Dobrava-Belgrade virus: Phylogeny, epidemiology, disease

Hybrid capture-based next-generation sequencing of new and old world Orthohantavirus strains and wild-type Puumala isolates from humans and bank voles

Orthohantaviruses, transmitted primarily by rodents, cause hemorrhagic fever with renal syndrome (HFRS) in Eurasia and hantavirus pulmonary syndrome in the Americas. These viruses, with documented human-to-human transmission, exhibit a wide case-fatality rate, 0.5-40 %, depending on the virus species, and no vaccine or effective treatment for severe Orthohantavirus infections exists. In Europe, the Puumala virus (PUUV), carried by the bank vole Myodes glareolus, causes a milder form of HFRS. Despite the reliance on serology and PCR for diagnosis, the three genomic segments of Swedish wild-type PUUV have yet to be completely sequenced. We have developed a targeted hybrid-capture method aimed at comprehensive genomic sequencing of wild-type PUUV isolates and the identification of other Orthohantaviruses. Our custom-designed panel includes >11,200 probes covering the entire Orthohantavirus genus. Using this panel, we sequenced complete viral genomes from bank vole lung tissue, human plasma samples, and cell-cultured reference strains. Analysis revealed that Swedish PUUV isolates belong to the Northern Scandinavian lineage, with nucleotide diversity ranging from 2.8 % to 3.7 % among them. Notably, no significant genotypic differences were observed between the viral sequences from reservoirs and human cases except in the nonstructural protein. Despite the high endemicity of PUUV in Northern Sweden, these are the first complete Swedish wild-type PUUV genomes and substantially increase our understanding of PUUV evolution and epidemiology. The panel's sensitivity enables genomic sequencing of human samples with viral RNA levels reflecting the natural progression of infection and underscores our panel's diagnostic value, and could help to uncover novel Orthohantavirus transmission routes.

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

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.

Phylogenetic Characterization of Orthohantavirus dobravaense (Dobrava Virus)

We report complete coding sequences of Orthohantavirus dobravaense (Dobrava virus) Igneada strains and phylogenetic characterization of all available complete coding sequences. Our analyses suggested separation of host-dependent lineages, followed by geographic clustering. Surveillance of orthohantaviruses using complete genomes would be useful for assessing public health threats from Dobrava virus.

Visual analysis of global hemorrhagic fever with renal syndrome research from 1980 to 2022: Based on CiteSpace and VOSviewer

OBJECTIVE

The development and current state of hemorrhagic fever with renal syndrome (HFRS) over the past 40 years are analyzed in this study, along with explored and discovered the hotspots and frontiers in the field, which serve as the foundation for future investigation.

METHODS

CiteSpace and VOSviewer analysis software were used to visually analyze the literature data on HFRS from 1980 to 2022, including the annual number of publications, countries and research institutions, authors, co-cited literature and keywords.

RESULTS

The number of pertinent papers published in the field of HFRS displayed an overall upward trend from 1980 to 2022. The United States, China, Germany, Sweden, and France are the top 5 countries in terms of publishing volume, with high intermediate centrality mainly concentrated in Europe and the United States. The top 10 co-occurring keywords were hemorrhagic fever, renal syndrome, infection, virus, epidemic, nephropathia epidemical, disease, hantavirus, outbreak, and transmission. According to keyword cluster analysis, there were 4 main research fields. In the HFRS-related study, there were mainly 21 notable keywords and "Korean hemorrhagic fever" had the highest hemorrhagic value (28.87).

CONCLUSION

The United States, China, Germany, Sweden and other countries attached great importance to the HFRS-related research. Moreover, the collaboration between authors and institutions in various collaborator clusters should be strengthened. In recent decades, investigations have focused on the study of viral infection and the clinical symptoms and pathophysiology of HFRS. Future research may concentrate on factors affecting host population distribution and density, such as vaccine development and meteorological factors pertaining to virus transmission.

Hemorrhagic Fever with Renal Syndrome Patients Exhibit Increased Levels of Lipocalin-2, Endothelin-1 and NT-proBNP

Hemorrhagic fever with renal syndrome (HFRS) is an acute zoonotic disease caused by viruses of the Orthohantavirus genus. This syndrome is characterized by renal and cardiopulmonary implications detectable with different biomarkers. Here, we explored the role of serum and urine levels of lipocalin-2, endothelin-1 and N-terminal pro-brain natriuretic peptide (NT-proBNP) in HFRS pathology. A total of twenty-eight patients hospitalized due to a Puumala orthohantavirus infection were included, with serum and urine samples collected on patient admission (acute phase) and discharge (convalescent phase). In comparison to healthy individuals, patients exhibited significantly higher acute-phase serum and urine levels of lipocalin-2, serum levels of endothelin-1 and serum and urine levels of NT-proBNP. Patients in the convalescent phase showed a significant decrease in urine lipocalin-2, serum endothelin-1 and serum and urine NT-proBNP levels. We recorded a strong correlation between serum levels of lipocalin-2 and endothelin-1 and urine levels of lipocalin-2 with several kidney injury markers, such as serum creatinine, urea, urine white blood cell count and proteinuria. We also demonstrated an independent correlation of serum and urine lipocalin-2 levels with acute kidney injury in HFRS. All in all, our results show an involvement of NT-proBNP, lipocalin-2 and endothelin-1 in the renal and cardiac pathology of HFRS.

Hantavirus in humans: a review of clinical aspects and management

Hantavirus infections are part of the broad group of viral haemorrhagic fevers. They are also recognised as a distinct model of an emergent zoonotic infection with a global distribution. Many factors influence their epidemiology and transmission, such as climate, environment, social development, ecology of rodent hosts, and human behaviour in endemic regions. Transmission to humans occurs by exposure to infected rodents in endemic areas; however, Andes hantavirus is unique in that it can be transmitted from person to person. As hantaviruses target endothelial cells, they can affect diverse organ systems; increased vascular permeability is central to pathogenesis. The main clinical syndromes associated with hantaviruses are haemorrhagic fever with renal syndrome (HFRS), which is endemic in Europe and Asia, and hantavirus cardiopulmonary syndrome (HCPS), which is endemic in the Americas. HCPS and HFRS are separate clinical entities, but they share several features and have many overlapping symptoms, signs, and pathogenic alterations. For HCPS in particular, clinical outcomes are highly associated with early clinical suspicion, access to rapid diagnostic testing or algorithms for presumptive diagnosis, and prompt transfer to a facility with critical care units. No specific effective antiviral treatment is available.

