Predictors and kinetics of occult hepatitis B virus infection in HIV-infected persons.

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.

Development and clinical application of a fully controlled quantitative PCR assay for cell-free cytomegalovirus in human plasma.

BACKGROUND: Cytomegalovirus (HCMV) disease continues to be a major problem in certain patient groups, including bone marrow transplant (BMT) recipients. The quantification of HCMV genome is clinically useful for the diagnosis of HCMV disease, for the virological surveillance of high-risk patients and for monitoring antiviral therapy. OBJECTIVES: To develop a novel, robust, and fully controlled PCR (qPCR) for the quantification of HCMV DNA in plasma samples and to demonstrate its clinical usefulness in the BMT setting. STUDY DESIGN: The newly developed HCMV qPCR employs cell culture-derived murine CMV as an internal control for both extraction and amplification. Following amplification using common primers, detection of both internal control and patient HCMV amplicons is by specific probes and a chemiluminescence microtitre plate system. Its performance was evaluated using the routine non-quantitative nested HCMV PCR on whole blood (NQPCR) and correlated with clinical events such as disease and antiviral therapy. RESULTS: A high level of concordance (85.1%) was found between the novel assay and the NQPCR, with the qPCR being slightly more sensitive. The samples giving discordant results generally had levels of HCMV DNA close to the limit of detectability or had been stored for prolonged periods. CONCLUSIONS: The use of plasma as an analyte by the newly developed assay avoids the detection of cell-associated virus. On the other hand, testing a comparatively large volume of plasma ensures that sensitivity is not compromised by not detecting cell-associated HCMV. In a small preliminary evaluation in BMT recipients, changes in HCMV 'viral load' correlated with initiation and discontinuation of antiviral therapy and were biologically plausible.