Thrombocytopenia Syndrome Bunyavirus Research Articles

Real-time quantitative reverse transcription PCR assay for the detection of Nuomin virus – An emerging tick-borne virus

Nuomin virus (NOMV), an emerging tick-borne virus (TBVs) identified in 2020, has been associated with fever, headache, and potential liver dysfunction in infected individuals. This study presents a novel TaqMan real-time quantitative PCR method designed for the rapid, sensitive, and specific detection of NOMV, facilitating early diagnosis. Utilizing Beacon Designer software 8.0, we optimized the PCR assay including the development of primers and probes to precisely target the conserved region of the NOMV genome, followed by optimization of primer and probe concentrations and annealing temperature. The resulting assay demonstrated robust performance, with standard curve represented by the equation y=−3.29x+39.42, a high correlation coefficient (R2 = 0.995) and an efficiency 99.53 %. Importantly, the method exhibited exceptional specificity, which did not yield cross-reacting signals from other TBVs, including Songling virus (SGLV), Beiji virus (BJNV), tick-borne encephalitis virus (TBEV), Yezo virus (YEZV), Alongshan virus (ALSV), and severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). The assay’s detection limit was remarkably low, reaching 10 copies/μL, representing a 100-fold increase compared to semi-nested RT-PCR. Additionally, it demonstrated excellent repeatability, with coefficients of variation for intra- and inter-group tests consistently below 3 %. Clinical evaluations confirmed the assay’s superior performance, highlighting its high specificity, sensitivity, and reproducibility for NOMV detection. In conclusion, the method developed in this study provides a valuable tool to support timely management of NOMV infections, with significant implications for clinical practice.

SFTS bunyavirus NSs protein sequestrates mTOR into inclusion bodies and deregulates mTOR-ULK1 signaling, provoking pro-viral autophagy.

Autophagy is emerging as a critical player in host defense against diverse infections, in addition to its conserved function to maintain cellular homeostasis. Strikingly, some pathogens have evolved strategies to evade, subvert or exploit different steps of the autophagy pathway for their lifecycles. Here, we present a new viral mechanism of manipulating autophagy for its own benefit with severe fever with thrombocytopenia syndrome bunyavirus (SFTSV, an emerging high-pathogenic virus) as a model. SFTSV infection triggers autophagy, leading to complete autophagic flux. Mechanistically, we show that the nonstructural protein of SFTSV (NSs) interacts with mTOR, the pivotal regulator of autophagy, by targeting its kinase domain and captures mTOR into viral inclusion bodies (IBs) induced by NSs itself. Furthermore, NSsimpairs mTOR-mediated phosphorylation of unc-51-like kinase 1 (ULK1) at Ser757, disrupting the inhibitory effect of mTOR on ULK1 activity and thus contributing to autophagy induction. Pharmacologic treatment and Beclin-1 knockout experimental results establish that, in turn, autophagy enhances SFTSV infection and propagation. Moreover, the minigenome reporter system reveals that SFTSV ribonucleoprotein (the transcription and replication machinery) activity can be bolstered by autophagy. Additionally, we found that the NSs proteins of SFTSV-related bunyaviruses have a conserved function of targetingmTOR. Taken together, we unravel a viral strategy of inducing pro-viral autophagy by interacting with mTOR, sequestering mTOR into IBs and hence provoking the downstream ULK1 pathway, which presents a new paradigm for viral manipulation of autophagy and may help inform future development of specific antiviral therapies against SFTSV and related pathogens.

Analysis of cross neutralizing activity of antibodies from sera of severe fever with thrombocytopenia syndrome patients to deal with different genotype strains.

Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) is a tick-borne virus that causes severe communicable fever with thrombocytopenia syndrome (SFTS) with an average case fatality rate of 10%. In the study, we aimed to identify the cross-neutralizing antibody (nAb) against different genotype strains from sera of SFTSV infected patients. Firstly the genotype of SFTSV was identified by constructing a phylogenetic tree based on the M segments epidemic in the Jiaodong area of Shandong province, then different sera of subjects cross reactive with recombinant Gn (rGn-Fc) or recombinant Gc (rGc-Fc) of 0921 strain were examined. The levels of polyclonal nAbs from sera of 25 convalescents were measured by a pseudovirus-based neutralizing experiment. We found local endemic strains were mainly C2 and C3 isolates of SFTSV. 14 of 15 sera from donors reacted with 0921 rGn-Fc, and 9 of 15 sera from donors reacted with 0921 rGc-Fc. Cross nAbs were produced by 10 of 25 sera from donors during the period of 2019-2021. Among these, five nAbs (A2, A4, A5, L9, and L10) neutralized the pseudoviruses of HB29, Gangwon, HN13, HN20, SPL030A, and SD4 strains. Our data suggested that epidemic strains showed relatively stable heredity. Some blood sources from patients produced cross nAbs that could neutralize all of the strains examined. These findings highlight the important role played by humoral immunity in combatting SFTSV.

Associated microbiota and treatment of severe fever with thrombocytopenia syndrome complicated with infections.

The purpose of this study is to assess the incidence and management of co-infections in hospitalized severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) patients.We retrospectively evaluated the microbiological database records of the SFTS patients in the first affiliated hospital of Anhui Medical University from January 1, 2018, to December 1, 2021.According to the obtained results, co-infections including pulmonary infection, bloodstream infection, biliary tract infection, urinary tract infection, and abdominal infection were observed in SFTS patients. The incidence rate of fungal infections was found to be high in SFTS patients. Furthermore, we suggest that old age people should be evaluated for the risk of fungal infection. In comparison to the non-infection group, patients in the co-infection group were more likely to get mechanical ventilation, antibacterial treatment, antifungal treatment, and blood product therapy (p < 0.001), with a significantly longer length of stay (p < 0.05). In SFTS patients, the most prevalent strains were Aspergillus fumigatus, Aspergillus flavus, Candida, Klebsiella pneumonia, and Escherichia coli. In this investigation, 66.2% (106/160) of patients were given antibiotics, most often Piperacillin/tazobactam or minocycline. 15.6% (25/160) of patients were treated with antifungal drugs: 13.1% (21/160) with voriconazole. Patients with SFTS Associated Pulmonary Aspergillosis (SAPA) received active antifungal treatment, but the mortality rate was still 23.5% (8/34). Only 6 of the 11 patients with SFTS Associated Candidiasiswere treated with antifungal drugs with no mortality.Due to the high frequency of fungal pulmonary infection in SFTS patients, more standardized fungal detection program should be strengthened.

Fulminant myocarditis caused by severe fever with thrombocytopenia syndrome bunyavirus in a child

患儿 女，7岁，因“发热6 d，腹痛、呕吐3 d”于2021年7月就诊于安徽省儿童医院儿童重症医学科。患儿以发热、腹痛、呕吐及休克为主要临床表现。血新型布尼亚病毒核酸检测阳性，心电图示三度房室传导阻滞，床旁超声心动图示弥漫性室壁运动减低伴全心增大。诊断为暴发性心肌炎，予液体复苏、肾上腺素应用、营养心肌、利尿及丙种球蛋白冲击，并紧急植入临时心脏起搏器。临时起搏器安装术后48 h患儿自主心律恢复，术后第5天自主心律稳定，拔除起搏器，术后第14天顺利出院。出院后随访，患儿超声心动图未见异常。.

