Molecular insight into the neutralization mechanism of human-origin monoclonal antibody AH100 against Hantaan virus.

Both Old World and New World hantaviruses are transmitted through rodents and can lead to hemorrhagic fever with renal syndrome or hantavirus cardiopulmonary syndrome in humans without the availability of specific therapeutics. The square-shaped surface spikes of hantaviruses consist of four Gn-Gc heterodimers that are pivotal for viral entry into host cells and serve as targets for the immune system. Previously, a human-derived neutralizing monoclonal antibody, AH100, demonstrated specific neutralization against the Old World hantavirus, Hantaan virus. However, the precise mode binding of this neutralizing monoclonal antibody remains unclear. In the present study, we determined the structure of the Hantaan virus Gn-AH100 antigen-binding fragment complex and identified its epitope. Crystallography revealed that AH100 targeted the epitopes on domain A and b-ribbon and E3-like domain. Epitope mapping onto a model of the higher order (Gn-Gc)4 spike revealed its localization between neighboring Gn protomers, distinguishing this epitope as a unique site compared to the previously reported monoclonal antibodies. This study provides crucial insights into the structural basis of hantavirus neutralizing antibody epitopes, thereby facilitating the development of therapeutic antibodies.IMPORTANCEHantaan virus (HTNV) poses a significant threat to humans by causing hemorrhagic fever with renal syndrome with high mortality rates. In the absence of FDA-approved drugs or vaccines, it is urgent to develop specific therapeutics. Here, we elucidated the epitope of a human-derived neutralizing antibody, AH100, by determining the HTNV glycoprotein Gn-AH100 antigen-binding fragment (Fab) complex structure. Our findings revealed that the epitopes situated on the domain A and b-ribbon and E3-like domain of the HTNV Gn head. By modeling the complex structure in the viral lattice, we propose that AH100 neutralizes the virus by impeding conformational changes of Gn protomer, which is crucial for viral entry. Additionally, sequence analysis of all reported natural isolates indicated the absence of mutations in epitope residues, suggesting the potential neutralization ability of AH100 in diverse isolates. Therefore, our results provide novel insights into the epitope and the molecular basis of AH100 neutralization.

High-resolution phylogeographical surveillance of Hantaan orthohantavirus using rapid amplicon-based Flongle sequencing, Republic of Korea.

Orthohantaviruses, etiological agents of hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome, pose a critical public health threat worldwide. Hantaan orthohantavirus (HTNV) outbreaks are particularly endemic in Gyeonggi Province in northern area of the Republic of Korea (ROK). Small mammals were collected from three regions in the Gyeonggi Province during 2017 and 2018. Serological and molecular prevalence of HTNV was 25/201 (12.4%) and 10/25 (40%), respectively. A novel nanopore-based diagnostic assay using a cost-efficient Flongle chip was developed to rapidly and sensitively detect HTNV infection in rodent specimens within 3 h. A rapid phylogeographical surveillance of HTNV at high-resolution phylogeny was established using the amplicon-based Flongle sequencing. In total, seven whole-genome sequences of HTNV were newly obtained from wild rodents collected in Paju-si (Gaekhyeon-ri) and Yeoncheon-gun (Hyeonga-ri and Wangnim-ri), Gyeonggi Province. Phylogenetic analyses revealed well-supported evolutionary divergence and genetic diversity, enhancing the resolution of the phylogeographic map of orthohantaviruses in the ROK. Incongruences in phylogenetic patterns were identified among HTNV tripartite genomes, suggesting differential evolution for each segment. These findings provide crucial insights into on-site diagnostics, genome-based surveillance, and the evolutionary dynamics of orthohantaviruses to mitigate hantaviral outbreaks in HFRS-endemic areas in the ROK.

Clinical and etiological characteristics of severe hemorrhagic fever caused by coinfection of hantaan orthohantavirus and severe fever with thrombocytopenia syndrome virus.

