Deep mutationally scanned (DMS) CHIKV E3/E2 virus library maps viral amino acid preferences and predicts viral escape mutants of neutralizing CHIKV antibodies.

As outbreaks of chikungunya virus (CHIKV), a mosquito-borne alphavirus, continue to present public health challenges, additional research is needed to generate protective and safe vaccines and effective therapeutics. Prior research has established a role for antibodies in mediating protection against CHIKV infection, and the early appearance of CHIKV-specific IgG or IgG neutralizing antibodies protects against progression to chronic CHIKV disease in humans. However, the importance of epitope specificity for these protective antibodies and how skewed responses contribute to development of acute and chronic CHIKV-associated joint disease remains poorly understood.

Chikungunya virus infection disrupts lymph node lymphatic endothelial cell composition and function via MARCO.

Infection with chikungunya virus (CHIKV) causes disruption of draining lymph node (dLN) organization, including paracortical relocalization of B cells, loss of the B cell-T cell border, and lymphocyte depletion that is associated with infiltration of the LN with inflammatory myeloid cells. Here, we found that, during the first 24 hours of infection, CHIKV RNA accumulated in MARCO-expressing lymphatic endothelial cells (LECs) in both the floor and medullary LN sinuses. The accumulation of viral RNA in the LN was associated with a switch to an antiviral and inflammatory gene expression program across LN stromal cells, and this inflammatory response - including recruitment of myeloid cells to the LN - was accelerated by CHIKV-MARCO interactions.

Chikungunya virus infection disrupts lymph node lymphatic endothelial cell composition and function via MARCO.

Infection with chikungunya virus (CHIKV) causes disruption of draining lymph node (dLN) organization, including paracortical relocalization of B cells, loss of the B cell-T cell border, and lymphocyte depletion that is associated with infiltration of the LN with inflammatory myeloid cells. Here, we find that during the first 24 h of infection, CHIKV RNA accumulates in MARCO-expressing lymphatic endothelial cells (LECs) in both the floor and medullary LN sinuses. The accumulation of viral RNA in the LN was associated with a switch to an antiviral and inflammatory gene expression program across LN stromal cells, and this inflammatory response, including recruitment of myeloid cells to the LN, was accelerated by CHIKV-MARCO interactions.

Local Complement Contributes to Pathogenic Activation of Lung Endothelial Cells in SARS-CoV-2 Infection.

Endothelial dysfunction and inflammation contribute to the vascular pathology of coronavirus disease (COVID-19). However, emerging evidence does not support direct infection of endothelial or other vascular wall cells, and thus inflammation may be better explained as a secondary response to epithelial cell infection. In this study, we sought to determine whether lung endothelial or other resident vascular cells are susceptible to productive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and how local complement activation contributes to endothelial dysfunction and inflammation in response to hypoxia and SARS-CoV-2-infected lung alveolar epithelial cells.

COVID-19 Serology Control Panel Using the Dried-Tube Specimen Method.

The dried-tube specimen (DTS) procedure was used to develop the COVID-19 serology control panel (CSCP). The DTS offers the benefit of shipping materials without a cold chain, allowing for greater access without deterioration of material integrity. Samples in the panel were sourced from COVID-19 convalescent persons from March to May 2020.

Lipid nanoparticle formulation of niclosamide (nano NCM) effectively inhibits SARS-CoV-2 replication .

As exemplified by the COVID-19 pandemic, highly infective respiratory viruses can spread rapidly in the population because of lack of effective approaches to control viral replication and spread. Niclosamide (NCM) is an old anthelminthic drug (World Health Organization essential medicine list) with pleiotropic pharmacological activities. Several recent publications demonstrated that NCM has broad antiviral activities and potently inhibits viral replication, including replication of SARS-CoV-2, SARS-CoV, and dengue viruses.

MARCO lymphatic endothelial cells sequester arthritogenic alphaviruses to limit viremia and viral dissemination.

Viremia in the vertebrate host is a major determinant of arboviral reservoir competency, transmission efficiency, and disease severity. However, immune mechanisms that control arboviral viremia are poorly defined. Here, we identify critical roles for the scavenger receptor MARCO in controlling viremia during arthritogenic alphavirus infections in mice.

Mechanisms of SARS-CoV-2-induced lung vascular disease: potential role of complement.

