Range expansion can promote the evolution of plastic generalism in coarse-grained landscapes.

Phenotypic plasticity is one way for organisms to deal with variable environments through generalism. However, plasticity is not found universally and its evolution may be constrained by costs and other limitations such as complexity: the need for multiple mutational steps before the adaptation is realized. Theory predicts that greater experienced heterogeneity, such as organisms may encounter when spatial heterogeneity is fine-grained relative to dispersal, should favor the evolution of a broader niche. Here we tested this prediction via simulation. We found that, contrary to classical predictions, coarse-grained landscapes can be the most favorable for the evolution of plasticity, but only when populations encounter those landscapes through range expansion. During these range expansions, coarse-grained landscapes select for each step in the complex mutational pathway to plastic generalism by blocking the dispersal of specialists. These circumstances provide ecological opportunities for innovative mutations that change the niche. Our results indicate a new mechanism by which range expansion and spatially structured landscapes interact to shape evolution and reveal that the environments in which a complex adaptation has the highest fitness may not be the most favorable for its evolution.

Broad antiviral and anti-inflammatory efficacy of nafamostat against SARS-CoV-2 and seasonal coronaviruses in primary human bronchiolar epithelia.

Antiviral strategies that target host systems needed for SARS-CoV-2 replication and pathogenesis may have therapeutic potential and help mitigate resistance development. Here, we evaluate nafamostat mesylate, a potent broad-spectrum serine protease inhibitor that blocks host protease activation of the viral spike protein. SARS-CoV-2 is used to infect human polarized mucociliated primary bronchiolar epithelia reconstituted with cells derived from healthy donors, smokers and subjects with chronic obstructive pulmonary disease. Nafamostat markedly inhibits apical shedding of SARS-CoV-2 from all donors (log10 reduction). We also observe, for the first-time, anti-inflammatory effects of nafamostat on airway epithelia independent of its antiviral effects, suggesting a dual therapeutic advantage in the treatment of COVID-19. Nafamostat also exhibits antiviral properties against the seasonal human coronaviruses 229E and NL6. These findings suggest therapeutic promise for nafamostat in treating SARS-CoV-2 and other human coronaviruses.

Patient and Provider Perspectives on Postsurgical Recovery of Cushing Syndrome.

CONTEXT: Cushing syndrome (CS) is associated with impaired health-related quality of life (HRQOL) even after surgical cure. OBJECTIVE: To characterize patient and provider perspectives on recovery from CS, drivers of decreased HRQOL during recovery, and ways to improve HRQOL. DESIGN: Cross-sectional observational survey. PARTICIPANTS: Patients (n = 341) had undergone surgery for CS and were members of the Cushing's Support and Research Foundation. Physicians (n = 54) were Pituitary Society physician members and academicians who treated patients with CS. RESULTS: Compared with patients, physicians underestimated the time to complete recovery after surgery (12 months vs 18 months, P = 0.0104). Time to recovery did not differ by CS etiology, but patients with adrenal etiologies of CS reported a longer duration of cortisol replacement medication compared with patients with Cushing disease (12 months vs 6 months, P = 0.0025). Physicians overestimated the benefits of work (26.9% vs 65.3%, P < 0.0001), exercise (40.9% vs 77.6%, P = 0.0001), and activities (44.8% vs 75.5%, P = 0.0016) as useful coping mechanisms in the postsurgical period. Most patients considered family/friends (83.4%) and rest (74.7%) to be helpful. All physicians endorsed educating patients on recovery, but 32.4% (95% CI, 27.3-38.0) of patients denied receiving sufficient information. Some patients did not feel prepared for the postsurgical experience (32.9%; 95% CI, 27.6-38.6) and considered physicians not familiar enough with CS (16.1%; 95% CI, 12.2-20.8). CONCLUSION: Poor communication between physicians and CS patients may contribute to dissatisfaction with the postsurgical experience. Increased information on recovery, including helpful coping mechanisms, and improved provider-physician communication may improve HRQOL during recovery.

Systemic Expression of a Viral RdRP Protects against Retrovirus Infection and Disease.