Severe fever with thrombocytopenia syndrome (SFTS) and hemorrhagic fever with renal syndrome (HFRS) usually have different infection routes, and coinfection is relatively rare. This study examines the clinical and etiological characteristics of coinfection by these two pathogens to provide important references for clinical diagnosis and treatment. Blood samples from 22 clinically diagnosed patients with HFRS were collected for molecular detection of HFRS and common tick and mouse borne diseases. Inoculate the blood of six severe and critically patients into cells to isolate and proliferate potential viruses, and retest the cell culture to determine the pathogen. In addition, complete data were collected from these 22 HFRS and concurrent SFTS patients, and white blood cells (WBCs), platelet (PLT), blood urea nitrogen (BUN), creatinine (Cr) and other data were compared and analyzed. A total of 31 febrile patients, including 22 HFRS patients and 9 SFTS patients, were collected from September 2021 to October 2022. Among these HFRS patients, 11 were severe or critical. Severe and critical HFRS patients were characterized by rodent exposure history, pharyngeal and conjunctival hyperemia, abnormal WBC and PLT counts, and elevated BUN and Cr values. Virus isolation and molecular detection on blood samples from 6 patients showed that three of the six severe patients were positive for hantaan virus (HTNV), and two of the three HTNV positives were also positive for SFTS bunyavirus (SFTSV). The two coinfected patients exhibited different clinical and laboratory characteristics compared to those infected by either virus alone. Coinfection of HTNV and SFTSV leads to severe and complex hemorrhagic fever. Laboratory characteristics, such as the indicators of WBC, PLT, BUN, and Cr, may differ between HFRS and SFTS. These findings have implications and provide references for the diagnosis and treatment of coinfected cases.

Guanylate-binding protein 1 inhibits Hantaan virus infection by restricting virus entry.

Hantaan virus (HTNV) infection can cause hemorrhagic fever with renal syndrome (HFRS) in humans, and currently, there are no long-standing protective vaccines or specific antivirals available. Guanylate-binding protein 1 (GBP1) is an interferon-stimulated gene that defends against various pathogen infections. However, the function of GBP1 in HTNV infection remains unknown. Here, we describe how GBP1 prevents HTNV infection by obstructing virus entry. We found that HTNV infection induced GBP1 expression and that overexpression of GBP1 inhibited HTNV infection, while knockout of GBP1 had the opposite effect. Interestingly, GBP1 did not affect interferon (IFN) signaling during HTNV infection. Instead, GBP1 prevented HTNV from entering cells through clathrin-mediated endocytosis (CME). We also discovered that GBP1 specifically interacted with actin but not dynamin 2 (DNM2) and made it difficult for DNM2 to be recruited by actin, which may account for the suppression of CME during HTNV infection. These findings establish an antiviral role for GBP1 in inhibiting HTNV infection and help us better understand how GBP1 regulates HTNV entry and could potentially aid in developing treatments for this virus.

Replication kinetics of pathogenic Eurasian orthohantaviruses in human mesangial cells.

BACKGROUND: Eurasian pathogenic orthohantaviruses cause hemorrhagic fever with renal syndrome (HFRS) characterized by acute kidney injury (AKI). The virulence of orthohantaviruses varies enormously and direct infection of different renal cell types contribute to pathogenesis. Glomerular mesangial cells play an essential role in the interplay between kidney cells and proper kidney function. Therefore, we analyzed the replication competence of different orthohantavirus species in primary mesangial cells and a mesangial cell line. METHODS: We tested the suitability of the mesangial cell line CIHGM-1 (conditionally immortalized human glomerular mesangial cells) as cell culture model for orthohantavirus kidney infection by comparison with primary human renal mesangial cells (HRMCs). We analyzed infection with high pathogenic Hantaan virus (HTNV), moderate pathogenic Puumala virus (PUUV) and non-/low-pathogenic Tula virus (TULV). RESULTS: Effective viral spread was observed for PUUV only, whereas infection with HTNV and TULV was abortive. However, in contrast to TULV, HTNV exhibits an initially high infection rate and declines afterwards. This replication pattern was observed in HRMCs and CIHGM-1 cells. Viability or adhesion was neither impaired for PUUV-infected CIHGM-1 nor HRMCs. A loss of migration capacity was observed in PUUV-infected CIHGM-1 cells, but not in HRMCs. CONCLUSIONS: The identification of differences in the replication competence of pathogenic orthohantavirus strains in renal mesangial cells is of special interest and may provide useful insights in the virus-specific mechanisms of orthohantavirus induced AKI. The use of CIHGM-1 cells will facilitate the research in a relevant cell culture system.

