Hantaviruses--globally emerging pathogens

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.

Comparison of uridine and N1-methylpseudouridine mRNA platforms in development of an Andes virus vaccine

The rodent-borne Andes virus (ANDV) causes a severe disease in humans. We developed an ANDV mRNA vaccine based on the M segment of the viral genome, either with regular uridine (U-mRNA) or N1-methylpseudouridine (m1Ψ-mRNA). Female mice immunized by m1Ψ-mRNA developed slightly greater germinal center (GC) responses than U-mRNA-immunized mice. Single cell RNA and BCR sequencing of the GC B cells revealed similar levels of activation, except an additional cluster of cells exhibiting interferon response in animals vaccinated with U-mRNA but not m1Ψ-mRNA. Similar immunoglobulin class-switching and somatic hypermutations were observed in response to the vaccines. Female Syrian hamsters were immunized via a prime-boost regimen with two doses of each vaccine. The titers of glycoprotein-binding antibodies were greater for U-mRNA construct than for m1Ψ-mRNA construct; however, the titers of ANDV-neutralizing antibodies were similar. Vaccinated animals were challenged with a lethal dose of ANDV, along with a naïve control group. All control animals and two animals vaccinated with a lower dose of m1Ψ-mRNA succumbed to infection whereas other vaccinated animals survived without evidence of virus replication. The data demonstrate the development of a protective vaccine against ANDV and the lack of a substantial effect of m1Ψ modification on immunogenicity and protection in rodents.

Hantavirus Expansion Trends in Natural Host Populations in Brazil

Hantaviruses are zoonotic agents responsible for causing Hantavirus Cardiopulmonary Syndrome (HCPS) in the Americas, with Brazil ranking first in number of confirmed HCPS cases in South America. In this study, we simulate the monthly spread of highly lethal hantavirus in natural hosts by conjugating a Kermack-McCormick SIR model with a cellular automata model (CA), therefore simultaneously evaluating both in-cell and between-cell infection dynamics in host populations, using recently compiled data on main host species abundances and confirmed deaths by hantavirus infection. For both host species, our models predict an increase in the area of infection, with 22 municipalities where no cases have been confirmed to date expected to have at least one case in the next decade, and a reduction in infection in 11 municipalities. Our findings support existing research and reveal new areas where hantavirus is likely to spread within recognized epicenters. Highlighting spatial-temporal trends and potential expansion, we emphasize the increased risk due to pervasive habitat fragmentation and agricultural expansion. Consistent prevention efforts and One Health actions are crucial, especially in newly identified high-risk municipalities.

Preventive Practices of Hantavirus in a Rural Community in Panama: An Explanatory Sequential Mixed Methods Study

INTRODUCTION

Preventive care practices are a challenge in community care. This study examined hantavirus preventive practices and their relationship with personal and social factors, lifestyle, and cultural beliefs.

METHOD

An explanatory sequential mixed methods design, guided by Leininger's Theory of Culture Care Diversity and Universality, was used in two phases: (a) a cross-sectional relational design (n = 109) and (b) ethnonursing research (n = 30), in an endemic community in Panama. Univariate and bivariate analyses were used to analyze the quantitative data, whereas the Leininger's analysis model was used to analyze the qualitative data.

RESULTS

In the quantitative phase, the most frequent preventive practice was household hygiene, and the least frequent was vector control. Two of the eight preventive practices were associated with personal factors and two were associated with social factors. In the qualitative phase, lifestyle, beliefs, and context were found to influence the adoption of hantavirus preventive practices and help explain the quantitative findings.

DISCUSSION

Knowledge and understanding of the social and cultural contexts are essential for hantavirus prevention.

Design and validation of a novel multi-epitopes vaccine against hantavirus

Hantavirus is a member of the order Bunyavirales and an emerging global pathogen. Hantavirus infections have affected millions of people globally based on available epidemiological data and research studies. Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are the two main human diseases associated with hantavirus infections. Hence, efforts are required to develop a potent vaccine against the pathogen. The only vaccine that is in use for hantavirus is an inactivated virus vaccine, "Hantavax", but it failed to produce neutralizing antibodies. Vaccine development is of much importance in dealing with the surge of hantavirus globally. In this study, hantavirus five proteins (N protein, G1 and G2, L protein, and non-structural proteins) were used in NetCTL 1.2 program to predict T-cell epitopes. To predict major histocompatibility complex (MHC) binding alleles, an immune epitope database (IEDB) was used. All predicted epitopes were then investigated for different immunoinformatics analyses such as antigenicity and toxicity analyses. The good water-soluble, non-toxic, probable antigenic, and DRB*0101 binder was selected. A multi-epitopes-based vaccine designing was then done where linkers were used to connect the shortlisted epitopes. In addition, an adjuvant molecule was supplementary to the multi-epitopes peptide to improve the vaccine's immunogenic potential. The final vaccine construct's three-dimensional structure was modeled by ab initio method. The vaccine molecule was then evaluated for its binding potential with TLR-3 immune receptor, which is key for its recognition and processing by the host immune system. Docking studies were performed using HADDOCK software. The best-docked complex was selected and visualized for intermolecular binding and interactions using UCSF Chimera 1.16 software. The findings revealed that the designed vaccine might be a potential vaccine against hantavirus and can be used in experimental animal model testings.Communicated by Ramaswamy H. Sarma.

Spatial-temporal drivers and incidence heterogeneity of hemorrhagic fever with renal syndrome transmission in Shandong Province, China, 2016-2022

BACKGROUND

Hemorrhagic fever with renal syndrome (HFRS) signals a recurring risk in Eurasia in recent years owing to its continued rise in case notifications and the extension of geographical distribution. This study was undertaken to investigate the spatiotemporal drivers and incidence heterogeneity of HFRS transmission in Shandong Province.

METHODS

The epidemiological data for HFRS, meteorological data and socioeconomic data were obtained from China Information System for Disease Control and Prevention, China Meteorological Data Sharing Service System, and Shandong Statistical Yearbook, respectively. The spatial-temporal multicomponent model was employed to analyze the values of spatial-temporal components and the heterogeneity of HFRS transmission across distinct regions.

RESULTS

The total effect values of the autoregressive, epidemic, and endemic components were 0.451, 0.187, and 0.033, respectively, exhibiting significant heterogeneity across various cities. This suggested a pivotal role of the autoregressive component in propelling HFRS transmission in Shandong Province. The epidemic component of Qingdao, Weifang, Yantai, Weihai, and Jining declined sharply at the onset of 2020. The random effect identified distinct incidence levels associated with Qingdao and Weifang, signifying regional variations in HFRS occurrence.

CONCLUSIONS

The autoregressive component emerged as a significant driver in the transmission of HFRS in Shandong Province. Targeted preventive measures should be strategically implemented across various regions, taking into account the predominant component influencing the epidemic.

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.

Hantavirus Disease Cluster Caused by Seoul Virus, Germany

A cluster of 3 persons in Germany experienced hantavirus disease with renal insufficiency. Reverse transcription PCR-based genotyping revealed infection by Seoul hantavirus transmitted from pet rats. Seoul virus could be responsible for disease clusters in Europe, and infected pet rats should be considered a health threat.

