BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) is the most common zoonotic human viral disease in the Russian Federation. More than 98% of the HFRS cases are caused by Puumala orthohantavirus (PUU). Effective serological tests are required for laboratory diagnosis of HFRS.
OBJECTIVE: Construction of an enzyme immunoassay (ELISA) test system for detection of specific antibodies using standard antigen in the form of highly purified inactivated PUU virus as immunosorbent.
METHODS: Preparation of PUU virus antigen, designing the ELISA for detection of specific antibodies, developing parameters of the ELISA system, parallel titration of HFRS patients sera by fluorescent antibody technique (FAT) and the new ELISA.
CONCLUSIONS: For the first time, ELISA based on purified inactivated PUU virus as standard antigen directly absorbed onto immunoplate was developed. Parallel titration of 50 samples from HFRS patients blood sera using FAT and the developed ELISA showed high sensitivity and specificity of this ELISA, with 100% concordance of testing results and significant level of correlation between the titers of specific antibodies in the two assays.
CONCLUSIONS: The ELISA based on purified inactivated PUU virus as an immunosorbent can be effectively used for HFRS serological diagnosis and for mass seroepidemiological studies.
Введение. Геморрагическая лихорадка с почечным синдромом (ГЛПС) является наиболее распространенным зоонозным вирусным заболеванием человека на территории Российской Федерации. Более 98% заболеваемости ГЛПС вызвано ортохантавирусом Пуумала (ПУУ). Для лабораторной диагностики ГЛПС, в частности серодиагностики клинических случаев, требуются эффективные (высокочувствительные, специфичные, максимально объективные и быстрые в исполнении) серологические тесты, разработка которых является важнейшим элементом контроля данного вирусного заболевания. Цель исследования. Конструирование системы иммуноферментного анализа (ИФА) для определения специфических антител с использованием стандартного антигена в виде высокоочищенного инактивированного вируса ПУУ в качестве иммуносорбента. Материалы и методы. Получение препаратов высокоочищенного антигена вируса ПУУ, конструирование системы ИФА для определения специфических антител, отработка параметров системы ИФА, параллельное титрование сывороток крови больных ГЛПС методом флуоресцирующих антител (МФА) и новым вариантом ИФА. Результаты и обсуждение. Впервые в лабораторной практике исследования ГЛПС была сконструирована система ИФА на основе очищенного инактивированного вируса ПУУ (целевой компонент экспериментальной вакцины против ГЛПС) в качестве стандартного антигена при прямой сорбции на твердую фазу (иммунопанель). Параллельное титрование 50 образцов сывороток крови больных ГЛПС методами МФА и разработанного варианта ИФА показало высокую чувствительность и специфичность данного варианта ИФА, отмечены 100% совпадение результатов тестов (на уровне положительный/отрицательный результат) и значительный уровень корреляции величин титров специфических антител двух тестов. Заключение. Разработанный вариант ИФА для определения антител к вирусу ПУУ на основе очищенного инактивированного вируса ПУУ – целевого компонента вакцинного препарата против ГЛПС в качестве иммуносорбента – может быть эффективно использован для серодиагностики ГЛПС и массовых серо-эпидемиологических исследований.

Thrombocytopenia is a cardinal symptom of hantavirus-induced diseases including Puumala virus (PUUV)-induced hemorrhagic fever with renal syndrome (HFRS), which is associated with impaired platelet function, bleeding manifestations and augmented thrombotic risk. However, the underlying mechanisms causing thrombocytopenia and platelet hypo-responsiveness are unknown. Thus, we investigated the direct and indirect impact of PUUV on platelet production, function and degradation. Analysis of PUUV-HFRS patient blood revealed that platelet hypo-responsiveness in PUUV infection was cell-intrinsic and accompanied by reduced platelet-leukocyte aggregates (PLAs) and upregulation of monocyte tissue factor (TF), whereas platelet vasodilator-stimulated phosphoprotein (VASP) phosphorylation was comparable to healthy controls. Plasma CXCL4 levels followed platelet count dynamics throughout disease course. PUUV activated both neutrophils and monocytes in vitro, but platelet desialylation, degranulation and GPIIb/IIIa activation as well as PLA formation and endothelial adhesion under flow remained unaltered in the presence of PUUV. Further, MEG-01 megakaryocytes infected with PUUV displayed unaltered polyploidization, expression of surface receptors and platelet production. However, infection of endothelial cells with PUUV significantly increased platelet sequestration. Our data thus demonstrate that although platelet production, activation or degradation are not directly modulated, PUUV indirectly fosters thrombocytopenia by sequestration of platelets to infected endothelium. Upregulation of immunothrombotic processes in PUUV-HFRS may further contribute to platelet dysfunction and consumption. Given the pathophysiologic similarities of hantavirus infections, our findings thus provide important insights into the mechanisms underlying thrombocytopenia and highlight immune-mediated coagulopathy as potential therapeutic target.