HTNV infection induces activation and deficiency of CD8+MAIT cells in HFRS patients.

Hantaan virus (HTNV) infection causes an epidemic of hemorrhagic fever with renal syndrome (HFRS) mainly in Asia. Mucosal-associated invariant T (MAIT) cells are innate-like T lymphocytes known to play an important role in innate host defense during virus infection. However, their roles and phenotypes during HTNV infection have not yet been explored. We characterized CD8+MAIT cells from HFRS patients based on scRNA-seq data combined with flow cytometry data. We showed that HTNV infection caused the loss and activation of CD8+MAIT cells in the peripheral blood, which were correlated with disease severity. The production of granzyme B and IFN-γ from CD8+MAIT cells and the limitation of HTNV replication in endothelia cells indicated the anti-viral property of CD8+MAIT cells. In addition, in vitro infection of MAIT cells by HTNV or HTNV-exposed monocytes showed that the activation of MAIT cells was IL-18 mediated. In conclusion, this study identified, for the first time, gene expression profiles of MAIT cells, provided underlying molecular mechanisms for activation of MAIT cells during HTNV infection, and suggested a potential anti-viral role of MAIT cells in HFRS.

Clinical and laboratory features and factors predicting disease severity in pediatric patients with hemorrhagic fever with renal syndrome caused by Hantaan virus.

The clinical features and factors associated with disease severity in children with hemorrhagic fever with renal syndrome (HFRS) have not been well characterized. This study analyzed the clinical and laboratory factors associated with disease severity in children with HFRS caused by Hantaan virus. Data in pediatric patients with HFRS were retrospectively collected from Xi'an Children's Hospital over a 9-year period. Independent factors associated with disease severity were identified. Nomogram predicting disease severity was constructed based on variables filtered by feature selection. In total, 206 children with HFRS were studied. Fever, digestive tract symptoms, headache, backache, bleeding, and renal injury signs were the common symptoms. Elevated white blood cell, reduced platelet, hematuria, proteinuria, coagulation abnormalities, increased blood urea nitrogen (BUN) and procalcitonin (PCT), decreased estimated glomerular filtration rate and low serum Na+ , Cl- , and Ca2+ were the common laboratory findings. In the 206 patients, 21 patients had critical type disease and 4 patients (1.9%) died. Hydrothorax, hypotension and cerebral edema/cerebral herniation at hospital admission were independent clinical characteristics, and neutrophil %, prothrombin activity, PCT, BUN, and Ca2+ at hospital admission were independent laboratory factors associated with critical disease. Feature selection identified BUN, PCT and prothrombin time as independent factors related to critical disease. A nomogram integrating BUN and PCT at admission was constructed and calibration showed high accuracy for the probability prediction of critical disease. In conclusion, this study characterized the clinical and laboratory features and constructed a nomogram predicting disease severity in pediatric HFRS, providing references for disease severity evaluation in managing children HFRS.

Potential clinical biomarkers in monitoring the severity of Hantaan virus infection.

Hantavirus, which causes hemorrhagic fever with renal syndrome (HFRS) is almost prevalent worldwide. While Hantaan virus (HTNV) causes the most severe form of HFRS with typical clinical manifestations of thrombocytopenia, increased vascular permeability, and acute kidney injury. Although the knowledge of the pathogenesis of HFRS is still limited, immune dysfunction and pathological damage caused by disorders of immune regulation are proposed to play a vital role in the development of the disorder, and the endothelium is considered to be the primary target of hantaviruses. Here, we reviewed the production and function of multiple molecules, mainly focusing on their role in immune response, endothelium, vascular permeability regulation, and platelet and coagulation activation which are closely related to the pathogenesis of HTNV infection. meanwhile, the relationship between these molecules and characteristics of HTNV infection including the hospital duration, immune dysfunction, thrombocytopenia, leukocytosis, and acute kidney injury are also presented, to provide a novel insight into the potential role of these molecules as monitoring markers for HTNV infection.

Insight into the Hantaan virus RNA-dependent RNA polymerase inhibition using in-silico approaches.

