Viral Hemorrhagic Fevers: Disease Modeling and Transmission

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

(A) Study pathogenesis and pathophysiology of high biocontainment viral pathogens utilizing molecular technologies including reverse genetics systems: We continued to optimize mouse models for Crimean-Congo hemorrhagic fever virus (CCHFV) to study pathogenesis, immune responses and develop countermeasures. We have established a mouse adapted CCHFV variant that leads to severe infection in wildtype mice. This will be an extremely valuable tool for future countermeasure development. We were able to show that T-cells and interferon gamma are necessary for survival following CCHFV infection in mice. Recently, we have started to use the Collaborative Cross (CC) mouse model system to further evaluate the pathogenesis of CCHFV (Hawman et al., Microorganisms 2021; Hawman et al., Elife 2021; Leventhal et al., Viruses 2021) We have continued to establish a disease model for Reston virus (RESTV), one of the ebolavirus species, in a commercial pig breed. Young pigs, ranging in age from 3 -5 weeks, were highly susceptible to oral-nasal inoculation of RESTV. The animals developed acute severe respiratory distress with high but not uniform lethality. RESTV replicates mainly in respiratory tissues and virus is shed through mucosal membranes of the oronasal tract. The model will be instrumental for countermeasure development against a potential transboundary pathogen. (Haddock et al. PNAS, 2021) We have developed a lethal mouse model for Alkhurma hemorrhagic fever virus. This model is based on type I interferon receptor knockout mice. As the only lethal animal model for this flavivirus, it will be instrumental for pathogenesis studies and countermeasure development. (Bhatia et al., Microorganisms 2020; Bhatia et al., Emerg Microbes Infect 2021) (B) Study immune responses to infection and vaccination of high containment viral pathogens and develop new vaccine candidates: We assessed a DNA-based vaccine for CCHFV in the cynomolgus macaque model. Macaques were vaccinated with a DNA-based vaccine using in vivo electroporation-assisted delivery. The vaccine contained two plasmids encoding the glycoprotein precursor (GPC) and the nucleoprotein (NP) of CCHFV. This is the first evidence of a vaccine that can protect against CCHFV-induced disease in a nonhuman primate model. Further preclinical and clinical development of the vaccine is in progress. (Hawman et al., Nat Microbiol 2020) We have continued to optimize our vesicular stomatitis virus vaccine platform and could define Ebola virus glycoprotein domains associated with protective efficacy. This will be instrumental for the development of second generation VSV vaccine vectors that utilize the Ebola virus glycoprotein to target important immune cells. (Bhatia et al., Vaccines 2021). Furthermore, we demonstrated that a high dose of the licensed VSV-EBOV vaccine can cause vesicular disease in swine without horizontal transmission. This is an important result for vaccine safety and potentially food safety concerns. (Morozov et al., Emerg Microbes Infect 2021) (collaboration with J. Richt, Kansas State University) We have started a new Lassa virus wildlife vaccine based on the cytomegalovirus vector platform. For this, we have isolated and characterized Mastomys-specific cytomegaloviruses using animals from our Mastomys colony as well as wild-caught animals from West Africa. Viral vectors are currently being designed. (Nuismer et al., PLoS Negl Trop Dis 2020) (C) Study vector/reservoir transmission of high containment viral pathogens using appropriate animal models: We continued to study infection kinetics of Lassa virus in the Mastomys reservoir utilizing our unique colony at RML. The animals support Lassa virus replication and shedding for several weeks before virus gets cleared. The model will allow for important transmission studies. We also developed immunological tools to study host responses in Mastomys. Furthermore, we have defined hematologic and serum biochemistry reference intervals for Mastomys natalensis. Lastly, we detected multiple DNA viruses that are carried by Mastomys natalensis. The importance of this finding is not yet understood. (Calvignac-Spencer et al., Arch Virol 2020; Safronetz et al., Viruses 2021; Smith et al., Lab Anim 2021; Tang-Huau et al., Viruses 2021) (D) Utilize in vitro and in vivo systems to study the interactions between viral pathogen or viral components and host cells and develop new antiviral strategies: We tested the antiviral efficacy of favipiravir in the CCHFV Cynomolgus macaque disease model. In this model, favipiravir was only of limited benefit compared to the CCHFV mouse model. Nevertheless, given the bad performance of ribavirin in animal models, we propose to start human trials with favipiravir as the drug seems more potent against CCHFV. (Hawman et al. Antiviral Res 2020). In addition, we defined Lassa virus dynamics in nonhuman primates treated with favipiravir or ribavirin. (Lingas et al., PLoS Comput Biol 2021). Lastly, we studied the protection of favipiravir against Zika virus infection in the immunodeficient type I interferon receptor knockout mouse model. Surprisingly, outcome of favipiravir treatment was sex-dependent, with 87% of female but only 25% of male mice surviving lethal ZIKV infection. Sex-specific host responses likely explain the observed difference. (Matz et al., Microorganisms 2021) We defined biaryl sulfonamide derivative as a novel fusion inhibitor and a possible candidate for a pan-filovirus therapeutic. (Isono et al., Antiviral res 2020) (collaboration with A. Takada, Hokkaido University). Furthermore, we studied the role of supportive care on Ebola virus infection in the lethal cynomolgus macaque model. We found that the animals developed progressive severe organ dysfunction and profound shock preceding death and that the overall impact of supportive care on the observed pathophysiology was limited. (Biondi et al., Microorganisms 2021) We reviewed and published treatment strategies for Ebola and Lassa viruses. (Hansen et al., Microorganisms 2021; Hansen et al Expert Opin Investig Drugs 2021) (E) Study the epidemiology and ecology of high biocontainment pathogens utilizing newly developed rapid, sensitive and specific diagnostic test systems including those that can be applied under field conditions: Field studies for rodent-borne viruses have been started in the Bitterroot Valley. The initial phase of this project focused on Sin nombre hantavirus in deer mice. We found up to 20% of deer mice positive for SNV RNA in the lungs. In addition, we described the epidemiologic and diagnostic situation of hantavirus cardiopulmonary syndrome (HCPS) in Canada since discovery in the mid-1990s. Both studies are important for local public health. (Warner et al., Emerg Infect Dis 2020; Williamson et al. Viruses, 2021) Utilizing human serum samples from a Lassa epidemiology study we determined the Ebola virus IgG prevalence in Southern Mali. We found low seroprevalence in the population, indicating local exposure to Ebola virus or closely related ebolaviruses. This will add ebolaviruses as pathogens of concern to Malis public health system. (Bane et al Emerg Infect Dis 2021) We established a new serological assay for the detection of CCHFV antibodies utilizing purified CCHFV nucleoprotein as the antigen source. This assay will be helpful for diagnostics and field studies. (Lombe et al., Sci Rep 2021) Furthermore, we developed methanol fixation as a safe method for the inactivation of Ebola and Lassa viruses in peripheral blood smears on plastic microscope slides. This will be helpful for differential diagnostic purposes in endemic Central and West African countries (Relich et al., A, J Trop Med Hyg 2020).