Ribavirin for treating Crimean Congo haemorrhagic fever

Drug repositioning as a promising approach for the eradication of emerging and re-emerging viral agents

The global impact of emerging and re-emerging viral agents during epidemics and pandemics leads to serious health and economic burdens. Among the major emerging or re-emerging viruses include SARS-CoV-2, Ebola virus (EBOV), Monkeypox virus (Mpox), Hepatitis viruses, Zika virus, Avian flu, Influenza virus, Chikungunya virus (CHIKV), Dengue fever virus (DENV), West Nile virus, Rhabdovirus, Sandfly fever virus, Crimean-Congo hemorrhagic fever (CCHF) virus, and Rift Valley fever virus (RVFV). A comprehensive literature search was performed to identify existing studies, clinical trials, and reviews that discuss drug repositioning strategies for the treatment of emerging and re-emerging viral infections using databases, such as PubMed, Scholar Google, Scopus, and Web of Science. By utilizing drug repositioning, pharmaceutical companies can take advantage of a cost-effective, accelerated, and effective strategy, which in turn leads to the discovery of innovative treatment options for patients. In light of antiviral drug resistance and the high costs of developing novel antivirals, drug repositioning holds great promise for more rapid substitution of approved drugs. Main repositioned drugs have included chloroquine, ivermectin, dexamethasone, Baricitinib, tocilizumab, Mab114 (Ebanga™), ZMapp (pharming), Artesunate, imiquimod, saquinavir, capmatinib, naldemedine, Trametinib, statins, celecoxib, naproxen, metformin, ruxolitinib, nitazoxanide, gemcitabine, Dorzolamide, Midodrine, Diltiazem, zinc acetate, suramin, 5-fluorouracil, quinine, minocycline, trifluoperazine, paracetamol, berbamine, Nifedipine, and chlorpromazine. This succinct review will delve into the topic of repositioned drugs that have been utilized to combat emerging and re-emerging viral pathogens.

A Comparison of Clinical and Laboratory Features of Crimean-Congo Hemorrhagic Fever in Children and Adults: A Retrospective Single-Center Cohort Study and Literature Review

Background: Crimean-Congo hemorrhagic fever (CCHF) is a major emerging infectious disease threat, and children are reported to have a milder disease course compared with adults, in contrast to other viral hemorrhagic fevers. The aim of this study was to compare adult and pediatric patients with CCHF to improve understanding of pathogenesis and the natural history of the disease. Materials and Methods: A retrospective analysis of all children and adults admitted with confirmed CCHF between 2011 and 2020. Epidemiological, clinical, and laboratory features were collated on proformas, together with clinical management details. The Severity Grading Score (SGS) system was used to stratify mortality risk. Data from children were compared with adults in the same center and with other published pediatric cohort studies. Results: A total of 47 children with a median (ranges) age of 14 (2-17) years and 176 adults with a median (ranges) age of 52 (18-83) years with confirmed CCHF were included. The most frequent symptoms in adults were fever, muscle-joint pain, headache, nausea, and vomiting; the most frequent in children were fever, anorexia, nausea, vomiting, and abdominal pain. Adults had lower lymphocyte and platelet counts and higher liver transaminase and creatinine levels than children. SGS values were lower in children, but 97.9% children received ribavirin compared with 8.5% of adults (p < 0.001), and they had associated longer median lengths of hospital admission (10 vs. 7 days, p < 0.001). Mortality of 1 out of 47 (2.1%) children was similar to 11 other cohorts reported in Türkiye and lower than 13.1% in adults (23/176) in the same center (p = 0.059). Conclusions: Children have lower CCHF-related mortality, less severe disease, and different clinical syndromes at presentation. The majority of published case definitions for screening for CCHF in the main endemic countries do not differentiate between adults and children and omit four of the five most common presenting features in children.

Development of targeted whole genome sequencing approaches for Crimean-Congo haemorrhagic fever virus (CCHFV)

Crimean-Congo haemorrhagic fever (CCHF) is the most prevalent human tick-borne viral disease, with a reported case fatality rate of 30 % or higher. The virus contains a tri-segmented, negative-sense RNA genome consisting of the small (S), medium (M) and large (L) segments encoding respectively the nucleoprotein (NP), the glycoproteins precursor (GPC) and the viral RNA-dependent RNA polymerase (RDRP). CCHFV is one of the most genetically diverse arboviruses, with seven distinct lineages named after the region they were first reported in and based on S segment phylogenetic analysis. Due to the high genetic divergence of the virus, a single targeted tiling PCR strategy to enrich for viral nucleic acids prior to sequencing is difficult to develop, and previously we have developed and validated a tiling PCR enrichment method for the Europe 1 genetic lineage. We have developed a targeted, probe hybridisation capture method and validated its performance on clinical as well as cell-cultured material of CCHFV from different genetic lineages, including Europe 1, Europe 2, Africa 2 and Africa 3. The method produced over 95 % reference coverages with at least 10x sequencing depth. While we were only able to recover a single complete genome sequence from the tested Europe 1 clinical samples with the capture hybridisation protocol, the data provides evidence of its applicability to different CCHFV genetic lineages. CCHFV is an important tick-borne human pathogen with wide geographical distribution. Environmental as well as anthropogenic factors are causing increased CCHFV transmission. Development of strategies to recover CCHFV sequences from genetically diverse lineages of the virus is of paramount importance to monitor the presence of the virus in new areas, and in public health responses for CCHFV molecular surveillance to rapidly detect, diagnose and characterise currently circulating strains.