The Hantaan virus (HTN) is a member of the hantaviridae family. It is a segmented type, negative-strand virus (sNSVs). It causes hemorrhagic fever with renal syndrome, which includes fever, vascular hemorrhage, and renal failure. This illness is one of the most serious hemorrhagic diseases in the world, and it is a major public health concern due to its high mortality rate. The Hantaan virus RNA-dependent RNA polymerase complex (RdRp) is involved in viral RNA transcription and replication for the survival and transmission of this virus. Therefore, it is a primary target for antiviral drug development. Interference with the endonucleolytic "cap-snatching" reaction by the HTN virus RdRp endonuclease domain is a particularly appealing approach for drug discovery against this virus. This RdRp endonuclease domain of the HTN virus has a metal-dependent catalytic activity. We targeted this metal-dependent enzymatic activity to identify inhibitors that can bind and disrupt this endonuclease enzyme activity using in-silico approaches i.e., molecular docking, molecular dynamics simulation, predicted absorption, distribution, metabolism, excretion, toxicity (ADMET) and drug-likeness studies. The docking studies showed that peramivir, and ingavirin compounds can effectively bind with the manganese ions and engage with other active site residues of this protein. Molecular simulations also showed stable binding of these ligands with the active site of HTN RdRp. Simulation analysis showed that they were in constant contact with the active site manganese ions and amino acid residues of the HTN virus endonuclease domain. This study will help in better understanding the HTN and related viruses.

Serum superoxide dismutase level is a potential biomarker of disease prognosis in patients with hemorrhagic fever with renal syndrome caused by the Hantaan virus.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) is a disease with increased systemic inflammation and a high fatality rate. Oxidative stress is crucial for inflammation in the pathogeneses of various diseases. We aimed to identify biomarkers of oxidative stress that may assess the severity and disease outcomes of patients with HFRS. METHODS: Between January 2015 and September 2018, we analyzed a retrospective cohort of 149 HFRS patients and 30 healthy individuals. Serum levels of SOD were measured using an ELISA commercial kit, and survival analysis was carried out using the Kaplan-Meier method. RESULTS: Patients with HFRS had significantly lower serum SOD levels compared with healthy controls (108.40 ± 2.47 U/mL vs 164.23 ± 3.82 U/mL, P < 0.01). SOD levels in patients were lower at acute than at convalescent stage (108.40 ± 2.47 U/mL vs 138.27 ± 2.87 U/mL, P < 0.01), and in severe and critical patients than in moderate and mild patients (89.63 ± 2.38 U/mL vs 122.53 ± 3.18 U/mL, P < 0.01). A serum level of SOD < 88.6 U/mL at admission was associated with a significant increase in mortality risk in HFRS patients. CONCLUSION: Our results indicate that serum levels of SOD measured at admission can be used to assess disease severity and assign patients into high- and low-risk groups. SOD can be considered a novel biomarker of severity and outcomes in patients with HFRS.

Exosomal miR-145-5p derived from orthohantavirus-infected endothelial cells inhibits HTNV infection.

Human infection of orthohantavirus can cause potentially fatal diseases, such as hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus (HTNV) in Eurasia. Exosomes are new carriers for information exchange between cells. Cumulative findings suggest that exosomes released from parental infected cells can block or promote viral infection in recipient cells, but the role of exosomes in hantavirus infection is poorly understood. In our study, we identified the exosomes derived from HTNV-infected human vascular endothelial cells (HUVECs) (Exo-HV) and found the antiviral properties of Exo-HV in the uninfected recipient cells. High-throughput sequencing revealed the distinctly expressed miRNAs transcriptomes in Exo-HV. MiR-145-5p, one of the abundant miRNAs packaged into Exo-HV, was found to be able to transferred to recipient cells and functioned by directly targeting M RNA of HTNV 76-118 and inducing type I interferon (IFN-I) response, thus, blocking the viral replication. Concluding, this study indicated that exosomes released by HTNV-infected HUVECs were able to transfer active molecules, miR-145-5p as a proving sample, to mediate novel anti-HTNV activity in the neighboring uninfected cells, which will help us to explore new strategies for the treatment of infectious disease utilizing exosomes with miRNA.

New class of hantaan virus inhibitors based on conjugation of the isoindole fragment to (+)-camphor or (-)-fenchone hydrazonesv.

