Levels of HTNV-specific CD8+ T lymphocytes in PBMC from the patients with hemorrhagic fever with renal syndrome

Plasma thrombomodulin is a valuable biomarker to predict the severity of hemorrhagic fever with renal syndrome caused by the Hantaan virus

Objectives

This study aimed to investigate the Thrombomodulin (TM) levels in patients who suffered hemorrhagic fever with renal syndrome (HFRS) of varying severities, and to evaluate the predictive properties of TM for the seriousness of HFRS, thereby providing a clue for the monitoring and management of this patients in the future.

Methods

Chemiluminescence was used to determine the concentrations of TM in 196 patients with HFRS and 49 healthy controls. Conventional testing techniques were used to test the basic clinical reference values for leukocytes, platelets (PLT), C-reactive protein (CRP), creatine (Cr), uric acid (UA), and urea, and the values for activated partial thromboplastin time, prothrombin time, and fibrinogen. The colloidal gold method was used to measure HFRS antibody levels in the patients. The correlation of TM with conventional parameters was assessed using Spearman correlation analysis, and ordinal logistic regression analysis was used to analyze the severity risk factors. The predictive potency of TM for HFRS patients' severity was evaluated by receiver operating characteristics (ROC) curve analysis.

Results

The concentrations of TM increased with disease severity and peaked in the critical type patients. In addition, plasma levels of TM were proportionally correlated with the levels of leukocytes (r= 0.4218; p<0.01), creatine (r= 0.3797; p<0.01), urea (r= 0.3763; p<0.01), uric acid (r= 0.3624; p<0.01), and C-reactive protein (r= 0.2767; p<0.01). Conversely, there was an inverse correlation between TM, platelet counts (r= -0.4509; p<0.01), and fibrinogen levels (r= -0.2431; p<0.01). Furthermore, TM demonstrated significant predictive value for the severity of HFRS with an area under the ROC curve (AUC) of 0.872(95% CI: 0.822-0.921, P<0.001).

Conclusions

TM levels are associated with HFRS severity, suggesting that TM detection might be beneficial for monitoring the status and effective management of HFRS patients.

In Vitro Evaluation of Bunyavirus T Cell Immunity

Characterization and quantitation of T cell responses following infection and/or vaccination can provide insight into mechanisms of host cell immunity that provide resolution of acute infection or protection from future infection or disease. While these types of studies are very advanced for viruses such as HIV, influenza, and SARS-CoV-2, they are less well developed for most of the Bunyaviruses. Cytotoxic CD8T cells are especially relevant in the context of viral infections since they recognize virus-infected cells via interaction of the T cell receptor with virally derived peptides presented in the context of MHCI. CD4T follicular cells are especially important for augmenting the antiviral antibody response. This chapter provides methods for characterizing T cell responses post infection/vaccination in both mice and humans as well as several methods for quantifying virus-specific T cells with the goal of arming bunyavirus researchers with the tools needed to move the field forward.

Single cells and TRUST4 reveal immunological features of the HFRS transcriptome

The etiology of hemorrhagic fever with renal syndrome (HFRS) is significantly impacted by a variety of immune cells. Nevertheless, the existing techniques for sequencing peripheral blood T cell receptor (TCR) or B cell receptor (BCR) libraries in HFRS are constrained by both limitations and high costs. In this investigation, we utilized the computational tool TRUST4 to generate TCR and BCR libraries utilizing comprehensive RNA-seq data from peripheral blood specimens of HFRS patients. This facilitated the examination of clonality and diversity within immune libraries linked to the condition. Despite previous research on immune cell function, the underlying mechanisms remain intricate, and differential gene expression across immune cell types and cell-to-cell interactions within immune cell clusters have not been thoroughly explored. To address this gap, we performed clustering analysis on 11 cell subsets derived from raw single-cell RNA-seq data, elucidating characteristic changes in cell subset proportions under disease conditions. Additionally, we utilized CellChat, a tool for cell-cell communication analysis, to investigate the impact of MIF family, CD70 family, and GALECTIN family cytokines-known to be involved in cell communication-on immune cell subsets. Furthermore, hdWGCNA analysis identified core genes implicated in HFRS pathogenesis within T cells and B cells. Trajectory analysis revealed that most cell subsets were in a developmental stage, with high expression of transcription factors such as NFKB and JUN in Effector CD8+ T cells, as well as in Naive CD4+ T cells and Naive B cells. Our findings provide a comprehensive understanding of the dynamic changes in immune cells during HFRS pathogenesis, identifying specific V genes and J genes in TCR and BCR that contribute to advancing our knowledge of HFRS. These insights offer potential implications for the diagnosis and treatment of this autoimmune disease.

