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An indirect enzyme linked immunosorbent assay (ELISA) (Parvoscan-B19; Sweden) was compared with an in-house MACRIA for the detection of B19 specific IgM. A Parvoscan-B19 IgG test was also evaluated for its ability to detect a recent B19 infection in paired sera. Two hundred and twenty sera submitted to the laboratory for B19 serology and four MACRIA positive control sera were assayed for B19 IgM. Confirmation of the response of sera giving discordant results in the two assays was sought by the use of a "nested" polymerase chain reaction (PCR) for the detection of B19 DNA. The Parvoscan-B19 IgM test was 79% sensitive and 96% specific. Parvoscan-B19 was poor at detecting parvovirus infection in sera collected two to three months after the onset of symptoms. When sera collected more than seven weeks after the onset of symptoms were excluded from the analysis, Parvoscan-B19 IgM was 84% sensitive and 96% specific. Rubella specific IgM positive sera, rheumatoid factor positive sera, and heterophil antibody positive sera were also assayed for B19 IgM. No false positive results were encountered with these problematic sera. By using the cut off criteria for the Parvoscan-IgM test previously advocated by the manufacturers, 90% sensitivity and 87% specificity could be achieved. False positive results, however, occurred with six of the 17 rubella IgM positive sera, four of the 10 rheumatoid factor positive sera, and two of the 11 heterophil antibody positive sera tested. It is concluded that the Parvoscan-B19 was specific but insensitive when compared with in-house assays. [ABSTRACT FROM PUBLISHER]

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., ((c) 2007 Wiley-Liss, Inc.)

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.

Background: Although several diagnostic methods are available for the surveillance of patients at risk of human cytomegalovirus (CMV) infection and disease, little data is available on their comparative performances in the diagnostic setting., Objectives: To compare different assays for CMV detection, especially assays based on (quantitative) DNA and mRNA detection., Study Design: Eight allogeneic bone marrow and stem cell transplant recipients at high risk for developing CMV disease (donor CMV-negative, recipient positive) were regularly tested for 7-20 weeks post-transplant by spin-amplification rapid culture from urine (viruria), antigenemia (pp65 assay), pp67 mRNA in whole blood (NASBA), and CMV DNA both qualitatively (in-house PCR, whole blood) and quantitatively (in-house PCR, plasma; Cobas Amplicor CMV Monitor Test, plasma and whole blood; Hybrid Capture, whole blood)., Results: Four patients (50%) suffered CMV reactivation during follow-up. Out of 104 sample dates, 41 (39.4%) yielded a positive CMV result in at least one assay. Out of the 28 samples tested by all assays, the highest percentage of positive results was obtained with the in-house quantitative PCR (60.7%), followed by the Hybrid Capture system (39.3%), the Cobas Amplicor CMV Monitor Test, plasma version (35.7%), the Cobas Amplicor CMV Monitor Test, whole blood version (32.1%), in-house qualitative PCR (28.6%), and the mRNA assay (21.4%). Viruria was positive in one sample and pp65 antigenemia was found in two samples., Conclusions: Despite a considerable incidence of CMV reactivations, pre-emptive anti-CMV chemotherapy prevented the development of CMV disease with the exception of one case. The molecular assays had superior sensitivity to conventional ones. The antigenemia assay proved unsuitable for the surveillance of hematological transplant patients. However, none of the tests recognized all timepoints with CMV reactivation. Further comparative studies are needed to determine their respective diagnostic values.