While the measurement of neutralizing antibodies is considered a valuable tool in assessing protection against SARS-CoV-2, neutralization tests employ live-virus isolates and cell culture, requiring advanced laboratory biosafety levels. Including a large sample panel (over 700 samples), this study provides adapted cutoff values calculated for seven commercial immunoassays (including four surrogate neutralization assays and a protein-based microarray) that robustly correlate with specific titers of neutralizing antibodies.

Multiple sclerosis (MS) is an immune-mediated demyelinating disease. Epstein-Barr virus (EBV) encodes for the EBNA-1_381-452 region that induces autoreactive antibody responses, which are likely critically involved in MS pathogenesis. Here we investigate whether these EBNA-1_381-452-specific antibodies can serve as a biomarker to identify at-risk individuals for MS. We quantify EBNA-1_381-452-specific antibody titers from 324 relapsing-remitting MS patients and 324 matched controls in longitudinal follow-up plasma samples, starting from the individual’s EBV-seroconversion. In MS patients, significantly elevated EBNA-1_381-452-specific IgG titers are identified that are increased already as early as nine months after EBV-seroconversion (OR:5.7; 95% CI: 4.1-8.1; P < 0.0001) and a median 5.4 years prior to MS diagnosis. Especially, the presence of continuously high EBNA-1_381-452-specific antibody titers is associated with a more rapid MS diagnosis after EBV-seroconversion (P < 0.0001). Thus, the quantification of EBNA-1_381-452-specific IgG antibody levels may provide a prognostic biomarker to determine the individual’s risk for the diagnosis of MS.

The developmental course of antibodies produced after a SARS-CoV-2 infection has been insufficiently investigated so far. Therefore, the aim of this study was to investigate the dynamics of SARS-CoV-2 antibody levels against the viral nucleocapsid- and spike-protein among Austrian blood donors as a representative group of a supposedly healthy population within the first year after a SARS-CoV-2 infection. The impact of age, sex, vaccination status, AB0-blood group and awareness about the infection was evaluated. Our study shows that the level of anti-N antibodies is declining, while anti-S antibody levels remain stable. Antibodies detected were functional in vitro. Age, sex and blood group do not influence antibody dynamics. However, blood group AB shows significantly lower antibody levels and in vitro functionality compared to other blood groups. Our data reveal that one out of five individuals was not aware of a previous SARS-CoV-2 infection and that the disease course neither affects the level of antibody production nor the in vitro functionality. We also found that 14% of participants show persisting COVID-19-related symptoms for up to nine months. Our results provide valuable insights into the dynamics of the immune response after a SARS-CoV-2 infection in a representative cohort of adult blood donors in Central Europe.

The provision of suitable blood units for patients carrying clinically significant antibodies to high-frequency antigens (HFAs) is a special challenge for blood establishments. Typing of donors and screening for HFA-negative individuals is increasingly performed by genotyping. In this context the selection of the HFAs of interest, the molecular background of some model antigens, and the different requirements for donor screening versus resolving serological problems are addressed. In addition, several published approaches for mass-scale donor genotyping are reviewed. Furthermore, the results of a DNA-based donor screening for 12 HFAs in 11,400 Austrian donors that resulted in finding 94 newly identified HFA-negative donors are referred to.

The COVID-19 pandemic has elicited the need to analyse and store large amounts of infectious samples for laboratory diagnostics. Therefore, there has been a demand for sample storage buffers that effectively inactivate infectious viral particles while simultaneously preserving the viral RNA. Here, we present a storage buffer containing guanidine-hydrochloride that fulfils both requirements. Its ability to preserve RNA stability was confirmed by RT-qPCR, and virus-inactivating properties were tested by tissue culture infectious dose assay. Our data revealed that RNA from samples diluted in this storage buffer was efficiently preserved. Spiking samples with RNase A resulted in RNAse concentrations up to 100 ng/mL being efficiently inhibited, whereas spiking samples with infectious SARS-CoV-2 particles demonstrated rapid virus inactivation. In addition, our buffer demonstrated good compatibility with several commercially available RNA extraction platforms. The presented guanidine-hydrochloride-based storage buffer efficiently inactivates infectious SARS-CoV-2 particles and supports viral RNA stability, leading to a reduced infection risk during sample analysis and an increased period for follow-up analysis, such as sequencing for virus variants. Because the presented buffer is uncomplicated to manufacture and compatible with a variety of commercially available test systems, its application can support and improve SARS-CoV-2 laboratory diagnostics worldwide.