Calcium channel blockers reduce severe fever with thrombocytopenia syndrome virus (SFTSV) related fatality.

Severe fever with thrombocytopenia syndrome (SFTS), an emerging tick-borne infectious disease caused by a novel phlebovirus (SFTS virus, SFTSV), was listed among the top 10 priority infectious diseases by the World Health Organization due to its high fatality of 12%-50% and possibility of pandemic transmission. Currently, effective anti-SFTSV intervention remains unavailable. Here, by screening a library of FDA-approved drugs, we found that benidipine hydrochloride, a calcium channel blocker (CCB), inhibited SFTSV replication in vitro. Benidipine hydrochloride was revealed to inhibit virus infection through impairing virus internalization and genome replication. Further experiments showed that a broad panel of CCBs, including nifedipine, inhibited SFTSV infection. The anti-SFTSV effect of these two CCBs was further analyzed in a humanized mouse model in which CCB treatment resulted in reduced viral load and decreased fatality rate. Importantly, by performing a retrospective clinical investigation on a large cohort of 2087 SFTS patients, we revealed that nifedipine administration enhanced virus clearance, improved clinical recovery, and remarkably reduced the case fatality rate by >5-fold. These findings are highly valuable for developing potential host-oriented therapeutics for SFTS and other lethal acute viral infections known to be inhibited by CCBs in vitro.

Therapeutic effects of favipiravir against severe fever with thrombocytopenia syndrome virus infection in a lethal mouse model: Dose-efficacy studies upon oral administration.

Severe fever with thrombocytopenia syndrome (SFTS), caused by SFTS virus (SFTSV), is a viral hemorrhagic fever with a high case fatality rate. Favipiravir was reported to be effective in the treatment of SFTSV infection in vivo in type I interferon receptor knockout (IFNAR-/-) mice at treatment dosages of both 60 mg/kg/day and 300 mg/kg/day for a duration of 5 days. In this study, the efficacy of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day against SFTSV infection in an IFNAR-/- mouse infection model was investigated. IFNAR-/- mice were subcutaneously infected with SFTSV at a 1.0 × 10(6) 50% tissue culture infectious dose followed by twice daily administration of favipiravir, comprising a total dose of either 120 mg/kg/day or 200 mg/kg/day. The treatment was initiated either immediately post infection or at predesignated time points post infection. Neutralizing antibodies in the convalescent-phase mouse sera was examined by the pseudotyped VSV system. All mice treated with favipiravir at dosages of 120 mg/kg/day or 200 mg/kg/day survived when the treatment was initiated at no later than 4 days post infection. A decrease in body weight of mice was observed when the treatment was initiated at 3-4 days post infection. Furthermore, all control mice died. The body weight of mice did not decrease when treatment with favipiravir was initiated immediately post infection at dosages of 120 mg/kg/day and 200 mg/kg/day. Neutralizing antibodies were detected in the convalescent-phase mouse sera. Similar to the literature-reported peritoneal administration of favipiravir at 300 mg/kg/day, the oral administration of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day to IFNAR-/- mice infected with SFTSV was effective.

Reactive plasmacytosis mimicking multiple myeloma associated with SFTS virus infection: a report of two cases and literature review.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus named SFTS virus (SFTSV), which is classified into the genus Phlebovirus and family Phenuiviridae. Reactive plasmacytosis mimicking multiple myeloma is a very rare condition in association with SFTS. Here, we describe two SFTS cases who presented with hyperimmunoglobulinemia, as well as extensive bone marrow and peripheral blood plasmacytosis, which mimicked multiple myeloma (MM). CASE PRESENTATION: We report two cases who presented with fever and blood routine abnormity which were conformed as SFTS eventually. They were performed bone marrow aspiration and were admitted to the department of hematology with a preliminary diagnosis of MM. They all had hyperimmunoglobulinemia, extensive bone marrow and peripheral blood plasma cells, prolonged activated partial thromboplastin time (APTT), elevated hepatic enzyme. The two patients recovered with treatment of doxycycline, human immunoglobulins, plasma transfusion, and other supporting treatments. But case 1 occurred lymphoma 8 months later and died. CONCLUSION: SFTS might be one of differential diagnosis of MM in certain endemic area. We also conclude that SFTSV is a pantropic virus that could injure most tissues and cells of the human body.

NSs Protein of Sandfly Fever Sicilian Phlebovirus Counteracts Interferon (IFN) Induction by Masking the DNA-Binding Domain of IFN Regulatory Factor 3.