Hantavirus: an overview and advancements in therapeutic approaches for infection

Hantaviruses are a significant and emerging global public health threat, impacting more than 200,000 individuals worldwide each year. The single-stranded RNA viruses belong to the Hantaviridae family and are responsible for causing two acute febrile diseases in humans: Hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS). Currently, there are no licensed treatments or vaccines available globally for HTNV infection. Various candidate drugs have shown efficacy in increasing survival rates during the early stages of HTNV infection. Some of these drugs include lactoferrin, ribavirin, ETAR, favipiravir and vandetanib. Immunotherapy utilizing neutralizing antibodies (NAbs) generated from Hantavirus convalescent patients show efficacy against HTNV. Monoclonal antibodies such as MIB22 and JL16 have demonstrated effectiveness in protecting against HTNV infection. The development of vaccines and antivirals, used independently and/or in combination, is critical for elucidating hantaviral infections and the impact on public health. RNA interference (RNAi) arised as an emerging antiviral therapy, is a highly specific degrades RNA, with post-transcriptional mechanism using eukaryotic cells platform. That has demonstrated efficacy against a wide range of viruses, both in vitro and in vivo. Recent antiviral methods involve using small interfering RNA (siRNA) and other, immune-based therapies to target specific gene segments (S, M, or L) of the Hantavirus. This therapeutic approach enhances viral RNA clearance through the RNA interference process in Vero E6 cells or human lung microvascular endothelial cells. However, the use of siRNAs faces challenges due to their low biological stability and limited in vivo targeting ability. Despite their successful inhibition of Hantavirus replication in host cells, their antiviral efficacy may be hindered. In the current review, we focus on advances in therapeutic strategies, as antiviral medications, immune-based therapies and vaccine candidates aimed at enhancing the body's ability to control the progression of Hantavirus infections, with the potential to reduce the risk of severe disease.

External quality assessment of orthohantavirus and lymphocytic choriomeningitis virus molecular detection and serology in Europe, 2021

BackgroundRodent-borne viruses such as orthohantaviruses and arenaviruses cause considerable disease burden with regional and temporal differences in incidence and clinical awareness. Therefore, it is important to regularly evaluate laboratory diagnostic capabilities, e.g. by external quality assessments (EQA).AimWe wished to evaluate the performance and diagnostic capability of European expert laboratories to detect orthohantaviruses and lymphocytic choriomeningitis virus (LCMV) and human antibody response towards orthohantaviruses.MethodsWe conducted an EQA in 2021; molecular panels consisted of 12 samples, including different orthohantaviruses (Seoul, Dobrava-Belgrade (DOBV), Puumala (PUUV) and Hantaan orthohantavirus), LCMV and negative controls. Serological panels consisted of six human serum samples reactive to PUUV, DOBV or negative to orthohantaviruses. The EQA was sent to 25 laboratories in 20 countries.ResultsThe accuracy of molecular detection of orthohantaviruses varied (50‒67%, average 62%) among 16 participating laboratories, while LCMV samples were successfully detected in all 11 participating laboratories (91-100%, average 96%). The accuracy of serological diagnosis of acute and past orthohantavirus infections was on average 95% among 20 participating laboratories and 82% in 19 laboratories, respectively. A variety of methods was used, with predominance of in-house assays for molecular tests, and commercial assays for serological ones.ConclusionSerology, the most common tool to diagnose acute orthohantavirus infections, had a high accuracy in this EQA. The molecular detection of orthohantaviruses needs improvement while LCMV detection (performed in fewer laboratories) had 95% accuracy. Further EQAs are recommended to be performed periodically to monitor improvements and challenges in the diagnostics of rodent-borne diseases.

Cases of Hemorrhagic Fever with Renal Syndrome in Russia during 2000-2022

During 2000-2022, a total of 69 of Russia's 85 administrative regions reported 164,580 hemorrhagic fever with renal syndrome (HFRS) cases, with an annual average rate of 4.9 cases/100,000 population (10⁵ popul.). European Russia reported 162,045 (98.5%) cases in 53/60 regions with 9.7 cases/10⁵ popul. Asian Russia reported 2535 (1.5%) cases in 16/25 regions with 0.6 cases/10⁵ popul. In the same period, Russia reported 668 (0.4%) fatal HFRS cases, and 4030 (2.4%) cases among children under the age of 14 years. Most HFRS cases occurred during autumn and winter. The incidence among rural residents was 6.7 per 10⁵ popul., higher than the urban 4.4 per 10⁵ popul.; however, among HFRS patients, rural and urban residents account for 35% and 65%, respectively. Six hantaviruses, causing HFRS of different clinical severity, were recognized as pathogens: Hantaan (HTNV) and Amur (AMUV) of Orthohantavirus hantanense species, Seoul (SEOV) of Orthohantavirus seoulense species, Puumala (PUUV) of Orthohantavirus puumalaense species, and Kurkino (KURV) and Sochi (SOCV) of Orthohantavirus dobravaense species, with the principal hosts Apodemus agrarius coreae, Apodemus peninsulae, Rattus norvegicus, Myodes glareolus, Apodemus agrarius agrarius, and Sylvaemus ponticus, respectively. It was found that 97.7% of HFRS cases are caused by PUUV, therefore, this virus plays the main role in the HFRS morbidity structure in Russia.

Characterization of a Panel of Cross-Reactive Hantavirus Nucleocapsid Protein-Specific Monoclonal Antibodies

Hantaviruses are emerging pathogens with a worldwide distribution that can cause life-threatening diseases in humans. Monoclonal antibodies (MAbs) against hantavirus nucleocapsid (N) proteins are important tools in virus diagnostics, epidemiological studies and basic research studies on virus replication and pathogenesis. Here, we extend the collection of previously generated MAbs raised against a segment of Puumala orthohantavirus (PUUV) N protein harbored on virus-like particles (VLPs) and MAbs against N proteins of Sin Nombre orthohantavirus/Andes orthohantavirus by generating nine novel MAbs against N proteins of Dobrava-Belgrade orthohantavirus (DOBV), Tula orthohantavirus (TULV), Thottapalayam thottimvirus (TPMV) and PUUV. In order to have a wide collection of well-described hantavirus-specific MAbs, the cross-reactivity of novel and previously generated MAbs was determined against N proteins of 15 rodent- and shrew-borne hantaviruses by different immunological methods. We found that all MAbs, excluding TPMV-specific MAbs, demonstrated different cross-reactivity patterns with N proteins of hantaviruses and recognized native viral antigens in infected mammalian cells. This well-characterized collection of cross-reactive hantavirus-specific MAbs has a potential application in various fields of hantavirus research, diagnostics and therapy.

Pet Rats as the Likely Reservoir for Human Seoul Orthohantavirus Infection

Seoul orthohantavirus (SEOV) is a rat-associated zoonotic pathogen with an almost worldwide distribution. In 2019, the first autochthonous human case of SEOV-induced hemorrhagic fever with renal syndrome was reported in Germany, and a pet rat was identified as the source of the zoonotic infection. To further investigate the SEOV reservoir, additional rats from the patient and another owner, all of which were purchased from the same vendor, were tested. SEOV RNA and anti-SEOV antibodies were found in both of the patient's rats and in two of the three rats belonging to the other owner. The complete coding sequences of the small (S), medium (M), and large (L) segments obtained from one rat per owner exhibited a high sequence similarity to SEOV strains of breeder rat or human origin from the Netherlands, France, the USA, and Great Britain. Serological screening of 490 rats from breeding facilities and 563 wild rats from Germany (2007-2020) as well as 594 wild rats from the Netherlands (2013-2021) revealed 1 and 6 seropositive individuals, respectively. However, SEOV RNA was not detected in any of these animals. Increased surveillance of pet, breeder, and wild rats is needed to identify the origin of the SEOV strain in Europe and to develop measures to prevent transmission to the human population.

