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During the course of infection with a hemorrhagic fever virus (HFV), the checks and balances associated with normal coagulation are perturbed resulting in hemorrhage in severe cases and, in some patients, disseminated intravascular coagulopathy (DIC). While many HFVs have animal models that permit the analyses of systemic coagulopathy, animal infection models do not exist for all HFVs and moreover do not always recapitulate the pathology observed in human tissues. Furthermore, molecular analyses of how coagulation is affected are not always straightforward or practical when using ex-vivo animal-derived samples, thus reinforcing the importance of cell culture studies. This chapter highlights procedures utilizing human umbilical vein endothelial cells (HUVECs) as a model system to evaluate components of the intrinsic (prekallikrein (PK), factor XII (FXII), kininogen, and bradykinin (BK)) and extrinsic (Tissue Factor (TF)) systems. Specifically, protocols are included for the generation of a coculture blood vessel model, plating and infection of HUVEC monolayers and assays designed to measure activation of PK and FXII, cleavage of kininogen, and to measure the expression of TF mRNA and protein.

We three authors, the two past presidents (HWL and AV) and the current president (CSS) of the International Society for Hantaviruses (ISH) have attended most of the nine International Conferences on HFRS, HPS and Hantaviruses (Table 1). These conferences have provided a forum for a synergistic group of clinicians, basic researchers, mammalogists, epidemiologists and ecologists to share their expertise and interests in all aspects of hantavirus research. Much of what is now hantavirus dogma was only conjecture when HWL organized the first conference in Seoul, Korea in 1989. Herein, we provide our reflections on key events in hantavirus research. As we come from distinct areas of the world and have had individual historical experiences, we certainly have our own geocentric opinions about the key events. Nevertheless, we agree that the discovery of hantaviruses has taken an interesting and unpredictable track to where we are today., (Published by Elsevier B.V.)

DNA vaccines can be constructed to produce specific immunogens while avoiding the risks associated with propagating infectious viruses. Plasmid DNA vaccines have well established manufacturing procedures and are safe in that they are replication defective, cannot revert to virulence and cannot be transmitted from person-to-person or into the environment. In addition, DNA vaccines can be combined to form multivalent formulations and can be delivered by a variety of methods. Because of these numerous advantages, we have developed DNA vaccines expressing the envelope glycoprotein genes of hantaviruses causing hemorrhagic fever with renal syndrome (HFRS). We have demonstrated that these DNA vaccines elicit neutralizing antibodies in multiple laboratory animal species when delivered to skin or muscle tissues. Moreover, these vaccines delivered as active vaccines or passive vaccines (e.g., transfer of sera from vaccinated rabbits or nonhuman primates), protected hamsters from infection with HFRS-causing hantaviruses. Early clinical studies of HFRS vaccines expressing Hantaan virus or Puumala virus genes have been completed and show promise for further development. Despite these advantages, issues relating to inconsistent immunogenicity and immune interference remain to be addressed., (Published by Elsevier B.V.)

Hantaviruses cause two human diseases thought to be immune-mediated: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). We recently reported that the nucleocapsid (N) protein of HFRS-causing Hantaan virus (HTNV) inhibits tumor necrosis factor-alpha (TNF-alpha) activation of nuclear factor-kappaB (NF-kappaB). Here we measured the ability of other hantaviral N proteins to similarly interfere with the inflammatory process of TNF-alpha. We found that like HTNV N, the N proteins of HFRS-causing Seoul and Dobrava viruses inhibited TNF-alpha activation of NF-kappaB and translocation of the NF-kappaB p65 subunit, but did not interfere with degradation of inhibitor of NF-kappaB (IkappaB). In contrast, the HFRS-causing Puumala virus and the HPS-causing Andes and Sin Nombre viruses did not prevent TNF-alpha activation of NF-kappaB or nuclear translocation of p65. These studies provide evidence that hantaviruses differ in their abilities to interfere with host innate immune responses.

