Anti-spike protein to determine SARS-CoV-2 antibody levels: Is there a specific threshold conferring protection in immunocompromised patients?

Background: Identifying a specific threshold level of SARS-CoV-2 antibodies that confers protection in immunocompromised patients has been very challenging. The aim was to assess the threshold of 264 binding antibody units (BAU)/ml using four different SARS-CoV-2 antibody assays (Abbott, Beckman, Roche, and Siemens) and to establish a new optimal threshold of protection for each of the four antibody assays.

Methods: This study was performed on data retrieved from 69 individuals, who received at least one dose of the Pfizer/BioNTech BNT162b2 or Moderna COVID-19 vaccine (Spikevax) at the Alphabio Laboratory in Marseille, France (European Hospital, Alphabio-Biogroup).

Comparison of Elecsys and Liaison immunoassays to determine Epstein-Barr virus serological status using further diagnostic approaches to clarify discrepant results.

Serological markers for Epstein-Barr virus (EBV) infection are commonly used to diagnose infectious mononucleosis and establish a serological status in pretransplant patients. This study prospectively assessed 1043 serum specimens sent to the laboratory for physician-ordered EBV testing. The three markers-antiviral capsid antigen (VCA) immunoglobulin M (IgM), anti-VCA immunoglobulin G (IgG), and anti-Epstein-Barr nuclear antigen (EBNA) antibodies-were tested using the Elecsys and the Liaison immunoassays.

[Use of « Reference change value » in medical biology: about two examples: total PSA and hemoglobin].

The interpretation of the variation between the results of two dosages performed on the same patient is generally quite empirical. It is usually based on the experience of the biologist or physician. Through two examples, total PSA and hemoglobin, we hoped to set up an indicator of the significance variation between results: The Reference change value or RCV to provide assistance to the validator biologist and prescriber based on measured statistical arguments.

Multicenter quality control for the detection of hepatitis C virus RNA in seminal plasma specimens.

The discrepant results available in the literature about the presence of hepatitis C virus (HCV) RNA in seminal plasma of men chronically infected by this agent are related, at least in part, to the molecular techniques used and particularly to the wide range of protocols dedicated to RNA extraction. In order to evaluate these protocols and to standardize the method of detection of HCV RNA in this fluid, a panel of coded specimens was tested blindly in 12 French laboratories; it included 14 seminal plasma specimens and four water controls spiked with HCV RNA ranging from 10 to 20000 IU/ml and two HCV-negative seminal plasma specimens. The extraction step was performed according to methods using either silica beads (NucliSens [Organon Teknika S.