Acute Hemorrhagic Fever: Clinical, Epidemiological and Laboratory Aspects in São Toméand Príncipe

Background: In the last 6 months, cases of acute hemorrhagic fever (AHF) have been recorded in Sao Tome and Principe (STP). Objective: To identify the clinical, epidemiological and laboratory parameters associated with AHF cases found in patients hospitalized in STP. Methods: Descriptive and quantitative analysis of AHF cases hospitalized in STP in the period December 2021 to May 19, 2022 through the variables: demographic data;clinical data;laboratory data and clinical outcome. Results: Analyzed 18 of 22 AHF cases, 50% of them male, mean age 33.7 years, 85.7% residing in the 2 largest districts of the country, 66.7% rural workers, administrative near maritime areas, sailors and domestics. 66.7% were healthy individuals. ≥50% had a fever, asthenia/weakness, myalgia, headache, lethargy, nausea, vomiting, and diarrhea. 22.2% to 33.3% had retro-orbital pain, abdominal pain, decreased consciousness, dyspnea/hypoxia, and cough. In a smaller register (5.6% - 11.1%), exanthema, convulsion, arthralgia, low back pain, chills, and chest pain. Bleeding from the digestive tract was found in 72.2%, followed by vaginal (33.3%), urethral (27.8%), nasal (22.2%), and oral (16.7%). 50% had laboratory confirmation for dengue, and another 50% with suspected clinical diagnosis without laboratory confirmation of the etiologic agent. Despite hemorrhage, 66.7% of confirmed cases were hemodynamically non-severe, and 88.9% of suspected cases were severe. Coinfection with malaria is evidenced in 11.1% of cases. 72.2% recovered and 27.8% died (deaths in 55.5% of suspected cases). Case deaths were male (100%), resident foreigners (40%), tool store employees, sailors and students, healthy (80%), and residing in the largest district in the country (60%). All deaths were hospitalized in serious condition, 80% were hospitalized for hemorrhage and shock, with bleeding arising between day 4 - 5 of illness in 60% and hospitalization on day 5 of illness. 60% died within ≤24 hours of hospitalization. 80% died from shock and multi-organ dysfunction and 20% from respiratory failure. Deaths had thrombocytopenia (100%), renal dysfunction (100%) and significantly increased transaminases (100%), anemia (75%) and leukocytosis (66.7%). 20% had a radiological change of pulmonary infiltrates. Conclusion: Our data reveal the complexity of the pathogens causing AHF and suggest the possible presence of other human pathogens usually unknown in the Santomean geographical territory.

Hemorrhagic fever with renal syndrome complicated with aortic dissection:A case report

BACKGROUND Hemorrhagic fever with renal syndrome is caused by hantaviruses presenting with high fever,hemorrhage,and acute kidney injury.Microvascular injury and hemorrhage in mucus were often observed in patients with hantavirus infection.Infection with bacterial and virus related aortic aneurysm or dissection occurs sporadically.Here,we report a previously unreported case of hemorrhagic fever with concurrent aortic dissection.CASE SUMMARY A 56-year-old man complained of high fever and generalized body ache,with decreased platelet counts of 10×10^9/L and acute kidney injury.The enzymelinked immunosorbent assays test for immunoglobulin M and immunoglobulin G hantavirus-specific antibodies were both positive.During the convalescent period,he complained sudden onset acute chest pain radiating to the back,and the computed tomography angiography revealed an aortic dissection of the descending aorta extending to iliac artery.He was diagnosed with hemorrhagic fever with renal syndrome and Stanford B aortic dissection.The patient recovered completely after surgery with other support treatments.CONCLUSION Hemorrhagic fever with renal syndrome complicated with aortic dissection is rare and a difficult clinical condition.Hantavirus infection not only causes microvascular damage presenting with hemorrhage but may be risk factor for acute macrovascular detriment.A causal relationship has yet to be confirmed.