Crimean-Congo haemorrhagic fever (CCHF): present and future therapeutic armamentarium

Crimean-Congo haemorrhagic fever (CCHF) is an emerging severe tick-borne illness. The expanding habitat of Hyalomma ticks, coupled with migratory birds harbouring CCHF-infected ticks, contributes to an increasing number of potential hosts. The seroprevalence of anti-CCHF virus antibodies in livestock is approximately one-quarter, with a noticeable upward trend in recent years. The management of CCHF patients predominantly relies on supportive therapy, although a potential arsenal of antivirals, convalescent and hyperimmune plasma, monoclonal antibodies, and vaccines exists, both currently and in the future. This review aims to critically examine the current therapeutic approaches to managing CCHF, highlighting both the potential and limitations of existing treatments, and identifying future directions for improving patient outcomes.

Crimean-Congo haemorrhagic fever among healthcare workers in Iran 2000-2023, a report of National Reference Laboratory

BACKGROUND

Crimean-Congo haemorrhagic fever (CCHF) is a lethal acute viral zoonosis with a case fatality rate of 5-50%. Due to the potential of human-to human transmission of the disease, healthcare workers (HCWs) are at risk of occupational exposure to CCHF virus. Little is known about CCHF virus route of transmission and risks in Iranian HCWs. Therefore this study was designed to identify the routes of exposure to the CCHF virus among Iranian HCWs.

METHODS

From Oct 2000 to Feb 2023, 96 CCHF suspected healthcare workers referred to national reference laboratory were tested for CCHF virus infection by the use of RT-PCR and IgM Capture Enzyme-Linked Immunosorbent Assay (MAC-ELISA) and exposure history of cases were investigated to determine the CCHF virus routes of transmission in nosocomial settings.

RESULTS

Twelve CCHF confirmed cases were identified including seven nurses and five physicians, with the median age of 32.5 years (range 23-53 years) and the median incubation period of 6.8 days (range from 1 to 22 days). None of the cases reported a history of tick bite or close contact with tissues or animal blood. The cases were from Razavi Khorasan (seven cases), Sistan and Baluchistan (two cases), Isfahan (one case), South Khorasan (one case) and Fars (one case). Percutaneous exposure (needle stick) (three cases), mucosal exposure (blood splash in to face) (three cases) and skin contact with blood (three cases) constituted the most prevalent routes of transmission. Since 2013, no CCHF cases have been identified among Iranian HCWs.

CONCLUSIONS

In healthcare settings, physicians and nurses are at risk of nosocomial CCHF virus infection. The routes of transmission mainly include direct exposures via needle-stick, mucosal or direct contact with the skin to infected blood. Continuous education and implementation of infection prevention and control measures are key factors to minimize the incidence of healthcare related CCHF.

Recent Advances in Crimean-Congo Hemorrhagic Fever Virus Detection, Treatment, and Vaccination: Overview of Current Status and Challenges

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus, and zoonosis, and affects large regions of Asia, Southwestern and Southeastern Europe, and Africa. CCHFV can produce symptoms, including no specific clinical symptoms, mild to severe clinical symptoms, or deadly infections. Virus isolation attempts, antigen-capture enzyme-linked immunosorbent assay (ELISA), and reverse transcription polymerase chain reaction (RT-PCR) are all possible diagnostic tests for CCHFV. Furthermore, an efficient, quick, and cheap technology, including biosensors, must be designed and developed to detect CCHFV. The goal of this article is to offer an overview of modern laboratory tests available as well as other innovative detection methods such as biosensors for CCHFV, as well as the benefits and limits of the assays. Furthermore, confirmed cases of CCHF are managed with symptomatic assistance and general supportive care. This study examined the various treatment modalities, as well as their respective limitations and developments, including immunotherapy and antivirals. Recent biotechnology advancements and the availability of suitable animal models have accelerated the development of CCHF vaccines by a substantial margin. We examined a range of potential vaccines for CCHF in this research, comprising nucleic acid, viral particles, inactivated, and multi-epitope vaccines, as well as the present obstacles and developments in this field. Thus, the purpose of this review is to present a comprehensive summary of the endeavors dedicated to advancing various diagnostic, therapeutic, and preventive strategies for CCHF infection in anticipation of forthcoming hazards.

A case of Crimean-Congo haemorrhagic fever complicated with portal vein thrombosis and hemophagocytosis

OBJECTIVES

Crimean-Congo haemorrhagic fever (CCHF) is a zoonotic viral infection which is an important public health problem in Turkey. CCHF causes fever and bleeding and can lead to severe health outcomes. The study aims to report a case of a male patient with severe CCHF, hemophagocytic lymphohistiocytosis (HLH) treated with steroids and portal vein thrombosis.

CASE REPORT

A 37-year-old man was admitted to the emergency department with complaints of high fever, headache, myalgia and diarrhoea. The patient travelled to the endemic region of Turkey. In laboratory findings, thrombocytopenia, abnormal liver function tests and elevated coagulation parameters were observed. Real-time polymerase chain reaction assay was used for diagnosis of CCHF. Hypofibrinogenemia, hypertriglyceridemia, elevated ferritin and d-dimer levels were observed in the clinical follow-up. Prednisolone treatment was performed due to considered the diagnosis of HLH. Portal vein thrombosis was detected on abdominal computed tomography scan. He was successfully treated with ribavirin, corticosteroids, anticoagulant and supportive therapy.

CONCLUSION

The clinical presentation of CCHF can range from self-limiting flu-like to severe symptoms possibly fatal. Acute portal vein embolism is a rare complication that has not been reported before to our knowledge. Corticosteroids may be a life-saving treatment for CCHF patients presenting with HLH.

