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Abstract: Background: Antibody responses to hepatitis C virus (HCV) occur delayed and overly decline after viral clearance indicating that the B-cell response to HCV is abnormal. Virus-specific memory B-cells have recently been found in infected individuals, but the viral exposure requirements for the generation of these cells is unknown. Objectives: The primary goal of this study was to quantify and compare the HCV-specific memory B-cell response between chronic and resolved HCV-infected individuals. A secondary goal was to examine if HIV-specific memory B-cell responses are maintained during HCV co-infection. Study design: HCV core protein- and HIV-specific memory B-cell responses were examined in HIV/HCV-infected individuals treated 4–30 weeks after HCV diagnosis. Memory B-cell frequencies were compared between chronically and transiently infected individuals. Results: Chronically infected individuals had vigorous HCV-specific memory B-cell responses and antibodies, whereas subjects with transient viremia showed low or undetectable virus-specific B-cell responses. In addition, chronically HIV/HCV-infected subjects had robust HIV-specific memory B-cell responses. Conclusions: Whereas chronic HCV infection induces virus-specific antibodies and memory B-cells, transient infection in individuals with sustained viral response to therapy does not stimulate a durable HCV-specific B-cell response indicating that the formation of long-lived virus-specific B-cells is suppressed in the early phase of infection. This may contribute to the inability to spontaneously clear HCV infection. [Copyright &y& Elsevier]

• Accurate dengue IgG tests are important for dengue pre-vaccination testing. • We compared the Panbio and the NovaLisa dengue IgG ELISAs. • 334 sera were positive in the Panbio and 403 sera were positive in NovaLisa test. • Use of the same calibrator increased the concordance of the ELISAs from 82.8 to 93%. • An optimized standard calibrator is needed to make dengue IgG testing more reliable. Dengue IgG testing is being recommended before dengue vaccination. Presently, the diagnostic method of choice is the dengue IgG ELISA. Determine the test performance and concordance of two commercial dengue IgG ELISA kits. A diagnostic study to examine the sensitivity, specificity, accuracy and concordance of the Panbio Dengue Indirect IgG ELISA kit and the NovaLisa Dengue IgG ELISA kit. Sera (483) were from dengue-endemic regions in Sudan. Test performance characteristics were determined when tests were performed as indicated in the test kits and when the Panbio calibrator sample was used for both tests. The sensitivity of the Panbio and the NovaLisa ELISA was 91.1% and 99.0% and the specificity was 79.4% and 50.9%. The Panbio test was slightly more accurate (87.5% compared with 84.0%). Quantitative measurement readings of the tests correlated. The calibrator samples gave different cutoff values. Replacing the NovaLisa cutoff sample with the Panbio calibrator sample raised the accuracy of the NovaLisa assay to 88% and increased the concordance of the tests from 82.8 to 93%. The study shows that the two dengue IgG ELISAs differed clearly in sensitivity and specificity and gave discordant results for 17.2% of the sera. For the most part the discrepancy depended on the calibrator sample. The findings indicate that an optimized dengue IgG calibrator standard can enhance accuracy and concordance of commercial dengue ELISAs. An optimized standard calibrator would make dengue IgG seroprevalence testing more reliable. [ABSTRACT FROM AUTHOR]