Fatal Puumala Hantavirus Infection in a Patient with Common Variable Immunodeficiency (CVID)

Puumala hantavirus (PUUV) infections usually show a mild or moderate clinical course, but may sometimes also lead to life-threatening disease. Here, we report on a 60-year-old female patient with common variable immunodeficiency (CVID) who developed a fatal PUUV infection with persistent renal failure, thrombocytopenia, and CNS infection with impaired consciousness and tetraparesis. Hantavirus-specific antibodies could not be detected due to the humoral immunodeficiency. Diagnosis and virological monitoring were based on the quantitative detection of PUUV RNA in blood, cerebrospinal fluid, bronchial lavage, and urine, where viral RNA was found over an unusually extended period of one month. Due to clinical deterioration and virus persistence, treatment with ribavirin was initiated. Additionally, fresh frozen plasma (FFP) from convalescent donors with a history of PUUV infection was administered. Despite viral clearance, the clinical condition of the patient did not improve and the patient died on day 81 of hospitalization. This case underlines the importance of the humoral immune response for the course of PUUV disease and illustrates the need for PCR-based virus diagnostics in those patients. Due to its potential antiviral activity, convalescent plasma should be considered in the therapy of severe hantavirus diseases.

Role of Seaports and Imported Rats in Seoul Hantavirus Circulation, Africa

Seoul orthohantavirus (SEOV) is not considered a major public health threat on the continent of Africa. However, Africa is exposed to rodentborne SEOV introduction events through maritime traffic after exponential growth of trade with the rest of the world. Serologic studies have already detected hantavirus antibodies in human populations, and recent investigations have confirmed circulation of hantavirus, including SEOV, in rat populations. Thus, SEOV is a possible emerging zoonotic risk in Africa. Moreover, the range of SEOV could rapidly expand, and transmission to humans could increase because of host switching from the usual brown rat (Rattus norvegicus) species, which is currently invading Africa, to the more widely installed black rat (R. rattus) species. Because of rapid economic development, environmental and climatic changes, and increased international trade, strengthened surveillance is urgently needed to prevent SEOV dissemination among humans in Africa.

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.

Kiwira Virus, a Newfound Hantavirus Discovered in Free-tailed Bats (Molossidae) in East and Central Africa

A novel hantavirus, named Kiwira virus, was molecularly detected in six Angolan free-tailed bats (Mops condylurus, family Molossidae) captured in Tanzania and in one free-tailed bat in the Democratic Republic of Congo. Hantavirus RNA was found in different organs, with the highest loads in the spleen. Nucleotide sequences of large parts of the genomic S and L segments were determined by in-solution hybridisation capture and high throughput sequencing. Phylogenetic analyses placed Kiwira virus into the genus Mobatvirus of the family Hantaviridae, with the bat-infecting Quezon virus and Robina virus as closest relatives. The detection of several infected individuals in two African countries, including animals with systemic hantavirus infection, provides evidence of active replication and a stable circulation of Kiwira virus in M. condylurus bats and points to this species as a natural host. Since the M. condylurus home range covers large regions of Sub-Saharan Africa and the species is known to roost inside and around human dwellings, a potential spillover of the Kiwira virus to humans must be considered.

Orthohantaviruses in Reservoir and Atypical Hosts in the Czech Republic: Spillover Infection and Indication of Virus-Specific Tissue Tropism

Orthohantaviruses (genus Orthohantavirus) are a diverse group of viruses that are closely associated with their natural hosts (rodents, shrews, and moles). Several orthohantaviruses cause severe disease in humans. Central and western Europe are areas with emerging orthohantavirus occurrences. In our study, several orthohantaviruses, including the pathogenic Kurkino virus (KURV), were detected in their natural hosts trapped at several study sites in the Czech Republic. KURV was detected mainly in its typical host, the striped field mouse (Apodemus agrarius). Nevertheless, spillover infections were also detected in wood mice (Apodemus sylvaticus) and common voles (Microtus arvalis). Similarly, Tula virus (TULV) was found primarily in common voles, and events of spillover to rodents of other host species, including Apodemus spp., were recorded. In addition, unlike most previous studies, different tissues were sampled and compared to assess their suitability for orthohantavirus screening and possible tissue tropism. Our data suggest possible virus-specific tissue tropism in rodent hosts. TULV was most commonly detected in the lung tissue, whereas KURV was more common in the liver, spleen, and brain. Moreover, Seewis and Asikkala viruses were detected in randomly found common shrews (Sorex araneus). In conclusion, we have demonstrated the presence of human-pathogenic KURV and the potentially pathogenic TULV in their typical hosts as well as their spillover to atypical host species belonging to another family. Furthermore, we suggest the possibility of virus-specific tissue tropism of orthohantaviruses in their natural hosts. IMPORTANCE Orthohantaviruses (genus Orthohantavirus, family Hantaviridae) are a diverse group of globally distributed viruses that are closely associated with their natural hosts. Some orthohantaviruses are capable of infecting humans and causing severe disease. Orthohantaviruses are considered emerging pathogens due to their ever-increasing diversity and increasing numbers of disease cases. We report the detection of four different orthohantaviruses in rodents and shrews in the Czech Republic. Most viruses were found in their typical hosts, Kurkino virus (KURV) in striped field mice (Apodemus agrarius), Tula virus (TULV) in common voles (Microtus arvalis), and Seewis virus in common shrews (Sorex araneus). Nevertheless, spillover infections of atypical host species were also recorded for KURV, TULV, and another shrew-borne orthohantavirus, Asikkala virus. In addition, indications of virus-specific patterns of tissue tropism were observed. Our results highlight the circulation of several orthohantaviruses, including KURV, which is pathogenic to humans, among rodents and shrews in the Czech Republic.

Virus-Associated Nephropathies: A Narrative Review

While most viral infections cause mild symptoms and a spontaneous favorable resolution, some can lead to severe or protracted manifestations, specifically in immunocompromised hosts. Kidney injuries related to viral infections may have multiple causes related to the infection severity, drug toxicity or direct or indirect viral-associated nephropathy. We review here the described virus-associated nephropathies in order to guide diagnosis strategies and treatments in cases of acute kidney injury (AKI) occurring concomitantly with a viral infection. The occurrence of virus-associated nephropathy depends on multiple factors: the local epidemiology of the virus, its ability to infect renal cells and the patient's underlying immune response, which varies with the state of immunosuppression. Clear comprehension of pathophysiological mechanisms associated with a summary of described direct and indirect injuries should help physicians to diagnose and treat viral associated nephropathies.

Trends and focuses of hantavirus researches: a global bibliometric analysis and visualization from 1980 to 2020

Background

There have been worldwide changes in the researches on hantaviruses in the past several decades. Nevertheless, there are few bibliometric analysis studies this field. We aim to evaluate and visualize the research focuses and trends of this field using a bibliometric analysis way to help understand the developmet and future hotspots of this field.

Material and methods

Publications related to hantavirus studies were culled from the Web of Science Core Collection to generate trend analysis. The articles and reviews were re-extracted and Countries, institutions, authors, references and keywords in this field were visually analyzed by using VOSviewer and CiteSpace.

Results

A total of 4408 studies were included and the number of publications regarding hantaviruses significantly increased yearly. Three thousand seven hundred sixteen research articles and reviews were retrieved to generate bibliometric analysis. These studies mainly come from 125 countries led by USA and China and 3312 institutions led by the University of Helsinki. Twelve thousand five hundred twenty nine authors were identified and Vaheri A were the most influential author. Journal of Virology was the journal with the most studies and citations. After analysis, Hemorrhagic fever with renal syndrome, Hantavirus cardiopulmonary syndrome, nephropathia epidemica and related genotypes, clinical symptoms and rodents were the most common keywords and developing areas.

Conclusion

Research on hantavirus is flourishing. Cooperation among different countries and institutions in this field must be strengthened in the future. The ecology and clinical symptoms of new genotypes, the vaccine development and factors that affect host population distribution and density are current and developing areas of study.