The Endless Wars: Severe Fever With Thrombocytopenia Syndrome Virus, Host Immune and Genetic Factors

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging arboviral infectious disease with a high rate of lethality in susceptible humans and caused by severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). Currently, neither vaccine nor specific antiviral drugs are available. In recent years, given the fact that both the number of SFTS cases and epidemic regions are increasing year by year, SFTS has become a public health problem. SFTSV can be internalized into host cells through the interaction between SFTSV glycoproteins and cell receptors and can activate the host immune system to trigger antiviral immune response. However, SFTSV has evolved multiple strategies to manipulate host factors to create an optimal environment for itself. Not to be discounted, host genetic factors may be operative also in the never-ending winning or losing wars. Therefore, the identifications of SFTSV, host immune and genetic factors, and their interactions are critical for understanding the pathogenic mechanisms of SFTSV infection. This review summarizes the updated pathogenesis of SFTS with regard to virus, host immune response, and host genetic factors to provide some novel perspectives of the prevention, treatment, as well as drug and vaccine developments.

Predisposing factors for person-to-person transmission of severe fever with thrombocytopenia syndrome bunyavirus

Person-to-person transmission of severe fever with thrombocytopenia syndrome virus (SFTSV) is a new threat to human health. Here we report an outbreak of nosocomial person-to-person transmission of SFTS. Among eight persons with face-to-face contact distance ≤50 cm and/or exposure time ≥30 min to the index patient, six became infected. Only one of the 17 persons with exposure distance ≥50 cm and exposure time ≤30 min became infected (75% vs 6.25%, P < 0.001). Epidemiological investigation revealed high viral load, bloody secretions and bleeding, exposure time, and distance as the key factors in person-to-person transmission.

Status of tick distribution and tick-borne pathogens in urban parks of Quzhou, Zhejiang, 2017–2019

Objective To understand the distribution and pathogen carriage of ticks in urban parks of Quzhou of Zhejiang province, and evaluate the transmission risk of tick-borne diseases in the urban parks. Methods From March to November during 2017−2019, a total of 18 urban parks in 6 counties (districts) of Quzhou were selected. The free ticks and parasitic ticks were collected by mannual lab-cloth flag method and animal surface collection method, and the tick species were identified. Borrelia burgdorferi, spotted fever group Rickettsia, Babesia microsatellite, Anaplasmosis/Eriksiella and severe fever with thrombocytopenia syndrome bunyavirus in ticks were detected by PCR. Results A total of 168 ticks were captured, and 41, 70 and 57 ticks were collected in spring, summer and autumn, respectively, the differences were not significant. All the 168 ticks were adult ticks, belonging to 7 species, 5 genera and 1 family. Dermacentor was predominant, accounting for 36.90%(62/168), followed by Haemaphysalis longicornis, accounting for 26.79%(45/168), Ixodes sinensis, accounting for 14.29%(24/168). There were 39 free ticks (23.21%) and 129 parasitic ticks (76.79%), in which 96 had rodents as host (74.42%), higher than other hosts. A total of 47 ticks were positive for five pathogens, and total positive rate was 27.98%, Among them, the positive rate of Borrelia burgdorferi was highest (13.10%), and the positive rate of Anaplasma/Eriksium was lowest(1.79%). Conclusion Dermacentor and H.longicornis were the main species of ticks captured in urban parks of Quzhou, carrying Borrelia burgdorferi, spotted fever group Rickettsia, severe fever with thrombocytopenia syndrome bunyavirus and other pathogens, the risk of tick bite and infection exists for the public.

Analysis on severe fever with thrombocytopenia syndrome bunyavirus infection combined with atrial fibrillation under digital model detection

