A patient with severe fever with thrombocytopenia syndrome and hemophagocytic lymphohistiocytosis-associated involvement of the central nervous system

Severe fever with thrombocytopenia syndrome (SFTS), a severe infectious disease caused by novel bunyavirus, SFTS virus (SFTSV), is endemic to China, Korea, and Japan. Most SFTS patients show abnormalities in consciousness. Pathological findings in the central nervous system (CNS) of SFTS patients are not reported. A 53-year-old Japanese man was admitted to Uwajima City Hospital with an 8-day history of fever and diarrhea. Laboratory tests revealed leukopenia, thrombocytopenia, and liver enzyme elevation. He was diagnosed as having severe fever with thrombocytopenia syndrome (SFTS) following detection of the SFTSV genome in his blood. Bone marrow aspiration revealed hemophagocytic lymphohistiocytosis. He suffered progressive CNS disturbance and died on day 13 from onset of first symptoms. The SFTSV genome load in blood and levels of certain cytokines increased over the disease course. Necrotizing lymphadenitis with systemic lymphoid tissues positive for nucleocapsid protein (NP) of SFTSV was revealed by immunohistochemical (IHC) analysis. SFTSV-NP-positive immunoblasts were detected in all organs examined, including the CNS, and in the vascular lumina of each organ. Parenchymal cells of all organs examined were negative for SFTSV-NP on IHC analysis. Microscopic examination of the pons showed focal neuronal cell degeneration with hemosiderin-laden macrophages around extended microvessels with perivascular inflammatory cell infiltration and intravascular fibrin deposition. Autopsy confirmed this patient with SFTS was positive for systemic hemophagocytic lymphohistiocytosis including in the CNS. This patient's neurological abnormalities may have been caused by both functional and organic abnormalities. These novel findings provide important insights into the pathophysiology of SFTS.     

一株发热伴血小板减少综合征布尼亚病毒的分离鉴定及其生长特性研究

目的 探索疑似发热伴血小板减少综合征病例中病原体的分离鉴定,了解病毒生长特性。方法 利用非洲绿猴肾细胞Vero E6从患者抗凝血标本中分离发热伴血小板减少综合征布尼亚病毒（SFTSV）,并通过血清学、形态学等方法对病毒进行鉴定;将分离的病毒接种不同细胞,利用荧光定量PCR检测不同时间细胞上清中病毒载量的变化。结果 从患者抗凝血标本中分离出SFTSV;免疫荧光显示感染病毒的细胞培养物能与患者血清发生阳性反应;在透射电镜下能观察到布尼亚病毒样颗粒。SFTSV可感染Vero E6、Hep G2、THP-1等多种细胞,但病毒在不同细胞中的复制水平差异明显。其中Vero E6细胞对SFTSV较易感,病毒可增殖至4.89109 copy/ml。而Hep-2和HT29细胞不能被SFTSV感染。结论 从疑似发热伴血小板减少综合征病例血液标本中成功分离出SFTSV。该病毒具有较广泛的细胞嗜性,对肾来源的细胞更易感。这些研究将为后续研究SFTSV的相关基础研究提供重要的线索。     

北京市发热伴血小板减少综合征监测和病原检测分析

目的 分析北京市发热伴血小板或白细胞减少综合征监测和严重发热伴血小板减少综合征病毒(SFTSV)感染情况.方法 对符合监测对象定义的病例(体温≥37.5℃伴血小板＜80×109/L或白细胞＜3.0×109/L)进行流行病学调查并采集乙二胺四乙酸抗凝和非抗凝血液标本分别检测嗜吞噬细胞无形体和SFTSV.结果 201...     

The combination of levodopa with levodopa-metabolizing enzyme inhibitors prevents severe fever with thrombocytopenia syndrome virus infection in vitro more effectively than single levodopa

Severe fever with thrombocytopenia syndrome is a hemorrhagic fever caused by a tick-borne infection. The causative agent, Dabie bandavirus, is also called the severe fever with thrombocytopenia syndrome virus (SFTSV). Ogawa et al. (2022) reported that levodopa, an antiparkinsonian drug with an o-dihydroxybenzene backbone, which is important for anti-SFTSV activity, inhibited SFTSV infection. Levodopa is metabolized by dopa decarboxylase (DDC) and catechol-O-methyltransferase (COMT) in vivo. We evaluated the anti-SFTSV efficacy of two DDC inhibitors, benserazide hydrochloride and carbidopa, and two COMT inhibitors, entacapone and nitecapone, which also have an o-dihydroxybenzene backbone. Only DDC inhibitors inhibited SFTSV infection with pretreatment of the virus (half-maximal inhibitory concentration [IC₅₀]: 9.0–23.6 μM), whereas all the drugs inhibited SFTSV infection when infected cells were treated (IC₅₀: 21.3–94.2 μM). Levodopa combined with carbidopa and/or entacapone inhibited SFTSV infection in both conditions: pretreatment of the virus (IC₅₀: 2.9–5.8 μM) and treatment of infected cells (IC₅₀: 10.7–15.4 μM). The IC₅₀ of levodopa in the above-mentioned study for pretreatment of the virus and treatment of infected cells were 4.5 and 21.4 μM, respectively. This suggests that a synergistic effect was observed, especially for treatment of infected cells, although the effect is unclear for pretreatment of the virus. This study demonstrates the anti-SFTSV efficacy of levodopa-metabolizing enzyme inhibitors in vitro. These drugs may increase the time for which the levodopa concentration is maintained in vivo. The combination of levodopa and levodopa-metabolizing enzyme inhibitors might be a candidate for drug repurposing.     

