147,500) and 60 (25-33,850) copies/ml respectively. HBV-DNA detection was associated with absence of surface antibody (anti-HBs), but not with CD4 or ALT levels. Among 11 HBV-DNA(+) persons who started antiretroviral therapy containing lamivudine or lamivudine/tenofovir, HBV-DNA was repeatedly undetectable over median 19 (3-43) months. However, HBV-DNA detection was intermittent among drug-naïve persons. Occult HBV infection is common in HBsAg(-)/anti-HBc(+) HIV-infected patients and predicted by undetectable anti-HBs. The intermittent nature of HBV-DNA detection poses a diagnostic challenge, but no association is observed with ALT levels.

In an unselected UK cohort, subtypes other than B accounted for 43.9% of new HIV-1 diagnoses. The prevalence of resistance mutations was 7.1% and highest in those born in the UK.

In resource-limited settings, the virological monitoring of antiretroviral therapy is limited by high cost and the lack of infrastructure. The Cavidi ExaVir Load assay employs a simple and inexpensive enzyme-linked immunosorbent assay format to measure human immunodeficiency virus (HIV) reverse transcriptase activity, which correlates with plasma RNA load. The version 3 assay has been described as having improved precision and sensitivity. There are limited data on its performance relative to those of current real-time assays

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The performance of the new Abbott real-time human immunodeficiency virus type 1 (HIV-1) assay for HIV-1 RNA load determination in plasma was compared to that of the Abbott LCx HIV-1 RNA quantitative assay following automated RNA isolation by the Abbott m1000 extractor. The measured viral loads of 89 clinical specimens differed by mean 0.19 log 10 copies/ml (95% confidence interval, 0.12 to 0.26 log 10 copies/ml). Although the difference in viral load determinations was positively skewed in favor of the LCx assay, it did not reach statistical significance (P ‫؍‬ 0.42). Results were linearly associated (R 2 ‫؍‬ 0.94) and strongly correlated (R ‫؍‬ 0.96). Good performance was observed with HIV-1 subtypes other than B and circulating recombinant forms, although results obtained with two subtype G specimens and one H specimen showed a more substantial difference.Since its introduction in the 1990s, measurement of plasma viral load (PVL) has become a cornerstone in the clinical management of human immunodeficiency virus type 1 (HIV-1) infection. The central role played by PVL has considerably increased laboratory workload, making necessary an improvement in technology. A variety of commercial assays are available for the measurement of HIV-1 PVL. Among them, realtime PCR is the latest development, offering many advantages over traditional molecular methods (3, 7, 11). These include (i) decreased performance time attributed to reduced cycle time, reduced amplicon size, and the elimination of an additional step needed for product detection; (ii) increased sensitivity as a result of the employment of fluorescence detection methods; (iii) decreased carryover contamination due to the use of a close system for the amplification and detection; and (iv) wider dynamic range. Further enhancements have been achieved by the introduction of automated nucleic acid extractions, resulting in completely automated assays with an average turnaround time of 2 h.The objective of this study was to evaluate the performance of the new Abbott real-time HIV-1 assay (referred to as the realtime assay) for PVL quantitation in comparison with the Abbott LCx HIV-1 RNA quantitative assay (referred to as the LCx assay). Both assays target the integrase region of the HIV-1 genome. In the LCx assay, 24 samples can be processed in one run, including 21 clinical specimens and 3 controls. The range of quantification is from 50 to 1 million copies/ml. In the real-time assay, 48 samples can be processed in one run. The range of quantification is 40 to 10 million copies/ml. Previous studies have assessed the performance of the LCx assay and found the test suitable for the management of patients infected by HIV-1 group M subtypes (1, 4, 8, 9). MATERIALS AND METHODSPatient and samples. Samples were randomly collected from 92 HIV-1-seropositive patients attending the Ian Charleson Day Centre clinic at Royal Free Hospital in London. Plasma was prepared from EDTA-anticoagulated blood and frozen at Ϫ80°C within 6 h of collection.Viral load determination. Plasma R...