Approximately 15% of individuals affected by coronavirus disease 2019 (COVID-19) develop severe disease, and 5% to 6% are critically ill (respiratory failure and/or multiple organ dysfunction or failure). 1,2 Severely ill and critically ill patients have a high mortality rate, especially with older age and coexisting medical conditions. Because there are still insufficient data on cause of death, we describe postmortem examinations in a case series of patients with COVID-19. Methods | Between April 4 and April 19, 2020, we conducted serial postmortem examinations in patients with proven severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection who died at the University Medical Center Augsburg (Germany). Autopsies were conducted according to published best practice. 3 Specimens from lung, heart, liver, spleen, kidney, brain, pleural effusion, and cerebrospinal fluid (CSF) were assessed. Postmortem nasopharyngeal, tracheal, bronchial swabs, pleural effusion, and CSF were tested for SARS-CoV-2 by reverse transcriptase-polymerase chain reaction. This study was approved by the local institutional review board, and written informed consent was obtained from next of kin.

The molecular diversity of receptors in human blood vessels remains largely unexplored. We developed a selection method in which peptides that home to specific vascular beds are identified after administration of a peptide library. Here we report the first in vivo screening of a peptide library in a patient. We surveyed 47,160 motifs that localized to different organs. This large-scale screening indicates that the tissue distribution of circulating peptides is nonrandom. High-throughput analysis of the motifs revealed similarities to ligands for differentially expressed cell-surface proteins, and a candidate ligand-receptor pair was validated. These data represent a step toward the construction of a molecular map of human vasculature and may have broad implications for the development of targeted therapies.

Characterizing the molecular diversity of the cell surface is critical for targeting gene therapy. Cell type-specific binding ligands can be used to target gene therapy vectors. However, targeting systems in which optimum eukaryotic vectors can be selected on the cells of interest are not available. Here, we introduce and validate a random adeno-associated virus (AAV) peptide library in which each virus particle displays a random peptide at the capsid surface. This library was generated in a three-step system that ensures encoding of displayed peptides by the packaged DNA. As proof-of-concept, we screened AAV-libraries on human coronary artery endothelial cells. We observed selection of particular peptide motifs. The selected peptides enhanced transduction in coronary endothelial cells but not in control nonendothelial cells. This vector targeting strategy has advantages over other combinatorial approaches such as phage display because selection occurs within the context of the capsid and may have a broad range of applications in biotechnology and medicine.

Merging tumor targeting and molecular-genetic imaging into an integrated platform is limited by lack of strategies to enable systemic yet ligand-directed delivery and imaging of specific transgenes. Many eukaryotic viruses serve for transgene delivery but require elimination of native tropism for mammalian cells; in contrast, prokaryotic viruses can be adapted to bind to mammalian receptors but are otherwise poor vehicles. Here we introduce a system containing cis-elements from adeno-associated virus (AAV) and single-stranded bacteriophage. Our AAV/phage (AAVP) prototype targets an integrin. We show that AAVP provides superior tumor transduction over phage and that incorporation of inverted terminal repeats is associated with improved fate of the delivered transgene. Moreover, we show that the temporal dynamics and spatial heterogeneity of gene expression mediated by targeted AAVP can be monitored by positron emission tomography. This new class of targeted hybrid viral particles will enable a wide range of applications in biology and medicine.