To heighten the diagnostic efficiency, in this study, the algebraic reconstruction technology (ART)-based echocardiography (ECG) was used to analyze severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) complicated by atrial fibrillation. From Jan. 2015 to Dec. 2019, 200 elderly patients with SFTSV infection and hypertrophic cardiomyopathy (HCM) admitted to our hospital were selected as the observation group, and 20 healthy volunteers were in the control group. Then 200 patients were randomly divided into two groups with 100 people in each group. One group received routine clinical observation after surgery, and the other group received artificial intelligence atrial fibrillation monitoring. ECG displayed the left ventricular ejection fraction (LVEF), left ventricular mass index (LVMI), left ventricular end diastolic volume index (EDVI), and end systolic volume index (ESVI) of patients. The accuracy and satisfaction of different methods in observation were recorded. The risk factors of postoperative atrial fibrillation in elderly patients with HCM were evaluated, and changes in their white blood cell levels were detected. The results showed that, there was a significant difference in ECG between normal people and patients after surgery. Also, differences were noted in accuracy and satisfaction of the two methods in observation group (P < 0.05). The atrial fibrillation group and the non-atrial fibrillation group showed notable differences in smoking history and age (P < 0.05); the white blood cell content of the atrial fibrillation group was 8.64 × 109, and that in non-atrial fibrillation group was 3.25 × 109. The content of ST-2 in postoperative atrial fibrillation group was 21.3 g/mL, and the content of Gal-3 was 9.57 g/mL, while the content of ST-2 in non-atrial fibrillation group was 17.24 g/mL, and the content of Gal-3 was 5.21 g/mL. There was no significant difference in LVEF, LVMI, EDVI, ESVI between postoperative atrial fibrillation and the non-atrial fibrillation group. In summary, ECG can effectively detect HCM, and the digital model demonstrated superb capabilities in monitoring atrial fibrillation after cardiac sympathetic block. The atrial fibrillation group showed a higher level of white blood cells after surgery and was more likely to develop SFTSV infection. Measures should be taken to prevent infection.

Epidemiological and clinical characteristics of severe fever with thrombocytopenia syndrome bunyavirus human-to-human transmission.

BackgroundSevere fever with thrombocytopenia syndrome (SFTS) was listed as one of the most severe infectious disease by world health organization in 2017. It can mostly be transmitted by tick bite, while human-to-human transmission has occurred on multiple occasions. This study aimed to explore the epidemiological and clinical characteristics and make risk analysis of SFTS human-to-human transmission.MethodsDescriptive and spatial methods were employed to illustrate the epidemiological and clinical characteristics of SFTS human-to-human transmission. The risk of SFTS human-to-human transmission was accessed through secondary attack rate (SAR) and basic reproductive number (R0). Logistic regression analysis was used to identify the associated risk factors.ResultsA total of 27 clusters of SFTS human-to-human transmission were reported in China and South Korea during 1996–2019. It mainly occurred among elder people in May, June and October in central and eastern China. The secondary cases developed milder clinical manifestation and better outcome than the index cases. The incubation period was 10.0 days (IQR:8.0–12.0), SAR was 1.72%-55.00%, and the average R0 to be 0.13 (95%CI:0.11–0.16). Being blood relatives of the index case, direct blood/bloody secretion contact and bloody droplet contact had more risk of infection (OR = 6.35(95%CI:3.26–12.37), 38.01 (95%CI,19.73–73.23), 2.27 (95%CI,1.01–5.19)).ConclusionsSFTS human-to-human transmission in China and South Korea during 1996–2019 had obvious spatio-temporal distinction. Ongoing assessment of this transmission risk is crucial for public health authorities though it continues to be low now.

Severe Anemia in a Patient With Mild T Cell Hypofunction Infected With Parvovirus B19

Severe Anemia in a Patient With Mild T Cell Hypofunction Infected With Parvovirus B19

Epidemiological and genetic investigation of a cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus

BackgroundTo analyze and discuss the transmission route of a cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus (SFTSV).MethodWe performed an epidemiological investigation and a genetic analysis of patients with severe fever with thrombocytopenia syndrome (SFTS) caused by SFTSV, their close contacts and the surrounding population.ResultsWe found that all patients had contact with the blood of the first patient. The comparison of gene sequences in the three isolated SFTSV strains showed that the strains were closely related. Six close contacts and nine individuals in the surrounding population were positive for SFTSV IgM antibody.ConclusionWe suspect that the cluster outbreak was transmitted via blood and that the natural reservoir host of SFTSV exists in the patients’ environment.

