Serum Markers Associated with Severity and Outcome of Hantavirus Pulmonary Syndrome.

BACKGROUND: Hantavirus pulmonary syndrome (HPS) is caused by Andes virus (ANDV) and related hantaviruses in the Americas. Despite a fatality rate of 40%, the pathogenesis of HPS is poorly understood and factors associated with severity, fatality, and survival remain elusive. METHODS: Ninety-three ANDV-infected HPS patients, of whom 34 had a fatal outcome, were retrospectively studied. Serum levels of cytokines and other inflammation-associated markers were analyzed using multiplex immunoassay and enzyme-linked immunosorbent assay. Associations with disease severity, fatal outcome, and survival were identified using logistic regression. RESULTS: HPS patients exhibited increased serum levels of markers associated with inflammation, intestinal damage, and microbial translocation compared to controls. Patients with fatal outcome displayed higher levels of interleukin (IL) 6, IL-10, interferon-γ, soluble tumor necrosis factor-related apoptosis-inducing ligand, and intestinal fatty acid-binding protein (I-FABP) than survivors. Levels of complement factor 5/5a were higher in survivors compared with fatal cases. IL-6 and I-FABP, the latter a marker for intestinal damage, were by multivariate analyses identified as independent markers associated with disease severity (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.01-5.01) and fatal outcome (OR, 1.64; 95% CI, 1.01-2.64), respectively. CONCLUSIONS: HPS patients displayed a multifaceted, systemic inflammatory response, with IL-6 and I-FABP as independent markers of disease severity and fatality, respectively.

Prediction of Pan-Specific B-Cell Epitopes From Nucleocapsid Protein of Hantaviruses Causing Hantavirus Cardiopulmonary Syndrome.

Hantaviruses are emerging viral pathogens that causes hantavirus cardiopulmonary syndrome (HCPS) in the Americas, a severe, sometimes fatal, respiratory disease in humans with a case fatality rate of ≥50%. IgM and IgG-based serological detection methods are the most common approaches used for laboratory diagnosis of hantaviruses. Such emerging viral pathogens emphasizes the need for improved rapid diagnostic devices and vaccines incorporating pan-specific epitopes of genotypes. We predicted linear B-cell epitopes for hantaviruses that are specific to genotypes causing HCPS in humans using in silico prediction servers. We modeled the Andes and Sin Nombre hantavirus nucleocapsid protein to locate the identified epitopes. Based on the mean percent prediction probability score, epitope IMASKSVGS/TAEEKLKKKSAF was identified as the best candidate B-cell epitope specific for hantaviruses causing HCPS. Promiscuous epitopes were identified in the C-terminal of the protein. Our study for the first time has reported pan-specific B-cell epitopes for developing immunoassays in the detection of antibodies to hantaviruses causing HCPS. Identification of epitopes with pan-specific recognition of all genotypes causing HCPS could be valuable for the development of immunodiagnositic tools toward pan-detection of hantavirus antibodies in ELISA. J. Cell. Biochem. 118: 2320-2324, 2017. © 2017 Wiley Periodicals, Inc.

Effect of Vandetanib on Andes virus survival in the hamster model of Hantavirus pulmonary syndrome.

Hantavirus pulmonary syndrome (HPS) is a severe disease caused by hantavirus infection of pulmonary microvascular endothelial cells leading to microvascular leakage, pulmonary edema, pleural effusion and high case fatality. Previously, we demonstrated that Andes virus (ANDV) infection caused up-regulation of vascular endothelial growth factor (VEGF) and concomitant downregulation of the cellular adhesion molecule VE-cadherin leading to increased permeability. Analyses of human HPS-patient sera have further demonstrated increased circulating levels of VEGF. Here we investigate the impact of a small molecule antagonist of the VEGF receptor 2 (VEGFR-2) activation in vitro, and overall impact on survival in the Syrian hamster model of HPS.

Role of vascular and lymphatic endothelial cells in hantavirus pulmonary syndrome suggests targeted therapeutic approaches.