2018-2020年浙江省舟山市蜱类分布及发热伴血小板减少综合征病例调查

  目的   了解浙江省舟山市蜱类季节消长规律、种群分布情况及发热伴血小板减少综合征病例发生情况,分析其相关性。  方法   2018 — 2020年在舟山市定海、普陀、岱山、嵊泗区（县）发热伴血小板减少综合征确诊病例发生地周围采用布旗法收集游离蜱,采用体表检蜱法收集寄生蜱,运用荧光反转录酶聚合酶链式反应（RT-PCR）检测新型布尼亚病毒核酸。采用Excel 2017软件汇总数据,用SPSS 19.0 软件进行数据分析。  结果  2018 — 2020年共捕获游离蜱612只,以长角血蜱为主（83.82%）,镰形扇头蜱次之（14.05%）。 共有发热伴血小板减少综合征病例20例,发病基本集中在岱山县。 在确诊病例发生地周围共捕获51只游离蜱,86只寄生蜱,均为长角血蜱,经检测新型布尼亚病毒核酸均为阴性。  结论  舟山市优势蜱种为长角血蜱,农村外环境是蜱的主要生活环境,每年5 — 9月是蜱的活动高峰时间,发热伴血小板减少综合征病例的发生与蜱的活动高峰密切相关。     

L-DOPA,a treatment for Parkinson's disease,and its enantiomer D-DOPA inhibit severe fever with thrombocytopenia syndrome virus infection in vitro

Severe fever with thrombocytopenia syndrome (SFTS) is a hemorrhagic fever. Patients mainly develop fever, thrombocytopenia, and leukopenia. A high case fatality rate of 16.2–47% has been reported. Vaccines and antivirals that are effective against SFTS virus (SFTSV) are not yet available in clinical practice. We previously showed that o-dihydroxybenzene is the important chemical core structure for anti-SFTSV activity. In this study, we evaluated the anti-SFTSV efficacy of 3-Hydroxy-L-tyrosine (L-DOPA), a treatment for Parkinson's disease and its enantiomer, 3-hydroxy-D-tyrosine (D-DOPA), both of which have an o-dihydroxybenzene backbone. SFTSV was preincubated with L- or D-DOPA and then inhibition of viral infection as well as viral attachment to host cells were evaluated by viral quantification. Both L- and D-DOPA inhibited SFTSV infection in a dose-dependent manner, mainly by blocking viral attachment to host cells. The half-maximal inhibitory concentration (IC₅₀) of L-DOPA was 4.46–5.09 μM. IC₅₀ of D-DOPA was 4.23–6.72 μM. IC₅₀ of L-DOPA is very close to its maximum blood concentration after oral administration as a therapy for Parkinson's disease. D-DOPA, which IC₅₀ was almost the same as that of L-DOPA, might not cause side effect. Thus, our present study demonstrated that L- and D-DOPA are potentially useful candidates for anti-SFTSV drugs.     

Steroid pulse therapy in patients with encephalopathy associated with severe fever with thrombocytopenia syndrome

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease caused by the SFTS virus (SFTSV). Clinical symptoms of SFTS often involve encephalopathy and other central neurological symptoms, particularly in seriously ill patients; however, pathogenesis of encephalopathy by SFTSV is largely unknown. Herein, we present case reports of three patients with SFTS, complicated by encephalopathy, admitted to Tokushima University hospital: one patient was a 63-year-old man, while the other two were 83- and 86-year-old women. All of them developed disturbance of consciousness around the 7th day post onset of fever. After methylprednisolone pulse therapy of 500 mg/day, all of them recovered without any neurological sequelae. SFTSV genome was not detected in the cerebrospinal fluid of 2 out of the 3 patients that were available for examination. In these patients, disturbance of consciousness seemed to be an indirect effect of the cytokine storm triggered by SFTSV infection. We propose that short-term glucocorticoid therapy might be beneficial in the treatment of encephalopathy during early phase of SFTSV infection.     