A Portable Diagnostic Assay, Genetic Diversity, and Isolation of Seoul Virus from Rattus norvegicus Collected in Gangwon Province, Republic of Korea

Seoul virus (SEOV), an etiological agent for hemorrhagic fever with renal syndrome, poses a significant public health threat worldwide. This study evaluated the feasibility of a mobile Biomeme platform for facilitating rapid decision making of SEOV infection. A total of 27 Rattus norvegicus were collected from Seoul Metropolitan City and Gangwon Province in Republic of Korea (ROK), during 2016–2020. The serological and molecular prevalence of SEOV was 5/27 (18.5%) and 2/27 (7.4%), respectively. SEOV RNA was detected in multiple tissues of rodents using the Biomeme device, with differences in Ct values ranging from 0.6 to 2.1 cycles compared to a laboratory benchtop system. Using amplicon-based next-generation sequencing, whole-genome sequences of SEOV were acquired from lung tissues of Rn18-1 and Rn19-5 collected in Gangwon Province. Phylogenetic analysis showed a phylogeographical diversity of rat-borne orthohantavirus collected in Gangwon Province. We report a novel isolate of SEOV Rn19-5 from Gangwon Province. Our findings demonstrated that the Biomeme system can be applied for the molecular diagnosis of SEOV comparably to the laboratory-based platform. Whole-genome sequencing of SEOV revealed the phylogeographical diversity of orthohantavirus in the ROK. This study provides important insights into the field-deployable diagnostic assays and genetic diversity of orthohantaviruses for the rapid response to hantaviral outbreaks in the ROK.

A fatal case of haemorrhagic fever with renal syndrome in Kursk Region, Russia, caused by a novel Puumala virus clade

Haemorrhagic fever with renal syndrome (HFRS) is the most widespread natural-focal human disease in the Russian Federation. In this study, we report virological assessment of a fatal case of HFRS-PUUV (Puumala virus) in the Kursk Region. The infection caused severe multiorgan failure and the maximum viral load was detected in the tissue of the spleen. Viral sequences were obtained from the patient's autopsy material and lung tissues of bank voles captured in the region. These sequences formed a new clade in the PUUV phylogenetic tree, an outgroup to all known Russian (RUS) lineage sequences. On the other hand viruses collected in the Kursk Region grouped with the RUS lineage and are separated from all other PUUV linages. We propose to nominate this novel group as W-RUS as the identified viruses were collected near the western Russian boundary. The recombination signals between their ancestors and RUS lineage representatives from the Volga region were revealed. The strain Samara_94/CG/2005 suggestively emerged as the result of reassortment between the ancestors of W-RUS and DTK-Ufa-97.

Hyperamylasemia Caused by the Hantaan Virus: A Retrospective Study of 101 Patients with Hemorrhagic Fever with Renal Syndrome in West China

Background. Hyperamylasemia (HA) is an inconspicuous manifestation of hemorrhagic fever with renal syndrome (HFRS) in Baoji city, West China. Hantaan virus (HTNV) is the only pathogen-caused HFRS in this region, but the knowledge about HA in the local HFRS patients has been limited. The aim of this study was to investigate the characteristics of HA and its predictive risk factors for doctors to engage in timely monitoring and dealing with the possible serious changes prewarned by HA in the early stages of the disease to improve the final outcome. Methods. All HFRS patients with and without HA (HA and nHA groups, respectively) were treated in Baoji People’s Hospital. The clinical characteristics between the two groups were compared by Student’s $\mathit{t}$ -test or Chi-square test. The risk factors for prognosis were measured by the logistic regression analysis. The predictive effects of prognosis in clinical and laboratory parameters were analyzed by the receiver operating characteristic curves. Results. 46.53% of the patients demonstrated HA, among which 71.7% were severe and critical types of HFRS, greater than that in the nHA group (19.57%, $\mathit{P}<\mathbf{0.001}$ ). The hospitalization day and the general incidence of acute pancreatitis (AP) were longer or greater in the HA group than in the nHA group ( $\mathit{P}<\mathbf{0.01}$ ). Age and the time from the onset of the first symptom to the patient being admitted to hospital ( $T_{\text{OA}}$ ) were the predictive risk factors for HA. The best cut-off values were the age of 54 years and $T_{\text{OA}}$ of 5.5 days. Conclusion. HTNV-induced HA is a common clinical presentation of HFRS patients in West China. It can increase the severity, the hospitalization days of patients, and the incidence of AP in HFRS. Age and $T_{\text{OA}}$ constituted independent risk factors for HA caused by HTNV.

Central nervous system infection with Seoul Orthohantavirus in a child after hematopoietic stem cell transplantation: a case report

Background

Patients with allogeneic hematopoietic stem cell transplantation (allo-HSCT) are prone to complicate viral infection. Central nervous system (CNS) involvement caused by the viruses is rare but with poor prognosis. Hantavirus, which usually cause hemorrhagic fever with renal syndrome (HFRS), and none case has been reported about these infection in allo-HSCT patients.

Case presentation

In August 2021, a 13-year-old male child developed intermittent fever and refractory hypotension after allo-HSCT. Magnetic resonance imaging of the head revealed abnormal signal foci in the left midbrain cerebral peduncle and bilateral thalamus. His family reported traces of mouse activity in the patient’s home kitchen. HFRS was suspected, but with no significant kidney damage. The specific immunoglobulin (Ig) G and M of hantavirus were negative. The metagenomic next-generation sequencing (mNGS) detected Seoul Orthohantavirus (SEOV) sequences directly in cerebrospinal fluid and blood.

Conclusions

Allo-HSCT patients are a high-risk group for infection. Usually the causative agent of infection is difficult to determine, and sometimes the site of infection is concealed. This report highlights the importance of suspecting hantavirus infection in allo-HSCT patients with CNS symptoms despite the absence of renal syndromes. The mNGS is a powerful tool for detecting pathogens. CNS infection with Seoul orthohantavirus in transplant patients is rare but possible as demonstrated in this case. To the best of our knowledge, this is the first reported case employing mNGS to diagnose SEOV caused CNS infection in an allo-HSCT patient.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01766-6.

Human antibody recognizing a quaternary epitope in the Puumala virus glycoprotein provides broad protection against orthohantaviruses

The rodent-borne hantavirus Puumala virus (PUUV) and related agents cause hemorrhagic fever with renal syndrome (HFRS) in humans. Other hantaviruses, including Andes virus (ANDV) and Sin Nombre virus, cause a distinct zoonotic disease, hantavirus cardiopulmonary syndrome (HCPS). Although these infections are severe and have substantial case fatality rates, no FDA-approved hantavirus countermeasures are available. Recent work suggests that monoclonal antibodies may have therapeutic utility. We describe here the isolation of human neutralizing antibodies (nAbs) against tetrameric Gn/Gc glycoprotein spikes from PUUV-experienced donors. We define a dominant class of nAbs recognizing the "capping loop" of Gn that masks the hydrophobic fusion loops in Gc. A subset of nAbs in this class, including ADI-42898, bound Gn/Gc complexes but not Gn alone, strongly suggesting that they recognize a quaternary epitope encompassing both Gn and Gc. ADI-42898 blocked the cell entry of seven HCPS- and HFRS-associated hantaviruses, and single doses of this nAb could protect Syrian hamsters and bank voles challenged with the highly virulent HCPS-causing ANDV and HFRS-causing PUUV, respectively. ADI-42898 is a promising candidate for clinical development as a countermeasure for both HCPS and HFRS, and its mode of Gn/Gc recognition informs the development of broadly protective hantavirus vaccines.