A replicating RNA vaccine confers protection in a rhesus macaque model of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne febrile illness with a wide geographic distribution. In recent years the geographic range of Crimean-Congo hemorrhagic fever virus (CCHFV) and its tick vector have increased, placing an increasing number of people at risk of CCHFV infection. Currently, there are no widely available vaccines, and although the World Health Organization recommends ribavirin for treatment, its efficacy is unclear. Here we evaluate a promising replicating RNA vaccine in a rhesus macaque (Macaca mulatta) model of CCHF. This model provides an alternative to the established cynomolgus macaque model and recapitulates mild-to-moderate human disease. Rhesus macaques infected with CCHFV consistently exhibit viremia, detectable viral RNA in a multitude of tissues, and moderate pathology in the liver and spleen. We used this model to evaluate the immunogenicity and protective efficacy of a replicating RNA vaccine. Rhesus macaques vaccinated with RNAs expressing the CCHFV nucleoprotein and glycoprotein precursor developed robust non-neutralizing humoral immunity against the CCHFV nucleoprotein and had significant protection against the CCHFV challenge. Together, our data report a model of CCHF using rhesus macaques and demonstrate that our replicating RNA vaccine is immunogenic and protective in non-human primates after a prime-boost immunization.

Crimean-Congo Hemorrhagic Fever Survivors Elicit Protective Non-Neutralizing Antibodies that Target 11 Overlapping Regions on Viral Glycoprotein GP38

Crimean-Congo hemorrhagic fever virus can cause lethal disease in humans yet there are no approved medical countermeasures. Viral glycoprotein GP38, unique to Nairoviridae, is a target of protective antibodies, but extensive mapping of the human antibody response to GP38 has not been previously performed. Here, we isolated 188 GP38-specific antibodies from human survivors of infection. Competition experiments showed that these antibodies bind across five distinct antigenic sites, encompassing eleven overlapping regions. Additionally, we reveal structures of GP38 bound with nine of these antibodies targeting different antigenic sites. Although GP38-specific antibodies were non-neutralizing, several antibodies were found to have protection equal to or better than murine antibody 13G8 in two highly stringent rodent models of infection. Together, these data expand our understanding regarding this important viral protein and inform the development of broadly effective CCHFV antibody therapeutics.

Inhibition of tick-borne encephalitis virus in cell cultures by ribavirin

Tick-borne encephalitis virus (TBEV) belonging to arboviruses is a major member of zoonotic pathogens. TBEV infection causes severe human encephalitis without specific antiviral drugs. Due to its use of antiviral drug against a wide range of viruses, we investigated antiviral effect of ribavirin against TBEV in susceptible human cell lines A549 and SH-SY5Y. Ribavirin displayed minor cytotoxicity on multiple cell lines. Ribavirin obviously impaired TBEV replication and protected the infected cells from cytopathic effect. Importantly, ribavirin markedly inhibited TBEV propagation, as evidenced by impairment of TBEV production and viral RNA replication. Treatment with ribavirin (co-treatment and post-treatment) led to a dose-dependent reduction in TBEV titers as well as the viral RNA levels. Antiviral protein myxovirus resistance A mRNA expression was significantly up-regulated and signal transducer and activator of transcription 3 was activated in TBEV-infected A549 cells upon the ribavirin treatment. Induction of inflammatory cytokine tumor necrosis factor alpha by TBEV was decreased in A549 cells with the treatment of ribavirin, whereas interleukin 1 beta release appeared to be unaffected. These results suggest that ribavirin might represent a promising safe and effective antiviral drug against TBEV.

Crimean-Congo Hemorrhagic Fever, Spain, 2013-2021

Crimean-Congo hemorrhagic fever (CCHF) is a viral infectious disease for which distribution of the main vector, Hyalomma spp. ticks, is expanding. We analyzed all 10 cases of CCHF diagnosed in Spain during 2013-2021; case-patient median age was 56.5 years, and 7 were men. We identified CCHF virus genotypes III and V. Six case-patients acquired the infection in urban areas. Sixty percent of patients were infected in summer and 40% in spring. Two patients met criteria for hemophagocytic syndrome. Seven patients survived. The epidemiologic pattern of CCHF in Spain is based on occasional cases with an elevated mortality rate. Genotype III and, to a less extent also genotype V, CCHF circulates in humans in a common geographic area in Spain. Those data suggest that the expansion pathways are complex and may change over time. Physicians should remain alert to the possibility of new CCHF cases.

The Effect of Fetuin-A and Other Laboratory Paremeters on Prognosis and Mortality in Crimean-Congo Hemorrhagic Fever

BACKGROUND

Crimean-Congo Hemorrhagic Fever (CCHF) is a disease with high morbidity and mortality, which is an important health problem in the world. Therefore, we aimed to evaluate the effects of plasma fetuin-A (FA) level, which is a new parameter in terms of prognosis and mortality of CCHF.

METHODS

A total of 87 patients were included who presented to the Emergency Department, Bağcılar Training and Research Hospital, İstanbul, Turkey with the diagnosis of CCHF from Feb 1, 2019 to Feb 1, 2020. The patients were divided into three groups as tick bite, contact history, and endemic area travel according to the transmission type, and two groups according to the presence of mortality or not. The laboratory data of the patients were compared within these groups. Relationship of hemogram, C-reactive protein (CRP), D-Dimer, sedimentation, lactate, and FA levels between groups were evaluated.

RESULTS

The average age of the patients was 62.52±14.94 years and 27(31%) of them were women. Mortality rates were in 6(6.9%) patients from endemic areas (P=0.015). While the FA level of the mortality group was 171.6±30.0 mg/L, it was 230.3±25.0 mg/L in the survivors (P=0.001). There was a moderate and strong negative correlation of FA level with mortality, tick history, and hospitalization. In ROC curve analysis of mortality and FA levels, parameters were determined as sensitivity 97.4% and specificity 96.2%.