There are no FDA approved drugs for the treatment of hemorrhagic fever with renal syndrome (HFRS), a serious human illnesses caused by hantaviruses. Clinical studies using ribavirin (RBV) to treat HFRS patients suggest that it provides an improved prognosis when given early in the course of disease. Given the unique antiviral activity of RBV and the lack of other lead scaffolds, we prepared a diverse series of 3-substituted 1,2,4-triazole-beta-ribosides and identified one with antiviral activity, 1-beta-d-ribofuranosyl-3-ethynyl-[1,2,4]triazole (ETAR). ETAR showed an EC(50) value of 10 and 4.4 microM for Hantaan virus (HTNV) and Andes virus, respectively. ETAR had weak activity against Crimean Congo hemorrhagic fever virus, but had no activity against Rift Valley fever virus. Intraperitoneally delivered ETAR offered protection to suckling mice challenged with HTNV with a approximately 25% survival at 12.5 and 25mg/kg ETAR, and a MTD of 17.1+/-0.7 days. ETAR was phosphorylated in Vero E6 cells to its 5'-triphosphate and reduced cellular GTP levels. In contrast to RBV, ETAR did not increase mutation frequency of the HTNV genome, which suggests it has a different mechanism of action than RBV. ETAR is an exciting and promising lead compound that will be elaborated in further synthetic investigations as a framework for the rational design of new antivirals for treatment of HFRS.

The discovery of Hantaan virus as an etiologic agent of hemorrhagic fever with renal syndrome in South Korea in 1978 led to identification of related pathogenic and nonpathogenic rodent-borne viruses in Asia and Europe. Their global distribution was recognized in 1993 after connecting newly discovered relatives of these viruses to hantavirus pulmonary syndrome in the Americas. The 1971 description of the shrew-infecting Hantaan-virus-like Thottapalayam virus was long considered an anomaly. Today, this virus and many others that infect eulipotyphlans, bats, fish, rodents, and reptiles are classified among several genera in the continuously expanding family Hantaviridae. [ABSTRACT FROM AUTHOR]

Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are diseases caused by hantavirus infections and are characterized by vascular leakage due to alterations of the endothelial barrier. Hantavirus-infected endothelial cells (EC) display no overt cytopathology; consequently, pathogenesis models have focused either on the influx of immune cells and release of cytokines or on increased degradation of the adherens junction protein, vascular endothelial (VE)-cadherin, due to hantavirus-mediated hypersensitization of EC to vascular endothelial growth factor (VEGF). To examine endothelial leakage in a relevant in vitro system, we co-cultured endothelial and vascular smooth muscle cells (vSMC) to generate capillary blood vessel-like structures. In contrast to results obtained in monolayers of cultured EC, we found that despite viral replication in both cell types as well as the presence of VEGF, infected in vitro vessels neither lost integrity nor displayed evidence of VE-cadherin degradation. Here, we present evidence for a novel mechanism of hantavirus-induced vascular leakage involving activation of the plasma kallikrein-kinin system (KKS). We show that incubation of factor XII (FXII), prekallikrein (PK), and high molecular weight kininogen (HK) plasma proteins with hantavirus-infected EC results in increased cleavage of HK, higher enzymatic activities of FXIIa/kallikrein (KAL) and increased liberation of bradykinin (BK). Measuring cell permeability in real-time using electric cell-substrate impedance sensing (ECIS), we identified dramatic increases in endothelial cell permeability after KKS activation and liberation of BK. Furthermore, the alterations in permeability could be prevented using inhibitors that directly block BK binding, the activity of FXIIa, or the activity of KAL. Lastly, FXII binding and autoactivation is increased on the surface of hantavirus-infected EC. These data are the first to demonstrate KKS activation during hantavirus infection and could have profound implications for treatment of hantavirus infections. [ABSTRACT FROM AUTHOR]

The 10th International Conference on Hantaviruses, organized by the International Society on Hantaviruses, was held from May 31-June 3, 2016 at Colorado State University, Fort Collins, CO, USA. These conferences have been held every three years since 1980. The current report summarizes research presented on all aspects of hantavirology: ecology and epidemiology, virus replication, phylogeny, pathogenesis, immune response, clinical studies, vaccines and therapeutics. [ABSTRACT FROM AUTHOR]