Caffeic acid,a coffee-related organic acid,inhibits infection by severe fever with thrombocytopenia syndrome virus in vitro

Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) causes tick-borne hemorrhagic fever in East Asia. The disease is characterized by high morbidity and mortality. Here, we evaluated the effects of caffeic acid (CA), a coffee-related organic acid with antiviral effects, against SFTSV infection. CA dose-dependently inhibited SFTSV infection in permissive human hepatoma Huh7.5.1–8 cells when SFTSV was added into the culture medium with CA. However, quinic acid (QA), another coffee-related organic acid, did not inhibit SFTSV infection. The 50% inhibitory concentration (IC₅₀) of CA against SFTSV was 0.048 mM, whereas its 50% cytotoxic concentration was 7.6 mM. The selectivity index (SI) was 158. Pre-incubation of SFTSV with CA for 4 h resulted in a greater inhibition of SFTSV infection (IC₅₀ = 0.019 mM; SI = 400). The pre-incubation substantially decreased viral attachment to the cells. CA treatment of the SFTSV-infected cells also inhibited the infection, albeit less effectively. CA activity after cell infection with SFTSV was more pronounced at a low multiplicity of infection (MOI) of 0.01 per cell (IC₅₀ = 0.18 mM) than at a high MOI of 1 per cell (IC₅₀ > 1 mM). Thus, CA inhibited virus spread by acting directly on the virus rather than on the infected cells. In conclusion, CA acted on SFTSV and inhibited viral infection and spread, mainly by inhibiting the binding of SFTSV to the cells. We therefore demonstrated CA to be a potential anti-SFTSV drug for preventing and treating SFTS.     

Seroprevalence of severe fever with thrombocytopenia syndrome (SFTS) virus antibodies in humans and animals in Ehime prefecture,Japan, an endemic region of SFTS

Severe fever with thrombocytopenia syndrome (SFTS) was first identified as an emerging tick-borne infectious disease caused by the SFTS virus (SFTSV) in China and has also been found to be endemic to Japan and South Korea, indicating that SFTS is of great concern in East Asia. The aim of the present study was to determine the seroprevalence of SFTSV antibodies in humans and animals in SFTS-endemic regions of Japan. One of 694 (0.14%) healthy persons over 50 years of age and 20 of 107 (18.7%) wild and domestic animals in Ehime prefecture of western Japan were determined to be seropositive for SFTSV antibodies by virus neutralization test and ELISA, respectively. The seropositive person, a healthy 74-year-old woman, was a resident of the southwest part of Ehime prefecture engaged in citriculture and field work. This woman's sample exhibited neutralizing activity against SFTSV although she had neither a clear experience with tick bites nor SFTS-like clinical illness. These findings indicate that most people living in the endemic regions are not infected with SFTSV and suggest that most of the SFTS patients reported so far do not reflect the tip of an iceberg of people infected with SFTSV, but at the same time, that SFTSV infection does not always induce severe SFTS-associated symptoms. These findings also suggested that SFTSV has been maintained in nature within animal species and ticks.     

Pathophysiology of severe fever with thrombocytopenia syndrome and development of specific antiviral therapy

Severe fever with thrombocytopenia syndrome (SFTS) caused by SFTS virus (SFTSV), a novel phlebovirus, was reported to be endemic to central and northeastern PR China and was also to be endemic to South Korea and western Japan. SFTS is an emerging viral infection, which should be categorized as a viral hemorrhagic fever disease as Crimean-Congo hemorrhagic fever (CCHF) is caused by CCHF virus. SFTS is a tick-borne viral infection. SFTSV is maintained between several species of ticks and wild and domestic animals in nature. Patients with SFTS show symptoms of fever, general fatigue, and gastrointestinal symptoms such as bloody diarrhea. The severely ill SFTS patients usually show gastrointestinal hemorrhage and deteriorated consciousness. The case fatality rate of SFTS ranges from 5 to 40%. Pathological studies on SFTS have revealed that the mechanisms behind the high case fatality rate are virus infection-related hemophagocytic syndrome associated with cytokine storm, coagulopathy due to disseminated intravascular coagulation causing bleeding tendency, and multi-organ failure. Favipiravir was reported to show 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. SFTSV is circulating in nature in PR China, Korea, and Japan, indicating that we cannot escape from the risk being infected with SFTSV. The development of specific therapy and preventive measures is a pressing issue requiring resolution to reduce the morbidity and mortality of SFTS patients.     