CONCLUSION

In addition to FA levels, as anticipated by our hypothesis, lactate, CRP, and sedimentation values can be used to predict prognosis and mortality in cases of CCHF.

Molecular docking and dynamics simulation analysis of nucleoprotein from the Crimea-Congo hemorrhagic fever virus strain Baghdad-12 with FDA approved drugs

Crimea-Congo hemorrhagic fever virus is considered a potential public health threat due to the high case fatality ratio of the disease hemorrhagic phase and absence of approved vaccines or antiviral agents. Therefore, it is of interest to screen FDA approved drugs against the nucleoprotein crystal of Crimea-Congo hemorrhagic fever virus strain Baghdad-12 by using molecular docking and dynamics simulation. Hence, we report that the beta receptor blocker Nebivolol and the antihistamine Loratadine may bind to RNA binding region on nucleoprotein for further consideration in drug design and development.

Development of multivalent vaccine targeting M segment of Crimean Congo Hemorrhagic Fever Virus (CCHFV) using immunoinformatic approaches

Crimean-Congo Hemorrhagic Fever (CCHF) is a tick-borne viral infection with no licensed vaccine or therapeutics available for its treatment. In the present study we have developed the first multi-epitope subunit vaccine effective against all the seven genotypes of CCHF virus (CCHFV). The vaccine contains five B-cell, two MHC-II (HTL), and three MHC-I (CTL) epitopes screened from two structural glycoproteins (Gc and Gn in M segment) of CCHFV with an N-terminus human β-defensin as an adjuvant, as well as an N-terminus EAAAK sequence. The epitopes were rigorously investigated for their antigenicity, allergenicity, IFN gamma induction, anti-inflammatory responses, stability, and toxicity. The three-dimensional structure of the vaccine was predicted and docked with TLR-3, TLR-8, and TLR-9 receptors to find the strength of the binding complexes via molecular dynamics simulation. After codon adaptation, the subunit vaccine construct was developed in a pDual-GC plasmid and has population coverage of 98.47% of the world's population (HLA-I & II combined). The immune simulation studies were carried out on the C-ImmSim in-silico interface showing a marked increase in the production of cellular and humoral response (B-cell and T-cell) as well as TGFβ, IL-2, IL-10, and IL-12 indicating that the proposed vaccine would be able to sufficiently provoke both humoral and cell-mediated immune responses. Thus, making it a new and promising vaccine candidate against CCHFV.

[Crimean-Congo hemorrhagic fever]

Crimean-Congo hemorrhagic fever (CCHF) is an acute febrile illness with a high case fatality rate caused by the infection with Crimean-Congo hemorrhagic fever virus (CCHFV). The disease is endemic to a wide regions from the African continent to Asia through Europe. CCHFV is maintained in nature between Hyalomma species ticks and some species of animals. Humans are infected with CCHFV from CCHFV-positive tick bite or through a close contact with viremic animals in clucling hum am patients with CCHF. The CCHF-endemic regions depend on the distribution of the species of ticks such as Hyalomma species ticks, main vectors for CCHFV. There have been no confirmed cases of CCHF patients in Japan so far. CCHF is one of the zoonotic virus infections. Main clinical signs of the disease in humans are fever with nonspecific symptoms, and hemorrhage and deterioration in consciousness appear in severe cases. CCHF is classified in the disease category of viral hemorrhagic fevers, which include ebolavirus disease. Viral tick-borne diseases including tick-borne encephalitis, severe fever with thrombocytopenia syndrome, and Yezo virus infection, which has recently been discovered as a novel bunyavirus infection in Hokkaido, Japan, are becoming major concerns for public health in Japan. Trends of CCHF in terms of epidemiology should closely be monitored.

In-line treatments and clinical initiatives to fight against COVID-19 outbreak

In December 2019, when the whole world is waiting for Christmas and New Year, the physicians of Wuhan, China, are astounded by clusters of patients suffering from pneumonia from unknown causes. The pathogen isolated from the respiratory epithelium of the patients is similar to previously known coronaviruses with some distinct features. The disease was initially called nCoV-2019 or SARS-nCoV-2 and later termed as COVID-19 by WHO. The infection is rapidly propagating from the day of emergence, spread throughout the globe and now became a pandemic which challenged the competencies of developed nations in terms of health care management. As per WHO report, 216 countries are affected with SARS-CoV-19 by August 5, 2020 with 18, 142, 718 confirmed cases and 691,013 deaths reports. Such huge mortality and morbidity rates are truly threatening and calls for some aggressive and effective measures to slow down the disease transmission. The scientists are constantly engaged in finding a potential solution to diagnose and treat the pandemic. Various FDA approved drugs with the previous history of antiviral potency are repurposed for COVID-19 treatment. Different drugs and vaccines are under clinical trials and some rapid and effective diagnostic tools are also under development. In this review, we have highlighted the current epidemiology through infographics, disease transmission and progression, clinical features and diagnosis and possible therapeutic approaches for COVID-19. The article mainly focused on the development and possible application of various FDA approved drugs, including chloroquine, remdesivir, favipiravir, nefamostate mesylate, penciclovir, nitazoxanide, ribavirin etc., vaccines under development and various registered clinical trials exploring different therapeutic measures for the treatment of COVID-19. This information will definitely help the researchers to understand the in-line scientific progress by various clinical agencies and regulatory bodies against COVID-19.