DETERMINATION OF URINE TUMOR NECROSIS FACTOR, IL-6, IL-8 AND SERUM IL-6 IN PATIENTS WITH HEMORRHAGIC FEVERS WITH RENAL SYNDROME

Objective To explore the roles of cytokines in the pathogenesis of hemorrhagic fever with renal syndrome(HFRS). Methods Double-antibody sandwich ELISA was used to determine serum interleukin (IL)-6, urine tumor necrosis factor (TNF), IL-6 and IL-8 levels in 56 patients with HFRS. Results Serum IL-6, urine TNF, IL-6 and IL-8 concentrations in HFRS patients were significantly higher than those in control group, respectively (P<0.001). The concentrations increased at fever stage, then continued to increase during hypotension stage and peaked at oliguria stage. The concentrations of serum IL-6, urine TNF, IL-6 and IL-8 increased in accord with the severity of the disease and differed greatly among different types of the disease. Serum IL-6 had remarkable relationships with serum specific antibodies. It was positively related to serum β_2-microglobulin (β_2-MG), blood ureanitrogen (BUN) and creatinine (Cr). Significant positive relationships were also found both between urine IL-6 and TNF, and between IL-6 and IL-8 (r=0.5768, P<0.05; r=0.3760, P<0.01). Conclusion TNF, IL-6 and IL-8 activated during the course of the disease. IL-6 is associated with the immunopathological lesions caused by the hyperfunction of humoral immune response. IL-6, IL-8 and TNF are involved in the renal immune impairment. Determining them might, in certain extent, be used in predicting the prognosis and outcome of patients with HFRS.

A Retrospective Study of Continuous Renal Therapy and Anticoagulation in Patients with Hemorrhagic Fever with Renal Syndrome

Objective To observe the application of continuous renal replacement therapy(CRRT) and heparin anticoagulation in patients with HFRS, and to explore a more suitable anticoagulant strategy. Methods Eighty-five severe-type patients(severe group) and 71 critical-type patients(critical group) were enrolled in this study. The frequency of CRRT was compared between the two groups; the frequency of CRRT treated with and without heparin anticoagulation and the frequency of hemorrhage and channel blood clotting induced by the two anticoagulant strategies were observed. Results The frequency of CRRT in the critical group was higher than that in the severe group(P < 0.001). The frequency of CRRT initiated during the overlapping phases in the critical group was significantly higher than that of the severe group(P = 0.032). The total times of CRRT was 103, and 70 of them were treated with heparin anticoagulation. The frequencies of hemorrhage induced by heparin anticoagulation and no heparinization were 16 and 0, respectively, and the frequencies of channel blood clotting were 2 and 4, respectively. Conclusions CRRT has been used extensively in the critical-type patients with HFRS. The heparin anticoagulation and no anticoagulant strategies should be used more rationally in patients treated with CRRT, according to the clinical characteristics of the disease.

Crimean-Congo hemorrhagic fever from the immunopathogenesis, clinical, diagnostic, and therapeutic perspective: A scoping review

Crimean-Congo hemorrhagic fever virus(CCHFV) is responsible for widespread tick-borne zoonotic viral disease CCHF in African, Middle Eastern, Asian, and European countries. CCHFV can be spread to humans through tick bites or contact with infected animals or humans, and it often progresses from asymptomatic to severe/lethal illness, with fatality rates ranging from 10% to 40% in humans. Today, CCHF is growing into a significant public health concern due to its very high prevalence, severity of the condition, and lack of available vaccines and specific treatments. Recent research has been drawn towards a more accurate study of CCHFV characteristics, including the structure, genetic diversity, mechanisms involved in pathogenesis and immunopathogenesis, and clinical features. In addition, the use of animal models(mouse and non-human primates) and advanced diagnostic tools in recent years has resulted in a significant advance in CCHF related studies. In this context, we summarized the latest findings about CCHF research, its health complications, animal models, current diagnosis, vaccination, and CCHF treatments, and therapeutic strategies. Furthermore, we discussed existing deficiencies and problems in CCHFV analysis, as well as areas that still need to yield conclusive answers.