Hemophagocytic Lymphohistiocytosis after Severe Fever with Thrombocytopenia Syndrome Virus Infection

This investigation reports of a case of hemophagocytic lymphohistiocytosis caused by severe fever with thrombocytopenia syndrome bunya virus, a novel virus first described in 2011. This patient presented with high fever and laboratory study revealed the presence of thrombocytopenia. Further laboratory examinations confirmed the coexistence of severe fever with thrombocytopenia syndrome and hemophagocytic lymphohistiocytosis. Review of relevant publications led to a proposal that severe fever with thrombocytopenia syndrome as a trigger of hemophagocytic lymphohistiocytosis. More attention should be paid to severe fever with thrombocytopenia syndrome associated hemophagocytic lymphohistiocytosis and further studies be conducted

Suppression of the IFN-α and -β Induction through Sequestering IRF7 into Viral Inclusion Bodies by Nonstructural Protein NSs in Severe Fever with Thrombocytopenia Syndrome Bunyavirus Infection.

Induction of type I IFNs during viral infection is crucial for host defense. IRF 3 and IRF7 play a critical role as key transcription factors in the activation of the IFN induction. Viruses have evolved a variety of strategies to evade innate immunity. Our previous studies have shown that the nonstructural protein (NSs) of the severe fever with thrombocytopenia syndrome virus (SFTSV) can suppress the IFN-β induction through its interaction with tank-binding kinase-1 and sequestering the inhibitor of nuclear factor kappa B kinase(IKK) complex into the inclusion bodies formed by NSs. In this study, we characterized the unique function of IRF7 in innate immunity and its role in inducing IFN-α in particular, regulated by NSs during the SFTSV infection in several cell types of human origin. Whereas IRF3 is constitutively expressed, IRF7 was significantly induced differentially in various cell types in response to SFTSV infection, promoted the induction of IFN-α2 and -α4, and further induced IFN-β, thus contributing to suppressing the viral replication. Our data indicate that NSs directly interacted with and sequestered IRF7 into the inclusion bodies, which is different from IRF3 indirectly interacting with NSs. Although interaction of NSs with IRF7 did not inhibit IRF7 phosphorylation, p-IRF7 was trapped in the inclusion bodies, resulting in a significant reduction of the IFN-α2 and -α4 induction and therefore enhanced viral replication. Interaction of the viral NSs with both IRF7 and IRF3 and subsequent sequestration of these transcription factors into viral inclusion bodies, a unique strategy used by this phlebovirus, may ensure effective evasion and suppression of host innate immunity.

A cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus infection in China, 1996: A retrospective serological study.

BackgroundA cluster of eleven patients, including eight family members and three healthcare workers with fever and thrombocytopenia occurred in Yixing County, Jiangsu Province, China, from October to November 1996. However, the initial investigation failed to identify its etiology. Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS bunyavirus (SFTSV), which was first discovered in 2009. The discovery of novel SFTSV resulted in our consideration to test SFTSV on the remaining samples of this cluster in September 2010.Methodology/Principal findingsWe retrospectively analyzed the epidemiological and clinical data of this cluster. The first case, one 55-year-old man with fulminant hemorrhagic diseases, died on October 14, 1996. His younger brother (the second case) developed similar hemorrhagic diseases after nursing him and then died on November 3. From November 4 to November 15, nine other patients, including six family members and three medical staffs, developed fever and thrombocytopenia after exposure to the second case. The sera of six patients were collected on November 24, 1996. IgM antibodies against SFTSV were detected in all of the six patients’ sera using enzyme-linked immunosorbent assay (ELISA), while IgG antibodies were detected in one patient’s serum using an indirect immunofluorescence assay (IFA). We also found that IgG antibodies against SFTSV were still detected in four surviving patients’ sera 14 years after illness onset.Conclusions and significanceThe mysterious pathogen of the cluster in 1996 was proved to be SFTSV on the basis of its epidemiological data, clinical data and serological results. It suggests that SFTSV has been circulating in China for more than 10 years before being identified in 2009, and SFTSV IgG antibodies can persist for up to 14 years.