Sandfly fever Sicilian virus (SFSV) is one of the most widespread and frequently identified members of the genus Phlebovirus (order Bunyavirales, family Phenuiviridae) infecting humans. Being transmitted by Phlebotomus sandflies, SFSV causes a self-limiting, acute, often incapacitating febrile disease ("sandfly fever," "Pappataci fever," or "dog disease") that has been known since at least the beginning of the 20th century. We show that, similarly to other pathogenic phleboviruses, SFSV suppresses the induction of the antiviral type I interferon (IFN) system in an NSs-dependent manner. SFSV NSs interfered with the TBK1-interferon regulatory factor 3 (IRF3) branch of the RIG-I signaling pathway but not with NF-κB activation. Consistently, we identified IRF3 as a host interactor of SFSV NSs. In contrast to IRF3, neither the IFN master regulator IRF7 nor any of the related transcription factors IRF2, IRF5, and IRF9 were bound by SFSV NSs. In spite of this specificity for IRF3, NSs did not inhibit its phosphorylation, dimerization, or nuclear accumulation, and the interaction was independent of the IRF3 activation or multimerization state. In further studies, we identified the DNA-binding domain of IRF3 (amino acids 1 to 113) as sufficient for NSs binding and found that SFSV NSs prevented the association of activated IRF3 with the IFN-ß promoter. Thus, unlike highly virulent phleboviruses, which either destroy antiviral host factors or sequester whole signaling chains into inactive aggregates, SFSV modulates type I IFN induction by directly masking the DNA-binding domain of IRF3.IMPORTANCE Phleboviruses are receiving increased attention due to the constant discovery of new species and the ongoing spread of long-known members of the genus. Outbreaks of sandfly fever were reported in the 19th century, during World War I, and during World War II. Currently, SFSV is recognized as one of the most widespread phleboviruses, exhibiting high seroprevalence rates in humans and domestic animals and causing a self-limiting but incapacitating disease predominantly in immunologically naive troops and travelers. We show how the nonstructural NSs protein of SFSV counteracts the upregulation of the antiviral interferon (IFN) system. SFSV NSs specifically inhibits promoter binding by IFN transcription factor 3 (IRF3), a molecular strategy which is unique among phleboviruses and, to our knowledge, among human pathogenic RNA viruses in general. This IRF3-specific and stoichiometric mechanism, greatly distinct from the ones exhibited by the highly virulent phleboviruses, correlates with the intermediate level of pathogenicity of SFSV.

[Recent topics in the research field of severe fever with thrombocytopenia syndrome (SFTS)].

Seven years have passed since the discovery of a novel infectious disease, severe fever with thrombocytopenia syndrome (SFTS) caused by a novel Phlebovirus, SFTS virus (SFTSV), in PR China. It was also confirmed that SFTS was endemic to Japan through an identification of a woman, who died of SFTSV infection in Yamaguchi prefecture in late 2012. Approximately 6 years have passed since the discovery of SFTS-endemicity in Japan. At present, SFTS is endemic to PR China, South Korea and western Japan. SFTSV is maintained between several species of ticks such as Haemaphysalis longicornis and wild and domestic animals in nature. Therefore, we cannot escape from the risk of being infected with SFTSV. Based on the similarity in the characteristics of the clinical symptoms including the high case fatality rate, mode of infection to humans, pathology and virology between SFTS and Crimean-Congo hemorrhagic fever (CCHF), SFTS should be classified as viral hemorrhagic fever. Although the time from the discovery of SFTS is still short, there have been many scientific reports on the epidemiological, clinical, and/or pathological, and virological studies on SFTS. Favipiravir was reported to show an efficacy in the prevention and treatment of SFTSV infections in an animal model. A clinical study to evaluate the efficacy of favipiravir in the treatment of SFTS patients has been initiated in Japan. Specific and effective treatment with antiviral drugs for and preventive measures of SFTS with vaccination shoued be developed through scientific, clinical, and basic research.