Significance of IL-1Ra and IL-6 gene variants in Turkish patients with Crimean-Congo hemorrhagic fever

Objective: To investigate the association between IL-1 Ra variable number of tandem repeat(rs2234663), IL-6-597 GA(rs1800797), IL-6-572 GC(rs1800796) and the risk of CrimeanCongo hemorrhagic fever(CCHF) in the Turkish patients. Methods: This study included 50 patients infected with CCHF and 50 healthy controls. These variants were genotyped using polymerase chain reaction and/or restriction fragment length polymorphism method. Results: The distribution of the IL-6-572 GC genotypes and alleles varied significantly between the patients and the controls. The subjects carrying IL-6-572 GC GG genotype and G allele had increased risk of developing CCHF compared to the control group(P=0.006, P=0.014, respectively). IL-6-572 GC GC genotype was higher in the controls than the patients(P=0.006). For the triple genotype combinations, the 1/2-GC-GG genotype combination was detected more frequently in the control group than CCHF patients(P=0.016). IL-6(-572/-597) GG-GG genotype was significantly higher in the patient group(P=0.015), while the GC-GG genotype was significantly lower in the patient group(P=0.005). Additionally, the G-G haplotype was significantly higher in the patient group(P=0.042), whereas C-G was found to be significantly lower in the patients than the control group(P=0.037). Conclusions: The results of this study suggest the IL-6-572 GC variant might be genetic markers of sensitivity to CCHF in the Turkish population and may facilitate greater protection against the disease.

Determination of CD_(30) Expression on Peripheral Blood T Lymphocyte Subsets in Patients with Hemorrhagic Fever with Renal Syndrome by FCM

To determine the CD 30 expression on peripheral blood T lymphocyte subsets in patients with hemorrhagic fever with renal syndrome (HFRS) and its clinical implications, double immunofluorescence technique and flow cytometry were used. There was no significant difference among the severe group, mild-moderate group and normal control group in the CD + 4CD - 30 T lymphocyte subset. While the CD + 4CD + 30 T cells of HFRS patients were increased and the difference between severe group and mild-moderate group or normal control group were very significant (P<0.01) and the difference between the mild-moderate group and normal control group was also significant (P<0.05). The CD + 8CD - 30 T cells were increased while the CD + 8CD + 30 T cells decreased obviously in HFRS patients, and the differences among three groups in both subsets were very significant (P<0.01). The results showed that the humoral immunity and cellular immunity are overactive in HFRS patients during acute phase. The loss of balance between T lymphocyte subsets may play an important role in the pathophysiology of HFRS and is closely correlated with the severity of the HFRS.

Epidemic Hemorrhagic Fever in Hubei Frovince,The Peoples Repulic of China: A Clinical and Serological Study

Between July 1975 and April 1980, 71 patients were admitted to the 2ndAttached Hospital of Hubei Provincial Medical College in Wuchang withthe diagnosis of Epidemic Hemorrhagic Fever (EHF). The clinical courseamong these patients was similar to that described for patients with KoreanHemorrhagic Fever, Nephropathica Epidemica of Scandanavia and Hemor-rhagic Fever with Renal Syndrome of the U.S.S.R. The overall mortalitywas 11.2％. Sera obtaincd from some of these patients as well as frompatients admitted to the First Attached Hospital of Hubei Provincial Me-dical College were tested against an antigen associated with Korean He-morrhagic Fever and showed exceedingly high antibody titers. We concludethat EHF in Centfal China represents the same disease process as KoreanHemorrhagic Fever.

