Diagnostic Performance of an Automated System for Assaying Anti-Hepatitis E Virus Immunoglobulins M and G Compared with a Conventional Microplate Assay.

To evaluate the diagnostic performance of the Liaison® Murex anti-HEV IgM and IgG assays running on the Liaison® instrument and compare the results with those obtained with Wantai HEV assays. We tested samples collected in immunocompetent and immunocompromised patients during the acute (HEV RNA positive, anti-HEV IgM positive) and the post-viremic phase (HEV RNA negative, anti-HEV IgM positive) of infections. The specificity was assessed by testing HEV RNA negative/anti-HEV IgG-IgM negative samples. The clinical sensitivity of the Liaison® IgM assay was 100% for acute-phase samples (56/56) and 57.4% (27/47) for post-viremic samples from immunocompetent patients. It was 93.8% (30/32) for acute-phase (viremic) samples and 71%% (22/31) for post-viremic samples from immunocompromised patients. The clinical sensitivity of the Liaison® IgG assay was 100% for viremic samples (56/56) and 94.6% (43/47) for post-viremic samples from immunocompetent patients. It was 84.3% (27/32) for viremic samples and 93.5% (29/31) for post-viremic samples from immunocompromised patients. Specificity was very high (>99%) in both populations. We checked the limit of detection stated for the Liaison® IgG assay (0.3 U/mL). The clinical performance of the Liaison® ANTI-HEV assays was good. These rapid, automated assays for detecting anti-HEV antibodies will greatly enhance the arsenal for diagnosing HEV infections.

Are antibodies to fine specificities of citrullinated peptides/proteins useful for stratification of rheumatoid arthritis patients?

BACKGROUND: In rheumatoid arthritis (RA), antibodies to citrullinated protein (ACPA) are believed to be heterogeneous and patient stratification by antibody profiling raised clinical interest for patient management. However, heterogeneity might be partially artificial because of the use of heterogeneous methods for ACPA detection. In recent work instead, we found that ACPA were mainly directed towards a single fibrin-derived peptide, ß60-74BiotNt, but a comparative analysis with the presence of other ACPA specificities is still lacking. OBJECTIVES: To present an overview of RA patients' stratification based on the detection of the main ACPA fine specificities with the same method as compared to that of anti-ß60-74BiotNt antibodies. METHODS: Over 4500 measurements were performed with more than 22 standardised ELISAs, sera from 180 RA patients and 200 to 436 non-RA rheumatic disease controls. RESULTS: Four to 81% of RA patients had ACPA towards various targets, confirming the heterogeneity of ACPA specificities. However, the subgroups of patients overlapped up to 97% with ACPA levels of correlation coefficients up to 0.8, showing redundancy of some targets. Multiplexing decreased diagnostic specificity from 95% to 64%. Instead, anti-ß60-74BiotNt detection identified almost all ACPA-positive patients. CONCLUSIONS: Antibodies to citrullinated protein multiplexing shows some degree of redundancy and is not suitable for diagnostic purposes. ACPA fine specificities might be less heterogeneous than perceived by sera testing on multiple peptides. Patient stratification largely depends on detection methods and requires standardisation.