发热伴血小板减少综合征的血象及骨髓象分析

目的研究发热伴血小板减少综合征(SFTS)患者的血象和骨髓象特点。方法回顾性总结分析30例SFTS确诊患者的资料。结果 SFTS布尼亚病毒(SFTSV)感染机体可导致外周血白细胞、血小板减少,网织红细胞减低,并出现异型淋巴细胞,在疾病极期-晚期骨髓增生减低,造血细胞明显受抑,并出现较多噬血细胞。结论外周血和骨髓检测对SFTS的诊断、预后判断有一定的临床意义。     

Structural basis of antiviral activity of caffeic acid against severe fever with thrombocytopenia syndrome virus

Caffeic acid (CA), a coffee-related natural compound, has various beneficial biological effects, including antiviral effects. Our former studies demonstrated that the CA dose-dependently inhibited the in vitro infection with Dabie bandavirus, which was previously named as severe fever with thrombocytopenia syndrome virus (SFTSV), mainly at the step of virus attachment. Therefore, we studied the structural basis of CA for conferring anti-SFTSV activity to clarify the mechanism of action of CA against SFTSV. In this study, the anti-SFTSV activity of nine CA analogs were examined. The treatment of SFTSV with the 3,4-dihydroxyhydrocinnamic acid (DHCA) as well as CA inhibited the SFTSV infection in a dose-dependent manner, whereas other CA analogs did not. Both CA and DHCA only possessed the o-dihydroxybenzene backbone. When SFTSV was treated with catechol (o-dihydroxybenzene), SFTSV infection was also dose-dependently inhibited. Additionally, four compounds having the o-dihydroxybenzene backbone; CA phenethyl ester, methyl CA, 3,4-dihydroxyphenylacetic acid, and 3,4-dihydroxybenzoic acid, dose-dependently inhibited the viral infection, although these compounds were more toxic or less effective than CA. In conclusion, the o-dihydroxybenzene backbone in CA and its analogs was a critical structure for the anti-SFTSV activity. Based on these findings, modifications of the o-dihydroxybenzene backbone with various other residues might improve the antiviral effect and cytotoxicity for SFTSV.     

江苏省发热伴血小板减少综合征布尼亚病毒血清流行病学调查

目的 调查江苏省人与动物发热伴血小板减少综合征布尼亚病毒(SFTSV)血清流行病学情况,为控制疫情提供流行病学线索。 方法 2010年7-11月在江苏省南京江宁区、溧水县,常州溧阳市,无锡宜兴市,淮安盱眙县和连云港东海县共采集2853份血清,其中人血清1922份、动物(犬、羊、猪、牛、鹅、鼠和鸡)血清931份, 运用双抗原夹心ELISA法检测血清中SFTSV总抗体,并进行不同地区SFTSV总抗体阳性率比较。 结果 本次调查2853份血清样本中SFTSV总抗体阳性血清121份,阳性率为4.24%,提示江苏省存在SFTSV的流行。在7种被调查的动物样本中,5种动物(犬、羊、牛、猪、鸡)血清样本SFTSV总抗体阳性,阳性率分别为6.40%、57.14%、31.82%、5.33%和0.98%;人血清中SFTSV总抗体阳性率为0.94%。血清中SFTSV总抗体阳性率存在地区差异。人群与动物SFTSV血清总抗体阳性率存在正相关关系。 结论 江苏省是SFTSV的流行区域,需加强SFTSV的预防意识及诊断能力。     

Several catechins and flavonols from green tea inhibit severe fever with thrombocytopenia syndrome virus infection in vitro

IntroductionSevere fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne hemorrhagic fever caused by SFTS virus (SFTSV). The mortality rate of SFTS is pretty high, but no vaccines and antiviral drugs are currently available.MethodsThe antiviral effects of six green tea-related polyphenols, including four catechins and two flavonols, on SFTSV were evaluated to identify natural antiviral compounds.ResultsPretreatment with all polyphenols inhibited SFTSV infection in a concentration-dependent manner. The half-maximal inhibitory concentrations of (?)-epigallocatechin gallate (EGCg) and (?)-epigallocatechin (EGC) were 1.7–1.9 and 11–39 μM, respectively. The selectivity indices of EGCg and EGC were larger than those of the other polyphenols. Furthermore, pretreatment with EGCg and EGC dose-dependently decreased viral attachment to the host cells. Additionally, the treatment of infected cells with EGCg and EGC inhibited infection more significantly at a lower multiplicity of infection (MOI) than at a higher MOI, and this effect was less effective than that of pretreatment. Pyrogallol, a trihydroxybenzene that is the structural backbone of both EGCg and EGC, also inhibited SFTSV infection, as did gallic acid.ConclusionsOur study revealed that green tea-related polyphenols, especially EGCg and EGC, are useful as candidate anti-SFTSV drugs. Furthermore, the structural basis of their antiviral activity was identified, which should enable investigations of more active drugs in the future.