Patient with suspected co-infection of hemorrhagic fever with renal syndrome and malaria: a case report

Background

Hemorrhagic fever with renal syndrome (HFRS) is a natural epidemic disease that can be caused by the Hantaan virus (HTNV). Malaria is caused by plasmodium and can be transmitted by a mosquito bite. The similar manifestations shared by these disorders pose a challenge for clinicians in differential diagnosis, in particular, coupled with a false-positive serological test.

Case presentation

A 46-year-old man was admitted for fever and chills for over 10 days and was suspected of being co-infected with HFRS and malaria due to a history of travel to malaria-endemic areas and a positive HTNV-immunoglobulin M (IgM) test. Although leukocytosis, thrombocytopenia, renal injury, lymphocytosis, overexpression of interleukin-6, and procalcitonin were observed during the hospitalization, the hypotensive, oliguria, and polyuria phases of the HFRS course were not observed. Instead, typical symptoms of malaria were found, including a progressive decrease in erythrocytes and hemoglobin levels with signs of anemia. Furthermore, because the patient had no history of exposure to HFRS endemic areas, exposure to an HTNV-infected rodent, or a positive HTNV-IgG test, and false serological tests of IgM can be caused by various factors, the HFRS coinfection with malaria was ruled out.

Conclusion

Misdiagnosis can be easily induced by a false serological test, in particular the IgM test which can be influenced by various factors. A combination of health history, epidemiology, physical examination, precise application of specific examinations involving tests of conventional laboratory parameters as well as well-accepted methods such as the immunochromatographic (ICG) test, real-time reverse transcription-polymerase chain reaction (PCR), and Western blot (WB), and acquaintance with disorders with similar manifestations will contribute to the precise diagnosis in clinical treatment.

The Adaptive Immune Response against Bunyavirales

The Bunyavirales order includes at least fourteen families with diverse but related viruses, which are transmitted to vertebrate hosts by arthropod or rodent vectors. These viruses are responsible for an increasing number of outbreaks worldwide and represent a threat to public health. Infection in humans can be asymptomatic, or it may present with a range of conditions from a mild, febrile illness to severe hemorrhagic syndromes and/or neurological complications. There is a need to develop safe and effective vaccines, a process requiring better understanding of the adaptive immune responses involved during infection. This review highlights the most recent findings regarding T cell and antibody responses to the five Bunyavirales families with known human pathogens (Peribunyaviridae, Phenuiviridae, Hantaviridae, Nairoviridae, and Arenaviridae). Future studies that define and characterize mechanistic correlates of protection against Bunyavirales infections or disease will help inform the development of effective vaccines.

Predictive value of CD4+CD8+ double positive T cells for the severity of hemorrhagic fever with renal syndrome

PURPOSES

We aimed to investigate the levels of CD4+CD8+ double positive (DP) T cells in patients with various severities of hemorrhagic fever with renal syndrome (HFRS), and the predictive capacity of DP T cells for the severity of this disorder.

METHODS

The levels of DP T cells in 213 patients and 48 healthy donors were measured by flow cytometry, as were the levels of CD4+ T cells, CD8+ T cells, B lymphocytes, and natural killer (NK) cells. In each type of HFRS patient, we tested the basic clinical reference values for leukocytes, platelets, creatinine (Cr), uric acid (UA), and urea, and the values for activated partial thromboplastin time, prothrombin time, and fibrinogen, using conventional methods. The colloidal gold method was used to measure HFRS antibody levels in the patients.

RESULTS

The frequency of DP T cells increased with disease severity and peaked in patients with critical disease. Furthermore, the level of DP T cells proportionally correlated with the levels of Cr, UA, and urea in the serum. In contrast, there was an inverse correlation between DP T cells and platelets. Interestingly, the pattern of change in DP T cell frequency was similar to those of CD8+ T cells, B cells, and NK cells, but an inverse tendency was observed for CD4+ T cells. DP T cells demonstrated significant predictive value for the severity of HFRS.