A Pediatric Case of Severe Fever with Thrombocytopenia Syndrome in Korea.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease and elderly people living in rural areas have the greatest risk of infection. We report the first pediatric case of SFTS in Korea and the clinical characteristics and disease progression in children. A 10-year-old child from Chonnam province visited the hospital with myalgia and a history of fever over the previous 8 days. Her father noticed a tick on her head and removed it before fever developed. Because the symptoms continued, her father consulted the community health center and SFTS virus was detected both from the tick (Haemaphysalis longicornis) and the patient's blood. On hospitalization, fever and severe myalgia were improved and no gastrointestinal and hemorrhagic symptoms were observed. The patient was successfully treated with a combination of steroids, IVIG, and ribavirin. In this report, a pediatric case of SFTS presents a mild clinical course but close attention must be paid to the screening of children with mild symptoms consisting of SFTS.

Common adverse events associated with ribavirin therapy for Severe Fever with Thrombocytopenia Syndrome.

Severe Fever with Thrombocytopenia Syndrome (SFTS) is associated with high mortality rate, for which antiviral therapy with ribavirin was recommended. Based on our previous study, no visible effect of ribavirin therapy in improving clinical outcome was observed. Here we have accumulated the sample size to 634, and by performing prospective observation on the clinical progress and laboratory parameters, we found a significantly higher incidence of anemia and hyperamylasemia in patients who received ribavirin therapy in comparison with those who received no therapy. Generalized estimating equation model disclosed a significant effect on hemoglobin reduction and blood amylase augmentation from ribavirin administration. The occurrence of anemia and hyperamylasemia was associated with SFTS patients receiving ribavirin therapy, which might be adverse event of this drug administration. The recommendation of ribavirin for treating SFTS should be applied with caution.

Efficacy of dinotefuran, permethrin and pyriproxyfen combination spot-on on dogs against Phlebotomus perniciosus and Ctenocephalides canis.

This study was conducted to evaluate the efficacy of a new topical ectoparasiticidal spot-on containing 4.95% dinotefuran (w/w), 36.08% permethrin (w/w) and 0.44% pyriproxyfen (w/w) (Vectra 3D, Ceva, Libourne, France) against Portuguese strain of Phlebotomus perniciosus and a French strain of Ctenocephalides canis in dogs. Twelve beagle dogs were exposed for 1 h to 100 P. perniciosus on day 6 for allocation in two groups. One group was treated on day 0, and the other group was the control group. The dogs were exposed for 1 h to 100 P. perniciosus on days 1, 7, 14, 21 and 28. After each sandfly challenge, the same dogs were infested with 100 C. canis. Counts of living fleas were determined 48 h after infestation on days 4, 3, 9, 16, 23 and 30. For sandflies, the anti-feeding effect was 96.9, 99.7, 98.7, 83.5 and 87.0 % on days 1, 7, 14, 21 and 28, respectively. The mortality effect was 97.8, 99.8, 73.7, 27.5 and 39.6% on days 1, 7, 14, 21 and 28, respectively. At each challenge point, the mortality and anti-feeding effects on sandflies were significantly different between the control and treatment groups (p < 0.05). The adulticidal effect on C. canis remained above 99% throughout the study period. The results indicate that a combination with dinotefuran, permethrin and pyriproxyfen may be used as an effective part of an overall flea and sandfly control strategy in dogs for monthly use.

Case-fatality ratio and effectiveness of ribavirin therapy among hospitalized patients in china who had severe fever with thrombocytopenia syndrome.

BACKGROUND: The wide distribution and high case-fatality ratio of severe fever with thrombocytopenia syndrome (SFTS) have made it a significant public health problem. This study was designed to identify the predictors of fatal outcomes and to evaluate the effectiveness of antiviral therapy in treating SFTS virus (SFTSV)-infected patients. METHODS: A cross-sectional study was performed in a general hospital located in Xinyang city, whereas the largest number of patients with SFTS in China were treated during 2011-2012. The primary outcome for the treatment effect analysis was death. Other outcomes included sequential platelet levels and viral loads observed throughout the hospitalization and the interval between the initiation of ribavirin therapy and the return of the platelet count to a normal level. RESULTS: A total of 311 SFTSV-infected patients were included in the study. The most frequent clinical presentations were fever, weakness, myalgia, and gastrointestinal symptoms. Each patient had thrombocytopenia, leukopenia, or both. The case-fatality ratio (CFR) was 17.4% (95% confidence interval [CI], 13.1%-21.6%). Older age (odds ratio [OR], 1.061; 95% CI, 1.023-1.099; P = .001), decreased level of consciousness (OR, 5.397; 95% CI, 2.660-10.948; P < .001), and elevated levels of lactate dehydrogenase (>1200 U/L; OR, 2.620; 95% CI, 1.073-6.399; P = .035) and creatine kinase (>800 U/L; OR, 2.328; 95% CI, 1.129-4.800; P = .022) were significantly associated with fatal outcome. The CFRs were similar between patients who received ribavirin and those who did not. Ribavirin treatment showed no significant effect on either platelet counts or viral loads during hospitalization of patients with fatal or nonfatal cases. CONCLUSIONS: These findings can improve knowledge about the characteristics of patients with fatal outcomes and the use of antiviral drug for SFTS.