The innate immune system is normally programmed for immediate but transient upregulation in response to invading pathogens, and interferon (IFN)-stimulated gene (ISG) activation is a central feature. In contrast, chronic innate immune system activation is typically associated with autoimmunity and a broad array of autoinflammatory diseases that include the interferonopathies. Here, we studied retroviral susceptibility in a transgenic mouse model with lifelong innate immune system hyperactivation. The mice transgenically express low levels of a picornaviral RNA-dependent RNA polymerase (RdRP), which synthesizes double-stranded RNAs that are sensed by melanoma differentiation-associated protein 5 (MDA5) to trigger constitutive upregulation of many ISGs. However, in striking counterpoint to the paradigm established by numerous human and murine examples of ISG hyperactivation, including constitutive MDA5 activation, they lack autoinflammatory sequelae. RdRP-transgenic mice (RdRP mice) resist infection and disease caused by several pathogenic RNA and DNA viruses. However, retroviruses are sensed through other mechanisms, persist in the host, and have distinctive replication and immunity-evading properties. We infected RdRP mice and wild-type (WT) mice with various doses of a pathogenic retrovirus (Friend virus) and assessed immune parameters and disease at 1, 4, and 8 weeks. Compared to WT mice, RdRP mice had significantly reduced splenomegaly, viral loads, and infection of multiple target cell types in the spleen and the bone marrow. During chronic infection, RdRP mice had 2.35 ± 0.66 log10 lower circulating viral RNA than WT. Protection required ongoing type I IFN signaling. The results show that the reconfigured RdRP mouse innate immune system substantially reduced retroviral replication, set point, and pathogenesis.IMPORTANCE Immune control of retroviruses is notoriously difficult, a fundamental problem that has been most clinically consequential with the HIV-1 pandemic. As humans expand further into previously uninhabited areas, the likelihood of new zoonotic retroviral exposures increases. The role of the innate immune system, including ISGs, in controlling retroviral infections is currently an area of intensive study. This work provides evidence that a primed innate immune system is an effective defense against retroviral pathogenesis, resulting in reduced viral replication and burden of disease outcomes. RdRP mice also had considerably lower Friend retrovirus (FV) viremia. The results could have implications for harnessing ISG responses to reduce transmission or control pathogenesis of human retroviral pathogens.

HIV-1 intron-containing RNA expression induces innate immune activation and T cell dysfunction.

Low levels of type I interferon (IFN-I) are thought to be a driving force for immune activation and T-cell exhaustion in HIV-1 infected individuals on combination antiretroviral therapy (cART), though the causative mechanisms for persistent IFN-I signaling have remained unclear. Here, we show Rev-CRM1-dependent nuclear export and peripheral membrane association of intron-containing HIV-1 RNA, independent of primary viral sequence or viral protein expression, is subject to sensing and signaling via MAVS, resulting in IFN-I-dependent pro-inflammatory responses in macrophages. Additionally, HIV-1 intron-containing-RNA-induced innate immune activation of macrophages leads to upregulation of inhibitory receptor expression and functional immune exhaustion of co-cultured T cells. Our findings suggest that persistent expression of HIV-1 intron-containing RNA in macrophages contributes to chronic immune activation and T-cell dysfunction and that use of HIV RNA expression inhibitors as adjunct therapy might abrogate aberrant inflammation and restore immune function in HIV-infected individuals on cART.

Virion-Associated Vpr Alleviates a Postintegration Block to HIV-1 Infection of Dendritic Cells.