Dengue hemorrhagic fever and the liver

Dengue hemorrhagic fever(DHF)is one of the most rapidly emerging infections of tropical and subtropical regions worldwide.It affects more rural and urban areas due to many factors,including climate change.Although most people with dengue viral infection are asymptomatic,approximately 25%experience a selflimited febrile illness with mild to moderate biochemical abnormalities.Severe dengue diseases develop in a small proportion of these patients,and the common organ involvement is the liver.The hepatocellular injury was found in 60%-90%of DHF patients manifested as hepatomegaly,jaundice,elevated aminotransferase enzymes,and critical condition as an acute liver failure(ALF).Even the incidence of ALF in DHF is very low(0.31%-1.1%),but it is associated with a relatively high mortality rate(20%-68.3%).The pathophysiology of liver injury in DHF included the direct cytopathic effect of the DENV causing hepatocytes apoptosis,immunemediated hepatocyte injury induced hepatitis,and cytokine storm.Hepatic hypoperfusion is another contributing factor in dengue shock syndrome.The reduction of morbidity and mortality in DHF with liver involvement is dependent on the early detection of warning signs before the development of ALF.

Study on Biologic Activity for Membrane of Normal Bone Marrow Cells with Infection of Epidemic Hemorrhagic Fever Virus

Using DPH fluorescence probe, the membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus (EHFV) was labeled. The membrane lipid fluidity was obviously decreased from the membrane lipid fluorescence polarization. The membrane lipid fluidity of lympho- cyte, monocyte and neutrophilic granulocyte was dynamically observed. After culturing the cells for 1, 6, 24 and 72 h, it was found that all the membrane lipid fluidity of the infected cells was de- creased obviously with the longer the culturing time, the more obvious it. Compared with the normal control groups, there was a significant difference statistically (P<0. 05-0. 01). It was suggested that the decrease of the membrane lipid fluidity of normal bone marrow cell with infection of EHFV had correlation with the degree of virus invading and cellfunction injury.

Dengue hemorrhagic fever and cardiac involvement

Dengue viral infection(DVI)is one of the world’s most significant viral infections spreading.Most of the patients have been asymptomatic,with relatively benign clinical manifestations and outcomes.However,a small number of patients have progressed to severe dengue diseases,including hemorrhage,multi-organ impairment,and increased vascular leakage causing hypovolemic shock,which can cause cardiovascular collapse and death.Numerous lines of evidence have demonstrated that DVI could also cause cardiac dysfunction,arrhythmias,and severe myocarditis.The treatment for dengue hemorrhagic fever(DHF)patients remains symptomatic and supportive,with close monitoring of hemodynamic status.The contributory role of cardiac dysfunction in DHF patients has potentially critical implications on the management.This review will address the current knowledge of cardiac involvement in DHF patients and the management strategy to reduce the fatality outcome.

The Risk of Severe Acute Kidney Injury Requiring Renal Replacement Therapy in Viral Hemorrhagic Fevers. A Review of Literature

Objective: It demonstrates the correlation of the viral hemorrhagic fever with kidney failure and the treatment as well as the outcome. Method: A PubMed search of the English literature from 1999 to 2019 was performed using “viral hemorrhagic fever, Case Report, Renal Failure” as the subject. The inclusion criteria were the following: 1) case report and case series of two or more patients;2) the report detailed the clinical presentation and reported the status of the renal system;3) the report described the management of renal failure if any;and 4) the etiology of the infection is known and is one of the known agents of viral hemorrhagic fever, listed on the centers of disease control website. We excluded infections related to vaccination related to viral hemorrhagic fever. Result: We found the mean age of these patients was 41.5. The male to female ratio was about 3.5:1. Dengue and Hantaviruses constituted 70.5% of patients. The overall mortality of the study cohort was 32.2%. Half of the patients had acute kidney injury and required renal replacement therapy. The chi-square statistic is 0.41;The p-value is 0.51;The chi-square statistic is 6.4254. Overall mortality was 32.3% in one cohort of 78 patients. The illness goes through several stages [1] [2] of clinical features and some viruses in the group have a high case fatality rate. Conclusions: Early diagnosis with aggressive supportive care is critical for improving clinical outcomes. Renal involvement is common. Amongst the cohort reviewed, of patients who had acute kidney injury, half of the patients required renal replacement support. However, some viruses cause greater kidney injury than others, for instance, kidney injury is more severe in Dengue hemorrhagic fevers when compared to Hantaviruses. Simultaneous management of public health by prevention and control of outbreaks is particularly important.