Identification and characterization of codon usage pattern and influencing factors in HFRS-causing hantaviruses

Hemorrhagic fever with renal syndrome (HFRS) is an acute viral zoonosis carried and transmitted by infected rodents through urine, droppings, or saliva. The etiology of HFRS is complex due to the involvement of viral factors and host immune and genetic factors which hinder the development of potential therapeutic solutions for HFRS. Hantaan virus (HTNV), Dobrava-Belgrade virus (DOBV), Seoul virus (SEOV), and Puumala virus (PUUV) are predominantly found in hantaviral species that cause HFRS in patients. Despite ongoing prevention and control efforts, HFRS remains a serious economic burden worldwide. Furthermore, recent studies reported that the hantavirus nucleocapsid protein is a multi-functional protein and plays a major role in the replication cycle of the hantavirus. However, the precise mechanism of the nucleoproteins in viral pathogenesis is not completely understood. In the framework of the current study, various in silico approaches were employed to identify the factors influencing the codon usage pattern of hantaviral nucleoproteins. Based on the relative synonymous codon usage (RSCU) values, a comparative analysis was performed between HFRS-causing hantavirus and their hosts, suggesting that HTNV, DOBV, SEOV, and PUUV, were inclined to evolve their codon usage patterns that were comparable to those of their hosts. The results indicated that most of the overrepresented codons had AU-endings, which revealed that mutational pressure is the major force shaping codon usage patterns. However, the influence of natural selection and geographical factors cannot be ignored on viral codon usage bias. Further analysis also demonstrated that HFRS causing hantaviruses adapted host-specific codon usage patterns to sustain successful replication and transmission chains within hosts. To our knowledge, no study to date reported the factors influencing the codon usage pattern within hantaviral nucleoproteins. Thus, the proposed computational scheme can help in understanding the underlying mechanism of codon usage patterns in HFRS-causing hantaviruses which lend a helping hand in designing effective anti-HFRS treatments in future. This study, although comprehensive, relies on in silico methods and thus necessitates experimental validation for more solid outcomes. Beyond the identified factors influencing viral behavior, there could be other yet undiscovered influences. These potential factors should be targets for further research to improve HFRS therapeutic strategies.

Discovering common pathogenic processes between COVID-19 and HFRS by integrating RNA-seq differential expression analysis with machine learning

Zoonotic virus spillover in human hosts including outbreaks of Hantavirus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) imposes a serious impact on the quality of life of patients. Recent studies provide a shred of evidence that patients with Hantavirus-caused hemorrhagic fever with renal syndrome (HFRS) are at risk of contracting SARS-CoV-2. Both RNA viruses shared a higher degree of clinical features similarity including dry cough, high fever, shortness of breath, and certain reported cases with multiple organ failure. However, there is currently no validated treatment option to tackle this global concern. This study is attributed to the identification of common genes and perturbed pathways by combining differential expression analysis with bioinformatics and machine learning approaches. Initially, the transcriptomic data of hantavirus-infected peripheral blood mononuclear cells (PBMCs) and SARS-CoV-2 infected PBMCs were analyzed through differential gene expression analysis for identification of common differentially expressed genes (DEGs). The functional annotation by enrichment analysis of common genes demonstrated immune and inflammatory response biological processes enriched by DEGs. The protein-protein interaction (PPI) network of DEGs was then constructed and six genes named RAD51, ALDH1A1, UBA52, CUL3, GADD45B, and CDKN1A were identified as the commonly dysregulated hub genes among HFRS and COVID-19. Later, the classification performance of these hub genes were evaluated using Random Forest (RF), Poisson Linear Discriminant Analysis (PLDA), Voom-based Nearest Shrunken Centroids (voomNSC), and Support Vector Machine (SVM) classifiers which demonstrated accuracy >70%, suggesting the biomarker potential of the hub genes. To our knowledge, this is the first study that unveiled biological processes and pathways commonly dysregulated in HFRS and COVID-19, which could be in the next future used for the design of personalized treatment to prevent the linked attacks of COVID-19 and HFRS.

Phylogeographic analysis of Tula hantavirus highlights a single introduction to central Europe

Orthohantaviruses are zoonotic pathogens of humans, unique among the bunyaviruses in not being transmitted by an arthropod vector. Tula orthohantavirus (TULV) is an old-world hantavirus, of yet unclear human pathogenicity, with few reported cases of clinically relevant human infection. So far, phylogeographic studies exploring the global pathways of hantaviral migration are scarce and generally do not focus on a specific hantavirus species. The aim of the present study was to reconstruct the dispersal history of TULV lineages across Eurasia based on S segment sequences sampled from different geographic areas. Maximum-likelihood and Bayesian inference methods were used to perform the phylogenetic analysis and phylogeographic reconstructions. Sampling time and trapping localities were obtained for a total of 735 TULV S segment sequences available in public databases at the time of the study. The estimated substitution rate of the analyzed partial S segment alignment was 2.26 × 10-3 substitutions/site/year (95 per cent highest posterior density interval: 1.79 × 10-3 to 2.75 × 10-3). Continuous phylogeography of TULV S segment sequences placed the potential root and origin of TULV spread in the Black Sea region. In our study, we detect a single-lineage introduction of TULV to Europe, followed by local viral circulation further on.

Comprehensive computational analysis reveals YXXΦ[I/L/M/F/V] motif and YXXΦ-like tetrapeptides across HFRS causing Hantaviruses and their association with viral pathogenesis and host immune regulation

Hemorrhagic fever with renal syndrome (HFRS) is an acute zoonotic disease transmitted through aerosolized excrement of rodents. The etiology of HFRS is complex due to the involvement of viral factors and host immune and genetic factors. The viral species that dominantly cause HFRS are Puumala virus (PUUV), Seoul virus (SEOV), Dobrava-Belgrade virus (DOBV), and Hantaan virus (HTNV). Despite continuous prevention and control measures, HFRS remains a significant public health problem worldwide. The nucleocapsid protein of PUUV, SEOV, DOBV, and HTNV is a multifunctional viral protein involved in various stages of the viral replication cycle. However, the exact role of nucleoproteins in viral pathogenesis is yet to be discovered. Targeting a universal host protein exploited by most viruses would be a game-changing strategy that offers broad-spectrum solutions and rapid epidemic control. The objective of this study is to understand the replication and pathogenesis of PUUV, SEOV, DOBV, and HTNV by targeting tyrosine-based motif (YXXΦ[I/L/M/F/V]) and YXXΦ-like tetrapeptides. In the light of the current study, in silico analysis uncovered many different YXXΦ[I/L/M/F/V] motifs and YXXΦ-like tetrapeptides within nucleoproteins of PUUV, SEOV, DOBV, and HTNV. Following that, the 3D structures of nucleoproteins were predicted using AlphaFold2 to map the location of YXXΦ[I/L/M/F/V] motif and YXXΦ-like tetrapeptides in a 3D environment. Further, in silico analysis and characterization of Post Translational Modifications (PTMs) revealed multiple PTMs sites within YXXΦ[I/L/M/F/V] motif and YXXΦ-like tetrapeptides, which contribute to virulence and host immune regulation. Our study proposed that the predicted YXXΦ[I/L/M/F/V] motif and YXXΦ-like tetrapeptides may confer specific functions such as virulence, host immune regulation, and pathogenesis to nucleoproteins of PUUV, SEOV, DOBV, and HTNV. However, in vivo and in vitro studies on YXXΦ[I/L/M/F/V] motif and YXXΦ-like tetrapeptides will assign new biological roles to these antiviral targets.

Adenosine Deaminase is a Potential Molecular Marker for Diagnosis and Prognosis of Haemorrhagic Fever with Renal Syndrome

Objective

Haemorrhagic fever with renal syndrome (HFRS) is a serious zoonotic disease which seriously endangers physical health and mainly occurs in China. To date, there is still a lack of early and novel biomarkers to detect the severity of disease and prognosis of HFRS. This study was aimed to examine the value of the serum Adenosine deaminase (ADA) concentrations in the patients with HFRS.