Characterization of Hantavirus N Protein Intracellular Dynamics and Localization

Hantaviruses are enveloped viruses that possess a tri-segmented, negative-sense RNA genome. The viral S-segment encodes the multifunctional nucleocapsid protein (N), which is involved in genome packaging, intracellular protein transport, immunoregulation, and several other crucial processes during hantavirus infection. In this study, we generated fluorescently tagged N protein constructs derived from Puumalavirus (PUUV), the dominant hantavirus species in Central, Northern, and Eastern Europe. We comprehensively characterized this protein in the rodent cell line CHO-K1, monitoring the dynamics of N protein complex formation and investigating co-localization with host proteins as well as the viral glycoproteins Gc and Gn. We observed formation of large, fibrillar PUUV N protein aggregates, rapidly coalescing from early punctate and spike-like assemblies. Moreover, we found significant spatial correlation of N with vimentin, actin, and P-bodies but not with microtubules. N constructs also co-localized with Gn and Gc albeit not as strongly as the glycoproteins associated with each other. Finally, we assessed oligomerization of N constructs, observing efficient and concentration-dependent multimerization, with complexes comprising more than 10 individual proteins.

Urinary Tract Infections: Virus

Although viruses are common in the urinary tract in healthy people, viral infections can become a major concern in immunocompromised individuals. Patients undergoing hematopoietic stem cell or solid organ transplantation may be particularly susceptible to BK and other viruses, and experience a high risk of mortality. The most common presentation in this setting is hemorrhagic cystitis. The treatment is mostly supportive, including the reduction of immunosuppression; a variety of experimental agents has also been proposed. A different context is offered by chronic (HBV, HCV, HIV) or acute/subacute (Dengue, Hantavirus, etc.) infections, where the kidneys can be secondarily involved and suffer from several glomerular syndromes. Many protocols based on different oral direct-acting antivirals and combined antiretrovirals are available, according to the systemic infection. Viral infections can be classified according to the organ involved, i.e. lower (bladder) or upper urinary tract (kidneys, ureters), and to the mechanism of injury. A section is dedicated to the current breakout of SARS-CoV-2, which does not spare the urinary tract, sometimes with serious implications. Even if this topic is mostly the discipline of ultra-dedicated physicians, this overview has a practical approach and could be useful to a wider medical audience, especially in times of viral pandemics.

OUP accepted manuscript

Hantavirus-induced diseases are emerging zoonoses with endemic appearances and frequent outbreaks in different parts of the world. In humans, hantaviral pathology is characterized by the disruption of the endothelial cell barrier followed by increased capillary permeability, thrombocytopenia due to platelet activation/depletion and an overactive immune response. Genetic vulnerability due to certain human leukocyte antigen haplotypes is associated with disease severity. Typically, two different hantavirus-caused clinical syndromes have been reported: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). The primarily affected vascular beds differ in these two entities: renal medullary capillaries in HFRS caused by Old World hantaviruses and pulmonary capillaries in HCPS caused by New World hantaviruses. Disease severity in HFRS ranges from mild, e.g. Puumala virus-associated nephropathia epidemica, to moderate, e.g. Hantaan or Dobrava virus infections. HCPS leads to a severe acute respiratory distress syndrome with high mortality rates. Due to novel insights into organ tropism, hantavirus-associated pathophysiology and overlapping clinical features, HFRS and HCPS are believed to be interconnected syndromes frequently involving the kidneys. As there are no specific antiviral treatments or vaccines approved in Europe or the USA, only preventive measures and public awareness may minimize the risk of hantavirus infection. Treatment remains primarily supportive and, depending on disease severity, more invasive measures (e.g., renal replacement therapy, mechanical ventilation and extracorporeal membrane oxygenation) are needed.

Hantavirus

Hantaviruses are tri-segmented lipid-enveloped RNA viruses belonging to the Bunyaviridae family. Human infection corresponds to a zoonosis associated with two different clinical syndromes: hemorrhagic fever with renal syndrome that occurs in Asia and Europe and hantavirus cardiopulmonary syndrome (HCPS) that occurs in the North America, Central America and South America. The major pathogenic mechanisms in HCPS include (1) direct microvascular endothelial injury leading to increased capillary permeability and the development of noncardiogenic pulmonary edema and acute respiratory distress syndrome, and (2) exaggerated host immune response leading to secondary organ damage. The incubation period for this disease is quite long (6-39 days, median: 18 days); however, rapid progression to respiratory failure and shock can occur highlighting the importance of high index of clinical suspicion. Management revolves around high-quality supportive care. Various management and preventative strategies are currently being explored and warrant further examination to improve the overall outlook following infection with hantavirus.

Coumarin Derivative N6 as a Novel anti-hantavirus Infection Agent Targeting AKT

Hantaviruses are globally emerging zoonotic viruses that can cause hemorrhagic fever with renal syndrome (HFRS) in Asia and Europe, which is primarily caused by Hantaan virus (HTNV) infection, results in profound morbidity and mortality. However, no specific treatment is available for this disease. Coumarin derivatives have been reported as antiviral molecules, while studies about the bioactivity of coumarin derivatives against HTNV infection are limited. To study the potential antiviral activity of coumarin derivatives, 126 coumarin derivatives are synthesized, and their inhibitory activity against HTNV is analyzed in vitro. Among these compounds, N6 inhibits HTNV with relatively high selectivity index at 10.9, and the viral titer of HTNV is reduced significantly after 5, 10, and 20 μM N6 treatments. Furthermore, the administration of N6 at the early stage of HTNV infection can inhibit the replication and production of infectious HTNV in host cell, this therapeutic efficacy is confirmed in HTNV-infected newborn mice at the early stage of infection. The molecular docking results show that N6 forms interactions with the key amino acid residues at its active site, and reveals several molecular interactions responsible for the observed affinity, and the treatment of N6 can inhibit the expression of p (Ser473)Akt and HTNV nucleocapsid protein significantly. As such, these observations demonstrate that coumarin derivative N6 might be used as a potential agent against HTNV infection.

Population survey of small rodents on islands located inside a region of endemism for hantavirus pulmonary syndrome

Ecological studies of rodent species, especially as reservoirs of zoonoses, can identify spatiotemporal conditions associated with irruptions of abundances, as well as predict areas and times with higher risk of disease transmission. The aims of this research were to describe and identify (i) the rodent community composition; (ii) their population structure and breeding season; (iii) temporal and spatial variations in their population abundance; and (iv) the environmental factors associated with these variations on islands of upper Paraná River Delta, a zone of endemism for hantavirus pulmonary syndrome (HPS) in Argentina (Entre Ríos and Santa Fe provinces). We carried out seasonal surveys over 3 years (2014–2017) with live capture traps on seven islands (natural protected areas and under livestock grazing). Three hundred seventy-seven sigmodontine rodents of seven species were captured. While the maximum richness was seven, only four species coexisted at most on an island at the same time. Although changes in reproduction were detected throughout the year, seasonality, land use, and vegetation structure did not explain changes in abundance of rodents. Rodent abundances were affected mainly by flooding-related factors and meteorological conditions (rainfall and temperatures). The recovery of rodent populations after river flooding was species-specific and heterogeneous. The abundance of Oxymycterus rufus and Akodon azarae was affected by El Niño Southern Oscillation (ENSO); A. azarae did not recover after the flood at least during the study period. After the flood, populations of Oligoryzomys flavescens, the reservoir of HPS, also declined; however, this species’ populations were the first to recover its numbers, becoming dominant in the post-flood rodent community.

Development and design of the Hantavirus registry - HantaReg - for epidemiological studies, outbreaks and clinical studies on hantavirus disease

Background

Frequent outbreaks around the globe and endemic appearance in different parts of the world emphasize the substantial risk of hantavirus diseases. Increasing incidence rates, trends of changing distribution of hantavirus species and new insights into clinical courses of hantavirus diseases call for multinational surveillance. Furthermore, evidence-based guidelines for the management of hantavirus diseases and scoring systems, which allow stratification of patients into risk categories, are lacking.