CONCLUSIONS

The level of DP T cells is associated with HFRS severity, suggesting that it may be a potent indicator for the course of this disorder.

The Presence of Circulating Nucleated Red Blood Cells Is Associated With Disease Severity in Patients of Hemorrhagic Fever With Renal Syndrome

Hemorrhagic fever with renal syndrome (HFRS) is a regional infectious disease of epidemic potential caused by the Hantaan virus (HTNV). Red blood cells (RBCs) are the major components of peripheral blood. However, pathological changes in RBCs and the underlying mechanisms during HTNV infection remain largely unclear. Therefore, this study sought to explore changes in RBCs in the peripheral blood of HFRS patients. We isolated PBMCs from HFRS patients and performed single-cell RNA sequencing. The results showed that clusters of RBCs in the peripheral blood of HFRS could be classified as nucleated red blood cells (NRBC) based on their cellular components, gene expression profiles and cell surface markers. In addition, it was shown that the higher the count of NRBC in peripheral blood, the more severe the disease status was. Moreover, hematological indices related to RBCs were analyzed and the results showed that impairment in the folate pathway might be the possible reason behind the presence of NRBCs. This study, for the first time showed that the presence of NRBCs in the peripheral blood of HFRS patients was associated with disease severity. This was also the first study to show that infection with the HTNV virus hindered the maturation of RBCs. Therefore, this work provides further insights on the role of and pathological changes in RBCs during HTNV infection.

Immunogenicity and safety of a modified three-dose priming and booster schedule for the Hantaan virus vaccine (Hantavax): A multi-center phase III clinical trial in healthy adults

BACKGROUND

Hemorrhagic fever with renal syndrome is a serious health problem in Eurasian countries. This study aimed to evaluate the immunogenicity and safety of formalin-inactivated Hantaan virus vaccine (Hantavax®) with a 3 + 1 vaccination schedule.

METHODS

A phase III, multi-center clinical trial was conducted to evaluate the immunogenicity and safety of Hantavax® (three primary doses and a booster dose schedule at 0, 1, 2 and 13 months) among healthy adults. Immune responses were assessed using the plaque reduction neutralizing antibody test (PRNT) and immunofluorescent antibody assay (IFA). Systemic and local adverse events were assessed.

RESULTS

A total of 320 healthy subjects aged ≥19 years were enrolled. Following three primary doses of Hantavax®, the seroconversion rate was 80.97% and 92.81% by PRNT and IFA, respectively. With booster administration, seropositive rates were 67.47% and 95.68% at one-month post-vaccination according to PRNT and IFA, respectively. Solicited local and systemic adverse events were reported in 30.50-42.81% and 16.67-33.75% during the three primary dose vaccination, while those were reported 36.57% and 21.36% after the booster doses. Both local and systemic adverse events did not increase with repeated vaccinations.

CONCLUSION

Hantavax® showed a high seroconversion rate after the three-dose priming, and additional dose administration with 11-month interval induced good booster effects. (ClinicalTrials.gov Identifier: NCT02553837).

Comparison of Lymphocyte Populations in Patients With Dobrava or Puumala orthohantavirus Infection

Hemorrhagic fever with renal syndrome (HFRS), caused by Dobrava (DOBV) and Puumala (PUUV) orthohantaviruses, is an endemic disease in Slovenia. DOBV is mainly responsible for a more severe disease, whereas PUUV usually causes a milder form. Therefore, the aim of our study was to determine whether any differences in lymphocyte population in patients infected with these two viruses exist. Mononuclear cells from peripheral blood (PBMCs) were isolated from DOBV or PUUV infected patients and different lymphocyte subpopulations were analyzed with flow cytometry. Decreased concentrations of lymphocyte subpopulation were observed in DOBV and in PUUV infected patients compared with a healthy control, which was especially evident in DOBV infected patients. The lower values of T cells are likely due to the extravasation of the activated cells from the circulation to the infected tissue. Higher percentage of NK cells were detected in DOBV infected patients in comparison to PUUV infected patients, which could be associated with a more severe HFRS caused by DOBV. PUUV infected patients had a significantly higher concentration of activated T cell subsets, expressing markers CD25, CD69, and HLA-DR in comparison to DOBV infected patients. Higher activation of T cell subsets in PUUV infected patients could be a contributor to a milder HFRS. Further studies are necessary to elucidate the relation between the protective and the harmful role of activated lymphocytes subsets in HFRS pathogenesis.

