The presence of long COVID (LC) following SARS-CoV-2 infection is a common condition that affects the quality of life of patients and represents a diagnostic challenge due to the diversity of symptoms that may coexist. We still do not have accurate information regarding the pathophysiological pathways that generate the presence of LC, and so it is important to know the inflammatory and immunothrombotic biomarker profiles and their implications in order to characterize risk subgroups and establish early therapeutic strategies. We performed the determination of inflammatory and immunothrombotic biomarkers in volunteers with previous diagnoses of SARS-CoV-2. The inflammatory biomarkers were analyzed in plasma by flow cytometry, and we analyzed the von Willebrand factor (vWF) in the plasma samples using ELISA. The clinical variables and the presence or absence of long COVID symptoms were then analyzed. IL-6, sCD40L, p-Selectin, PSGL-1, PAI-1, tPA, D-Dimer, TF, and Factor IX levels were elevated in the groups with LC, especially in the subgroup of patients with metabolic syndrome (MetS). VWF levels were found to be increased in patients with sequelae and MetS. Our results confirmed the persistence of an active immunothrombotic state, and so it is important to identify the population at risk in order to provide adequate clinical follow-up.

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus associated with congenital Zika syndrome and Guillain-Barré syndrome in adults. The recombinant ZIKV envelope (E) antigen can be useful for serodiagnosis of ZIKV infection and for monitoring immune responses during preclinical and clinical ZIKV vaccine development. In this study, we describe production of ZIKV E using the modified polyethyleneimine (PEI) transfection in HEK293 cells to improve cost-effective large-scale production. We show that the secretion of ZIKV E in HEK293 cells is dependent on cell culture incubation temperatures where incubation at a low temperature of 28 °C improved protein secretion of both, E-CD4 and E, whereas a substantial decrease in secretion was observed at 37 °C. The resulting E-CD4 produced at low temperature yielded similar binding profiles in ELISAs in comparison with a commercially available E protein using human seropositive sera to ZIKV. We also show that ZIKV NS1 and NS1 β-ladder antigens produced in HEK293 cells, have similar binding profiles in ELISA which suggests that both NS1 or NS1 β-ladder can be used for serodiagnosis of ZIKV. In conclusion, we propose a cost-effective production of the ZIKV E and NS1, suitable for both, clinical and research applications in endemic countries.

COVID-19 has been associated with an active immunothrombotic process. The involvement of endothelial cells (ECs) in the feedback loop of the inflammatory and thrombotic process characteristic of COVID-19, as well as its differences with other infectious inflammatory conditions, remains an area requiring further elucidation. This study aimed to assess the immunothrombotic phenotype induced by the SARS-CoV-2 Spike (S) protein and its receptor-binding domain (RBD) in endothelial-derived cell lines. HUVEC and EA.hy926 cell lines were exposed to S protein and to its RBD. Inflammatory, thrombotic, and fibrinolytic mediators were quantified. Molecular docking assays were conducted to identify potential EC receptors for S protein. EC activation was dependent on both protein concentration and stimulation time. An increased release of immunothrombotic biomarkers were observed in endothelial-derived cells exposed to the S protein and to its RBD. The RBD induced a stronger endothelial response. Molecular docking demonstrated high affinity and a possible interaction between the S protein and endothelial receptors: CD-141, CD-147, IL-6R, TLR 2, 4, and 7. These findings confirm that the S protein and its RBD can induce an immunothrombotic phenotype in EC-derived cell lines, potentially exacerbating the disease pathology. We propose possible endothelial receptors mediating this response.