Methods

The clinical and laboratory data of 124 adult patients with HFRS and 131 patients with similar clinical symptoms to HFRS were analyzed. A receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of ADA in HFRS.

Results

The ADA levels in the serum of HFRS patients were significantly higher than those in control patients (P < 0.001), and ADA has a strong positive correlation with HFRS (r = 0.785, P < 0.001). The optimal cut-off value of ADA for diagnosis of HFRS was 18 U/L and the area under the curve (AUC) was 0.953 (95% CI: 0.925, 0.981). The sensitivity was 84.8%, the specificity was 93.1%, the positive predictive value was 92.2%, the negative predictive value was 86.5% and the Youden index was 77.9%. Serum ADA levels in patients with HFRS tended to decrease at discharge compared with those at admission.

Conclusion

ADA could be a potential molecular marker for diagnosis and prognosis of HFRS patients.

Monitoring Urban Zoonotic Virus Activity: Are City Rats a Promising Surveillance Tool for Emerging Viruses?

Urban environments represent unique ecosystems where dense human populations may come into contact with wildlife species, some of which are established or potential reservoirs for zoonotic pathogens that cause human diseases. Finding practical ways to monitor the presence and/or abundance of zoonotic pathogens is important to estimate the risk of spillover to humans in cities. As brown rats (Rattus norvegicus) are ubiquitous in urban habitats, and are hosts of several zoonotic viruses, we conducted longitudinal sampling of brown rats in Vienna, Austria, a large population center in Central Europe. We investigated rat tissues for the presence of several zoonotic viruses, including flaviviruses, hantaviruses, coronaviruses, poxviruses, hepatitis E virus, encephalomyocarditis virus, and influenza A virus. Although we found no evidence of active infections (all were negative for viral nucleic acids) among 96 rats captured between 2016 and 2018, our study supports the findings of others, suggesting that monitoring urban rats may be an efficient way to estimate the activity of zoonotic viruses in urban environments.

[Infection outbreak among German and Finish troups in Eastern Lapland during World War II - First description of hantavirus disease in the German language area]

Eight decades ago, a report on "a swamp fever-like disease in German troups in Lapland" was published in this journal. The disease outbreak had occurred in 1942 and affected more than 1000 soldiers at the Finish front. The published, precise analysis of the clinical picture was obviously the first description of hantavirus disease in the German language area. Nowadays, hantavirus disease - in Central and Northern Europe also known as Nephropathia epidemica - is one of the most frequent notifiable virus diseases in Germany and Finland.

Electrochemical determination of hantavirus using gold nanoparticle-modified graphene as an electrode material and Cu-based metal-organic framework assisted signal generation

An electrochemical biosensor was prepared for nucleic acid-based hantavirus detection using a Cu-based metal-organic framework (CuMOF) as a signal tag. The CuMOF was synthesized by the solvothermal method and then covalently bonded with signal DNA (sDNA) probes. The Au nanoparticles and reduced graphene oxide composite were deposited on the electrode surface by electroreduction as support substrate and was then functionalized with capture DNA (cDNA) probes by self-assembly. Through the complementary base pairing, the target DNA (tDNA) fragment of hantavirus hybridized with the cDNA and the sDNA in a sandwich-type format. The tDNA was detected according to the current signal of the CuMOF catalyzed reaction using o-phenylenediamine as redox substrate. The peak current of the biosensor at - 0.55 V increased linearly in proportion to the logarithmic value of the tDNA concentration from 10^-15 to 10^-9 mol/L, with a detection limit of 0.74 × 10^-15 mol/L. Moreover, the proposed biosensor was successfully applied to detect hantavirus and was able to distinguish hantavirus from other arboviruses.

A comprehensive screening of the whole proteome of hantavirus and designing a multi-epitope subunit vaccine for cross-protection against hantavirus: Structural vaccinology and immunoinformatics study

Hantaviruses are an emerging zoonotic group of rodent-borne viruses that are having serious implications on global public health due to the increase in outbreaks. Since there is no permanent cure, there is increasing interest in developing a vaccine against the hantavirus. This research aimed to design a robust cross-protective subunit vaccine using a novel immunoinformatics approach. After careful evaluation, the best predicted cytotoxic & helper T-cell and B-cell epitopes from nucleocapsid proteins, glycoproteins, RdRp proteins, and non-structural proteins were considered as potential vaccine candidates. Among the four generated vaccine models with different adjuvant, the model with toll-like receptor-4 (TLR-4) agonist adjuvant was selected because of its high antigenicity, non-allergenicity, and structural quality. The selected model was 654 amino acids long and had a molecular weight of 70.5 kDa, which characterizes the construct as a good antigenic vaccine candidate. The prediction of the conformational B-lymphocyte (CBL) epitope secured its ability to induce the humoral response. Thereafter, disulfide engineering improved vaccine stability. Afterwards, the molecular docking confirmed a good binding affinity of -1292 kj/mol with considered immune receptor TLR-4 and the dynamics simulation showed high stability of the vaccine-receptor complex. Later, the in silico cloning confirmed the better expression of the constructed vaccine protein in E. coli K12. Finally, in in silico immune simulation, significantly high levels of immunoglobulin M (IgM), immunoglobulin G1 (IgG1), cytotoxic & helper T lymphocyte (CTL & HTL) populations, and numerous cytokines such as interferon-γ (IFN-γ), interleukin-2 (IL-2) etc. were found as coherence with actual immune response and also showed faster antigen clearance for repeated exposures. Nonetheless, experimental validation can demonstrate the safety and cross-protective ability of the proposed vaccine to fight against hantavirus infection.

Seroprevalence of Old World Hantaviruses and Crimean Congo Hemorrhagic Fever Viruses in Human Populations in Northwestern Ukraine

In Ukraine, a retrospective review of clinical case reports by public health officials suggest that human cases of febrile illnesses associated with hemorrhage may be due to infections of Crimean-Congo hemorrhagic fever virus (CCHFV) and Old World hantaviruses. In a serosurvey of 966 healthy individuals in the Lviv Oblast, Ukraine, bordering Poland, we found that 1.6% showed cross-reactivity to hantaviral antigens by an immunofluorescence assay (IFA) and 1.7% of the study participants had antibodies cross-reactive to CCHFV by enzyme-linked immunosorbent assay (ELISA). Demographic variables and history of exposures obtained through questionnaires were assessed by logistic regression models for association with seroprevalence for both viruses with no significant risk factors found. Analysis of spatial distribution identified two clusters of samples positive for antibodies to both hantaviruses and CCHFV, which, however, were not statistically significant (p > 0.05). In general, the study results suggest that the population of the study area is exposed to hantaviruses and CCHFV. Further surveillance for respective pathogens in Ukraine is warranted and prospective surveillance of febrile patients with unidentified febrile illness.