Novel Identified HLA-A*0201-Restricted Hantaan Virus Glycoprotein Cytotoxic T-Cell Epitopes Could Effectively Induce Protective Responses in HLA-A2.1/Kb Transgenic Mice May Associate with the Severity of Hemorrhagic Fever with Renal Syndrome

Hantaan virus (HTNV) infections can cause severe hemorrhagic fever with renal syndrome (HFRS) in humans, which is associated with high fatality rates. Cytotoxic T cell (CTL) responses contribute to virus elimination; however, to date, HLA class I allele-restricted HTNV glycoprotein (GP) epitopes recognized by CTLs have not been reported, limiting our understanding of CTL responses against HTNV infection in humans. In this study, 34 HTNV GP nine-mer epitopes that may bind to HLA-A*0201 molecules were predicted using the BIMAS and SYFPEITHI database. Seven of the epitopes were demonstrated to bind to HLA-A*0201 molecules with high affinity via the T2 cell binding assay and were successfully used to synthesize peptide/HLA-A*0201 tetramers. The results of tetramer staining showed that the frequencies of each epitope-specific CTL were higher in patients with milder HFRS, which indicated that the epitopes may induce protective CTL responses after HTNV infection. IFN-γ-enzyme-linked immunospot analysis further confirmed the immunoreactivity of epitopes by eliciting epitope-specific IFN-γ-producing CTL responses. In an HTNV challenge trial, significant inhibition of HTNV replication characterized by lower levels of antigens and RNA loads was observed in major target organs (liver, spleen, and kidneys) of HLA-A2.1/K^b transgenic mice pre-vaccinated with nonapeptides VV9 (aa8–aa16, VMASLVWPV), SL9 (aa996–aa1004, SLTECPTFL) and LL9 (aa358–aa366, LIWTGMIDL). Importantly, LL9 exhibited the best ability to induce protective CTL responses and showed a prominent effect on the kidneys, potentially preventing kidney injury after HTNV infection. Taken together, our results highlight that HTNV GP-derived HLA-A*0201-restricted epitopes could elicit protective CTL responses against the virus, and that epitope LL9 functions as an immunodominant protective epitope that may advance the design of safe and effective CTL-based HTNV peptide vaccines for humans.

Hemorrhagic Fever with Renal Syndrome: Pathogenesis and Clinical Picture

Hantaan virus (HTNV) causes hemorrhagic fever with renal syndrome (HFRS), which is a zoonosis endemic in eastern Asia, especially in China. The reservoir host of HTNV is field mouse (Apodemus agraricus). The main manifestation of HFRS, including acute kidney injury, increases vascular permeability, and coagulation abnormalities. In this paper, we review the current knowledge of the pathogenesis of HFRS including virus factor, immunity factor and host genetic factors. Furthermore, the treatment and prevention will be discussed.

Elevated serum levels of decoy receptor 3 are associated with disease severity in patients with hemorrhagic fever with renal syndrome

Hemorrhagic fever with renal syndrome (HFRS) is an acute viral infectious disease characterized by fever, hemorrhage and renal failure. HFRS has become a serious public health problem in China. Unfortunately, the pathogenesis of HFRS has not been completely clarified. The aim of this study is to investigate the changes of decoy receptor 3 (DcR3) and to further explore its potential roles in HFRS. The levels of serum DcR3 were measured by sandwich ELISA. We found serum DcR3 levels increased significantly, which reached peak value during the oliguric phase and in the critical group. Moreover, serum DcR3 levels were closely related to the levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and parameters reflecting kidney injury including BUN, creatinine (Cr) and proteinuria. This study indicates that high levels of serum DcR3 have associations with the disease stages, severity and degree of kidney damage. Meanwhile, our results suggest that DcR3 may play a dual role in HFRS pathogenesis. First, DcR3 is involved in the inflammatory cascade response resulting in capillary permeability and kidney injury in the early stage. Secondly, HTNV infection induced DcR3 expression at the convalescent phase may act as a feed-back mechanism in anti-inflammatory response. Thus, a study of DcR3 is essential for a better understanding of HFRS pathogenesis.