Structure of severe fever with thrombocytopenia syndrome virus nucleocapsid protein in complex with suramin reveals therapeutic potential.

Severe fever with thrombocytopenia syndrome is an emerging infectious disease caused by a novel bunyavirus (SFTSV). Lack of vaccines and inadequate therapeutic treatments have made the spread of the virus a global concern. Viral nucleocapsid protein (N) is essential for its transcription and replication. Here, we present the crystal structures of N from SFTSV and its homologs from Buenaventura (BUE) and Granada (GRA) viruses. The structures reveal that phleboviral N folds into a compact core domain and an extended N-terminal arm that mediates oligomerization, such as tetramer, pentamer, and hexamer of N assemblies. Structural superimposition indicates that phleboviral N adopts a conserved architecture and uses a similar RNA encapsidation strategy as that of RVFV-N. The RNA binding cavity runs along the inner edge of the ring-like assembly. A triple mutant of SFTSV-N, R64D/K67D/K74D, almost lost its ability to bind RNA in vitro, is deficient in its ability to transcribe and replicate. Structural studies of the mutant reveal that both alterations in quaternary assembly and the charge distribution contribute to the loss of RNA binding. In the screening of inhibitors Suramin was identified to bind phleboviral N specifically. The complex crystal structure of SFTSV-N with Suramin was refined to a 2.30-Å resolution. Suramin was found sitting in the putative RNA binding cavity of SFTSV-N. The inhibitory effect of Suramin on SFTSV replication was confirmed in Vero cells. Therefore, a common Suramin-based therapeutic approach targeting SFTSV-N and its homologs could be developed for containing phleboviral outbreaks.

Histological description of the lymphadenopathy related to Toscana virus infection. Report of a case.

Toscana virus (TOSV) infection is a frequent cause of meningitis in central Italy during summer. The disease generally has a benign course. Rarely, the infection produces a severe disease, with encephalitis and signs of systemic involvement, including lymphadenopathy. Since there is no clinical necessity of performing lymph node biopsy in such cases, the histopathological feature of TOSV-related lymphadenitis is not known. We herein present a case in which lymphadenopathy preceded the onset of meningitis. The excised lymph node showed a non-specific mixed-type lymphoid hyperplasia, with follicular hyperplasia, sinusal expansion and paracortical involvement. We also demonstrated the presence of viral protein and viral RNA in the lymph node tissue.

[Sandfly fever Naples virus (serotype Toscana) infection with meningeal involvement after a vacation in Italy]. / Toskana-Virus-Infektion mit meningealer Beteiligung nach Italienaufenthalt.

HISTORY AND CLINICAL FINDINGS: A 69-year-old man was admitted to our hospital with severe headache, recurrent episodes of fever and deterioration of general health. He returned from a vacation in Tuscany (Italy) a few days before admission. Physical examination revealed slight nuchal rigidity and an elevated body temperature of 37.8 C but was otherwise unremarkable. INVESTIGATIONS: Differential blood count showed a lymphocytopenia. Other abnormal laboratory findings included an elevated blood sedimentation rate and a slightly increased C-reactive protein value. Abdominal sonography demonstrated a marginally enlarged spleen. DIAGNOSIS, TREATMENT AND CLINICAL COURSE: A lumbar puncture was performed. Cerebrospinal fluid analysis revealed a lymphocytic meningitis. Serological examination of a blood sample showed specific IgM-antibodies against sandfly fever Naples virus (SFNV), subtype Toscana virus (TOSV). After this diagnosis had been made initially instituted intravenous administration of antibiotics and antiviral medication were discontinued. The patient's symptoms improved rapidly under symptomatic treatment. Slight headaches without episodes of fever persisted for a few weeks without residual neurological symptoms. CONCLUSIONS: A history of travel should always be sought in patients with clinical signs for meningitis. Considering the increasing spread and incidence of SFNV and its subtype Toscana in mediterranean countries, such virus should be kept in mind when treating patients who present such symptoms after returning from those countries during the summer season.