Crimean-Congo Hemorrhagic Fever Virus: Current Advances and Future Prospects of Antiviral Strategies

Crimean-Congo hemorrhagic fever virus (CCHFV) is a widespread, tick-borne pathogen that causes Crimean-Congo hemorrhagic fever (CCHF) with high morbidity and mortality. CCHFV is transmitted to humans through tick bites or direct contact with patients or infected animals with viremia. Currently, climate change and globalization have increased the transmission risk of this biosafety level (BSL)-4 virus. The treatment options of CCHFV infection remain limited and there is no FDA-approved vaccine or specific antivirals, which urges the identification of potential therapeutic targets and the design of CCHF therapies with greater effort. In this article, we discuss the current progress and some future directions in the development of antiviral strategies against CCHFV.

Strategy, Progress, and Challenges of Drug Repurposing for Efficient Antiviral Discovery

Emerging or re-emerging viruses are still major threats to public health. Prophylactic vaccines represent the most effective way to prevent virus infection; however, antivirals are more promising for those viruses against which vaccines are not effective enough or contemporarily unavailable. Because of the slow pace of novel antiviral discovery, the high disuse rates, and the substantial cost, repurposing of the well-characterized therapeutics, either approved or under investigation, is becoming an attractive strategy to identify the new directions to treat virus infections. In this review, we described recent progress in identifying broad-spectrum antivirals through drug repurposing. We defined the two major categories of the repurposed antivirals, direct-acting repurposed antivirals (DARA) and host-targeting repurposed antivirals (HTRA). Under each category, we summarized repurposed antivirals with potential broad-spectrum activity against a variety of viruses and discussed the possible mechanisms of action. Finally, we proposed the potential investigative directions of drug repurposing.

Recovery of NanoLuc Luciferase-Tagged Canine Distemper Virus for Facilitating Rapid Screening of Antivirals in vitro

Canine distemper virus (CDV), belonging to the genus Morbillivirus in the family Paramyxoviridae, is a highly contagious pathogen, affecting various domestic, and wild carnivores. Conventional methods are too cumbersome to be used for high-throughput screening of anti-CDV drugs. In this study, a recombinant CDV was rescued using reverse genetics for facilitating screening of anti-CDV drug in vitro. The recombinant CDV could stably express the NanoLuc® luciferase (NLuc), a novel enzyme that was smaller and “brighter” than others. The intensity of NLuc-catalyzed luminescence reaction indirectly reflected the anti-CDV effect of a certain drug, due to a positive correlation between NLuc expression and virus propagation in vitro. Based on such a characteristic feature, the recombinant CDV was used for anti-CDV assays on four drugs (ribavirin, moroxydine hydrochloride, 1-adamantylamine hydrochloride, and tea polyphenol) via analysis of luciferase activity, instead of via conventional methods. The result showed that out of these four drugs, only the ribavirin exhibited a detectable anti-CDV effect. The NLuc-tagged CDV would be a rapid tool for high-throughput screening of anti-CDV drugs.

A DNA-based vaccine protects against Crimean-Congo haemorrhagic fever virus disease in a Cynomolgus macaque model

There is currently no specific prophylaxis or vaccine against Crimean-Congo hemorrhagic fever virus (CCHFV). Crimean-Congo hemorrhagic fever (CCHF) is a severe febrile-illness transmitted by Hyalomma ticks in endemic areas, handling of infected livestock or care of infected patients. We report here the successful protection against CCHFV-mediated disease in a non-human primate disease model. Cynomolgus 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. Animals received three vaccinations and we recorded potent antibody and T-cell responses after vaccination. While all sham-vaccinated animals developed viremia, high tissue viral loads and CCHF-induced disease, the NP + GPC vaccinated animals were significantly protected. In conclusion, this is the first evidence of a vaccine that can protect against CCHFV-induced disease in a non-human primate model. This supports clinical development of the vaccine to protect groups at risk for contracting the infection.

A DNA-based vaccine confers significant protection from CCHFV infection in Cynomolgus macaques

Crimean-Congo hemorrhagic fever virus strains Hoti and Afghanistan cause viremia and mild clinical disease in cynomolgus monkeys

BACKGROUND

Development of vaccines and therapies against Crimean-Congo hemorrhagic fever virus (CCHFV) have been hindered by the lack of immunocompetent animal models. Recently, a lethal nonhuman primate model based on the CCHFV Hoti strain was reported. CCHFV Hoti caused severe disease in cynomolgus monkeys with 75% lethality when given by the intravenous (i.v.) route.

METHODOLOGY/PRINCIPAL FINDINGS

In a series of experiments, eleven cynomologus monkeys were exposed i.v. to CCHFV Hoti and four macaques were exposed i.v. to CCHFV Afghanistan. Despite transient viremia and changes in clinical pathology such as leukopenia and thrombocytopenia developing in all 15 animals, all macaques survived to the study endpoint without developing severe disease.

CONCLUSIONS/SIGNIFICANCE

We were unable to attribute differences in the results of our study versus the previous report to differences in the CCHFV Hoti stock, challenge dose, origin, or age of the macaques. The observed differences are most likely the result of the outbred nature of macaques and low animal numbers often used by necessity and for ethical considerations in BSL-4 studies. Nonetheless, while we were unable to achieve severe disease or lethality, the CCHFV Hoti and Afghanistan macaque models are useful for screening medical countermeasures using biomarkers including viremia and clinical pathology to assess efficacy.