Genetic diversity and evolution of Hantaan virus in China and its neighbors

BACKGROUND

Hantaan virus (HTNV; family Hantaviridae, order Bunyavirales) causes hemorrhagic fever with renal syndrome (HFRS), which has raised serious concerns in Eurasia, especially in China, Russia, and South Korea. Previous studies reported genetic diversity and phylogenetic features of HTNV in different parts of China, but the analyses from the holistic perspective are rare.

METHODOLOGY AND PRINCIPAL FINDINGS

To better understand HTNV genetic diversity and gene evolution, we analyzed all available complete sequences derived from the small (S) and medium (M) segments with bioinformatic tools. Eleven phylogenetic groups were defined and showed geographic clustering; 42 significant amino acid variant sites were found, and 19 of them were located in immune epitopes; nine recombinant events and eight reassortments with highly divergent sequences were found and analyzed. We found that sequences from Guizhou showed high genetic divergence, contributing to multiple lineages of the phylogenetic tree and also to the recombination and reassortment events. Bayesian stochastic search variable selection analysis revealed that Heilongjiang, Shaanxi, and Guizhou played important roles in HTNV evolution and migration; the virus may originate from Zhejiang Province in the eastern part of China; and the virus population size expanded from the 1980s to 1990s.

CONCLUSIONS/SIGNIFICANCE

These findings revealed the original and evolutionary features of HTNV, which will help to illustrate hantavirus epidemic trends, thus aiding in disease control and prevention.

Orthohantavirus Pathogenesis and Cell Tropism

Orthohantaviruses are zoonotic viruses that are naturally maintained by persistent infection in specific reservoir species. Although these viruses mainly circulate among rodents worldwide, spill-over infection to humans occurs. Orthohantavirus infection in humans can result in two distinct clinical outcomes: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). While both syndromes develop following respiratory transmission and are associated with multi-organ failure and high mortality rates, little is known about the mechanisms that result in these distinct clinical outcomes. Therefore, it is important to identify which cell types and tissues play a role in the differential development of pathogenesis in humans. Here, we review current knowledge on cell tropism and its role in pathogenesis during orthohantavirus infection in humans and reservoir rodents. Orthohantaviruses predominantly infect microvascular endothelial cells (ECs) of a variety of organs (lungs, heart, kidney, liver, and spleen) in humans. However, in this review we demonstrate that other cell types (e.g., macrophages, dendritic cells, and tubular epithelium) are infected as well and may play a role in the early steps in pathogenesis. A key driver for pathogenesis is increased vascular permeability, which can be direct effect of viral infection in ECs or result of an imbalanced immune response in an attempt to clear the virus. Future studies should focus on the role of identifying how infection of organ-specific endothelial cells as well as other cell types contribute to pathogenesis.

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.

Dynamics of Puumala hantavirus outbreak in Black Sea Region, Turkey

BACKGROUND

Some of the hantavirus species in Euro-Asia cause haemorrhagic fever with renal syndrome (HFRS) in humans. The first documented human hantavirus infection in Turkey was diagnosed in 2009. This report describes the dynamics of the first hantavirus outbreak that emerged in humans in the Western Black Sea Region of Turkey.

METHODS

All the suspected cases of hantavirus infection were admitted to the Infectious Diseases and Clinical Microbiology Department at the Zonguldak Bülent Ecevit University Hospital in Zonguldak, Turkey. The patients were carefully interviewed, examined and evaluated using routine laboratory tests and hantavirus diagnostic tools. Hantavirus-reactive antibodies (IgM and IgG) in serum samples were detected via enzyme immune assay (EIA) and immunofluorescence assay (IFA) in the acute and convalescence stages of the disease. The presence of hantavirus ribonucleic acid (RNA) was analysed via reverse transcription polymerase chain reaction (RT-PCR) in serum and urine samples. A focus reduction neutralization test (FRNT) was performed to confirm specific hantavirus serotypes. In addition, a case-control study was conducted to identify possible risk factors for hantavirus transmission in the outbreak area. A control group was composed of asymptomatic individuals who were seronegative for hantavirus IgM and IgG and living in the outbreak area.

RESULTS

A total of 55 suspected cases of hantavirus infection were admitted to the inpatient clinic between February and June of 2009. Twenty-four patients were diagnosed with acute HFRS via EIA or IFA. In 22 of the 24 infected patients, Puumala virus (PUUV) was identified as the causative hantavirus type by detecting IgM in the acute stage and an increase in the IgG level in follow-up serum samples. PUUV was also verified as the infecting agent by FRNT in two of the 24 cases. Among the 24 laboratory-confirmed HFRS cases, 21 (87.5%) were males and 3 (12.5%) were females, and the mean age was 45.92 years (standard deviation ± 16.90 years). Almost all these individuals were living in villages or rural areas. The 24 HFRS cases were matched with 26 healthy controls for statistical analyses and according to binary logistic regression analysis, and dealing with rodent control activities in gardens or in annexes of their homes (p = 0.021 and Odds ratio [OR] = 17.11) and being male (p = 0.019 and OR = 22.37) were detected as statistically significant risk factors for hantavirus infection. The most commonly observed clinical complaints were fatigue (95.8%), shivering (91.7%), fever (87.1%), headache (70.8%) and nausea (70.8%). Haemodialysis was required for four patients (16.7%). Except for the first case diagnosed with acute hantavirus infection, no patient died. The mean delay time to hospital admission from initiation of symptoms was 5.3 days, the mean duration of febrile days was 2.6 days, and the mean duration of hospital stay was 8.5 days.

CONCLUSION

Hantaviruses are circulating in Turkey and causing sporadic or epidemic infection in humans. Additional investigations are needed to better understand the dynamics of hantaviruses in this country.

Molecular characterization of Dobrava-Belgrade hantavirus in Serbia, 2007-2011

BACKGROUND

Hantaviruses are etiological agents of emerging zoonotic diseases worldwide, including hemorrhagic fever with renal syndrome (HFRS). A number of hantavirus species is known to be present in Europe. In Serbia, existing data on hantavirus presence and prevalence rely in serological findings. In this study, molecular analysis was performed in order to characterize HFRS causing hantaviruses in Serbia.

METHODS

Sixty four serum samples of HFRS cases, previously found seropositive to anti-hantaviral antibodies, were included in the study. Partial hantaviral L and S segments were PCR amplified producing 390nt and 598nt amplicons, respectively, in parallel with human beta-actin mRNA as external reverse transcription positive control. Hantavirus specific PCR products were DNA sequenced in both direction and the obtained sequences phylogenetically confirmed and analyzed.

RESULTS

PCR detection of hantavirus L and S genome segments was positive in 18/64 and 11/64 tested samples, respectively. Positive PCR results involved samples obtained from different locations, mostly from central and southern parts of Serbia. All the obtained sequences were identified as Dobrava-Belgrade virus (DOBV). In the phylogenetic analysis sequences from Serbia tended to cluster in distinctive, geographically related clusters.

CONCLUSIONS

Our findings indicate DOBV as the main HFRS causing hantavirus in Serbia, the site of its initial isolation.