The outbreak of COVID-19 disease, caused by SARS-CoV-2 beta-coronovirus, urges a focused search for the underlying mechanisms and treatment options. The lung is the major target organ of COVID-19, wherein the primary cause of mortality is hypoxic respiratory failure, resulting from acute respiratory distress syndrome, with severe hypoxemia, often requiring assisted ventilation. While similar in some ways to acute respiratory distress syndrome secondary to other causes, lungs of some patients dying with COVID-19 exhibit distinct features of vascular involvement, including severe endothelial injury and cell death via apoptosis and/or pyroptosis, widespread capillary inflammation, and thrombosis.

Development and Validation of a Multiplex Microsphere Immunoassay Using Dried Blood Spots for SARS-CoV-2 Seroprevalence: Application in First Responders in Colorado, USA.

Serological testing of large representative populations for antibodies to SARS-CoV-2 is needed to estimate seroprevalence, transmission dynamics, and the duration of antibody responses from natural infection and vaccination. In this study, a high-throughput SARS-CoV-2 multiplex microsphere immunoassay (MMIA) was developed for the receptor binding domain (RBD) and nucleocapsid (N) that was more sensitive than enzyme-linked immunosorbent assay (ELISA) (98% versus 87%). The MMIA was then applied and validated in 264 first responders in Colorado using serum and dried blood spot (DBS) eluates, compared to ELISA, and evaluated for neutralizing antibodies.

A New SARS-CoV-2 Dual-Purpose Serology Test: Highly Accurate Infection Tracing and Neutralizing Antibody Response Detection.

Many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology tests have proven to be less accurate than expected and do not assess antibody function as neutralizing, correlating with protection from reinfection. A new assay technology measuring the interaction of the purified SARS-CoV-2 spike protein receptor binding domain (RBD) with the extracellular domain of the human angiotensin-converting enzyme 2 (hACE2) receptor detects these important antibodies. The cPass surrogate virus neutralization test (sVNT), compared directly with eight SARS-CoV-2 IgG serology and two live-cell neutralization tests, gives similar or improved accuracy for qualitative delineation between positive and negative individuals in a fast, scalable, and high-throughput assay.

Presence and short-term persistence of SARS-CoV-2 neutralizing antibodies in COVID-19 convalescent plasma donors.

Background: In March 2020, the Food and Drug Administration (FDA) approved use of COVID-19 convalescent plasma (CCP) as an investigational new drug for treatment of COVID-19. Since then, collection of CCP from COVID-19-recovered patients has been implemented in donor centers nationwide. Children's Hospital Colorado rapidly put into practice a CCP collection protocol, necessitating development and implementation of assays to evaluate SARS-CoV-2 antibodies in CCP units.

The vaccinia virus based Sementis Copenhagen Vector vaccine against Zika and chikungunya is immunogenic in non-human primates.

The Sementis Copenhagen Vector (SCV) is a new vaccinia virus-derived, multiplication-defective, vaccine technology assessed herein in non-human primates. Indian rhesus macaques () were vaccinated with a multi-pathogen recombinant SCV vaccine encoding the structural polyproteins of both Zika virus (ZIKV) and chikungunya virus (CHIKV). After one vaccination, neutralising antibody responses to ZIKV and four strains of CHIKV, representative of distinct viral genotypes, were generated.

Complex Genetic Architecture Underlies Regulation of Influenza-A-Virus-Specific Antibody Responses in the Collaborative Cross.

Host genetic factors play a fundamental role in regulating humoral immunity to viral infection, including influenza A virus (IAV). Here, we utilize the Collaborative Cross (CC), a mouse genetic reference population, to study genetic regulation of variation in antibody response following IAV infection. CC mice show significant heritable variation in the magnitude, kinetics, and composition of IAV-specific antibody response.

Chikungunya Virus Evades Antiviral CD8 T Cell Responses To Establish Persistent Infection in Joint-Associated Tissues.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes explosive epidemics of a febrile illness characterized by debilitating arthralgia and arthritis that can endure for months to years following infection. In mouse models, CHIKV persists in joint tissues for weeks to months and is associated with chronic synovitis. Using a recombinant CHIKV strain encoding a CD8 T cell receptor epitope from ovalbumin, as well as a viral peptide-specific major histocompatibility complex class I tetramer, we interrogated CD8 T cell responses during CHIKV infection.

MyD88-dependent influx of monocytes and neutrophils impairs lymph node B cell responses to chikungunya virus infection via Irf5, Nos2 and Nox2.

Humoral immune responses initiate in the lymph node draining the site of viral infection (dLN). Some viruses subvert LN B cell activation; however, our knowledge of viral hindrance of B cell responses of important human pathogens is lacking. Here, we define mechanisms whereby chikungunya virus (CHIKV), a mosquito-transmitted RNA virus that causes outbreaks of acute and chronic arthritis in humans, hinders dLN antiviral B cell responses.

