Diagnostic and analytical performance of the hepatitis B core related antigen immunoassay in hepatitis B patients.

BACKGROUND: Novel serological markers for Hepatitis B virus (HBV) infection are needed for prognosis and guidance of therapy. OBJECTIVE: We evaluated the diagnostic performance of the Fujirebio Lumipulse G HBcrAg immunoassay on the Fujirebio LUMIPULSE G1200 analyzer. STUDY DESIGN: Analytical performance was examined using three HBeAg positive HBV samples. Diagnostic specificity was assessed using subpanels of 54 confirmed acute HAV, HCV, HEV, B19, CMV and EBV infections. Diagnostic sensitivity was investigated in well-defined HBV positive patient groups, both treated and untreated, including immunocompromised patients. RESULTS: The Lumipulse G HBcrAg immunoassay provided a linear measurement at a dilution between 1:100 and1:10,000. Six out of 54 samples showed non-specific reactivity in sera from acute CMV, EBV and HEV infections, of which 2 of them >3 log U/ml. The highest levels of HBcrAg were measured in HBeAg positive patients, in both treated and untreated as well as in immunocompromised patients. Untreated patients had relatively low serum HBcrAg levels in the inactive carrier phase, which increased upon progression into the HBeAg-negative hepatitis phase. Also, we showed that the applicability of HBcrAg to distinguish between patients with resolved HBV infection and false-positive reactivity to solitary anti-HBc is limited. CONCLUSIONS: Our study demonstrated significant differences in HBcrAg levels depending on HBeAg status, the clinical phase, as well as the treatment status. Specificity of the assay is good; only 2 out of 54 samples showed reactivity above 3 log U/ml. Before implementing the assay in clinical practice, additional research in larger patient cohorts should be carried out.

An analysis of the predictive value of the HIV Ag/Ab screening assay within the performance characteristics of the DiaSorin LIAISON XL for the detection of blood-borne viruses.

BACKGROUND: Correct identification of blood borne viral infections, such as hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) is crucial in detection and follow up of infection in patients. OBJECTIVES: We evaluated the diagnostic performance of the DiaSorin LIAISON XL (LIAISON XL) for screening of HBV, HCV and HIV infection. In addition, we investigated the variability of the signal-to-cuttoff ratio (S/CO) of the LIAISON XL HIV Ag/Ab assay and it's predictive value in subsequent confirmation of HIV-1 infection. STUDY DESIGN: We analyzed 16,497 blood samples on which HBV, HCV and HIV screening was performed. We defined A) archived samples previously tested with an arbitrary result in the Abbott ARCHITECT i2000SR system; B) prospectively collected samples which were simultaneously tested on the LIAISON XL and ARCHITECT i2000SR; C) prospectively collected serum samples for HIV testing which were tested solely on the LIAISON XL. RESULTS: The agreements of HBV-, HCV-, and HIV markers between the two compared systems are remarkably high. Among the samples which were prospectively tested for HIV Ab/Ag on the LIASON XL, 229 (1.6%) were reactive of which 141 (61.6%) could be confirmed. Increasing the signal-to-cutoff value to 4 could increase the positive predictive value (PPV) to 88.1% without decreasing sensitivity. CONCLUSIONS: The LIAISON XL system proved to be an excellent system for diagnosing HBV, HCV, and HIV. Our data for the first time showed that increasing the HIV S/CO ratio was safe and increased the PPV for confirmed HIV infection in the tested population.

Re-evaluation of routine dengue virus serology in travelers in the era of Zika virus emergence.

BACKGROUND: Diagnostic requests for both Zika virus (ZIKV) and dengue virus (DENV) infections in returning travelers have significantly increased during the recent ZIKV outbreak in the Americás. These flaviviruses have overlapping clinical syndromes and geographical distribution, but diagnostic differentiation is important because of different clinical consequences. As flaviviruses are known to have a short viremic period, diagnostics often rely on serological methods, which are challenging due to extensive cross-reactive antibodies. OBJECTIVE: To re-evaluate the performance of DENV serological assays in laboratory confirmed ZIKV-infected travelers. STUDY DESIGN: The extent of cross-reactivity of the DENV NS1 antigen, IgM and IgG ELISA was analyzed in 152 clinical blood samples collected from 69 qRT-PCR and 24 virus neutralization titer (VNT) confirmed ZIKV-infected travelers. RESULTS: The majority of travelers in the presented cohort returned to the Netherlands from Suriname and presented with symptoms of fever and rash. Twenty-three percent of the female travelers were pregnant. None of the 39 ZIKV RNA positive blood samples were cross-reactive in the DENV NS1 antigen ELISA. The rates of cross-reactivity of the DENV IgM and IgG ELISÁs were 31% and 54%, respectively, after excluding travelers with (potential) previous DENV exposure. CONCLUSIONS: Although the DENV NS1 antigen assay was highly specific in this cohort of laboratory confirmed ZIKV-infected travelers, we demonstrate high percentages of cross-reactivity of DENV IgM and IgG ELISÁs of which diagnostic laboratories should be aware. In addition, the high rate of DENV IgG background of >25% complicates a proper serological diagnosis in this group.