Orthohantaviruses belonging to three phylogroups all inhibit apoptosis in infected target cells

Orthohantaviruses, previously known as hantaviruses, are zoonotic viruses that can cause hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS) in humans. The HPS-causing Andes virus (ANDV) and the HFRS-causing Hantaan virus (HTNV) have anti-apoptotic effects. To investigate if this represents a general feature of orthohantaviruses, we analysed the capacity of six different orthohantaviruses – belonging to three distinct phylogroups and representing both pathogenic and non-pathogenic viruses – to inhibit apoptosis in infected cells. Primary human endothelial cells were infected with ANDV, HTNV, the HFRS-causing Puumala virus (PUUV) and Seoul virus, as well as the putative non-pathogenic Prospect Hill virus and Tula virus. Infected cells were then exposed to the apoptosis-inducing chemical staurosporine or to activated human NK cells exhibiting a high cytotoxic potential. Strikingly, all orthohantaviruses inhibited apoptosis in both settings. Moreover, we show that the nucleocapsid (N) protein from all examined orthohantaviruses are potential targets for caspase-3 and granzyme B. Recombinant N protein from ANDV, PUUV and the HFRS-causing Dobrava virus strongly inhibited granzyme B activity and also, to certain extent, caspase-3 activity. Taken together, this study demonstrates that six different orthohantaviruses inhibit apoptosis, suggesting this to be a general feature of orthohantaviruses likely serving as a mechanism of viral immune evasion.

Emerging Rodent-Borne Viral Zoonoses in Trento, Italy

Rodent-borne hanta- and arenaviruses are an emerging public health threat in Europe; however, their circulation in human populations is usually underestimated since most infections are asymptomatic. Compared to other European countries, Italy is considered 'low risk' for these viruses, yet in the Province of Trento, two pathogenic hantaviruses (Puumala and Dobrava-Belgrade virus) and one arenavirus (Lymphocytic Choriomeningitis Virus) are known to circulate in rodent reservoirs. In this paper, we performed a follow-up serological screening in humans to detect variation in the prevalence of these three viruses compared to previous analyses carried out in 2002. We also used a statistical model to link seropositivity to risk factors such as occupational exposure, cutting firewood, hunting, collecting mushrooms, having a garden and owning a woodshed, a dog or a companion rodent. We demonstrate a significant increase in the seroprevalence of all three target viruses between 2002 and 2015, but no risk factors that we considered were significantly correlated with this increase. We conclude that the general exposure of residents in the Alps to these viruses has probably increased during the last decade. These results provide an early warning to public health authorities, and we suggest more detailed diagnostic and clinical investigations on suspected cases.

Two cases of imported hemorrhagic fever with renal syndrome and systematic review of literature

Many factors are involved in the epidemiology of hemorrhagic fever with renal syndrome (HFRS). Imported cases, as well as those by emigrants, have been reported in literature worldwide. Our goal is to document two cases of HFRS, imported by two immigrants from two countries, and to make a review of the imported HFRS literature data. We performed a systematic literature review (PRISMA guidelines) of imported cases of HFRS and herein describe our two clinical cases. We found 20 published papers, with 16 of them in English and 4 in other languages. Twenty-three patients with travel- or immigration-associated HFRS, including our two cases, were identified. We included only papers that were in English. The average age of the patients was 35.9 ± 15.13 years, and the ratio of male to female was 8:1. Imported disease from Europe to Europe occurred in seven cases, America to Europe occurred in four cases, Europe to America occurred in two cases, America to America occurred in two cases, Asia to Asia in one case, Asia to Europe in one case, and Europe to Asia in one case. The results of the two cited cases are based on the clinical-laboratory, anamnestic, and serologic data for both the patients who tested positive for HFRS. Our systematic analysis shows that international travelers are important sources of infectious diseases. HFRS related to travel and immigration is a rare event. Principal risk factors for travelers and immigrants are camping outside recommended areas or under unsuitable conditions. In recent years, various publications have shown that international travelers and immigrants have expanded the spectrum of imported infectious diseases. The literature data show that the actual reported numbers of imported case of HFRS are limited.

Molecular epidemiology of Dobrava-Belgrade virus in Greece

In order to gain an insight into the genetic relatedness of the Dobrava-Belgrade virus (DOBV) in Greece, a phylogenetic analysis was performed based on all currently available DOBV sequences obtained from hospitalized cases with hemorrhagic fever with renal syndrome (HFRS). Most cases occurred in northwestern and north central part of the country. Two sequence datasets consisted of 41 S and 12 M partial DOBV RNA segment sequences were analyzed. All DOBV strains belong to Dobrava genotype which is associated with the rodent Apodemus flavicollis. In both phylogenetic trees (S and M segments), two main clusters of Greek strains could be distinguished. Phylogenetic analysis showed a spatial rather than temporal relation of the strains, since their genetic clustering was highly associated with the geographic distribution of the cases. Besides previous characterized endemic foci, novel ones have been identified, expanding our knowledge on the epidemiology of HFRS in Greece.

Population dynamics of wild rodents induce stochastic fadeouts of a zoonotic pathogen

Stochastic processes play an important role in the infectious disease dynamics of wildlife, especially in species subject to large population oscillations. Here, we study the case of a free ranging population of yellow-necked mice (Apodemus flavicollis) in northern Italy, where circulation of Dobrava-Belgrade hantavirus (DOBV) has been detected intermittently since 2001, until an outbreak emerged in 2010. We analysed the transmission dynamics of the recent outbreak using a computational model that accounts for seasonal changes of the host population and territorial behaviour. Model parameters were informed by capture-mark-recapture data collected over 14 years and longitudinal seroprevalence data from 2010 to 2013. The intermittent observation of DOBV before 2010 can be interpreted as repeated stochastic fadeouts after multiple introductions of infectious rodents migrating from neighbouring areas. We estimated that only 20% of introductions in a naïve host population results in sustained transmission after 2 years, despite an effective reproduction number well above the epidemic threshold (mean 4·5, 95% credible intervals, CI: 0·65-15·8). Following the 2010 outbreak, DOBV has become endemic in the study area, but we predict a constant probability of about 4·7% per year that infection dies out, following large population drops in winter. In the absence of stochastic fadeout, viral prevalence is predicted to continue its growth to an oscillating equilibrium around a value of 24% (95% CI: 3-57). We presented an example of invasion dynamics of a zoonotic virus where stochastic fadeout have played a major role and may induce future extinction of the endemic infection.

Recombinant DNA vaccine of Hantavirus Gn and LAMP1 induced long-term immune protection in mice

BACKGROUND

Prophylaxis is widely adopted the best choice against Hemorrhagic fever with renal syndrome (HFRS) caused by Hantavirus. However, loss of memory immune response maintenance remains as major shortcoming in current HFRS vaccine. A recombinant DNA vaccine, pVAX-LAMP/Gn was previously proved efficient, requiring long-term evaluations.

METHODS & RESULTS

Immune responses of Balb/c mice were assessed by specific and neutralizing antibodies, interferon-γ ELISpot assay, and cytotoxic T-lymphocyte cytotoxicity assay. HTNV-challenge assay identified long-term protection. Safety was confirmed by histological and behavioral analysis. Epitope-spreading phenomenon was noted, revealing two sets of dominant T-cell epitopes cross-species.

