Neutralizing antibodies (NAbs) are effective in treating COVID-19 but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment during prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. Real time imaging revealed that the virus spread sequentially from the nasal cavity to the lungs in mice and thereafter systemically to various organs including the brain, culminating in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days. In addition to direct neutralization, depletion studies indicated that Fc effector interactions of NAbs with monocytes, neutrophils and natural killer cells were required to effectively dampen inflammatory responses and limit immunopathology. Our study highlights that both Fab and Fc effector functions of NAbs are essential for optimal in vivo efficacy against SARS-CoV-2.

Characterization of the humoral response to SARS-CoV-2, the etiological agent of Covid-19, is essential to help control the infection. In this regard, we and others recently reported that the neutralization activity of plasma from COVID-19 patients decreases rapidly during the first weeks after recovery. However, the specific role of each immunoglobulin isotype in the overall neutralizing capacity is still not well understood. In this study, we selected plasma from a cohort of Covid-19 convalescent patients and selectively depleted immunoglobulin A, M or G before testing the remaining neutralizing capacity of the depleted plasma. We found that depletion of immunoglobulin M was associated with the most substantial loss of virus neutralization, followed by immunoglobulin G. This observation may help design efficient antibody-based COVID-19 therapies and may also explain the increased susceptibility to SARS-CoV-2 of autoimmune patients receiving therapies that impair the production of IgM.

Despite recent therapeutic advances, including the introduction of novel cytostatic drugs and therapeutic antibodies, many cancer patients will experience recurrent or metastatic disease. Current treatment options, particularly for those patients with metastatic breast, prostate, or skin cancers, are complex and have limited curative potential. Recent clinical trials, however, have shown that cell-based therapeutic vaccines may be used to generate broad-based, antitumor immune responses. Dendritic cells (DC) have proved to be the most efficacious cellular component for therapeutic vaccines, serving as both the adjuvant and antigen delivery vehicle. At present it is not possible to noninvasively determine the fate of DC-based vaccines after their administration to human subjects. In this study, we demonstrate that in vitro-generated mouse DC can be readily labeled with superparamagnetic iron oxide nanoparticles, Feridex, without altering cell morphology, or their phenotypic and functional maturation. Feridex-labeling enables the detection of DC in vivo after their migration to draining lymph nodes using a 1.5 T clinical magnetic resonance scanner. In addition, we report a semiquantitative approach for analysis of magnetic resonance images and show that the Feridex-induced signal void volume, and fractional signal loss, correlates with the delivery and migration of small numbers of in vitro-generated DC. These findings, together with ongoing preclinical studies, are key to gaining information critical for improving the efficacy of therapeutic vaccines for the treatment cancer, and potentially, chronic infectious diseases.

SARS-CoV-2 precipitates respiratory distress by infection of airway epithelial cells and is often accompanied by acute kidney injury. We report that Kidney Injury Molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1) is expressed in lung and kidney epithelial cells in COVID-19 patients and is a receptor for SARS-CoV-2. Human and mouse lung and kidney epithelial cells express KIM-1 and endocytose nanoparticles displaying the SARS-CoV-2 spike protein (virosomes). Uptake was inhibited both by anti-KIM-1 antibodies and by TW-37, our newly discovered inhibitor of KIM-1-mediated endocytosis. Enhanced KIM-1 expression by human kidney tubuloids increased uptake of virosomes. KIM-1 positive cells express less angiotensin-converting enzyme 2 (ACE2), the well-known receptor for SARS-CoV-2. Using microscale thermophoresis, the EC50 for KIM-1-SARS-CoV-2 spike protein, and receptor binding domain (RBD) interactions, were 19 and 10 nM respectively. Thus KIM-1 is an alternative receptor to ACE2 for SARS-CoV-2. KIM-1 targeted therapeutics may prevent and/or treat COVID-19.

Models for human cytomegalovirus (HCMV) brain infection have been developed in a variety of brain-derived cells in which the factors governing virus infectivity might be studied in vitro. Studies were initiated with brain endothelial cells, the likely portal of entry for virus into the central nervous system. Primary explant cultures of brain endothelial cells, derived from homogenates of healthy human brain, supported complete viral gene expression and cytopathic effect (CPE). Endothelial cells do not appear to be a barrier for HCMV passage into the central nervous system. Astroglial lines (primary explant or tumor-derived) varied in their ability to support HCMV replication. Some (T98G) supported incomplete (immediate-early) gene expression while others (A-172) did not support any detectable gene expression. Some astroglial lines (HS-683) supported extensive virus replication with minimal viral CPE. Neuronal cell lines (SK-N-MC) were fully permissive. The more differentiated glial lines (astrocytoma) were fully permissive to HCMV infection; however, the less differentiated glial lines (glioblastoma) were partly or nonpermissive.

ObjectiveTo longitudinally assess brain microstructure and function in female varsity athletes participating in contact and noncontact sports.MethodsConcussion-free female rugby players (n = 73) were compared to age-matched (ages 18–23) female swimmers and rowers (n = 31) during the in- and off-season. Diffusion and resting-state fMRI (rs-fMRI) measures were the primary outcomes. The Sports Concussion Assessment Tool and head impact accelerometers were used to monitor symptoms and impacts, respectively.ResultsWe found cross-sectional (contact vs noncontact) and longitudinal (in- vs off-season) changes in white matter diffusion measures and rs-fMRI network connectivity in concussion-free contact athletes relative to noncontact athletes. In particular, mean, axial, and radial diffusivities were increased with decreased fractional anisotropy in multiple white matter tracts of contact athletes accompanied with default mode and visual network hyperconnectivity (p < 0.001). Longitudinal diffusion changes in the brainstem between the in- and off-season were observed for concussion-free contact athletes only, with progressive changes observed in a subset of athletes over multiple seasons. Axial diffusivity was significantly lower in the genu and splenium of the corpus callosum in those contact athletes with a history of concussion.ConclusionsTogether, these findings demonstrate longitudinal changes in the microstructure and function of the brain in otherwise healthy, asymptomatic athletes participating in contact sport. Further research to understand the long-term brain health and biological implications of these changes is required, in particular to what extent these changes reflect compensatory, reparative, or degenerative processes.

We describe three patients with benign recurrent aseptic meningitis (Mollaret's meningitis). For one of these cases, the episodes of meningitis were associated with herpetic outbreaks. Mollaret cells, which are a hallmark of Mollaret's meningitis, were present in the CSF from two of the three patients. In all cases, herpes simplex virus type 2 DNA was present in the CSF during the acute illness as detected by polymerase chain reaction amplification, although viral cultures from CSF were all negative. Herpesviruses, notorious for frequent and sporadic recurrence, are ideal candidates for the cause of Mollaret's meningitis.

To study fetal brain infection with human cytomegalovirus (HCMV), an in vitro model was established using the human primary nontransformed neuronal cell line HCN-1A. On exposure to a mixture of factors promoting differentiation, HCN-1A cells differentiate into mature neurons. Both undifferentiated and differentiated neurons were permissive to HCMV replication as assessed by immunohistochemistry and in situ DNA hybridization. Infectious center assays revealed that the ratio of virus-infected differentiated cells to undifferentiated cells dropped from 11:1 to 2:1 7-21 days after infection. However, release of infectious progeny from the differentiated HCN-1A cells was greater by 100- to 1000-fold. Cytopathic effect appeared earlier and was more pronounced in differentiated cells. These results suggest that differentiation of HCN-1A cells dramatically affects the rate and amount of virus production from these cells. This model should be useful in the study of congenital HCMV disease and virus-host cell interaction.