Serum nitric oxide levels in patients with Crimean-Congo haemorrhagic fever

Cellular immunity to nucleoproteins (NP) of Crimean-Congo hemorrhagic fever virus (CCHFV) and Hazara Virus (HAZV)

Crimean-Congo Hemorrhagic Fever Virus (CCHFV) is a globally significant vector-borne pathogen with no internationally-licensed preventative and therapeutic interventions. Hazara virus (HAZV), on the other hand, a related Orthonairovirus, has not been reported as a human pathogen. HAZV has been proposed as a surrogate model for studying CCHFV, bisosafety level 4 (BSL-4) agent. Previously, we investigated the humoral immune responses between NPs of these viruses and in this study, we extended the scrutiny to cellular immune responses elicited by NPs of CCHFV and HAZV. Here, mice were immunized with recombinant CCHFV NP and HAZV NP to evaluate the correlates of cell-mediated immunity (CMI). Delayed-type hypersensitivity (DTH) responses were assessed by challenging immunized mice with CCHFV-rNP or HAZV-rNP on the footpad and lymphocyte proliferation assays (LPAs) were performed by stimulating splenocytes in vitro with CCHFV-rNP or HAZV-rNP to compare cellular immune responses. In all test groups, strong DTH and LPA responses were detected against homologous and heterologous challenging antigens. To assess the cytokine response, an RT-qPCR -specific for cytokine mRNAs was utilized. Interestingly, CCHFV NP stimulated groups exhibited a significantly elevated mRNA level of interleukin 17 A (IL-17) compared to HAZV NP, indicating a notable difference in immune responses. This study presents comparison between CMI elicited by NPs of CCHFV and HAZV and contributes to the understanding of a highly pathogenic virus, particularly in the context of the declaration of CCHFV by World Health Organization's (WHO) as a major viral threat to the world.

Exploring free amino acid profiles in Crimean-Congo hemorrhagic fever patients: Implications for disease progression

This study investigated the intricate interplay between Crimean-Congo hemorrhagic fever virus infection and alterations in amino acid metabolism. The primary aim is to elucidate the impact of Crimean-Congo hemorrhagic fever (CCHF) on specific amino acid concentrations and identify potential metabolic markers associated with viral infection. One hundred ninety individuals participated in this study, comprising 115 CCHF patients, 30 CCHF negative patients, and 45 healthy controls. Liquid chromatography-tandem mass spectrometry techniques were employed to quantify amino acid concentrations. The amino acid metabolic profiles in CCHF patients exhibit substantial distinctions from those in the control group. Patients highlight distinct metabolic reprogramming, notably characterized by arginine, histidine, taurine, glutamic acid, and glutamine metabolism shifts. These changes have been associated with the underlying molecular mechanisms of the disease. Exploring novel therapeutic and diagnostic strategies addressing specific amino acids may offer potential means to mitigate the severity of the disease.

Can Fractional Exhaled Nitric Oxide (FeNO) Serve as a Clinical Indicator for Patients Hospitalized with Crimean-Congo Hemorrhagic Fever?

Crimean-Congo hemorrhagic fever (CCHF), a zoonotic disease spread by infected viruses, can be a significant cause of morbidity and mortality in endemic areas. This prospective study aimed to establish the relationship between fractional exhaled nitric oxide (FeNO) levels and clinical prognosis of CCHF. The study included 85 participants: 55 patients followed up for CCHF from May to August 2022, and 30 healthy controls. FeNO levels were measured upon hospital admission and were 7.6 ± 3.3 parts per billion (ppb) in patients with mild/moderate CCHF, 2.5 ± 2.1 ppb in patients with severe CCHF, and 6.7 ± 1.7 ppb in the healthy control group. There was no statistically significant difference in FeNO levels between the control group and patients with mild/moderate CCHF (P = 0.09), whereas patients with severe CCHF had lower FeNO levels than those in the control group and patients with mild/moderate CCHF (P < 0.001 for both). FeNO measurement may offer a noninvasive and easily applied approach for predicting the clinical course and prognosis of CCHF in the early stages of the disease.

Crimean-Congo hemorrhagic fever virus strains Hoti and Afghanistan cause viremia and mild clinical disease in cynomolgus monkeys

BACKGROUND

Development of vaccines and therapies against Crimean-Congo hemorrhagic fever virus (CCHFV) have been hindered by the lack of immunocompetent animal models. Recently, a lethal nonhuman primate model based on the CCHFV Hoti strain was reported. CCHFV Hoti caused severe disease in cynomolgus monkeys with 75% lethality when given by the intravenous (i.v.) route.