Methods

Hantavirus registry (HantaReg) is a novel registry platform facilitating multinational research of hantavirus-caused diseases, such as haemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). HantaReg provides an electronic case report form and uses the General Data Protection Regulation compliant platform clinicalsurveys.net, which can be accessed from any internet browser in the world. Having a modular structure, the registry platform is designed to display or hide questions and items according to the documented case (e.g. patient with HFRS versus HCPS) to facilitate fast, but standardized, data entry. Information categories documented in HantaReg are demographics, pre-existing diseases, clinical presentation, diagnostic and therapeutic approaches, as well as outcome.

Conclusions

HantaReg is a novel, ready-to-use platform for clinical and epidemiological studies on hantavirus diseases and facilitates the documentation of the disease course associated with hantavirus infections. HantaReg is expected to promote international collaboration and contributes to improving patient care through the analysis of diagnostic and treatment pathways for hantavirus diseases, providing evidence for robust treatment recommendations. Moreover, HantaReg enables the development of prognosis-indicating scoring systems for patients with hantavirus disease.

Building a better antibody through the Fc: advances and challenges in harnessing antibody Fc effector functions for antiviral protection

Antibodies can provide antiviral protection through neutralization and recruitment of innate effector functions through the Fc domain. While neutralization has long been appreciated for its role in antibody-mediated protection, a growing body of work indicates that the antibody Fc domain also significantly contributes to antiviral protection. Recruitment of innate immune cells such as natural killer cells, neutrophils, monocytes, macrophages, dendritic cells and the complement system by antibodies can lead to direct restriction of viral infection as well as promoting long-term antiviral immunity. Monoclonal antibody therapeutics against viruses are increasingly incorporating Fc-enhancing features to take advantage of the Fc domain, uncovering a surprising breadth of mechanisms through which antibodies can control viral infection. Here, we review the recent advances in our understanding of antibody-mediated innate immune effector functions in protection from viral infection and review the current approaches and challenges to effectively leverage innate immune cells via antibodies.

Tula Virus as Causative Agent of Hantavirus Disease in Immunocompetent Person, Germany

We report molecular evidence of Tula virus infection in an immunocompetent patient from Germany who had typical signs of hantavirus disease. Accumulating evidence indicates that Tula virus infection, although often considered nonpathogenic, represents a threat to human health.

Autochthonous Ratborne Seoul Virus Infection in Woman with Acute Kidney Injury

Outside Asia, Seoul virus (SEOV) is an underestimated pathogen. In Germany, autochthonous SEOV-associated hantavirus disease has not been unequivocally diagnosed. We found clinical and molecular evidence for SEOV infection in a young woman; her pet rat was the source of infection.

Broad and potently neutralizing monoclonal antibodies isolated from human survivors of New World hantavirus infection

New World hantaviruses (NWHs) are endemic in North and South America and cause hantavirus cardiopulmonary syndrome (HCPS), with a case fatality rate of up to 40%. Knowledge of the natural humoral immune response to NWH infection is limited. Here, we describe human monoclonal antibodies (mAbs) isolated from individuals previously infected with Sin Nombre virus (SNV) or Andes virus (ANDV). Most SNV-reactive antibodies show broad recognition and cross-neutralization of both New and Old World hantaviruses, while many ANDV-reactive antibodies show activity for ANDV only. mAbs ANDV-44 and SNV-53 compete for binding to a distinct site on the ANDV surface glycoprotein and show potently neutralizing activity to New and Old World hantaviruses. Four mAbs show therapeutic efficacy at clinically relevant doses in hamsters. These studies reveal a convergent and potently neutralizing human antibody response to NWHs and suggest therapeutic potential for human mAbs against HCPS.

Engdahl et al. show that monoclonal antibodies isolated from human survivors of New World hantavirus infection display broad and potent neutralization across hantavirus species and recognize distinct sites on the glycoprotein spike. Multiple antibodies demonstrate potential therapeutic candidates for New World hantavirus infection. Some antibodies also neutralized Old World hantaviruses.

Monocyte subset redistribution from blood to kidneys in patients with Puumala virus caused hemorrhagic fever with renal syndrome

Innate immune cells like monocytes patrol the vasculature and mucosal surfaces, recognize pathogens, rapidly redistribute to affected tissues and cause inflammation by secretion of cytokines. We previously showed that monocytes are reduced in blood but accumulate in the airways of patients with Puumala virus (PUUV) caused hemorrhagic fever with renal syndrome (HFRS). However, the dynamics of monocyte infiltration to the kidneys during HFRS, and its impact on disease severity are currently unknown. Here, we examined longitudinal peripheral blood samples and renal biopsies from HFRS patients and performed in vitro experiments to investigate the fate of monocytes during HFRS. During the early stages of HFRS, circulating CD14-CD16+ nonclassical monocytes (NCMs) that patrol the vasculature were reduced in most patients. Instead, CD14+CD16- classical (CMs) and CD14+CD16+ intermediate monocytes (IMs) were increased in blood, in particular in HFRS patients with more severe disease. Blood monocytes from patients with acute HFRS expressed higher levels of HLA-DR, the endothelial adhesion marker CD62L and the chemokine receptors CCR7 and CCR2, as compared to convalescence, suggesting monocyte activation and migration to peripheral tissues during acute HFRS. Supporting this hypothesis, increased numbers of HLA-DR+, CD14+, CD16+ and CD68+ cells were observed in the renal tissues of acute HFRS patients compared to controls. In vitro, blood CD16+ monocytes upregulated CD62L after direct exposure to PUUV whereas CD16- monocytes upregulated CCR7 after contact with PUUV-infected endothelial cells, suggesting differential mechanisms of activation and response between monocyte subsets. Together, our findings suggest that NCMs are reduced in blood, potentially via CD62L-mediated attachment to endothelial cells and monocytes are recruited to the kidneys during HFRS. Monocyte mobilization, activation and functional impairment together may influence the severity of disease in acute PUUV-HFRS.

[Real-time PCR assay development for the control of vaccine against hemorrhagic fever with renal syndrome]

INTRODUCTION

Hemorrhagic fever with renal syndrome (HFRS) holds a leading place among natural focal human diseases in Russian Federation. There is no etiotropic therapy for the disease now. The vaccine prophylaxis is the most effective method to control this infection. The main criteria for inactivated vaccines evaluation are its immunogenicity and specific activity.The study purposes were to develop a sensitive and specific real-time PCR method for viral RNA quantification in the inactivated vaccine and to study the correlation between the viral RNA amount and vaccine immunogenicity.

MATERIAL AND METHODS

L-segment fragments of the Puumala, Hantaan, and Sochi vaccine strains were selected as diagnostic targets for oligonucleotides and fluorescent probes. The immunogenicity of experimental vaccines was determined by the induction of neutralizing antibodies in BALB/c mice.

RESULTS

A highly specific, sensitive and reproducible real-time PCR method has been developed. The analytical sensitivity was 1.24 ± 1.5 x 102 copies/ml for Puumala virus; 1.16 ± 1.4 * 102 copies/ml for Hantaan; 1.32 ± 1.8 * 102 copies/ ml for Sochi, with a virus content of 1.5 ± 0.5 lg FFU/ml; 1.8 ± 0.5 lg FFU/ml and 2.2 ± 0.5 lg FFU/ml, respectively. The viral RNA amount in experimental vaccine preparations inactivated with β-propiolactone was proportional to the neutralizing antibodies titer observed in mice following the immunization.

DISCUSSION

It was found that different virus inactivators differently affects the detected viral RNA amount, but not the vaccine immunogenicity, which indicates the same degree of the immunogenic proteins damage. The direct relationship between the viral RNA copy number and vaccine immunogenicity makes it possible to use this criterion for vaccine dosage preparation.