Molecular detection of Orthohantavirus puumalaense (PUUV) RNA during the course of the disease has been studied in blood of patients in Sweden and Slovenia. The use of urine has been poorly investigated. The aims of this work were to study PUUV RNA detection in plasma from a cohort of patients in France where a different PUUV lineage circulates and to assess the use of urine instead of plasma. Matched plasma and urine samples were collected daily from hospitalized patients presenting with fever, pain, and thrombocytopenia within the last 8 days and testing positive for IgM and IgG against PUUV in serum collected at inclusion and/or approximately 1 month after release. RNA was extracted from samples, and PUUV RNA was detected using real-time reverse transcription-PCR for plasma and urine samples. Sixty-seven patients presented a serologically confirmed acute hantavirus infection. At inclusion, PUUV RNA was detected in plasma from 55 of 62 patients (88.7%) sampled within the first week after disease onset, whereas it was detected in 15 of 60 (25.0%) of matched urine samples. It was then detected from 33 (71.7%) and 2 (4.4%) of 46 patients discharged from the hospital during the second week after disease onset, in plasma and urine, respectively. When PUUV RNA was detected in urine it was also detected in plasma, and not vice versa. Detection of PUUV RNA in plasma from hospitalized patients in France is similar to that observed in Sweden and Slovenia. Urine is not an appropriate sample for this detection.

The clinical outcome of Puumala hantavirus (PUUV) infection shows extensive variation, ranging from inapparent subclinical infection (70-80%) to severe hemorrhagic fever with renal syndrome (HFRS), with about 0.1% of cases being fatal. Most hospitalized patients experience acute kidney injury (AKI), histologically known as acute hemorrhagic tubulointerstitial nephritis. Why this variation? There is no evidence that there would be more virulent and less virulent variants infecting humans, although this has not been extensively studied. Individuals with the human leukocyte antigen (HLA) alleles B*08 and DRB1*0301 are likely to have a severe form of the PUUV infection, and those with B*27 are likely to have a benign clinical course. Other genetic factors, related to the tumor necrosis factor (TNF) gene and the C4A component of the complement system, may be involved. Various autoimmune phenomena and Epstein-Barr virus infection are associated with PUUV infection, but hantavirus-neutralizing antibodies are not associated with lower disease severity in PUUV HFRS. Wide individual differences occur in ocular and central nervous system (CNS) manifestations and in the long-term consequences of nephropathia epidemica (NE). Numerous biomarkers have been detected, and some are clinically used to assess and predict the severity of PUUV infection. A new addition is the plasma glucose concentration associated with the severity of both capillary leakage, thrombocytopenia, inflammation, and AKI in PUUV infection. Our question, \"Why this variation?\" remains largely unanswered.

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.

Puumala hantavirus (PUUV) causes most cases of haemorrhagic fever with renal syndrome (HFRS) in Europe. PUUV infection is characterised by acute kidney injury, thrombocytopenia and increased capillary leakage. Typical symptoms are fever, headache, nausea, abdominal and back pain. This study aimed to evaluate the amount and distribution of intraperitoneal, retroperitoneal and pleural fluid and the association of fluid collections to the symptoms and clinical findings in patients with acute PUUV infection.
Abdominal magnetic resonance imaging (MRI) was performed on 27 hospitalised patients with acute PUUV infection. The clinical and laboratory findings and patients\' symptoms were analysed in relation to the imaging findings. The thickness of the fluid collections was measured in millimetres (mm) from axial images.
Fluid collections were found in all patients. The amount of intraperitoneal fluid correlated positively with plasma C-reactive protein (CRP) level (r = 0.586, p = .001), while it had an inverse correlation with serum creatinine concentration (r = -0.418, p = .030). Retroperitoneal fluid also correlated inversely with serum creatinine and cystatin C concentrations (r = -0.501, p = .008 and r = -0.383, p = .048, respectively). The amount of fluid was not greater in patients with abdominal or back pain. Patients with back pain had higher serum creatinine compared with patients without back pain, 452 µmol/L (range 88-1071) vs. 83 µmol/L (range 60-679), p = .004.
Fluid collections were found in all patients. A greater amount of intraperitoneal fluid associates with higher CRP concentrations but not with higher serum creatinine levels. Back pain associates with higher creatinine level but not with the presence of fluids.

