ABSTRACT
The Architect EBV antibody panel is a new chemiluminescence immunoassay system used to determine the stage of Epstein-Barr virus (EBV) infection based on the detection of IgM and IgG antibodies to viral capsid antigen (VCA) and IgG antibodies against Epstein-Barr nuclear antigen 1 (EBNA-1). We evaluated its diagnostic accuracy in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis (IM) using the RecomLine EBV IgM and IgG immunoblots as the reference standard. In addition, the use of the antibody panel in a sequential testing algorithm based on initial EBNA-1 IgG analysis was assessed for cost-effectiveness. Finally, we investigated the degree of cross-reactivity of the VCA IgM marker during other primary viral infections that may present with an EBV IM-like picture. High sensitivity (98.3% [95% confidence interval {CI}, 90.7 to 99.7%]) and specificity (94.2% [95% CI, 87.9 to 97.8%]) were found after testing 162 precharacterized archived serum samples. There was perfect agreement between the use of the antibody panel in sequential and parallel testing algorithms, but substantial cost savings (23%) were obtained with the sequential strategy. A high rate of reactive VCA IgM results was found in primary cytomegalovirus (CMV) infections (60.7%). In summary, the Architect EBV antibody panel performs satisfactorily in the investigation of EBV IM in immunocompetent adolescents and young adults, and the application of an EBNA-1 IgG-based sequential testing algorithm is cost-effective in this diagnostic setting. Concomitant testing for CMV is strongly recommended to aid in the interpretation of EBV serological patterns.
Subject(s)
Antibodies, Viral/blood , Capsid Proteins/immunology , Epstein-Barr Virus Nuclear Antigens/immunology , Infectious Mononucleosis/diagnosis , Adolescent , Adult , Antigens, Viral/immunology , Capsid/immunology , Cost-Benefit Analysis , Cross Reactions/immunology , Cytomegalovirus Infections/diagnosis , Cytomegalovirus Infections/immunology , Herpesvirus 4, Human/immunology , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Infectious Mononucleosis/immunology , Luminescent Measurements/economics , Retrospective Studies , Sensitivity and Specificity , Serologic Tests/economics , Young AdultABSTRACT
BACKGROUND: The quantitative measurement of HIV-1 RNA levels in plasma ('viral load') is essential in the management of HIV-infected patients. OBJECTIVE: The new Artus HIV-1 QS-RGQ assay ('Artus(HIV)') for HIV-1 RNA quantification in plasma was compared to the Abbott RealTime HIV-1 assay ('RealTime') following automated RNA isolation by the QIAsymphony and Abbott m2000 extractors, respectively. Emphasis was placed on assay performance with diverse HIV-1 subtypes and in patients receiving antiretroviral therapy (ART). STUDY DESIGN: Plasma from 211 patients (105 subtype B, 87 non-B subtypes; 147 on ART) and serial dilutions of the WHO 2nd International HIV-1 RNA Standard (WHO-IS) were tested by the two assays in parallel. Assay relationship and agreement were determined by linear regression, correlation analysis, and Bland-Altman analysis. RESULTS: With 125 specimens quantified by both assays, measurements were linearly associated and strongly correlated. Overall Artus reported higher levels by mean 0.24 (95% confidence interval [CI] 0.16-0.32) log(10) copies/ml (P < 0.0001); 5 samples (subtypes A, B, CRF01, CRF03) fell outside the 95% agreement. Discordant results were obtained with 11 and 13 samples quantified by either ArtusHIV or RealTime alone respectively, at levels generally close to the lower limit of quantification, giving an overall discordance rate of 24/211 (11%). Both assays generally under-quantified the WHO-IS by between 0.1 and 0.4 log(10) copies/ml across seven dilutions. CONCLUSIONS: The ArtusHIV assay offers performance comparable to that of the RealTime assay across a wide range of HIV-1 subtypes and among both treated and untreated patients.