BACKGROUND: Hantaviruses in the Americas cause a highly lethal acute pulmonary edema termed hantavirus pulmonary syndrome (HPS). Hantaviruses nonlytically infect microvascular and lymphatic endothelial cells and cause dramatic changes in barrier functions without disrupting the endothelium. Hantaviruses cause changes in the function of infected endothelial cells that normally regulate fluid barrier functions. The endothelium of arteries, veins, and lymphatic vessels are unique and central to the function of vast pulmonary capillary beds that regulate pulmonary fluid accumulation. RESULTS: We have found that HPS-causing hantaviruses alter vascular barrier functions of microvascular and lymphatic endothelial cells by altering receptor and signaling pathway responses that serve to permit fluid tissue influx and clear tissue edema. Infection of the endothelium provides several mechanisms for hantaviruses to cause acute pulmonary edema, as well as potential therapeutic targets for reducing the severity of HPS disease. CONCLUSIONS: Here we discuss interactions of HPS-causing hantaviruses with the endothelium, roles for unique lymphatic endothelial responses in HPS, and therapeutic targeting of the endothelium as a means of reducing the severity of HPS disease.

Recognition of decay accelerating factor and alpha(v)beta(3) by inactivated hantaviruses: Toward the development of high-throughput screening flow cytometry assays.

Hantaviruses cause two severe diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). The lack of vaccines or specific drugs to prevent or treat HFRS and HCPS and the requirement for conducting experiments in a biosafety level 3 laboratory (BSL-3) limit the ability to probe the mechanism of infection and disease pathogenesis. In this study, we developed a generalizable spectroscopic assay to quantify saturable fluorophore sites solubilized in envelope membranes of Sin Nombre virus (SNV) particles. We then used flow cytometry and live cell confocal fluorescence microscopy imaging to show that ultraviolet (UV)-killed SNV particles bind to the cognate receptors of live virions, namely, decay accelerating factor (DAF/CD55) expressed on Tanoue B cells and alpha(v)beta(3) integrins expressed on Vero E6 cells. SNV binding to DAF is multivalent and of high affinity (K(d) approximately 26pM). Self-exchange competition binding assays between fluorescently labeled SNV and unlabeled SNV are used to evaluate an infectious unit-to-particle ratio of approximately 1:14,000. We configured the assay for measuring the binding of fluorescently labeled SNV to Tanoue B suspension cells using a high-throughput flow cytometer. In this way, we established a proof-of-principle high-throughput screening (HTS) assay for binding inhibition. This is a first step toward developing HTS format assays for small molecule inhibitors of viral-cell interactions as well as dissecting the mechanism of infection in a BSL-2 environment.

The Hantavirus Glycoprotein G1 Tail Contains Dual CCHC-type Classical Zinc Fingers.

Hantaviruses are distributed worldwide and can cause a hemorrhagic fever or a cardiopulmonary syndrome in humans. Mature virions consist of RNA genome, nucleocapsid protein, RNA polymerase, and two transmembrane glycoproteins, G1 and G2. The ectodomain of G1 is surface-exposed; however, it has a 142-residue C-terminal cytoplasmic tail that plays important roles in viral assembly and host-pathogen interaction. Here we show by NMR, circular dichroism spectroscopy, and mutagenesis that a highly conserved cysteine/histidine-rich region in the G1 tail of hantaviruses forms two CCHC-type classical zinc fingers. Unlike classical zinc fingers, however, the two G1 zinc fingers are intimately joined together, forming a compact domain with a unique fold. We discuss the implication of the hantaviral G1 zinc fingers in viral assembly and host-pathogen interaction.

Elevated generation of reactive oxygen/nitrogen species in hantavirus cardiopulmonary syndrome.

Hantavirus cardiopulmonary syndrome (HCPS) is a life-threatening respiratory disease characterized by profound pulmonary edema and myocardial depression. Most cases of HCPS in North America are caused by Sin Nombre virus (SNV), which is carried asymptomatically by deer mice (Peromyscus maniculatus). The underlying pathophysiology of HCPS is poorly understood. We hypothesized that pathogenic SNV infection results in increased generation of reactive oxygen/nitrogen species (RONS), which contribute to the morbidity and mortality of HCPS. Human disease following infection with SNV or Andes virus was associated with increased nitrotyrosine (NT) adduct formation in the lungs, heart, and plasma and increased expression of inducible nitric oxide synthase (iNOS) in the lungs compared to the results obtained for normal human volunteers. In contrast, NT formation was not increased in the lungs or cardiac tissue from SNV-infected deer mice, even at the time of peak viral antigen expression. In a murine (Mus musculus) model of HCPS (infection of NZB/BLNJ mice with lymphocytic choriomeningitis virus clone 13), HCPS-like disease was associated with elevated expression of iNOS in the lungs and NT formation in plasma, cardiac tissue, and the lungs. In this model, intraperitoneal injection of 1400W, a specific iNOS inhibitor, every 12 h during infection significantly improved survival without affecting intrapulmonary fluid accumulation or viral replication, suggesting that cardiac damage may instead be the cause of mortality. These data indicate that elevated production of RONS is a feature of pathogenic New World hantavirus infection and that pharmacologic blockade of iNOS activity may be of therapeutic benefit in HCPS cases, possibly by ameliorating the myocardial suppressant effects of RONS.