Chikungunya virus replication in skeletal muscle cells is required for disease development.

Chikungunya virus (CHIKV) is an arbovirus capable of causing a severe and often debilitating rheumatic syndrome in humans. CHIKV replicates in a wide variety of cell types in mammals, which has made attributing pathologic outcomes to replication at specific sites difficult. To assess the contribution of CHIKV replication in skeletal muscle cells to pathogenesis, we engineered a CHIKV strain exhibiting restricted replication in these cells via incorporation of target sequences for skeletal muscle cell-specific miR-206.

Discrete viral E2 lysine residues and scavenger receptor MARCO are required for clearance of circulating alphaviruses.

The magnitude and duration of vertebrate viremia is a critical determinant of arbovirus transmission, geographic spread, and disease severity. We find that multiple alphaviruses, including chikungunya (CHIKV), Ross River (RRV), and o'nyong 'nyong (ONNV) viruses, are cleared from the circulation of mice by liver Kupffer cells, impeding viral dissemination. Clearance from the circulation was independent of natural antibodies or complement factor C3, and instead relied on scavenger receptor SR-A6 (MARCO).

Clearance of Chikungunya Virus Infection in Lymphoid Tissues Is Promoted by Treatment with an Agonistic Anti-CD137 Antibody.

CD137, a member of the tumor necrosis factor receptor superfamily of cell surface proteins, acts as a costimulatory receptor on T cells, natural killer cells, B cell subsets, and some dendritic cells. Agonistic anti-CD137 monoclonal antibody (MAb) therapy has been combined with other chemotherapeutic agents in human cancer trials. Based on its ability to promote tumor clearance, we hypothesized that anti-CD137 MAb might activate immune responses and resolve chronic viral infections.

Chronic Chikungunya Virus Disease.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has caused both small- and large-scale epidemics of incapacitating musculoskeletal disease across the globe. A substantial proportion of infected individuals experience debilitating arthralgia and/or arthritis that can persist in relapsing or continuous forms for months to years, an occurrence that appears independent of viral strain and outbreak location. Due to the lack of CHIKV-specific vaccine or therapeutics, treatment of chronic CHIKV disease is limited to supportive care.

Blocking the Exit: CHIKV Neutralizing Antibodies Nip Viral Egress in the Bud.

Neutralizing antibody responses are critical for protection from virus-induced disease. In this issue of Cell Host & Microbe, Jin et al. (2018) use advanced microscopy to elucidate mechanisms by which anti-CHIKV neutralizing monoclonal antibodies block viral egress and activate ADCC, suggesting such antibodies may be "triply functional.

Type 1 IFN and PD-L1 Coordinate Lymphatic Endothelial Cell Expansion and Contraction during an Inflammatory Immune Response.

Lymph node (LN) expansion during an immune response is a complex process that involves the relaxation of the fibroblastic network, germinal center formation, and lymphatic vessel growth. These processes require the stromal cell network of the LN to act deliberately to accommodate the influx of immune cells to the LN. The molecular drivers of these processes are not well understood.

Chikungunya virus impairs draining lymph node function by inhibiting HEV-mediated lymphocyte recruitment.

Chikungunya virus (CHIKV) causes acute and chronic rheumatologic disease. Pathogenic CHIKV strains persist in joints of immunocompetent mice, while the attenuated CHIKV strain 181/25 is cleared by adaptive immunity. We analyzed the draining lymph node (dLN) to define events in lymphoid tissue that may contribute to CHIKV persistence or clearance.

Persistent RNA virus infections: do PAMPS drive chronic disease?

Chronic disease associated with persistent RNA virus infections represents a key public health concern. While human immunodeficiency virus-1 and hepatitis C virus are perhaps the most well-known examples of persistent RNA viruses that cause chronic disease, evidence suggests that many other RNA viruses, including re-emerging viruses such as chikungunya virus, Ebola virus and Zika virus, establish persistent infections. The mechanisms by which RNA viruses drive chronic disease are poorly understood.

Interferon-dependent immunoproteasome activity during mouse adenovirus type 1 infection.

The immunoproteasome is an inducible host mechanism that aids in the clearance of damaged proteins. The immunoproteasome also influences immune function by enhancing peptide presentation by MHC class I and promotes inflammation via IκB degradation and activation of NF-κB. We used mouse adenovirus type 1 (MAV-1) to characterize the role of the immunoproteasome in adenovirus pathogenesis.