Viral protein R (Vpr) is an HIV-1 accessory protein whose function remains poorly understood. In this report, we sought to determine the requirement of Vpr for facilitating HIV-1 infection of monocyte-derived dendritic cells (MDDCs), one of the first cell types to encounter virus in the peripheral mucosal tissues. In this report, we characterize a significant restriction of Vpr-deficient virus replication and spread in MDDCs alone and in cell-to-cell spread in MDDC-CD4+ T cell cocultures. This restriction of HIV-1 replication in MDDCs was observed in a single round of virus replication and was rescued by the expression of Vpr in trans in the incoming virion. Interestingly, infections of MDDCs with viruses that encode Vpr mutants unable to interact with either the DCAF1/DDB1 E3 ubiquitin ligase complex or a host factor hypothesized to be targeted for degradation by Vpr also displayed a significant replication defect. While the extent of proviral integration in HIV-1-infected MDDCs was unaffected by the absence of Vpr, the transcriptional activity of the viral long terminal repeat (LTR) from Vpr-deficient proviruses was significantly reduced. Together, these results characterize a novel postintegration restriction of HIV-1 replication in MDDCs and show that the interaction of Vpr with the DCAF1/DDB1 E3 ubiquitin ligase complex and the yet-to-be-identified host factor might alleviate this restriction by inducing transcription from the viral LTR. Taken together, these findings identify a robust in vitro cell culture system that is amenable to addressing mechanisms underlying Vpr-mediated enhancement of HIV-1 replication.IMPORTANCE Despite decades of work, the function of the HIV-1 protein Vpr remains poorly understood, primarily due to the lack of an in vitro cell culture system that demonstrates a deficit in replication upon infection with viruses in the absence of Vpr. In this report, we describe a novel cell infection system that utilizes primary human dendritic cells, which display a robust decrease in viral replication upon infection with Vpr-deficient HIV-1. We show that this replication difference occurs in a single round of infection and is due to decreased transcriptional output from the integrated viral genome. Viral transcription could be rescued by virion-associated Vpr. Using mutational analysis, we show that domains of Vpr involved in binding to the DCAF1/DDB1/E3 ubiquitin ligase complex and prevention of cell cycle progression into mitosis are required for LTR-mediated viral expression, suggesting that the evolutionarily conserved G2 cell cycle arrest function of Vpr is essential for HIV-1 replication.

Access of HIV-2 to CD169-dependent dendritic cell-mediated trans infection pathway is attenuated.

The mechanisms behind the low viral loads and lower mortality rates of HIV-2(+) individuals remain unknown. We hypothesized that reduced interaction of HIV-2 with CD169, the primary HIV-1 attachment factor on monocyte-derived dendritic cells (DCs) that targets captured virus particles to the trans infection pathway, contributes to its diminished pathogenic phenotype in vivo. We observed a significant decrease in capture of HIV-2 Gag-eGFP virus-like particles (VLPs) and infectious GFP-containing HIV-2 particles compared to corresponding HIV-1 particles by CD169(+) mature DCs. Interestingly, there was decreased co-localization of HIV-2 with HIV-1 Gag at plasma membrane microdomains in virus producer cells which correlated with reduced incorporation of GM3, the CD169 ligand, in HIV-2 virions, and reduction in mature DC-mediated HIV-2 trans infection compared to HIV-1. We conclude that limited interaction of HIV-2 with CD169 diminishes virus access to the mature DC-mediated trans infection pathway and might result in attenuated HIV-2 dissemination in vivo.

Quantifying lipid contents in enveloped virus particles with plasmonic nanoparticles.

Phosphatidylserine (PS) and monosialotetrahexosylganglioside (GM1 ) are examples of two host-derived lipids in the membrane of enveloped virus particles that are known to contribute to virus attachment, uptake, and ultimately dissemination. A quantitative characterization of their contribution to the functionality of the virus requires information about their relative concentrations in the viral membrane. Here, a gold nanoparticle (NP) binding assay for probing relative PS and GM1 lipid concentrations in the outer leaflet of different HIV-1 and Ebola virus-like particles (VLPs) using sample sizes of less than 3 × 10(6) particles is introduced. The assay evaluates both scattering intensity and resonance wavelength, and determines relative NP densities through plasmon coupling as a measure for the target lipid concentrations in the NP-labeled VLP membrane. A correlation of the optical observables with absolute lipid contents is achieved by calibration of the plasmon coupling-based methodology with unilamellar liposomes of known PS or GM1 concentration. The performed studies reveal significant differences in the membrane of VLPs that assemble at different intracellular sites and pave the way to an optical quantification of lipid concentration in virus particles at physiological titers.