High levels of cytokine-producing cells in the lung tissues of patients with fatal hantavirus pulmonary syndrome.

Hantavirus pulmonary syndrome (HPS) is characterized by the rapid onset of pulmonary edema and a high case-fatality rate. Hantavirus antigens have been demonstrated in pulmonary capillary endothelial cells, but the mechanisms causing capillary leakage remain unclear. Immunohistochemical staining was used to enumerate cytokine-producing cells (monokines: interleukin [IL]-1alpha, IL-1beta, IL-6, and tumor necrosis factor [TNF]-alpha; lymphokines: interferon-gamma, IL-2, IL-4, and TNF-beta) in tissues obtained at autopsy from subjects with HPS. High numbers of cytokine-producing cells were seen in the lung and spleen tissues of HPS patients, but only low numbers in the livers and kidneys. A modest increase in the numbers of cytokine-producing cells was detected in the lungs of patients who died with non-HPS acute respiratory distress syndrome (ARDS), and very few (or no) cytokine-producing cells were detected in the lungs of patients who died of causes other than ARDS. These results suggest that local cytokine production may play an important role in the pathogenesis of HPS.

Retrospective diagnosis of hantavirus pulmonary syndrome, 1978-1993: implications for emerging infectious diseases.

OBJECTIVE: To investigate the occurrence of unrecognized cases of hantavirus pulmonary syndrome preceding the detection of the 1993 outbreak in the southwestern United States and the initial description of the syndrome. DESIGN: Retrospective clinicopathologic and immunohistologic study. PATIENTS: Eighty-two patients who died prior to April 1993 with histologically unexplained noncardiogenic pulmonary edema. METHODS: Clinicopathologic review and immunohistochemical evaluation of autopsy tissues for evidence of hantaviral infection. RESULTS: Twelve retrospective fatal cases of hantavirus pulmonary syndrome were identified through clinicopathologic review and immunohistochemical testing of tissues. Patients' ages ranged from 16 to 49 years. The earliest identified case occurred in 1978, 15 years prior to the outbreak of hantavirus pulmonary syndrome in the southwestern United States. Immunohistochemical testing showed widespread deposition of hantaviral antigens, primarily within endothelial cells, similar to the pattern observed with current hantavirus pulmonary syndrome cases. CONCLUSIONS: Although hantavirus pulmonary syndrome was first recognized in 1993, the findings from this study document the earlier existence of this disease. These findings underscore the need for systematic archiving and analysis of clinical information and specimens from patients with diseases of unknown etiology to facilitate the study of new clinical entities and their associated etiologic agents.

Hantavirus pulmonary syndrome in the United States: a pathological description of a disease caused by a new agent.

An outbreak of an acute respiratory disease in the southwestern United States has led to the recognition of a new hantaviral illness. This report describes a unique spectrum of antemortem and postmortem pathological findings seen in a case series of nine surviving patients and 13 who died. Clinical, laboratory, and autopsy findings were derived from a consecutive series of individuals confirmed to have hantavirus pulmonary syndrome. Laboratory studies included chemical, hematological, and bone marrow analyses as well as flow cytometric and immunohistochemical phenotyping. Autopsy tissues were examined by routine histological stains, immunohistochemical methods, and transmission electron microscopy. The lung is the primary target organ in this illness. Pulmonary abnormalities include pleural effusions, alveolar edema and fibrin, and an interstitial mononuclear cell infiltrate. Large immunoblast type cells are seen in the lungs, blood, bone marrow, lymph nodes, liver, and spleen. A tetrad of hematological findings includes left-shifted neutrophilic leukocytosis, thrombocytopenia, hemoconcentration in severe cases, and circulating immunoblasts. In contrast to previously described nephropathic hantaviral syndromes, hantavirus pulmonary syndrome is characterized by a unique constellation of pulmonary, hematological, and reticuloendothelial pathological findings. The pulmonary findings are distinguishable from fatal adult respiratory distress syndrome. The data suggest a capillary leak syndrome restricted to the pulmonary circulation. Likewise, the hematological picture is unique and may be valuable in the rapid identification of cases for further diagnostic studies.