CONCLUSION

The developed method for viral RNA quantification is a promising tool for the specific activity control of the HFRS vaccine.

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.

Hantavirus pulmonary syndrome outbreaks associated with climate variability in Northwestern Argentina, 1997-2017

Background

Rodent-borne hantaviruses (genus Orthohantavirus) are the etiologic agents causing two human diseases: hemorrhagic fever with renal syndrome (HFRS) in Euroasia; and hantavirus pulmonary syndrome (HPS) in North and South America. In South America fatality rates of HPS can reach up to 35%–50%. The transmission of pathogenic hantaviruses to humans occurs mainly via inhalation of aerosolized excreta from infected rodents. Thus, the epidemiology of HPS is necessarily linked to the ecology of their rodent hosts and the contact with a human, which in turn may be influenced by climatic variability. Here we examined the relationship between climatic variables and hantavirus transmission aim to develop an early warning system of potential hantavirus outbreaks based on ecologically relevant climatic factors.

Methodology and main findings

We compiled reported HPS cases in northwestern Argentina during the 1997–2017 period and divided our data into biannual, quarterly, and bimestrial time periods to allow annual and shorter time delays to be observed. To evaluate the relationship of hantavirus transmission with mean temperature and precipitation we used dynamic regression analysis. We found a significant association between HPS incidence and lagged rainfall and temperature with a delay of 2 to 6 months. For the biannual and quarterly models, hantavirus transmission was positively associated with lagged rainfall and temperature; whereas the bimestrial models indicate a direct relationship with the rainfall but inverse for temperature in the second lagged period.

Conclusions/Significance

This work demonstrates that climate variability plays a significant role in the transmission of hantavirus in northwestern Argentina. The model developed in this study provides a basis for the forecast of potential HPS outbreaks based on climatic parameters. Our findings are valuable for the development of public health policies and prevention strategies to mitigate possible outbreaks. Nonetheless, a surveillance program on rodent population dynamics would lead to a more accurate forecast of HPS outbreaks.

Hantavirus pulmonary syndrome (HPS) is a Pan-American emerging disease with a high mortality rate caused by a rodent-borne virus. In Argentina, almost half of the HPS infections occur in the northwestern endemic region. Most of the reported cases (75%) developed severe respiratory insufficiency, of which 30% required mechanical ventilation and 15% with a fatal outcome. In this study area, nearly half of the population is below the poverty line, particularly in rural areas, where most infections occur. Since there are no vaccines currently available nor specific therapeutic treatments, prevention of hantavirus infection involves mainly environmental management practices and educational campaigns. Our results provide a framework for the planning and implementation of early public health prevention campaigns based on the significant relationship between hantavirus outbreaks and delayed climatic variables.

Hantavirus Infection during Pregnancy

Hantavirus infection is a global health challenge, causing widespread public concern. In recent years, cases of hantavirus infection in pregnant women have been reported in many countries. The infected pregnant women and their fetuses appear to have more severe clinical symptoms and worse clinical outcomes. Hence, to study the prevalence of hantavirus infection in pregnant women, this study will focus on the epidemiological distribution of the virus, different virus species penetrating the placental barrier, and factors affecting the incidence and clinical outcome of the infection in pregnant women and their fetuses. In addition, this review will also discuss the diagnostic tools and treatments for pregnant patients and provide an overview of the relevant future research.

A Genome-Wide CRISPR-Cas9 Screen Reveals the Requirement of Host Cell Sulfation for Schmallenberg Virus Infection

Schmallenberg virus (SBV) is an insect-transmitted orthobunyavirus that can cause abortions and congenital malformations in the offspring of ruminants. Even though the two viral surface glycoproteins Gn and Gc are involved in host cell entry, the specific cellular receptors of SBV are currently unknown. Using genome-wide CRISPR-Cas9 forward screening, we identified 3'-phosphoadenosine 5'-phosphosulfate (PAPS) transporter 1 (PAPST1) as an essential factor for SBV infection. PAPST1 is a sulfotransferase involved in heparan sulfate proteoglycan synthesis encoded by the solute carrier family 35 member B2 gene (SLC35B2). SBV cell surface attachment and entry were largely reduced upon the knockout of SLC35B2, whereas the reconstitution of SLC35B2 in these cells fully restored their susceptibility to SBV infection. Furthermore, treatment of cells with heparinase diminished infection with SBV, confirming that heparan sulfate plays an important role in cell attachment and entry, although to various degrees, heparan sulfate was also found to be important to initiate infection by two other bunyaviruses, La Crosse virus and Rift Valley fever virus. Thus, PAPST1-triggered synthesis of cell surface heparan sulfate is required for the efficient replication of SBV and other bunyaviruses.IMPORTANCE SBV is a newly emerging orthobunyavirus (family Peribunyaviridae) that has spread rapidly across Europe since 2011, resulting in substantial economic losses in livestock farming. In this study, we performed unbiased genome-wide CRISPR-Cas9 screening and identified PAPST1, a sulfotransferase encoded by SLC35B2, as a host entry factor for SBV. Consistent with its role in the synthesis of heparan sulfate, we show that this activity is required for efficient infection by SBV. A comparable dependency on heparan sulfate was also observed for La Crosse virus and Rift Valley fever virus, highlighting the importance of heparan sulfate for host cell infection by bunyaviruses. Thus, the present work provides crucial insights into virus-host interactions of important animal and human pathogens.

Molecular and epidemiological characteristics of human Puumala and Dobrava-Belgrade hantavirus infections, Germany, 2001 to 2017

Introduction

Two hantavirus species, Puumala (PUUV) and Dobrava-Belgrade (DOBV) virus (genotype Kurkino), are endemic in Germany. Recent PUUV outbreaks raised questions concerning increasing frequency of outbreaks and expansion of PUUV endemic areas.

Aims

To describe the epidemiology of human PUUV and DOBV infections in Germany.

Methods

We conducted an observational retrospective study analysing national hantavirus surveillance data notified to the national public health institute and hantavirus nucleotide sequences from patients collected at the national consultation laboratory between 2001 and 2017. Matching molecular sequences with surveillance data, we conducted epidemiological, phylogenetic and phylogeographic analyses.

Results

In total, 12,148 cases of symptomatic hantavirus infection were notified 2001–17 (mean annual incidence: 0.87/100,000; range: 0.09–3.51). PUUV infections showed a highly variable space-time disease incidence pattern, causing large outbreaks every 2–3 years with peaks in early summer and up to 3,000 annually reported cases. Sex-specific differences in disease presentation were observed. Of 202 PUUV nucleotide sequences obtained from cases, 189 (93.6%) fall into well-supported phylogenetic clusters corresponding to different endemic areas in Germany. DOBV infections caused few, mostly sporadic cases in autumn and winter in the north and east of Germany.

Conclusions

The frequency of PUUV outbreaks increased between 2001 and 2017 but our data does not support the suggested expansion of endemic areas. The epidemiology of PUUV and DOBV-Kurkino infections differs in several aspects. Moreover, the latter are relatively rare and combining efforts and data of several countries to identify risk factors and develop specific recommendations for prevention could be worthwhile.

Humoral Immunity to Hantavirus Infection

Hantaviruses are pathogens that sometimes pass from animals to humans, and they are found in parts of Europe, Asia, and North and South America. When human infection occurs, these viruses can cause kidney or lung failure, and as many as 40% of infected people die. Currently, there are no vaccines or therapeutics for hantavirus-related diseases available. A first step in developing prevention measures is determining what type of immune response is protective. Increasingly it has become clear that the induction of a type of response called a neutralizing antibody response is critical for protection from severe disease. Although virologists first described this family of viruses in the 1950s, there is limited information on what features on the surface of hantaviruses are recognized by the immune system. Here, we review the current state of knowledge of this information, which is critical for the design of effective therapeutics and vaccines.