This work presents the design and synthesis of camphor, fenchone, and norcamphor N-acylhydrazone derivatives as a new class of inhibitors of the Hantaan virus, which causes haemorrhagic fever with renal syndrome (HFRS). A cytopathic model was developed for testing chemotherapeutics against the Hantaan virus, strain 76-118. In addition, a study of the antiviral activity was carried out using a pseudoviral system. It was found that the hit compound possesses significant activity (IC50 = 7.6 ± 2 µM) along with low toxicity (CC50 > 1000 µM). Using molecular docking procedures, the binding with Hantavirus nucleoprotein was evaluated and the correlation between the structure of the synthesised compounds and the antiviral activity was established.

Predictive value of pentraxin-3 on disease severity and mortality risk in patients with hemorrhagic fever with renal syndrome.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus is characterized by systemic immunopathological injury. Pentraxin-3 is an acute-phase reactant involved in the processes of inflammation and infection. This study aimed to investigate the levels of plasma pentraxin-3 and evaluate its predictive value on disease severity and mortality risk in patients with HFRS. METHODS: This was a prospective real-world observational study. The concentrations of plasma pentraxin-3 were measured by enzyme linked immunosorbent assay (ELISA) in 105 HFRS patients and 27 healthy controls. We analyzed the clinical relevance between pentraxin-3 and clinical subtyping, hospital stay and conventional laboratory parameters of HFRS patients. Considering the prognosis (death) as the primary endpoint, the levels of pentraxin-3 between survivors and non-survivors were compared, and its association with mortality was assessed by Kaplan-Meier survival analysis. The predictive potency of pentraxin-3 for mortality risk in HFRS patients was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: The levels of pentraxin-3 during the acute phase were increased with the aggravation of the disease, and showed the highest expression in critical-type patients (P < 0.05). Pentraxin-3 demonstrated significant correlations with conventional laboratory parameters (WBC, PLT, AST, ALB, APTT, Fib) and the length of hospital stay. Compared with the survivors, non-survivors showed higher levels of pentraxin-3 and worse expressions of conventional laboratory parameters during the acute phase. The Kaplan-Meier survival curves showed that high levels of pentraxin-3 during the acute phase were significantly associated with the death in HFRS patients. Pentraxin-3 demonstrated significant predictive value for the mortality risk of HFRS patients, with the area under ROC curve (AUC) of 0.753 (95%CI: 0.593 ~ 0.914, P = 0.003). CONCLUSIONS: The detection of plasma pentraxin-3 might be beneficial to the evaluation of disease severity and to the prediction of mortality risk in HFRS patients.

Active Targeted Surveillance to Identify Sites of Emergence of Hantavirus.

BACKGROUND: Endemic outbreaks of hantaviruses pose a critical public health threat worldwide. Hantaan orthohantavirus (HTNV) causes hemorrhagic fever with renal syndrome (HFRS) in humans. Using comparative genomic analyses of partial and nearly complete sequences of HTNV from humans and rodents, we were able to localize, with limitations, the putative infection locations for HFRS patients. Partial sequences might not reflect precise phylogenetic positions over the whole-genome sequences; finer granularity of rodent sampling reflects more precisely the circulation of strains. METHODS: Five HFRS specimens were collected. Epidemiological surveys were conducted with the patients during hospitalization. We conducted active surveillance at suspected HFRS outbreak areas. We performed multiplex polymerase chain reaction-based next-generation sequencing to obtain the genomic sequence of HTNV from patients and rodents. The phylogeny of human- and rodent-derived HTNV was generated using the maximum likelihood method. For phylogeographic analyses, the tracing of HTNV genomes from HFRS patients was defined on the bases of epidemiological interviews, phylogenetic patterns of the viruses, and geographic locations of HTNV-positive rodents. RESULTS: The phylogeographic analyses demonstrated genetic clusters of HTNV strains from clinical specimens, with HTNV circulating in rodents at suspected sites of patient infections. CONCLUSIONS: This study demonstrates a major shift in molecular epidemiological surveillance of HTNV. Active targeted surveillance was performed at sites of suspected infections, allowing the high-resolution phylogeographic analysis to reveal the site of emergence of HTNV. We posit that this novel approach will make it possible to identify infectious sources, perform disease risk assessment, and implement preparedness against vector-borne viruses.