Identification of tick-borne pathogen diversity by metagenomic analysis in Haemaphysalis longicornis from Xinyang, China

BackgroundA wide variety of pathogens could be maintained and transmitted by Haemaphysalis longicornis. The aim of this study is to systematically examine the variety of pathogens carried by Haemaphysalis longicornis, an importnatn vector, in tick-borne diseases epidemic area, and to estimate the risk of human infection imposed by tick bites.MethodsAdult questing ticks were collected in Xinyang, central China. Genomic DNA and RNA were extracted from 144 H. longicornis ticks individually, and sequenced respectively as the templates for high-throughput sequencing. Clean reads were compared against the database of NCBI nucleotide collection and specific PCR was performed to confirm the presence of pathogen. Phylogenetic analysis was performed to explore the evolutionary status of pathogens.ResultsThe assignment of reads to taxa based on BLASTN results revealed the existence of several potential pathogens, including Anaplasma spp., Rickettsia spp., Babesia sp., as well as severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). Comfirmantory PCR assays revealed the existence of Anaplasma bovis (13/144, 9.03%), Anaplasma centrale (2/144, 1.39%), Rickettsia heilongjiangensis (3/144, 2.08%), Rickettsia sp. LON-13 (1/144, 0.69%), Rickettsia raoultii (5/144, 3.47%), Babesia sp. (1/144, 0.69%). SFTSV accounted for the highest detected pathogen with a positive rate of 18.75% (27/144). Three of the ticks (2.08%) were co-infected with SFTSV and A. bovis.ConclusionOur study provided a broadened list of microorganism that harbored by H. longicornis. In previously unrecognized endemic regions, prokaryotic and eukaryotic infection including Anaplasma spp., Rickettsiae spp., and Babesia spp. should be considered, along with the well-known SFTSV for patients with tick bites history. A novel Babesia species was identified in local natural foci, which needs further investigation in the future.

Clinical analysis of patients with severe fever with thrombocytopenia syndrome bunyavirus infection and hemorrhagic fever with renal syndrome

Objective To compare the differences of epidemiology, clinical characteristics, laboratory results and prognosis between patients with severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) infection and those with hemorrhagic fever with renal syndrome (HFRS). Methods Medical records of 16 hospitalized cases with SFTSV infection and 28 hospitalized HFRS cases from January 2012 to June 2016 were reviewed in affiliated Yijishan Hospital of Wannan Medical College. In details, the comparative analysis of patients between the two groups were conducted in sex, age, occupation, onset season, contact history, underlying diseases, fever duration, oliguria, bleeding (including petechiae, ecchymoses, gum bleeding, bloody stool and hematuria), secondary infection, consciousness disturbance, dialysis treatment, length of hospital stay, laboratory results and prognosis. Continuous variables of normal, non-normal distribution data were compared using two-sample t test and rank sum test, respectively. Categorical variables were showed in rate and compared using chi-square test. Results The differences between the two groups in age (t=2.585), occupation (χ2=4.914), onset season (χ2=4.325) and contact history (χ2=9.617) were all statistically significant (all P<0.05). In SFTSV infection group, the mean fever duration was (8.81±3.17) d. There were 2 cases of oliguria, 10 cases of bleeding, 7 cases of secondary infection, 5 cases of consciousness disturbance. No patient received dialysis. The average length of hospital stay was (13.44±7.91) d. In HFRS group, the mean fever duration was (5.96±2.20) d. In addition, there were 24 cases of oliguria, 25 cases of bleeding, 9 cases of secondary infection, 3 cases of consciousness disorder. Twelve cases received dialysis treatment in this group. The average length of hospital stay was (18.04±15.75) d. Furthermore, there were significant differences between the two groups in fever duration (t=3.511), oliguria (χ2=22.578), bleeding (χ2=4.490) and dialysis (χ2=7.392) (all P<0.05). The significant differences were also found in white blood cell count, blood urea nitrogen, serum creatinine, albumin, amylase, lipase, creatine kinase, serum sodium, chloride, calcium, carbon dioxide combining power and blood glucose between the SFTSV infection group and HFRS group (all P<0.05). However, there was no significant difference in prognosis between the two groups (Z=1.574, P=0.115). Conclusions There are differences in epidemiological history, clinical manifestations and laboratory findings between the SFTSV infection group and HFRS group, which may help differential diagnosis and treatment of these two diseases. Key words: Severe fever with thrombocytopenia syndrome bunyavirus; Hemorrhagic fever with renal syndrome; Clinical characteristic; Case analysis