Several viral infections are associated with acute and long-term complications. During the past two years, there have been many reports on post-infectious symptoms of the patients suffering from COVID-19 disease. Serious complications occasionally occur during the acute phase of Puumala orthohantavirus caused nephropathia epidemica. Severe long-term consequences are rare. Fatigue for several weeks is quite common. Hormonal insufficiencies should be excluded if the patient does not recover normally.

Puumala hantavirus (PUUV) causes hemorrhagic fever with renal syndrome. Characteristic clinical findings include acute kidney injury (AKI), thrombocytopenia, and capillary leakage. Smoking increases the risk of severe AKI, but it is not known whether alcohol consumption predisposes patients to a more severe infection. Liver and pancreatic enzymes, as well as biomarkers of alcohol consumption (gamma-glutamyl transferase, GGT; carbohydrate-deficient transferrin, CDT; GGT-CDT combination; and ethyl glucuronide, EtG), were measured from 66 patients with acute PUUV infection during hospitalization and at the convalescence phase. Alcohol consumption was present in 41% of the study population, 15% showing signs of heavy drinking. Alcohol use did not affect the severity of PUUV induced AKI nor the overall clinical picture of the infection. Liver enzyme levels (GGT or alanine aminotransferase, ALT) were elevated in 64% of the patients, but the levels did not associate with the markers reflecting the severity of the disease. Serum amylase activities at the convalescent stage were higher than those at the acute phase (p < 0.001). No cases with acute pancreatitis were found. In conclusion, our findings indicate that alcohol consumption does not seem to affect the clinical course of an acute PUUV infection.

Old-world orthohantaviruses cause hemorrhagic fever with renal syndrome (HFRS), characterized by acute kidney injury (AKI) with transient proteinuria. It seems plausible that proteinuria during acute HFRS is mediated by the disruption of the glomerular filtration barrier (GFB) due to vascular leakage, a hallmark of orthohantavirus-caused diseases. However, direct infection of endothelial cells by orthohantaviruses does not result in increased endothelial permeability, and alternative explanations for vascular leakage and diminished GFB function are necessary. Vascular integrity is partly dependent on an intact endothelial glycocalyx, which is susceptible to cleavage by heparanase (HPSE). To understand the role of glycocalyx degradation in HFRS-associated proteinuria, we investigated the levels of HPSE in urine and plasma during acute, convalescent and recovery stages of HFRS caused by Puumala orthohantavirus. HPSE levels in urine during acute HFRS were significantly increased and strongly associated with the severity of AKI and other markers of disease severity. Furthermore, increased expression of HPSE was detected in vitro in orthohantavirus-infected podocytes, which line the outer surfaces of glomerular capillaries. Taken together, these findings suggest the local activation of HPSE in the kidneys of orthohantavirus-infected patients with the potential to disrupt the endothelial glycocalyx, leading to increased protein leakage through the GFB, resulting in high amounts of proteinuria.

Puumala hantavirus (PUUV) causes hemorrhagic fever with renal syndrome. We aimed to evaluate whether ABO and rhesus blood groups associate with the susceptibility or the severity of PUUV infection. We analyzed blood groups in 289 adult patients treated in Tampere University hospital due to PUUV infection during the years 1982-2017. Patients\' blood group distribution was compared to that of healthy, voluntary blood donors living in the Tampere University Hospital responsibility area (n = 21,833). The severity of PUUV infection, as judged by the severity of acute kidney injury (AKI), thrombocytopenia, inflammation, capillary leakage, and the length of hospital care, was analyzed across the groups. The ABO and rhesus blood group distributions did not differ between the patients and blood donors. Patients with non-O blood groups had lower systolic blood pressure compared to patients with blood group O, but there was no difference in other markers of capillary leakage or in the severity of AKI. Minor deviations in the number of platelets and leukocytes were detected between the O and non-O blood groups. To conclude, patients with blood group O may be less susceptible to hypotension, but otherwise blood groups have no major influences on disease susceptibility or severity during acute PUUV infection.