Protective CD8+ T-cell response against Hantaan virus infection induced by immunization with designed linear multi-epitope peptides in HLA-A2.1/Kb transgenic mice.

BACKGROUND: An effective vaccine that prevents disease caused by hantaviruses is a global public health priority, but up to now, no vaccine has been approved for worldwide use. Therefore, novel vaccines with high prophylaxis efficacy are urgently needed. METHODS: Herein, we designed and synthesized Hantaan virus (HTNV) linear multi-epitope peptide consisting of HLA-A*02-restricted HTNV cytotoxic T cell (CTL) epitope and pan HLA-DR-binding epitope (PADRE), and evaluated the immunogenicity, as well as effectiveness, of multi-epitope peptides in HLA-A2.1/Kb transgenic mice with interferon (IFN)-γ enzyme-linked immunospot assay, cytotoxic mediator detection, proliferation assay and HTNV-challenge test. RESULTS: The results showed that a much higher frequency of specific IFN-γ-secreting CTLs, high levels of granzyme B production, and a strong proliferation capacity of specific CTLs were observed in splenocytes of mice immunized with multi-epitope peptide than in those of a single CTL epitope. Moreover, pre-immunization of multi-epitope peptide could reduce the levels of HTNV RNA loads in the liver, spleen and kidneys of mice, indicating that specific CTL responses induced by multi-epitope peptide could reduce HTNV RNA loads in vivo. CONCLUSIONS: This study may provide an important foundation for the development of novel peptide vaccines for HTNV prophylaxis.

Design and synthesis of HLA-A*02-restricted Hantaan virus multiple-antigenic peptide for CD8+ T cells.

BACKGROUND: Hantaan virus (HTNV) can cause hemorrhagic fever with renal syndrome (HFRS) in humans with severe morbidity and high mortality. Although inactivated HFRS vaccines are given annually for prevention in populations, China still has the highest number of HFRS cases and deaths worldwide. Consequently, vaccination for HFRS requires the development of novel, more effective vaccines. Epitope peptide vaccines have been developed rapidly in recent years and are considered a novel approach for the prevention of infection. Specifically, the multiple antigenic peptide (MAP) design with preferable immunogenicity can arouse a satisfactory immune response for vaccination. However, there are few reports on the design and evaluation of MAP for HTNV. METHODS: Three HLA-A*02-restricted 9-mer cytotoxic T lymphocyte (CTL) epitopes on HTNV glycoprotein and one HLA-A*02-restricted 9-mer CTL epitope on the HTNV nucleocapsid, which have been proven to be immunoprotective in our previous study, were selected for the design of HTNV MAP. A four-branched HTNV MAP was evaluated by the IFN-γ-secreting enzyme-linked immunospot assay and proliferation induction capacity of CD8+ T cells and compared with the single HTNV CTL epitope in 17 HLA-A*02+ patients with HFRS. The Mann-Whitney U test was used for comparison of parameters between different subject groups. RESULTS: The macromolecular HTNV MAP was designed with a polylysine core and four radially branched single CTL epitope chains. Importantly, HTNV MAP could stimulate CD8+ T cell secretion of IFN-γ in HLA-A*02+ patients with HFRS. The frequency of IFN-γ-secreting CD8+ T cells in the MAP stimulation group was significantly higher than that in the single HTNV CTL epitope stimulation groups (P < 0.005). Meanwhile, the activity of IFN-γ-secreting CD8+ T cells in the HTNV MAP group was also higher than that of the single CTL epitope groups (P < 0.05). Moreover, there was a much stronger ability of HTNV MAP to stimulate CD8+ T cell proliferation compared with that of a single HTNV CTL epitope. CONCLUSIONS: The designed HTNV MAP could induce CTL responses ex vivo and may be considered a candidate for the design and development of novel HTNV peptide vaccines.