A Cell-Based Reporter Assay for Screening Inhibitors of MERS Coronavirus RNA-Dependent RNA Polymerase Activity

Severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and coronavirus disease 2019 (COVID-19) are emerging zoonotic diseases caused by coronavirus (CoV) infections. The viral RNA-dependent RNA polymerase (RdRp) has been suggested as a valuable target for antiviral therapeutics because the sequence homology of CoV RdRp is highly conserved. We established a cell-based reporter assay for MERS-CoV RdRp activity to test viral polymerase inhibitors. The cell-based reporter system was composed of the bicistronic reporter construct and the MERS-CoV nsp12 plasmid construct. Among the tested nine viral polymerase inhibitors, ribavirin, sofosbuvir, favipiravir, lamivudine, zidovudine, valacyclovir, vidarabine, dasabuvir, and remdesivir, only remdesivir exhibited a dose-dependent inhibition. Meanwhile, the Z-factor and Z'-factor of this assay for screening inhibitors of MERS-CoV RdRp activity were 0.778 and 0.782, respectively. Ribavirin and favipiravir did not inhibit the MERS-CoV RdRp activity, and non-nucleoside HCV RdRp inhibitor, dasabuvir, partially inhibited MERS-CoV RdRp activity. Taken together, the cell-based reporter assay for MERS-CoV RdRp activity confirmed remdesivir as a direct inhibitor of MERS-CoV RdRp in cells. A cell-based MERS-CoV RdRp activity reporter assay is reliable and accurate for screening MERS-CoV RdRp-specific inhibitors. It may provide a valuable platform for developing antiviral drugs for emerging CoV infections.

Antivirals in medical biodefense

The viruses historically implicated or currently considered as candidates for misuse in bioterrorist events are poxviruses, filoviruses, bunyaviruses, orthomyxoviruses, paramyxoviruses and a number of arboviruses causing encephalitis, including alpha- and flaviviruses. All these viruses are of concern for public health services when they occur in natural outbreaks or emerge in unvaccinated populations. Recent events and intelligence reports point to a growing risk of dangerous biological agents being used for nefarious purposes. Public health responses effective in natural outbreaks of infectious disease may not be sufficient to deal with the severe consequences of a deliberate release of such agents. One important aspect of countermeasures against viral biothreat agents are the antiviral treatment options available for use in post-exposure prophylaxis. These issues were adressed by the organizers of the 16th Medical Biodefense Conference, held in Munich in 2018, in a special session on the development of drugs to treat infections with viruses currently perceived as a threat to societies or associated with a potential for misuse as biothreat agents. This review will outline the state-of-the-art methods in antivirals research discussed and provide an overview of antiviral compounds in the pipeline that are already approved for use or still under development.

Diagnostic Testing for Crimean-Congo Hemorrhagic Fever

Crimean-Congo hemorrhagic fever is the most geographically widespread tick-borne virus, with infection resulting in mortality in up to 30% of cases. Clinical diagnosis alone is difficult due to the nonspecific nature of symptoms; therefore, laboratory diagnostics should be utilized for patients with residence in or travel to regions of endemicity in whom the disease is suspected. This minireview provides an overview of laboratory tests available for Crimean-Congo hemorrhagic fever (CCHF) and their utility in diagnosis with a focus on diagnosing CCHF in humans.

Toolkit of methodological resources to conduct systematic reviews

Background: Systematic reviews (SR) can be classified by type depending on the research question they are based on. This work identifies and describes the most relevant methodological resources to conduct high-quality reviews that answer clinical questions regarding prevalence, prognosis, diagnostic accuracy and efficacy of interventions. Methods: Methodological resources have been identified from literature searches and consulting guidelines from institutions that develop SRs. The selected resources are organized by type of SR, and stage of development of the review (formulation of the research question, development of the protocol, literature search, risk of bias assessment, synthesis of findings, assessment of the quality of evidence, and report of SR results and conclusions). Results: Although the different types of SRs are developed following the same steps, each SR type requires specific methods, differing in characteristics and complexity. The extent of methodological development varies by type of SR, with more solid guidelines available for diagnostic accuracy and efficacy of interventions SRs. This methodological toolkit describes the most up-to-date risk of bias instruments: Quality in Prognostic Studies (QUIPS) tool and Prediction model study Risk Of Bias Assessment Tool (PROBAST) for prognostic SRs, Quality assessment of diagnostic accuracy studies tool (QUADAS-2) for diagnostic accuracy SRs, Cochrane risk of bias tool (ROB-2) and Risk of bias in non-randomised studies of interventions studies tool (ROBINS-I) for efficacy of interventions SRs, as well as the latest developments on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Conclusions: This structured compilation of the best methodological resources for each type of SR may prove to be a very useful tool for those researchers that wish to develop SRs or conduct methodological research works on SRs.

Toolkit of methodological resources to conduct systematic reviews

Background: Systematic reviews (SR) can be classified by type depending on the research question they are based on. This work identifies and describes the most relevant methodological resources to conduct high-quality reviews that answer health care questions regarding prevalence, prognosis, diagnostic accuracy and effects of interventions. Methods: Methodological resources have been identified from literature searches and consulting guidelines from institutions that develop SRs. The selected resources are organized by type of SR, and stage of development of the review (formulation of the research question, development of the protocol, literature search, risk of bias assessment, synthesis of findings, assessment of the quality of evidence, and report of SR results and conclusions). Results: Although the different types of SRs are developed following the same steps, each SR type requires specific methods, differing in characteristics and complexity. The extent of methodological development varies by type of SR, with more solid guidelines available for diagnostic accuracy and effects of interventions SRs. This methodological toolkit describes the most up-to-date risk of bias instruments: Quality in Prognostic Studies (QUIPS) tool and Prediction model study Risk Of Bias Assessment Tool (PROBAST) for prognostic SRs, Quality assessment of diagnostic accuracy studies tool (QUADAS-2) for diagnostic accuracy SRs, Cochrane risk of bias tool (ROB-2) and Risk of bias in non-randomised studies of interventions studies tool (ROBINS-I) for effects of interventions SRs, as well as the latest developments on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Conclusions: This structured compilation of the best methodological resources for each type of SR may prove to be a very useful tool for those researchers that wish to develop SRs or conduct methodological research works on SRs.

