Broad SARS-CoV-2 cell tropism and immunopathology in lung tissues from fatal COVID-19 (preprint)

Background Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection in patients with Coronavirus Disease 2019 (COVID-19) prominently manifests with pulmonary symptoms histologically reflected by diffuse alveolar damage (DAD), excess inflammation, pneumocyte hyperplasia and proliferation, and formation of platelet aggregates or thromboemboli. However, the mechanisms mediating these processes remain unclear. Methods We performed multicolor staining for viral proteins, and lineage cell markers to identify SARS-CoV-2 tropism and to define the lung pathobiology in postmortem tissues from five patients with fatal SARS-CoV-2 infections. Findings The lung parenchyma showed severe DAD with thromboemboli in all cases. SARS-CoV-2 infection was found in an extensive range of cells including alveolar epithelial type II/pneumocyte type II (AT2) cells (HT2-280), ciliated cells (tyr--tubulin), goblet cells (MUC5AC), club-like cells (MUC5B) and endothelial cells (CD31 and CD34). Greater than 90% of infiltrating immune cells were positive for viral proteins including macrophages and monocytes (CD68 and CD163), neutrophils (ELA-2), natural killer (NK) cells (CD56), B-cells (CD19 and CD20), and T-cells (CD3{varepsilon}). Most but not all infected cells were positive for the viral entry receptor angiotensin-converting enzyme-2 (ACE2). The numbers of infected and ACE2-positive cells correlated with the extent of tissue damage. The infected tissues exhibited low numbers of B-cells and abundant CD3{varepsilon}+ T-cells consisting of mainly T helper cells (CD4), few cytotoxic T cells (CTL, CD8), and no T regulatory cell (FOXP3). Antigen presenting molecule HLA-DR of B and T cells was abundant in all cases. Robust interleukin-6 (IL-6) expression was present in most uninfected and infected cells, with higher expression levels observed in cases with more tissue damage. Interpretation In lung tissues from severely affected COVID-19 patients, there is evidence for broad SARS-CoV-2 cell tropisms, activation of immune cells, and clearance of immunosuppressive cells, which could contribute to severe tissue damage, thromboemboli, excess inflammation and compromised adaptive immune responses.

Sensing of COVID-19 Antibodies in Seconds via Aerosol Jet Printed Three Dimensional Electrodes (preprint)

Rapid diagnosis is critical for the treatment and prevention of diseases. In this research, we report sensing of antibodies specific to SARS-CoV-2 virus in seconds via an electrochemical platform consisting of gold micropillar array electrodes decorated with reduced graphene oxide and functionalized with recombinant viral antigens. The array electrodes are fabricated by Aerosol Jet (AJ) nanoparticle 3D printing, where gold nanoparticles (3-5nm) are assembled in 3D space, sintered, and integrated with a microfluidic device. The device is shown to detect antibodies to SARS-CoV-2 spike S1 protein and its receptor-binding-domain (RBD) at concentrations down to 1pM via electrochemical impedance spectroscopy and read by a smartphone-based user interface. In addition, the sensor can be regenerated within a minute by introducing a low-pH chemistry that elutes the antibodies from the antigens, allowing successive testing of multiple antibody samples using the same sensor. The detection time for the two antibodies tested in this work is 11.5 seconds. S1 protein sensing of its antibodies is specific, which cross-reacts neither with other antibodies nor with proteins such as Nucleocapsid antibody and Interleukin-6 protein. The proposed sensing platform is generic and can also be used for the rapid detection of biomarkers for other infectious agents such as Ebola, HIV, and Zika, which will benefit the public health.