CONCLUSION

pVAX-LAMP/Gn established memory responses within a long-term protection. Lysosome-targeted strategy showed promise on Gn-based DNA vaccine and further investigations are warranted in other immunogenic Hantaviral antigens.

Hantavirus infection: a global zoonotic challenge

Hantaviruses are comprised of tri-segmented negative sense single-stranded RNA, and are members of the Bunyaviridae family. Hantaviruses are distributed worldwide and are important zoonotic pathogens that can have severe adverse effects in humans. They are naturally maintained in specific reservoir hosts without inducing symptomatic infection. In humans, however, hantaviruses often cause two acute febrile diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). In this paper, we review the epidemiology and epizootiology of hantavirus infections worldwide.

The assessment of Hantaan virus-specific antibody responses after the immunization program for hemorrhagic fever with renal syndrome in northwest China

Xianyang city is one of the main hemorrhagic fever with renal syndrome (HFRS) epidemic areas in northwest China. Although the HFRS immunity program has been provided in this city, HFRS is still occurred every year. In order to implement the vaccination program effectively and to control HFRS, the analysis of antibody responses specific to Hantaan virus (HTNV) in individuals after vaccination is essential. In this study, a total of 100 subjects were divided into 5 groups: unvaccinated, 1, 3, 29 and 33 months after boost vaccination. The levels and the positive rates of HTNV-NP-specific IgM and IgG antibodies as well as HTNV neutralizing antibodies were significantly increased in the serum of the vaccinated individuals. The positive rates and levels of HTNV-NP-specific IgG and HTNV neutralizing antibody reached their highest values at 3 months respectively and could be sustained up to 33 months after vaccination. Moreover, the titres of HTNV-NP-specific IgM or IgG antibody and the titres of HTNV neutralizing antibody at 1 month after vaccination have a positive correlation. The level of HTNV-NP-specific IgG antibody was much higher than that of HTNV-NP-specific IgM antibody or HTNV neutralizing antibody. In addition, the strongest responses of antibody-secreting cells were observed at 3 months after vaccination, which was consistent with the serum results. Therefore, the HFRS immunization program is effective to induce humoral immunity in the population of northwest China.

Immune response in Dobrava-Belgrade virus infections

Dobrava-Belgrade virus (DOBV) is a hantavirus that causes a disease in humans known as hemorrhagic fever with renal syndrome. Hallmarks of hantaviral infections are increased vascular permeability due to dysregulation of the endothelial cell barrier and acute thrombocytopenia. In order to gain insight into the immune response in DOBV infections, the serum levels of 27 cytokines in 24 hospitalized Greek HFRS patients were evaluated. Compared to the control group, significantly higher IL-1ra, IL-6, IL-8, IL-9, IL-10, GM-CSF, IP-10, MIP-1b, TNF-α and VEGF levels were found in severe cases, while in non-severe cases, IL-13 and TNF-α levels were significantly higher (p < 0.05). In all groups, IP-10 was increased and RANTES was decreased. Significant and time- (after onset of illness) dependent differences among fatal, severe and non-severe cases were seen. VEGF was positively associated with disease severity. A strong immune response was seen during the first week of illness, especially in severe cases, while the response in non-severe cases was weaker and delayed. The Th1 response was strong in non-severe cases and weak in the fatal case, while a mixed Th1/Th2 immune response was seen in the survivors of severe disease.

Companion Animals as a Source of Viruses for Human Beings and Food Production Animals

Companion animals comprise a wide variety of species, including dogs, cats, horses, ferrets, guinea pigs, reptiles, birds and ornamental fish, as well as food production animal species, such as domestic pigs, kept as companion animals. Despite their prominent place in human society, little is known about the role of companion animals as sources of viruses for people and food production animals. Therefore, we reviewed the literature for accounts of infections of companion animals by zoonotic viruses and viruses of food production animals, and prioritized these viruses in terms of human health and economic importance. In total, 138 virus species reportedly capable of infecting companion animals were of concern for human and food production animal health: 59 of these viruses were infectious for human beings, 135 were infectious for food production mammals and birds, and 22 were infectious for food production fishes. Viruses of highest concern for human health included hantaviruses, Tahyna virus, rabies virus, West Nile virus, tick-borne encephalitis virus, Crimean-Congo haemorrhagic fever virus, Aichi virus, European bat lyssavirus, hepatitis E virus, cowpox virus, G5 rotavirus, influenza A virus and lymphocytic choriomeningitis virus. Viruses of highest concern for food production mammals and birds included bluetongue virus, African swine fever virus, foot-and-mouth disease virus, lumpy skin disease virus, Rift Valley fever virus, porcine circovirus, classical swine fever virus, equine herpesvirus 9, peste des petits ruminants virus and equine infectious anaemia virus. Viruses of highest concern for food production fishes included cyprinid herpesvirus 3 (koi herpesvirus), viral haemorrhagic septicaemia virus and infectious pancreatic necrosis virus. Of particular concern as sources of zoonotic or food production animal viruses were domestic carnivores, rodents and food production animals kept as companion animals. The current list of viruses provides an objective basis for more in-depth analysis of the risk of companion animals as sources of viruses for human and food production animal health.

Conserved Endonuclease Function of Hantavirus L Polymerase

Hantaviruses are important emerging pathogens belonging to the Bunyaviridae family. Like other segmented negative strand RNA viruses, the RNA-dependent RNA polymerase (RdRp) also known as L protein of hantaviruses lacks an intrinsic "capping activity". Hantaviruses therefore employ a "cap snatching" strategy acquiring short 5' RNA sequences bearing 5'cap structures by endonucleolytic cleavage from host cell transcripts. The viral endonuclease activity implicated in cap snatching of hantaviruses has been mapped to the N-terminal domain of the L protein. Using a combination of molecular modeling and structure-function analysis we confirm and extend these findings providing evidence for high conservation of the L endonuclease between Old and New World hantaviruses. Recombinant hantavirus L endonuclease showed catalytic activity and a defined cation preference shared by other viral endonucleases. Based on the previously reported remarkably high activity of hantavirus L endonuclease, we established a cell-based assay for the hantavirus endonuclase function. The robustness of the assay and its high-throughput compatible format makes it suitable for small molecule drug screens to identify novel inhibitors of hantavirus endonuclease. Based on the high degree of similarity to RdRp endonucleases, some candidate inhibitors may be broadly active against hantaviruses and other emerging human pathogenic Bunyaviruses.

Genetic detection of hantaviruses in rodents, Albania

In order to have a first insight into the epidemiology of hantaviruses in Albania, 263 small mammals (248 rodents, 15 insectivores) were captured in 352 locations in 29 districts and tested for hantavirus infection. Dobrava-Belgrade virus (DOBV) was detected in 10 of 148 (6.7%) Apodemus flavicollis rodents. DOBV-positive A. flavicollis were detected in six districts (Diber, Korce, Kolonje, Librazhd, Pogradec, and Vlore). The obtained nucleotide sequences were highly similar to each other and to DOBV sequences from northwestern Greece. Understanding the epidemiology of hantaviruses and identifying the endemic foci enables the public health strategies to minimize the risk of human infection. J. Med. Virol. 88:1309-1313, 2016. © 2016 Wiley Periodicals, Inc.