Toolkit of methodological resources to conduct systematic reviews

Background: Systematic reviews (SR) can be classified by type depending on the research question they are based on. This work identifies and describes the most relevant methodological resources to conduct high-quality reviews that answer health care questions regarding prevalence, prognosis, diagnostic accuracy and effects of interventions. Methods: Methodological resources have been identified from literature searches and consulting guidelines from institutions that develop SRs. The selected resources are organized by type of SR, and stage of development of the review (formulation of the research question, development of the protocol, literature search, risk of bias assessment, synthesis of findings, assessment of the quality of evidence, and report of SR results and conclusions). Results: Although the different types of SRs are developed following the same steps, each SR type requires specific methods, differing in characteristics and complexity. The extent of methodological development varies by type of SR, with more solid guidelines available for diagnostic accuracy and effects of interventions SRs. This methodological toolkit describes the most up-to-date risk of bias instruments: Quality in Prognostic Studies (QUIPS) tool and Prediction model study Risk Of Bias Assessment Tool (PROBAST) for prognostic SRs, Quality assessment of diagnostic accuracy studies tool (QUADAS-2) for diagnostic accuracy SRs, Cochrane risk of bias tool (ROB-2) and Risk of bias in non-randomised studies of interventions studies tool (ROBINS-I) for effects of interventions SRs, as well as the latest developments on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Conclusions: This structured compilation of the best methodological resources for each type of SR may prove to be a very useful tool for those researchers that wish to develop SRs or conduct methodological research works on SRs.

Crimean-Congo Hemorrhagic Fever Mouse Model Recapitulating Human Convalescence

Crimean-Congo hemorrhagic fever virus (CCHFV) is a cause of severe hemorrhagic fever. Its tick reservoir and vector are widely distributed throughout Africa, Southern and Eastern Europe, the Middle East, and Asia. Serological evidence suggests that CCHFV can productively infect a wide variety of species, but only humans develop severe, sometimes fatal disease. The role of the host adaptive immunity in control or contribution to the severe pathology seen in CCHF cases is largely unknown. Studies of adaptive immune responses to CCHFV have been limited due to lack of suitable small animal models. Wild-type mice are resistant to CCHFV infection, and type I interferon-deficient mice typically develop a rapid-onset fatal disease prior to development of adaptive immune responses. We report here a mouse model in which type I interferon-deficient mice infected with a clinical isolate of CCHFV develop a severe inflammatory disease but ultimately recover. Recovery was coincident with development of CCHFV-specific B- and T-cell responses that were sustained for weeks postinfection. We also found that recovery from a primary CCHFV infection could protect against disease following homologous or heterologous reinfection. Together this model enables study of multiple aspects of CCHFV pathogenesis, including convalescence, an important aspect of CCHF disease that existing mouse models have been unsuitable for studying.IMPORTANCE The role of antibody or virus-specific T-cell responses in control of acute Crimean-Congo hemorrhagic fever virus infection is largely unclear. This is a critical gap in our understanding of CCHF, and investigation of convalescence following severe acute CCHF has been limited by the lack of suitable small animal models. We report here a mouse model of CCHF in which infected mice develop severe disease but ultimately recover. Although mice developed an inflammatory immune response along with severe liver and spleen pathology, these mice also developed CCHFV-specific B- and T-cell responses and were protected from reinfection. This model provides a valuable tool to investigate how host immune responses control acute CCHFV infection and how these responses may contribute to the severe disease seen in CCHFV-infected humans in order to develop therapeutic interventions that promote protective immune responses.

Crimean-Congo Hemorrhagic Fever, Kosovo, 2013-2016

During 2013–2016, a total of 32 patients were treated for Crimean-Congo hemorrhagic fever in Prishtina, Kosovo; 11 died. In the 11 patients who died, findings included viral loads >1 × 10^8.5/mL, lactate dehydrogenase >2,700 U/mL, bleeding, and impaired consciousness. Ribavirin therapy had no noticeable effect in this small patient sample.

In silico structural elucidation of RNA-dependent RNA polymerase towards the identification of potential Crimean-Congo Hemorrhagic Fever Virus inhibitors

The Crimean-Congo Hemorrhagic Fever virus (CCHFV) is a segmented negative single-stranded RNA virus (-ssRNA) which causes severe hemorrhagic fever in humans with a mortality rate of ~50%. To date, no vaccine has been approved. Treatment is limited to supportive care with few investigational drugs in practice. Previous studies have identified viral RNA dependent RNA Polymerase (RdRp) as a potential drug target due to its significant role in viral replication and transcription. Since no crystal structure is available yet, we report the structural elucidation of CCHFV-RdRp by in-depth homology modeling. Even with low sequence identity, the generated model suggests a similar overall structure as previously reported RdRps. More specifically, the model suggests the presence of structural/functional conserved RdRp motifs for polymerase function, the configuration of uniform spatial arrangement of core RdRp sub-domains, and predicted positively charged entry/exit tunnels, as seen in sNSV polymerases. Extensive pharmacophore modeling based on per-residue energy contribution with investigational drugs allowed the concise mapping of pharmacophoric features and identified potential hits. The combination of pharmacophoric features with interaction energy analysis revealed functionally important residues in the conserved motifs together with in silico predicted common inhibitory binding modes with highly potent reference compounds.