Effect of High-Quality Nursing on Patients with Hemorrhagic Fever with Renal Syndrome

Objective:To explore and analyze the effect of high-quality nursing on patients with epidemic hemorrhagic fever with renal syndrome.Methods:Ninety patients with epidemic hemorrhagic fever with renal syndrome treated in Huyi District People’s Hospital from October 2021 to January 2022 were randomly divided into an experimental group and a control group,with 45 cases in each group.The control group received routine nursing and the experimental group received high-quality nursing.The effect of routine nursing and high-quality nursing were compared and analyzed based on the Self-Rating Anxiety Scale(SAS),Self-Rating Depression Scale(SDS),the degree of satisfaction with nursing care,and the patients’quality of life.Results:Before nursing,there was no significant difference in the patients’psychological state between the two groups(P>0.05);after nursing,there was significant difference in the patients’psychological state between the two groups(P<0.05);the degree of satisfaction with nursing care of the experimental group was significantly higher than that of the control group(P<0.05);comparing the quality of life of the two groups,the quality-of-life score of the control group was significantly lower than that of the experimental group(P<0.05).Conclusion:For patients with epidemic hemorrhagic fever with renal syndrome,high-quality nursing can significantly and effectively improve their psychological state,level of satisfaction with nursing care,and quality of life.

CLINICAL SIGNIFICANCE OF DETECTING SERUM ANTIBODIES TO NUCLEOPROTEIN AND GLYCOPROTEIN G_2 OF HANTAAN VIRUS IN PATIENTS WITH HEMORRHAGIC FEVER WITH RENAL SYNDROME

Antibody blocking enzyme linked immunosorbent assays, respectively detecting antibodies to Hantaan virus nucleoprotein (NPAb) and glycoprotein GZ (G,Ab), were developed using monoclonal antibody L133, L13r3, LV48A and LVZB28B NPAb and GZAb in 291 serum samples from 65 patientswith kemorrkagic fever with renal syudrome (HFRS) were detfrmlned by these methods. The positive rates or NPAb were 90N on day 2-3 and 100 % on day 8-9 arter onset of disease, respectively.NPAb titers Increased during fever period and reached Peak levels during kypotensive and oliguric periods of HFRS. It was suggested that NPAb might be an important component Involved in the immunopathogenlc lin'alrmeut of HFRS and the detection of NPAb might be useful for the early diagnosis or HFRS. The I,osltlve rates and titers of GZAh were very low during the rirst three periods,namely rever, hypoteuslve and ollgurlc periods, and reached high levels during the convalescent period. GRAb titers were negatively related to the I,rotelnurla levels during the course of HFRS. It wasIndicated that GZAb might be the main component or neutralizing autlhodles to Hantaan virus Infection and the efrlclent production or GZAb was a good marker ror predicting the recovery and betterprognosis of HFRS.