Two clinical cases of renal syndrome caused by Dobrava/Saaremaa hantaviruses imported to the Netherlands from Poland and Belarus, 2012-2014

We report the rare event of two imported cases in the Netherlands presenting with renal syndrome caused by Dobrava (DOBV)/Saaremaa (SAAV) hantaviruses. DOBV/SAAV hantaviruses are not circulating in the Netherlands and their clinical manifestation is typically more severe than that of the endemic Puumala virus (PUUV). This report aims to increase awareness among healthcare professionals and diagnostic laboratories to consider different hantaviruses as a cause of renal failure.

Construction and evaluation of DNA vaccine encoding Hantavirus glycoprotein N-terminal fused with lysosome-associated membrane protein

BACKGROUND

Hantaviral diseases can have a high case fatality rate within the absence of broadly effective antiviral treatments or vaccines. We developed a DNA vaccine targeting the Hantavirus glycoprotein N-terminal (Gn) to major histocompatibility complex class II compartment by fusing the antigen with lysosome-associated membrane protein 1 (LAMP1), which altered antigen presenting pathway and activated the CD4+ T cells.

METHODS

The segments of Gn and LAMP1 were cloned into vector pVAX1, and recombinant plasmid was constructed by inserting Gn sequence into LAMP1, between luminal and the transmembrane/cytoplasmic domains. Subsequently, the protein expression was identified through immunoprecipitation, western blot and Immunofluorescent assay. Adaptive immune responses were assessed by the presence of specific and neutralizing antibodies, interferon (ELISpot results, and cytotoxic T-lymphocyte (CTL) cytotoxicity. Epitope mapping was performed to study the T-cell epitopes. Protective immunity in vivo was evaluated using a novel HTNV-challenging model, and safety evaluation was based on histological and behavioral observations.

RESULTS

Native or LAMP1 targeting HTNV Gn was successfully identified. Humoral immune responses were enhanced, featuring with satisfying titers of specific and neutralizing antibody production. The boosted activities of IFN-γ and CTL cytotoxicity witnessed enhanced cellular immune responses. Effective protection against HTNV in vivo was conferred in all three vaccine groups by the challenge model. Safety was confirmed and one dominant T-cell epitope screened from immunized mice overlapped the specific T-cell hot spot in HFRS patients.

CONCLUSION

LAMP1 targeting strategy successfully enhanced the efficacy of HTNV Gn-based vaccine, which is highly immunogenic and safe, showing promise for immunoprophylaxis against HFRS. Further investigations are warranted in the future.

Hantaviruses--globally emerging pathogens

Hantaviruses are emerging zoonotic viruses which cause human disease in Africa, America, Asia, and Europe. This review summarizes the progress in hantavirus epidemiology and diagnostics during the previous decade. Moreover, we discuss the influence of ecological factors on the worldwide virus distribution and give an outlook on research perspectives for the next years.

Viral hemorrhagic fever cases in the country of Georgia: Acute Febrile Illness Surveillance Study results

Minimal information is available on the incidence of Crimean-Congo hemorrhagic fever (CCHF) virus and hantavirus infections in Georgia. From 2008 to 2011, 537 patients with fever ≥ 38°C for ≥ 48 hours without a diagnosis were enrolled into a sentinel surveillance study to investigate the incidence of nine pathogens, including CCHF virus and hantavirus. Of 14 patients with a hemorrhagic fever syndrome, 3 patients tested positive for CCHF virus immunoglobulin M (IgM) antibodies. Two of the patients enrolled in the study had acute renal failure. These 2 of 537 enrolled patients were the only patients in the study positive for hantavirus IgM antibodies. These results suggest that CCHF virus and hantavirus are contributing causes of acute febrile syndromes of infectious origin in Georgia. These findings support introduction of critical diagnostic approaches and confirm the need for additional surveillance in Georgia.

Genetic analysis of Dobrava-Belgrade virus from western Serbia--a newly detected focus in the Balkan Peninsula

Dobrava-Belgrade virus (DOBV) is a hantavirus species that causes the most severe form of haemorrhagic fever with renal syndrome (HFRS) in Europe. DOBV has been detected in three Apodemus rodents: A. flavicollis, A. agrarius and A. ponticus. These emerging viruses appear throughout the Balkan Peninsula including Serbia as its central part. In this study, we examined the seroprevalence, molecular epidemiology and phylogenetics of DOBV from A. flavicollis captured at six Serbian localities. Furthermore, we applied microsatellite typing of host animal genome to analyse the role of host kinship in DOBV animal transmission. The overall IgG seropositivity rate over 3 years (2008-2010) was 11.9% (22/185). All seropositive samples were subjected to RT-PCR and DNA sequencing for S and L genome segments (pos. 291-1079 nt and 2999-3316 nt, respectively). DOBV was genetically detected in three samples from mountain Tara in western Serbia, a newly detected DOBV focus in the Balkans. No sequence data from human cases from Serbia are available for the studied period. However, collected DOBV isolates in this work phylogenetically clustered together with isolates from Serbian human cases dating from 2002, with 1.9% nucleotide divergence. We determined the level of kinship between seropositive and seronegative animal groups and found no significant difference, suggesting that horizontal virus transmission in the studied population was the same within and among the hatches. Our findings are the first genetic detection of DOBV in rodents in Serbia. We confirm wide and continuous hantavirus presence in the examined parts of the Balkans, underlying the necessity of continual monitoring of hantavirus circulation in A. flavicollis.

Genetic detection of Dobrava-Belgrade hantavirus in the edible dormouse (Glis glis) in central Serbia

Hantaviruses are endemic in the Balkans, particularly in Serbia, where sporadic cases and/or outbreaks of hantaviral human disease have been reported repeatedly, and evidenced serologically. Here, we present genetic detection of Dobrava-Belgrade virus (DOBV) hantaviral sequences in wild rodents trapped in central Serbia. All the animals were pre-screened serologically by indirect immunofluorescence (IF) test and only those with a positive finding of hantaviral antigens were further tested by polymerase chain reaction. Of the total of 104 trapped animals, 20 were found to be IF positive and of those three were positive for hantaviral RNA: one Microtus arvalis for Tula virus, and one each of Apodemus agrarius and Glis glis for DOBV. Phylogenetic analysis of the obtained sequences implies putative DOBV spillover infection of A. agrarius and G. glis from Apodemus flavicollis. However, future investigations should help to identify the most common natural host and geographical distribution of DOBV in its reservoir hosts in Serbia.

Dobrava virus carried by the yellow-necked field mouse Apodemus flavicollis, causing hemorrhagic fever with renal syndrome in Romania

Hemorrhagic fever with renal syndrome (HFRS) has been confirmed by serological methods during recent years in Romania. In the present study, focus-reduction neutralization tests (FRNT) confirmed Dobrava hantavirus (DOBV) as the causative agent in some HFRS cases, but could not distinguish between DOBV and Saaremaa virus (SAAV) infections in other cases. DOBV was detected by a DOBV-specific TaqMan assay in sera of nine patients out of 22 tested. Partial sequences of the M genomic segment of DOBV were obtained from sera of three patients and revealed the circulation of two DOBV lineages in Romania. Investigation of rodents trapped in Romania found three DOBV-positive Apodemus flavicollis out of 83 rodents tested. Two different DOBV lineages were also detected in A. flavicollis as determined from partial sequences of the M and S genomic segments. Sequences of DOBV in A. flavicollis were either identical or closely related to the sequences obtained from the HFRS patients. The DOBV strains circulating in Romania clustered in two monophyletic groups, together with strains from Slovenia and the north of Greece. This is the first evidence for the circulation of DOBV in wild rodents and for a DOBV etiology of HFRS in Romania.