Diagnostic tests for Crimean-Congo haemorrhagic fever: a widespread tickborne disease

Crimean-Congo haemorrhagic fever (CCHF) is a widespread tickborne disease that circulates in wild and domestic animal hosts, and causes severe and often fatal haemorrhagic fever in infected humans. Due to the lack of treatment options or vaccines, and a high fatality rate, CCHF virus (CCHFV) is considered a high-priority pathogen according to the WHO R&D Blueprint. Several commercial reverse transcriptase PCR (RT-PCR) and serological diagnostic assays for CCHFV are already available, including febrile agent panels to distinguish CCHFV from other viral haemorrhagic fever agents; however, the majority of international laboratories use inhouse assays. As CCHFV has numerous amplifying animal hosts, a cross-sectoral 'One Health' approach to outbreak prevention is recommended to enhance notifications and enable early warning for genetic and epidemiological shifts in the human, animal and tick populations. However, a lack of guidance for surveillance in animals, harmonisation of case identification and validated serodiagnostic kits for animal testing hinders efforts to strengthen surveillance systems. Additionally, as RT-PCR tests tend to be lineage-specific for regional circulating strains, there is a need for pan-lineage sensitive diagnostics. Adaptation of existing tests to point-of-care molecular diagnostic platforms that can be implemented in clinic or field-based settings would be of value given the potential for CCHFV outbreaks in remote or low-resource areas. Finally, improved access to clinical specimens for validation of diagnostics would help to accelerate development of new tests. These gaps should be addressed by updated target product profiles for CCHFV diagnostics.

Recent advances in understanding Crimean-Congo hemorrhagic fever virus

Crimean-Congo hemorrhagic fever virus (CCHFV) is a widely distributed hemorrhagic fever virus and the cause of hemorrhagic disease in Africa, Southern and Eastern Europe, the Middle East, India and Asia. Recent emergence of CCHFV into Spain indicates that the geographic range of this virus is expanding and the presence of its tick vector in several countries without reported disease suggest that CCHFV will continue to spread. Research into CCHFV was historically limited by a lack of suitable animal models and tools to study viral pathogenesis. However, in the past few years the toolset for studying CCHFV has expanded with small animal and non-human primate models for CCHFV being developed along with a reverse genetics system that allows for investigation of viral determinants of disease. These tools have been utilized to understand how CCHFV antagonizes host restriction factors and to develop novel vaccine candidates that may help limit the substantial morbidity and mortality in humans caused by CCHFV.

Ribavirin for treating Crimean Congo haemorrhagic fever

BACKGROUND

Crimean Congo haemorrhagic fever (CCHF) is a tick-borne disease that occurs in parts of Asia, Europe and Africa. Since 2000 the infection has caused epidemics in Turkey, Iran, Russia, Uganda and Pakistan. Good-quality general supportive medical care helps reduce mortality. There is uncertainty and controversy about treating CCHF with the antiviral drug ribavirin.

OBJECTIVES

To assess the effects of ribavirin for treating people with Crimean Congo haemorrhagic fever.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; the Central Register of Controlled Trials (CENTRAL); MEDLINE (PubMed); Embase (OVID); Science Citation Index-Expanded, Social Sciences Citation index, conference proceedings (Web of Science); and CINAHL (EBSCOHost). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov for trials in progress. We conducted all searches up to 16 October 2017. We also contacted experts in the field and obtained further studies from these sources.

SELECTION CRITERIA

We evaluated studies assessing the use of ribavirin in people with suspected or confirmed Crimean Congo haemorrhagic fever. We included randomised control trials (RCTs); non-randomised studies (NRSs) that included more than 10 participants designed as cohort studies with comparators; and case-control studies.

DATA COLLECTION AND ANALYSIS

Two review authors assessed eligibility, risk of bias, and extracted data. For non-randomized studies we used the ROBINS-I tool to assess risk of bias. The main effects analysis included all studies where we judged the risk of bias to be low, moderate or high. We summarized dichotomous outcomes using risk ratios (RRs) and continuous outcomes using mean differences (MDs), and used meta-analyses where appropriate. We carried out a subsidiary appraisal and analysis of studies with critical risk of bias for the primary outcome, as these are often cited to support using ribavirin.

MAIN RESULTS

For the main effects analysis, five studies met our inclusion criteria: one RCT with 136 participants and four non-randomized studies with 612 participants. We excluded 18 non-randomized studies with critical risk of bias, where none had attempted to control for confounding.We do not know if ribavirin reduces mortality (1 RCT; RR 1.13, 95% confidence interval (CI) 0.29 to 4.32; 136 participants; very low-certainty evidence; 3 non-randomized studies; RR 0.72, 95% CI 0.41 to 1.28; 549 participants; very low-certainty evidence). We do not know if ribavirin reduces the length of stay in hospital (1 RCT: mean difference (MD) 0.70 days, 95% CI -0.39 to 1.79; 136 participants; and 1 non-randomized study: MD -0.80, 95% CI -2.70 to 1.10; 50 participants; very low-certainty evidence). We do not know if it reduces the risk of patients needing platelet transfusions (1 RCT: RR 1.23, 95% CI 0.77 to 1.96; 136 participants; very low-certainty evidence). For adverse effects (including haemolytic anaemia and a need to discontinue treatment), we do not know whether there is an increased risk with ribavirin in people with CCHF as data are insufficient.We do not know if adding ribavirin to early supportive care improves outcomes. One non-randomized study assessed mortality in people receiving ribavirin and supportive care within four days or less from symptom onset compared to after four days since symptom onset: mortality was lower in the group receiving early supportive care and ribavirin, but it is not possible to distinguish between the effects of ribavirin and early supportive medical care alone.In the subsidiary analysis, 18 studies compared people receiving ribavirin with those not receiving ribavirin. All had a critical risk of bias due to confounding, reflected in the mortality point estimates favouring ribavirin.

AUTHORS' CONCLUSIONS

We do not know if ribavirin is effective for treating Crimean Congo haemorrhagic fever. Non-randomized studies are often cited as evidence of an effect, but the risk of bias in these studies is high.