Crimean-Congo hemorrhagic fever virus in Central,Eastern,and South-eastern Asia

Crimean-Congo hemorrhagic fever(CCHF),caused by Crimean-Congo hemorrhagic fever virus(CCHFV),is endemic in Africa,Asia,and Europe,but CCHF epidemiology and epizootiology is only rudimentarily defined for most regions.Here we summarize what is known about CCHF in Central,Eastern,and South-eastern Asia.Searching multiple international and country-specific databases using a One Health approach,we defined disease risk and burden through identification of CCHF cases,anti-CCHFV antibody prevalence,and CCHFV isolation from vector ticks.We identified 2313 CCHF cases that occurred in 1944–2021 in the three examined regions.Central Asian countries reported the majority of cases(2,026).In Eastern Asia,China was the only country that reported CCHF cases(287).In South-eastern Asia,no cases were reported.Next,we leveraged our previously established classification scheme to assign countries to five CCHF evidence levels.Six countries(China,Kazakhstan,Kyrgyzstan,Tajikistan,Turkmenistan,and Uzbekistan)were assigned to level 1 or level 2 based on CCHF case reports and the maturity of the countries’surveillance systems.Two countries(Mongolia and Myanmar)were assigned to level 3 due to evidence of CCHFV circulation in the absence of reported CCHF cases.Thirteen countries in Eastern and South-eastern Asia were categorized in levels 4 and 5 based on prevalence of CCHFV vector ticks.Collectively,this paper describes the past and present status of CCHF reporting to inform international and local public-health agencies to strengthen or establish CCHFV surveillance systems and address shortcomings.

Transcriptome profiling highlights regulated biological processes and type III interferon antiviral responses upon Crimean-Congo hemorrhagic fever virus infection

Crimean-Congo hemorrhagic fever virus(CCHFV)is a biosafety level-4(BSL-4)pathogen that causes Crimean-Congo hemorrhagic fever(CCHF)characterized by hemorrhagic manifestation,multiple organ failure and high mortality rate,posing great threat to public health.Despite the recently increasing research efforts on CCHFV,host cell responses associated with CCHFV infection remain to be further characterized.Here,to better understand the cellular response to CCHFV infection,we performed a transcriptomic analysis in human kidney HEK293 cells by high-throughput RNA sequencing(RNA-seq)technology.In total,496 differentially expressed genes(DEGs),including 361 up-regulated and 135 down-regulated genes,were identified in CCHFV-infected cells.These regulated genes were mainly involved in host processes including defense response to virus,response to stress,regulation of viral process,immune response,metabolism,stimulus,apoptosis and protein catabolic process.Therein,a significant up-regulation of type III interferon(IFN)signaling pathway as well as endoplasmic reticulum(ER)stress response was especially remarkable.Subsequently,representative DEGs from these processes were well validated by RT-qPCR,confirming the RNA-seq results and the typical regulation of IFN responses and ER stress by CCHFV.Furthermore,we demonstrate that not only type I but also type III IFNs(even at low dosages)have substantial anti-CCHFV activities.Collectively,the data may provide new and comprehensive insights into the virus-host interactions and particularly highlights the potential role of type III IFNs in restricting CCHFV,which may help inform further mechanistic delineation of the viral infection and development of anti-CCHFV strategies.

HLA-E-restricted Hantaan virus-specific CD8^(+)T cell responses enhance the control of infection in hemorrhagic fever with renal syndrome

Infection with the Hantaan virus(HTNV)may result in severe hemorrhagic fever with renal syndrome(HFRS).The functions of HLA-E-restricted CD8^(+)T lymphocytes in virus control and vaccine development have recently received increased attention.The purpose of this research is to discover HLA-E-restricted CD8^(+)T cell epitopes on HTNV as well as the features of these epitope-specific CD8^(+)T cells in HFRS patients.To anticipate HLA-Erestricted HTNV epitopes,the NetMHCpan servers were utilized.The K562/HLA-E cell binding test and the enzyme-linked immunospot assay were used to confirm epitope binding to HLA-E.The number and features of HLA-E-restricted epitope-specific CD8^(+)T lymphocytes in HFRS patients were investigated using tetramer staining,intracellular cytokine labeling,proliferation,and cytotoxicity assays.Six HTNV-derived HLA-Erestricted CD8^(+)T cell epitopes were found in this study.In mild/moderate HFRS patients,the frequency of HLA-E-restricted epitope-specific CD8^(+)T cells was greater than in severe/critical patients.CD38+HLA-DR+HLA-E-restricted CD8^(+)T cells were identified.Meanwhile,CD45RA^(+)CCR7^(-)effector memory-re-expressing CD45RA T cells with early and intermediate maturation and differentiation characteristics predominated.Notably,CD8^(+)T cells from milder HFRS patients produced more interferon-γ,interleukin-2,and granzyme B,had a stronger proliferative potential,and were inversely linked with the amount of plasma HTNV virus load.Furthermore,HLA-E-restricted epitope-specific CD8^(+)T cells demonstrated improved cytotoxic activity in vitro during the acute stage of HFRS.Taken together,the findings demonstrate the protective effects of HLA-E-restricted CD8^(+)T cells during HTNV infection,suggesting that HLA-E-targeted vaccines against HTNV might be developed for HLA-diverse populations.

