Recombinant SARS-CoV-2 S Protein Binds to Glycans of the Lactosamine Family in vitro.

Many viruses, beside binding to their main cell target, interact with other molecules that promote virus adhesion to the cell; often, these additional targets are glycans. The main receptor for SARS-CoV-2 is a peptide motif in the ACE2 protein. We studied interaction of the recombinant SARS-CoV-2 spike (S) protein with an array of glycoconjugates, including various sialylated, sulfated, and other glycans, and found that the S protein binds some (but not all) glycans of the lactosamine family. We suggest that parallel influenza infection will promote SARS-CoV-2 adhesion to the respiratory epithelial cells due to the unmasking of lactosamine chains by the influenza virus neuraminidase.

A new methodological approach to estimation of IgA1 and IgA2 content in human serum using recombinant IgA1 protease from Neisseria meningitidis.

OBJECTIVES: A new approach to estimation of IgA subclass levels and IgA1/IgA2 ratio using enzymatically active and inactive forms of Neisseria meningitidis IgA1 protease was developed. RESULTS: The approach was tested using the sera of healthy volunteers and patients with meningococcal meningitis. There was a significant increase in the IgA1 level in patients with meningitis (mean titer 1:1546 ± 352) compared to healthy volunteers (mean titer 1:546 ± 282), while the IgA2 content remained unchanged. The IgA1/IgA2 ratio was 6.3 for the healthy volunteers and 12.8 for patients with meningitis. IgA2 for the patients with meningitis and the healthy volunteers were almost unchanged, 1:86 ± 61 and 1:121 ± 46, respectively. CONCLUSIONS: The proposed method is economical and reliable and can be used for evaluation of IgA1 and IgA2 in clinical laboratories or for research purposes.

Evaluation of multimeric tyrosine-O-sulfate as a cytoprotectant in an in vivo model of acute myocardial infarction in pigs.

OBJECTIVES: Intracoronary administration of glycosaminoglycan analogs, including the complement inhibitor dextran sulfate, attenuates myocardial ischemia/reperfusion injury (I/R injury). However, dextran sulfate has a distinct anticoagulatory effect, possibly limiting its use in specific situations in vivo. We therefore developed multimeric tyrosine sulfate (sTyr-PAA), a novel, minimally anticoagulatory, fully synthetic non-carbohydrate-containing polyacrylamide conjugate, for in vivo testing in an acute closed-chest porcine model of acute myocardial infarction. METHODS: Following balloon occlusion of the left anterior descending artery just after the first diagonal branch (60-minute ischemia), sTyr-PAA (approx. 10 mg/kg bodyweight, fraction with strongest complement-inhibitory and minimal anticoagulatory properties, n = 11) or phosphate-buffered saline (controls, n = 9) was administered intracoronarily into ischemic myocardium prior to 120 min of reperfusion. RESULTS: sTyr-PAA significantly reduced infarct size (from 61.0 ± 12.0% of the ischemic area at risk to 39.4 ± 17.0%), plasma creatine kinase, local complement deposition and tissue factor upregulation, without affecting systemic coagulation. Protection was associated with significantly reduced myocardial neutrophil extravasation and translated into a significant improvement of ejection fraction and left ventricular enddiastolic pressure. CONCLUSIONS: sTyr-PAA protected significantly against myocardial I/R injury without substantially affecting systemic coagulation. Local intravascular sTyr-PAA administration may prove advantageous in situations where bleeding complications are likely or are to be avoided at all costs.