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T cell responses specific for HIV-1 Gag peptides increased in HIV-positive recipients of two broadly neutralizing antibodies with prolonged suppression of blood viremia during antiretroviral treatment interruption. Combination antiretroviral therapy (ART) is highly effective in controlling human immunodeficiency virus (HIV)-1 but requires lifelong medication due to the existence of a latent viral reservoir(1,2). Potent broadly neutralizing antibodies (bNAbs) represent a potential alternative or adjuvant to ART. In addition to suppressing viremia, bNAbs may have T cell immunomodulatory effects as seen for other forms of immunotherapy(3). However, this has not been established in individuals who are infected with HIV-1. Here, we document increased HIV-1 Gag-specific CD8(+) T cell responses in the peripheral blood of all nine study participants who were infected with HIV-1 with suppressed blood viremia, while receiving bNAb therapy during ART interruption(4). Increased CD4(+) T cell responses were detected in eight individuals. The increased T cell responses were due both to newly detectable reactivity to HIV-1 Gag epitopes and the expansion of pre-existing measurable responses. These data demonstrate that bNAb therapy during ART interruption is associated with enhanced HIV-1-specific T cell responses. Whether these augmented T cell responses can contribute to bNAb-mediated viral control remains to be determined.

Interferon gamma (IFN-gamma) was shown to be a macrophage activating factor already in 1984. Consistently, inborn errors of IFN-gamma immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD). MSMD is characterized by genetic predisposition to disease caused by weakly virulent mycobacterial species. Paradoxically, macrophages from patients with MSMD were little tested. Here, we report a disease modeling platform for studying IFN-gamma related pathologies using macrophages derived from patient specific induced pluripotent stem cells (iPSCs). We used iPSCs from patients with autosomal recessive complete- and partial IFN-gamma R2 deficiency, partial IFN-gamma R1 deficiency and complete STAT1 deficiency. Macrophages from all patient iPSCs showed normal morphology and IFN-gamma-independent functionality like phagocytic uptake of bioparticles and internalization of cytokines. For the IFN-gamma-dependent functionalities, we observed that the deficiencies played out at various stages of the IFN-gamma pathway, with the complete IFN-gamma R2 and complete STAT1 deficient cells showing the most severe phenotypes, in terms of upregulation of surface markers and induction of downstream targets. Although iPSC-derived macrophages with partial IFN-gamma R1 and IFN-gamma R2 deficiency still showed residual induction of downstream targets, they did not reduce the mycobacterial growth when challenged with Bacillus Calmette-Guerin. Taken together, we report a disease modeling platform to study the role of macrophages in patients with inborn errors of IFN-gamma immunity.

Implicit in the RNA world hypothesis is that prebiotic RNA synthesis, despite occurring in an environment without biochemical catalysts, produced the long RNA polymers which are essential to the formation of life. In order to investigate the prebiotic formation of long RNA polymers, we consider a general solution of functionally identical monomer units that are capable of bonding to form linear polymers by a step-growth process. Under the assumptions that (1) the solution is well-mixed and (2) bonding/unbonding rates are independent of polymerization state, the concentration of each length of polymer follows the geometric Flory-Schulz distribution. We consider the rate dynamics that produce this equilibrium; connect the rate dynamics, Gibbs free energy of bond formation, and the bonding probability; solve the dynamics in closed form for the representative special case of a Flory-Schulz initial condition; and demonstrate the effects of imposing a maximum polymer length. Afterwards, we derive a lower bound on the error introduced by truncation and compare this lower bound to the actual error found in our simulation. Finally, we suggest methods to connect these theoretical predictions to experimental results.

Antillean manatees produce vocalizations reported to be important for communication, but their vocal behavior throughout their geographic range is poorly understood. A SoundTrap recorder (sample rates: 288/576kHz) was deployed in Belize to record vocalizations of wild manatees in a seagrass channel and of a young rehabilitated and released manatee in a shallow lagoon. Spectral analysis revealed broadband vocalizations with frequencies up to 150kHz and a high proportion of calls with ultrasonic components. Ultrasonic frequency components appear prevalent in their vocal repertoire and may be important to manatee communication. (C) 2020 Acoustical Society of America

Staphylococcal bi-component pore-forming toxins, also known as leukocidins, target and lyse human phagocytes in a receptor-dependent manner. S-components of the leukocidins Panton-Valentine leukocidin (PVL), gamma-haemolysin (HlgAB) and CB (HlgCB), and leukocidin ED (LukED) specifically employ receptors that belong to the class of G-protein coupled receptors (GPCRs). Although these receptors share a common structural architecture, little is known about the conserved characteristics of the interaction between leukocidins and GPCRs. In this study, we investigated host cellular pathways contributing to susceptibility towards S. aureus leukocidin cytotoxicity. We performed a genome-wide CRISPR/Cas9 library screen for toxin-resistance in U937 cells sensitized to leukocidins by ectopic expression of different GPCRs. Our screen identifies post-translational modification (PTM) pathways involved in the sulfation and sialylation of the leukocidin-receptors. Subsequent validation experiments show differences in the impact of PTM moieties on leukocidin toxicity, highlighting an additional layer of refinement and divergence in the staphylococcal host-pathogen interface. Leukocidin receptors may serve as targets for anti-staphylococcal interventions and understanding toxin-receptor interactions will facilitate the development of innovative therapeutics. Variations in the genes encoding PTM pathways could provide insight into observed differences in susceptibility of humans to infections with S. aureus.