STUDY ON AEROSOL TRANSMISSION ROUTES OF HEMORRHAGIC FEVER WITH RENAL SYNDROME (HFRS)

The present paper reviews our studies on transmission routes and prophylactic measures of Hemorrhagic Fever with Renal Syndrome (HFRS), including aerosol inhalation, skin injury/mucosa, insect vectors, peroral infection and vertical transmission. The results show that HFRS is transmitted by Hantaan virus via multi-routes. One of them, the aerosol transmission, is perhaps the main route transmitting HFRS from mouse to human beings. The injury and mu-cosa is the main transmission route from mouse to mouse and also an important agent from mouse to human beings. The peroral infection may occur in very serious pollution of foods. The insect vectors may play an important role in the focus of HFRS and in the transmission of HFRS from mouse to human. The epidemiological significance of vertical transmission is yet uncertain. According to the results, four proposals should be emphasized including killing insects and mice, long lasting and combined prophylactics, intensive studies on prophylactic measures on viral aerosols and the blocking of transmission of HFRS from mouse to human via aerosols.

Cryo-EM structure of glycoprotein C from Crimean-Congo hemorrhagic fever virus

Crimean-Congo hemorrhagic fever virus(CCHFV)is a causative agent of serious hemorrhagic diseases in humans with high mortality rates.CCHFV glycoprotein Gc plays critical roles in mediating virus-host membrane fusion and has been studied extensively as an immunogen.However,the molecular mechanisms involved in membrane fusion and Gc-specific antibody-antigen interactions remain unresolved largely because structural information of this glycoprotein is missing.We designed a trimeric protein including most of the ectodomain region of Gc from the prototype CCHFV strain,Ib Ar10200,which enabled the cryo-electron microscopy structure to be solved at a resolution of 2.8Å.The structure confirms that CCHFV Gc is a class Ⅱ fusion protein.Unexpectedly,structural comparisons with other solved Gc trimers in the postfusion conformation revealed that CCHFV Gc adopted hybrid architectural features of the fusion loops from hantaviruses and domain Ⅲ from phenuiviruses,suggesting a complex evolutionary pathway among these bunyaviruses.Antigenic sites on CCHFV Gc that protective neutralizing antibodies target were mapped onto the CCHFV Gc structure,providing valuable information that improved our understanding of potential neutralization mechanisms of various antibodies.

Spatial cluster analysis of human cases of Crimean Congo hemorrhagic fever reported in Pakistan

Background:Crimean Congo hemorrhagic fever(CCHF)is a tick-borne viral zoonotic disease that has been reported in almost all geographic regions in Pakistan.The aim of this study was to identify spatial clusters of human cases of CCHF reported in country.Methods:Kulldorff’s spatial scan statisitc,Anselin’s Local Moran’s I and Getis Ord Gi*tests were applied on data(i.e.number of laboratory confirmed cases reported from each district during year 2013).Findings:The analyses revealed a large multi-district cluster of high CCHF incidence in the uplands of Balochistan province near it border with Afghanistan.The cluster comprised the following districts:Qilla Abdullah;Qilla Saifullah;Loralai,Quetta,Sibi,Chagai,and Mastung.Another cluster was detected in Punjab and included Rawalpindi district and a part of Islamabad.Conclusion:We provide empirical evidence of spatial clustering of human CCHF cases in the country.The districts in the clusters should be given priority in surveillance,control programs,and further research.