Development and validation of a real-time reverse transcriptase PCR assay for sensitive detection of SFTSV.

Severe fever with thrombocytopenia syndrome bunyavirus (sftsv) is an emerging tick-borne rna virus recently identified as the pathogen that causes severe fever with thrombocytopenia syndrome (sfts) in china. the existing commercial nucleic acid testing (comnat) assay with a relatively high claimed limit of quantitative detection (loqd) is not capable of sensitive detection and quantitation of sftsv. Thus, a new real-time reverse transcriptase (rt)-pcr assay with improved sensitivity is needed for clinical diagnosis; it could also be used to screen blood donors if necessary. We developed a new sftsv rt-pcr nat assay (newnat). About 129 plasma samples from 93 suspected sfts patients with typical clinical symptoms were tested using an anti-sftsv total antibody elisa and both comnat and newnat. The test performance of the two nat assays was evaluated and compared. The newnat had a lower limit for quantitative testing compared to comnat. Twelve samples were comnat negative but newnat positive. Out of 35 suspected sfts patients who were comnat negative and anti-sftsv total antibody negative, four tested positive by the newnat assay and one of these four seroconverted within 2-4 days after testing newnat positive. A high correlation was observed between the cts of the newnat and comnat assays. The newnat assay was sensitive for quantitative detection of sftsv and may be applicable to clinical diagnosis and studies of the need for blood donor screening.

Isolation, characterization, and phylogenic analysis of three new severe fever with thrombocytopenia syndrome bunyavirus strains derived from Hubei Province, China

Hubei Province is a major epidemic area of severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) in China. However, to date, a few SFTSV strains have been isolated from Hubei Province, preventing effective studies of epidemic outbreaks. Here, we report three confirmed patients (2015-2016) with typical symptoms of severe fever with thrombocytopenia syndrome disease (SFTS) who were farmers resident in different regions in Hubei Province. Three new SFTSV strains were isolated from the serum samples of each patient. Characterization of viral growth properties showed that there were no significant differences in virus production. All strains were completely sequenced, and phylogenetic analysis showed that unlike the other strains from Hubei province, which belonged to the SFTSV C3 genotype, one of the three strains belonged to the SFTSV C2 genotype. These results suggested that multiple SFTSV genotypes have been circulating in Hubei Province, providing insights into SFTSV evolution and improving our understanding of SFTSV prevalence in Hubei Province.

Migration, recombination, and reassortment are involved in the evolution of severe fever with thrombocytopenia syndrome bunyavirus

Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) has been identified as the etiological agent causing severe fever with thrombocytopenia syndrome (SFTS). SFTSV was reported in recent years as a newly emerging tick-borne virus in China, Japan and South Korea and is a novel member of the genus Phlebovirus, family Bunyaviridae, which is suspected to be transmitted by the tick Haemaphysalis longicornis. The genetic diversity and evolutionary relationships between geographically distributed SFTSV strains are currently unclear. In this study we used extensive bioinformatics analyses to provide deep insight into the mechanisms of evolution and relationships among SFTSV strains. The genetic diversity of SFTSV was characterized and found to be generated through recombination and reassortment events. Further, potential correlations between the geographic distribution and migration pathways of SFTSV were subject to in-depth analysis. The potential of birds migration related to SFTSV migration were also discussed. The results of this study will facilitate better understanding of the mechanisms of evolution of SFTSV, which will be important in developing public-health interventions and strategies for SFTS disease control and prevention in endemic areas.