Identification of hantavirus infection by Western blot assay and TaqMan PCR in patients hospitalized with acute kidney injury

Hantaviruses, one of the causative agents of viral hemorrhagic fevers, represent a considerable healthcare threat. In Hungary, Dobrava-Belgrade virus (DOBV) and Puumala virus (PUUV) are the main circulating hantavirus species, responsible for the clinical picture known as hemorrhagic fever with renal syndrome, a disease that may be accompanied by acute kidney injury (AKI), requiring hospitalization with occasionally prolonged recovery phase. A total of 20 patient sera were collected over a 2-year period from persons hospitalized with AKI, displaying clinical signs and laboratory findings directly suggestive for hantavirus infection. Samples were tested using an immunoblot assay, based on complete viral nucleocapsid proteins to detect patients' IgM and IgG antibodies against DOBV and PUUV. In parallel, all specimens were also tested by 1-step real-time TaqMan reverse-transcriptase polymerase chain reaction to confirm infection and to determine the causative hantavirus genotype. We present here the first Hungarian clinical study spanning across 2 years and dedicated specifically to assess acute kidney injuries, in the context of hantavirus prevalence.

Hantavirus disease in Germany due to infection with Dobrava-Belgrade virus genotype Kurkino

Members of the Dobrava-Belgrade virus (DOBV) species are hantaviruses carried by different Apodemus mice as reservoir hosts and causing haemorrhagic fever with renal syndrome (HFRS) in humans. In Central Europe, the Kurkino genotype of DOBV, associated with the striped field mouse, Apodemus agrarius, is prevalent. This paper presents the first extensive study of the serological and molecular diagnostics, epidemiology and clinics of DOBV-Kurkino infections in Central Europe. Serum samples from 570 German patients living in the habitat of A. agrarius (north and northeast Germany) and exhibiting febrile disease, were analysed. All samples were tested by ELISA, subsets of samples were also analysed by immunoblot, neutralization assay, and RT-PCR. A group of 86 individuals was confirmed as DOBV-infected. The virus neutralization assay allowed a reliable identification of DOBV antibodies during both acute and convalescent phases of infection. However, differentiation of relevant DOBV genotypes was not possible by neutralization test but required molecular analysis. Whereas DOBV IgM antibodies tend to persist in the infected organism, RNAaemia seems to be short. Nucleotide sequences were amplified from four patients, and their analysis demonstrated infection by DOBV-Kurkino. With respect to the initial results, the high degree of identity of local patient-derived and A. agrarius-derived virus sequences may allow a closer allocation of the geographical place where the human infection occurred. In contrast to moderate/severe HFRS caused by the DOBV genotypes Dobrava or Sochi, all available data showed a mild clinical course of HFRS caused by DOBV-Kurkino infection without lethal outcomes.

Vascular endothelial growth factor levels in dobrava/belgrade virus infections

The levels of vascular endothelial growth factor-A (VEGF) were estimated in 102 serum samples from 63 hospitalized Greek patients with hemorrhagic fever with renal syndrome (HFRS) caused by Dobrava/Belgrade virus. Significantly higher VEGF levels were seen in the severe when compared with non-severe cases (mean values 851.96 pg/mL and 326.75 pg/mL, respectively; p = 0.003), while a significant difference was observed among groups based on the day after the onset of illness. In both severe and non-severe cases, VEGF peaked in the second week of illness; however, elevation of VEGF in the severe cases started later and remained high until convalescence, suggesting that the role of VEGF was associated with repair of vascular damage rather than with increased permeability.

Phylogeography and evolutionary history of rodent-borne hantaviruses

Hantavirus (Family Bunyaviridae) are mostly associated to rodents and transmitted to man by inhalation of aerosolized infected excreta of these animals. The human infection by hantaviruses can lead to severe diseases such as hemorrhagic fever with renal syndrome (HFRS) in Asia and Europe, and pulmonary syndrome (HPS) in the Americas. To determine the origin, spreading and evolutionary dynamics of rodent-borne hantaviruses, 190 sequences of nucleoprotein (N) of hantaviruses identified in 30 countries, from 1985 to 2010, were retrieved from the GenBank and analyzed using the BEAST program. Our evolutionary analysis indicates that current genetic diversity of N gene of rodent-borne hantaviruses probably was originated around 2000 years ago. Hantavirus harbored by Murinae and Arvicolinae subfamilies, probably, were originated in Asia 500-700 years ago and later spread toward Siberia, Europe, Africa and North America. Hantavirus carried by Neotominae subfamily, probably, emerged 500-600 years ago in Central America and spread toward North America. Finally, hantaviruses associated to Sigmodontinae occurred in Brazil 400 years ago and were, probably, originated from Neotominae-associated virus from northern South America. These data offer subsidies to understand the time-scale and worldwide dissemination dynamics of rodent-borne hantaviruses.

Molecular characterization of Dobrava and Kurkino genotypes of Dobrava-Belgrade hantavirus detected in Hungary and Northern Croatia

Among the Hantavirus genus, Saaremaa virus (SAAV) has been the subject of taxonomical debates. While the International Committee on Taxonomy of Viruses declares SAAV as a distinct species, several European hantavirus experts proposed that SAAV is in fact a genotype of Dobrava-Belgrade virus (DOBV). In the present study we performed S-segment-based phylogenetic analysis of eight DOBV strains identified in rodents in Hungary and Northern Croatia. These new sequences considerably increase the number of complete nucleoprotein gene sequences deposited in the NCBI database. Our phylogenetic analysis clearly support the taxonomical nomenclature recently proposed for DOBV, i.e., genotypes such as Dobrava, Saaremaa, Kurkino, and Sochi should indeed be classified within the DOBV hantavirus species. Moreover, we found that only the Dobrava and Kurkino genotypes of DOBV species are circulating in Hungary while currently there is no evidence for the presence of Saaremaa genotype.

Serum TNF-α, sTNFR1, IL-6, IL-8 and IL-10 levels in hemorrhagic fever with renal syndrome

It is generally accepted that the pathogenesis of hantavirus infections is the result of virus-mediated host immune response. Hantaviruses, and mainly Dobrava-Belgrade virus, are present in Greece, and cause to humans hemorrhagic fever with renal syndrome (HFRS). Serum IL-6, IL-8, IL-10, TNF-α and sTNFR1 levels were measured in 29 HFRS Greek patients. Significant higher sTNFR1, IL-6, IL-8 and IL-10 levels were observed in severe than in mild/moderate cases, while TNF-α did not seem to be associated with disease severity. Correlations between cytokine levels and their fluctuation over time after onset of the illness, along with comparisons from previously published data on the field, led in building an immune response pattern for HFRS.