Hantaviruses are zoonotic pathogens found in parts of Europe, Asia, South America, and North America, which can cause renal and respiratory failure with fatality rates up to 40%. There are currently no FDA-approved vaccines or therapeutics for hantavirus-related diseases; however, it is evident that a robust neutralizing antibody response is critical for protection from severe disease. Although virologists first described this family of viruses in the 1950s, there is limited information on the neutralizing epitopes that exist on the hantavirus antigenic glycoproteins, Gn and Gc, and sites important for the design of effective therapeutics and vaccines. We provide a thorough summary of the hantavirus field from an immunological perspective. In particular, we discuss our current structural knowledge of antigenic proteins Gn and Gc, identification of B cell neutralizing epitopes, previously isolated monoclonal antibodies and their cross-reactivity between different hantavirus strains, and current developments toward vaccines and therapeutics. We conclude with some outstanding questions in the field and emphasize the need for additional studies of the human antibody response to hantavirus infection.

IMPORTANCE Hantaviruses are pathogens that sometimes pass from animals to humans, and they are found in parts of Europe, Asia, and North and South America. When human infection occurs, these viruses can cause kidney or lung failure, and as many as 40% of infected people die. Currently, there are no vaccines or therapeutics for hantavirus-related diseases available. A first step in developing prevention measures is determining what type of immune response is protective. Increasingly it has become clear that the induction of a type of response called a neutralizing antibody response is critical for protection from severe disease. Although virologists first described this family of viruses in the 1950s, there is limited information on what features on the surface of hantaviruses are recognized by the immune system. Here, we review the current state of knowledge of this information, which is critical for the design of effective therapeutics and vaccines.

Prevalence of the Puumala orthohantavirus Strains in the Pre-Kama Area of the Republic of Tatarstan, Russia

Puumala orthohantavirus (PUUV) causes nephropathia epidemica (NE), a mild form of hemorrhagic fever with renal syndrome (HFRS) commonly diagnosed in Europe. The majority of HFRS cases in the European part of Russia are diagnosed in the Volga Federal District, which includes the Republic of Tatarstan (RT). The current study aims to analyze the genetic variability of PUUV in Pre-Kama region of the RT bounded by the Volga, Kama, and Vyatka rivers. In 2017, bank voles were caught in seven isolated forest traps in the Pre-Kama region and for the 26 PUUV-positive samples, the partial small (S), medium (M), and large (L) genome segment sequences were obtained and analyzed. It was determined that all identified PUUV strains belong to the Russian (RUS) genetic lineage; however, the genetic distance between strains is not directly correlated with the geographical distance between bank vole populations. One of the identified strains has S and L segments produced from one parental strain, while the M segment was supplied by another, suggesting that this strain could be the reassortant. We suggest that the revealed pattern of the PUUV strains distribution could be the result of a series of successive multidirectional migratory flows of the bank voles to the Pre-Kama region in the postglacial period.

Replication in the Mononuclear Phagocyte System (MPS) as a Determinant of Hantavirus Pathogenicity

Members of different virus families including Hantaviridae cause viral hemorrhagic fevers (VHFs). The decisive determinants of hantavirus-associated pathogenicity are still enigmatic. Pathogenic hantavirus species, such as Puumala virus (PUUV), Hantaan virus (HTNV), Dobrava-Belgrade virus (DOBV), and Sin Nombre virus (SNV), are associated with significant case fatality rates. In contrast, Tula virus (TULV) only sporadically causes mild disease in immunocompetent humans and Prospect Hill virus (PHV) so far has not been associated with any symptoms. They are thus defined here as low pathogenic/apathogenic hantavirus species. We found that productive infection of cells of the mononuclear phagocyte system (MPS), such as monocytes and dendritic cells (DCs), correlated well with the pathogenicity of hantavirus species tested. HTNV (intermediate case fatality rates) replicated more efficiently than PUUV (low case fatality rates) in myeloid cells, whereas low pathogenic/apathogenic hantavirus species did not produce any detectable virus titers. Analysis of PHPUV, a reassortant hantavirus derived from a pathogenic (PUUV) and an apathogenic (PHV) hantavirus species, indicated that the viral glycoproteins are not decisive for replication in MPS cells. Moreover, blocking acidification of endosomes with chloroquine decreased the number of TULV genomes in myeloid cells suggesting a post-entry block for low pathogenic/apathogenic hantavirus species in myeloid cells. Intriguingly, pathogenic but not low pathogenic/apathogenic hantavirus species induced conversion of monocytes into inflammatory DCs. The proinflammatory programming of MPS cells by pathogenic hantavirus species required integrin signaling and viral replication. Our findings indicate that the capacity to replicate in MPS cells is a prominent feature of hantaviral pathogenicity.

Isolation and characterization of new Puumala orthohantavirus strains from Germany

Orthohantaviruses are re-emerging rodent-borne pathogens distributed all over the world. Here, we report the isolation of a Puumala orthohantavirus (PUUV) strain from bank voles caught in a highly endemic region around the city Osnabrück, north-west Germany. Coding and non-coding sequences of all three segments (S, M, and L) were determined from original lung tissue, after isolation and after additional passaging in VeroE6 cells and a bank vole-derived kidney cell line. Different single amino acid substitutions were observed in the RNA-dependent RNA polymerase (RdRP) of the two stable PUUV isolates. The PUUV strain from VeroE6 cells showed a lower titer when propagated on bank vole cells compared to VeroE6 cells. Additionally, glycoprotein precursor (GPC)-derived virus-like particles of a German PUUV sequence allowed the generation of monoclonal antibodies that allowed the reliable detection of the isolated PUUV strain in the immunofluorescence assay. In conclusion, this is the first isolation of a PUUV strain from Central Europe and the generation of glycoprotein-specific monoclonal antibodies for this PUUV isolate. The obtained virus isolate and GPC-specific antibodies are instrumental tools for future reservoir host studies.

Molecular Epidemiology and Genetic Diversity of Orthohantaviruses in Small Mammals in Western Poland

Orthohantaviruses are negative-sense, single-stranded RNA viruses harbored by multiple small mammals. Dobrava-Belgrade virus (DOBV) and Puumala virus (PUUV) cause hemorrhagic fever with renal syndrome (HFRS) in Europe. In Poland, serological surveys have demonstrated antibodies against DOBV and PUUV in patients with HFRS. Molecular evidence of DOBV and PUUV has been found in Apodemus flavicollis and Myodes glareolus, respectively, in southeastern Poland, and Seewis virus (SWSV) has been reported in Sorex araneus in central Poland. However, data on the geographic distribution and phylogeny of orthohantaviruses are unavailable for other regions in Poland. To ascertain the prevalence and genetic diversity of orthohantaviruses in western and northern Poland, lung tissues from 106 small mammals were analyzed for the presence of orthohantavirus RNA. DOBV and SWSV were detected in two of 42 (4.8%) Apodemus agrarius and in three of 10 (30%) S. araneus, respectively. Phylogenetic analyses of partial L- and S-segment sequences of DOBV indicated a shared genetic lineage with the Kurkino genotype from Slovakia, Russia, and Hungary, whereas the partial M segment of DOBV clustered with the Kurkino genotype from Germany. Phylogenetic relationships of the SWSV L and S segments showed a geographic lineage with SWSV strains from central Poland, Czech Republic, and Germany. In conclusion, the study provides insights into the molecular prevalence, phylogenetic diversity, and evolutionary relationship of DOBV in A. agrarius and SWSV in S. araneus. This report increases awareness among physicians for HFRS outbreaks in western Poland.