A case-control study on the risk factors for hemorrhagic fever with renal syndrome.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) is an endemic communicable disease in China, accounting for 90% of total reported cases worldwide. In this study, the authors want to investigate the risk factors for HFRS in recent years to provide the prevention and control advices. METHODS: A community-based, 1:2 matched case-control study was carried out to investigate the risk factors for HFRS. Cases were defined as laboratory-confirmed cases that tested positive for hantavirus-specific IgM antibodies. Two neighbourhood controls of each case were selected by sex, age and occupation. Standardized questionnaires were used to collect information and identify the risk factors for HFRS. RESULTS: Eighty-six matched pairs were investigated in the study. The median age of the cases was 55.0 years, 72.09% were male, and 73.26% were farmers. In the multivariate logistic regression analysis, cleaning spare room at home (OR = 3.310, 95%CI 1.335-8.210) was found to be risk factor for infection; storing food and crops properly (OR = 0.279 95%CI 0.097-0.804) provided protection from infection. CONCLUSION: Storing food and crops properly seemed to be protective factor, which was important for HFRS prevention and control. More attention should be paid to promote comprehensive health education and behaviour change among high-risk populations in the HFRS endemic area.

Investigation on risk factors of haemorrhagic fever with renal syndrome (HFRS) in Xuancheng City in Anhui Province, Mainland China.

Haemorrhagic fever with renal syndrome (HFRS), a rodent-borne disease, is a major public health concern in both developed and developing countries. China is the most severe endemic country in the world, constituting 90% of the cases. Although the incidence of HFRS has substantively decreased in most areas of China, HFRS has rebounded remarkably in some epidemic areas. Xuancheng is one of these areas. In this study, we collected the case data reported recently in Xuancheng and designed a 1:3 case-control study. The Chi-square test, univariate and multivariate logistic regression analysis were performed. In all cases, farmers made up the highest proportion of occupations. And there were 20 variables with statistical significance including indoor hygienic conditions; the surrounding environment; whether bitten by rats at work and other criteria. In addition, exposure to rodents and rats bites is a high-risk factor for HFRS. Rodent density was calculated at 20.9% (159/760), the virus carrier rate was 9.4% (15/159) and the index of rats with a virus was about 2.0%. Exposure to rodents and insect bites is also high-risk factors for HFRS among local residents in Xuancheng. More importantly, during the flood years, the increased density of rodents led to an increased risk of human exposure to rodents. As our statistical analysis proves, targeted strategies should be developed and implemented to reduce the incidence of local diseases in the future.

IFN-λs inhibit Hantaan virus infection through the JAK-STAT pathway and expression of Mx2 protein.

Hantaan virus (HTNV), member of the newly defined Hantaviridae family, within the order Bunyavirales, can cause a hemorrhagic fever with renal syndrome with high fatality rates in humans. However, no specific antiviral agents are currently available for HTNV infection approved by the US Food and Drug Administration. Although interferon lambdas (IFN-λs) have been shown to induce an antiviral state against HTNV, the molecular mechanisms remain to be determined. In this study, we found that IFN-λs exerted its anti-HTNV effect by activating Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway-mediated antiviral immunity in A549 cells. Simultaneously, IFN-λs downregulated suppressor of cytokine signaling proteins, which are the known negative feedback regulators of the JAK-STAT signaling pathway. Additionally, we demonstrated the role of IFN-λs-induced myxovirus resistance 2 (Mx2, also known as MxB) protein as a potential inhibitor for HTNV infection. These findings indicate that IFN-λs play an important role in cellular defenses against HTNV infection at an early stage and that human Mx2 may represent a potential therapeutic target for HTNV infection.

Anthropogenically driven environmental changes shift the ecological dynamics of hemorrhagic fever with renal syndrome.

Zoonoses are increasingly recognized as an important burden on global public health in the 21st century. High-resolution, long-term field studies are critical for assessing both the baseline and future risk scenarios in a world of rapid changes. We have used a three-decade-long field study on hantavirus, a rodent-borne zoonotic pathogen distributed worldwide, coupled with epidemiological data from an endemic area of China, and show that the shift in the ecological dynamics of Hantaan virus was closely linked to environmental fluctuations at the human-wildlife interface. We reveal that environmental forcing, especially rainfall and resource availability, exert important cascading effects on intra-annual variability in the wildlife reservoir dynamics, leading to epidemics that shift between stable and chaotic regimes. Our models demonstrate that bimodal seasonal epidemics result from a powerful seasonality in transmission, generated from interlocking cycles of agricultural phenology and rodent behavior driven by the rainy seasons.