The surface and lining tissues of our body are exposed to the external environment, and as such these epithelial tissues must form structural barriers able to defend against microbes, environmental toxins, and mechanical stress. Their cells are equipped to detect a diverse array of surface perturbations, and then launch signaling relays to the immune system. The aim of these liaisons is to coordinate the requisite immune cell response needed to preserve and/or restore barrier integrity and defend the host. It has been recently appreciated that epithelial cells learn from these experiences. Following inflammatory exposure, long-lived stem cells within the tissue retain an epigenetic memory that endows them with heightened responsiveness to subsequent encounters with stress. Here, we review the recent literature on how epithelial cells sense signals from microbes, allergens, and injury at the tissue surface, and transmit this information to immune cells, while embedding a memory of the experience within their chromatin.

A chemogenetic approach was developed for cell-type-specific drug-inducible protein synthesis inhibition in mice. It was used to show that consolidation of long-term aversive memories requires rapid neuronal protein synthesis in the amygdala. New protein synthesis is known to be required for the consolidation of memories, yet existing methods of blocking translation lack spatiotemporal precision and cell-type specificity, preventing investigation of cell-specific contributions of protein synthesis. Here we developed a combined knock-in mouse and chemogenetic approach for cell-type-specific drug-inducible protein synthesis inhibition that enables rapid and reversible phosphorylation of eukaryotic initiation factor 2 alpha, leading to inhibition of general translation by 50% in vivo. We use cell-type-specific drug-inducible protein synthesis inhibition to show that targeted protein synthesis inhibition pan-neuronally and in excitatory neurons in the lateral amygdala (LA) impaired long-term memory. This could be recovered with artificial chemogenetic activation of LA neurons, although at the cost of stimulus generalization. Conversely, genetically reducing phosphorylation of eukaryotic initiation factor 2 alpha in excitatory neurons in the LA enhanced memory strength but reduced memory fidelity and behavioral flexibility. Our findings provide evidence for a cell-specific translation program during consolidation of threat memories.

Animal circadian rhythms are controlled by central and peripheral molecular clocks, whose components generate oscillations in their own abundance and activity. Insights into how these clocks time the function of organs and tissues is increasing our understanding of animal physiology. To accommodate daily recurring environmental changes, animals show cyclic variations in behaviour and physiology, which include prominent behavioural states such as sleep-wake cycles but also a host of less conspicuous oscillations in neurological, metabolic, endocrine, cardiovascular and immune functions. Circadian rhythmicity is created endogenously by genetically encoded molecular clocks, whose components cooperate to generate cyclic changes in their own abundance and activity, with a periodicity of about a day. Throughout the body, such molecular clocks convey temporal control to the function of organs and tissues by regulating pertinent downstream programmes. Synchrony between the different circadian oscillators and resonance with the solar day is largely enabled by a neural pacemaker, which is directly responsive to certain environmental cues and able to transmit internal time-of-day representations to the entire body. In this Review, we discuss aspects of the circadian clock in Drosophila melanogaster and mammals, including the components of these molecular oscillators, the function and mechanisms of action of central and peripheral clocks, their synchronization and their relevance to human health.

PURPOSE. Extracellular vesicles (EVs) contain RNA and protein cargo reflective of the genotype and phenotype of the releasing cell of origin. Adult neural retina EV release, RNA transfer, and proteomic cargo are the focus of this study. METHODS. Adult wild-type mouse retinae were cultured and released EV diameters and concentrations quantified using Nanosight. Immunogold transmission electron microscopy (TEM) was used to image EV ultrastructure and marker protein localization. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze retinal cell transcripts present in EVs. Super-resolution microscopy was used to image fluorescent (green) RNA and (red) lipid membrane labeled EVs, released by adult retina, and internalized by isolated retinal cells. Mass spectrometry was used to characterize the proteomes of adult retina and EVs. RESULTS. Adult neural retina released EVs at a rate of 1.42 +/- 0.08 x 10(8)/mL over 5 days, with diameters ranging from 30 to 910 nm. The canonical EV markers CD63 and Tsg101 localized to retinal EVs. Adult retinal and neuronal mRNA species present in both retina and EVs included rhodopsin and the neuronal nuclei marker NeuN. Fluorescently labeled RNA in retinal cells was enclosed in EVs, transported to, and uptaken by co-cultured adult retinal cells. Proteomic analysis revealed 1696 protein species detected only in retinal cells, 957 species shared between retina and EVs, and 82 detected only in EVs. CONCLUSIONS. The adult neural retina constitutively releases EVs with molecular cargo capable of intercellular transport and predicted involvement in biological processes including retinal physiology, mRNA processing, and transcription regulation within the retinal microenvironment.