Antiviral Immunoglobulins of Chicken Egg Yolk for Potential Prevention of SARS-CoV-2 Infection.

Background: Some viruses cause outbreaks, which require immediate attention. Neutralizing antibodies could be developed for viral outbreak management. However, the development of monoclonal antibodies is often long, laborious, and unprofitable. Here, we report the development of chicken polyclonal neutralizing antibodies against SARS-CoV-2 infection. Methods: Layers were immunized twice with 14-day intervals using the purified receptor-binding domain (RBD) of the S protein of SARS-CoV-2/Wuhan or SARS-CoV-2/Omicron. Eggs were harvested 14 days after the second immunization. Polyclonal IgY antibodies were extracted. Binding of anti-RBD IgYs was analyzed by immunoblot and indirect ELISA. Furthermore, the neutralization capacity of anti-RBD IgYs was measured in Vero-E6 cells infected with SARS-CoV-2-mCherry/Wuhan and SARS-CoV-2/Omicron using fluorescence and/or cell viability assays. In addition, the effect of IgYs on the expression of SARS-CoV-2 and host cytokine genes in the lungs of Syrian Golden hamsters was examined using qRT-PCR. Results: Anti-RBD IgYs efficiently bound viral RBDs in situ, neutralized the virus variants in vitro, and lowered viral RNA amplification, with minimal alteration of virus-mediated immune gene expression in vivo. Conclusions: Altogether, our results indicate that chicken polyclonal IgYs can be attractive targets for further pre-clinical and clinical development for the rapid management of outbreaks of emerging and re-emerging viruses.

Isolation and mass spectrometry analysis of urinary extraexosomal proteins.

The aim of the present study was to develop a LC-MS/MS-based proteomic analysis method of urinary exosomal proteins that has the potential to discover disease biomarkers. In short, urinary exosomes from healthy subjects were isolated by immunocapture on magnetic beads, detected by immunofluorescence and TEM, trypsin digested directly on the beads for an accelerated time with no addition of detergents before performing an LC-MS analysis of the trypsinate. To our knowledge, this is the first proteomic analysis of proteins displayed on the outer surface of exosomes. The outer exosome proteome may contain proteins that are of higher biomarker value compared to soluble cargo protein as the proteins projecting into the extracellular milieu might be more directly involved in physiological functions of exosomes. The proteomic analysis identified 49 proteins that were considered significant; the majority is involved in carbohydrate and lipid metabolism or in immune responses. Thirty of the proteins are linked to diseases. The developed proteomic method exploiting urinary exosomes might be of great value in search for diagnostic or prognostic biomarkers of especially metabolic and immune-related diseases.

Why less is more when generating tryptic peptides in bottom-up proteomics.

Proteolytic digestion is a time consuming and critical step in bottom-up proteomic analysis. The most widely used protease, trypsin, has high specificity and generates peptides that are considered to be ideally suited for bottom-up LC-MS technology. By exploiting key factors affecting enzymatic activity we obtained a simple, straightforward, and rapid in-solution digest protocol that performed better than the conventional overnight digestion method in terms of amino acid coverage of proteins, number of peptides generated, and peptide ion abundances. Prolonged digestion time, such as overnight digestion, leads to decline in protein amino acid coverage and loss of tryptic peptides. This was found to be caused by complete digestion by trypsin leading to an increased number of small peptides that are not LC-MS detectable. Slow-rate nontryptic digestion of peptides is a contributing factor for loss of peptide ion intensities during extended digestion time. Our work demonstrates that for both qualitative and quantitative bottom-up proteomic studies it is beneficial to prevent trypsin digestion to go to completion by reducing treatment time from the conventional several hours to a few minutes cleavage time.