METHODOLOGY/PRINCIPAL FINDINGS

In a series of experiments, eleven cynomologus monkeys were exposed i.v. to CCHFV Hoti and four macaques were exposed i.v. to CCHFV Afghanistan. Despite transient viremia and changes in clinical pathology such as leukopenia and thrombocytopenia developing in all 15 animals, all macaques survived to the study endpoint without developing severe disease.

CONCLUSIONS/SIGNIFICANCE

We were unable to attribute differences in the results of our study versus the previous report to differences in the CCHFV Hoti stock, challenge dose, origin, or age of the macaques. The observed differences are most likely the result of the outbred nature of macaques and low animal numbers often used by necessity and for ethical considerations in BSL-4 studies. Nonetheless, while we were unable to achieve severe disease or lethality, the CCHFV Hoti and Afghanistan macaque models are useful for screening medical countermeasures using biomarkers including viremia and clinical pathology to assess efficacy.

The protective effect and diagnostic performance of NOX-5 in Crimean-Congo haemorrhagic fever patients

INTRODUCTION

Crimean-Congo haemorrhagic fever (CCHF) is an acute viral haemorrhagic disease. Reactive oxygen species that are mainly generated by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) enzyme family have a pivotal role in the pathophysiology of many diseases. The serum levels of NOX isoforms in patients with CCHF have yet to be assessed.

METHODS

This prospective study was conducted at Cumhuriyet University, Turkey. Only patients with CCHF confirmed by the National Reference Virology Laboratory were enrolled in the study. The study subjects comprised 67 CCHF patients and 70 healthy control subjects. The quantitative sandwich ELISA technique was used for the determination of serum NOX 1, 2, 4 and 5.

RESULTS

Higher median median NOX-1 (P=0.001) and NOX-5 (P<0.001) levels were found in patients compared to the control group. Higher median serum NOX-5 levels were found in the low-grade disease group compared to the intermediate-high disease group according to two different severity scores (P=0.003). Negative correlations were also found between the serum NOX-5 levels and the severity scores [(P<0.05, r=-0.259), (P<0.01, r=-0.417)]. The area under the curve (AUC) values for the NOX-1 and NOX-5 were 0.67 (confidence interval: 0.58-0.75) and 0.99 (confidence interval: 0.95-1.00), respectively. Lower NOX-5 levels were found in patients receiving thrombocyte suspension (P=0.004)Conclusions. NOX-5 may have a protective effect on CCHF patients and the measurement of serum NOX-5 levels may be used as a novel biochemical test in the diagnosis of CCHF.

Importance of endothelial dysfunction biomarkers in patients with Crimean-Congo hemorrhagic fever

The pathogenesis of the Crimean-Congo hemorrhagic fever (CCHF) and the cause of the hemorrhage are not yet fully understood. However, the endothelium plays a key role in the pathogenesis. The purpose of this study was to investigate endothelial dysfunction markers (asymmetrical dimethyl arginine [ADMA], endothelin 1[ET-1], thrombomodulin [TM], von Willebrand factor [vWf], and intercellular adhesion molecule [ICAM-1]) in serum in patients with CCHF and their associations with hemorrhage. Seventy-three patients with CCHF were included in the study. All patients' endothelial dysfunction markers were studied using routine biochemical and hematological tests. The data obtained were then subjected to statistical analysis. Statistically significant differences were determined between the patients and healthy control groups at time of presentation to hospital in terms of ADMA (P < 0.001), ET-1 (P < 0.001), TM (P = 0.039), vWf (P < 0.001), and ICAM-1 (P < 0.001) levels. Only the differences in TM and vWf were significant between the hemorrhagic and non-hemorrhagic groups (P < 0.05). Both serum ADMA and TM levels were significantly higher in the hemorrhage and non-hemorrhage CCHF groups on the 5th day compared to the 1st day (P < 0.05). Levels of endothelial dysfunction markers in CCHF vary in proportion to the damage occurring in the endothelium. ADMA and TM levels were lower in periods with mild endothelial injury. They were increased in line with severity endothelial injury. They may be an early marker in showing hemorrhage. Elevation in ADMA levels and low nitric oxide levels lead to endothelial injury and hemorrhage. Soluble TM that entered the circulation in line with the increased endothelial injury in hemorrhagic patients has been compromised the coagulation cascade.

Evaluation of endothelium functions by flow-mediated dilatation in pediatric patients with Crimean-Congo hemorrhagic fever

BACKGROUND

Crimean-Congo hemorrhagic fever (CCHF) is a systemic viral disease that also affects the endothelium. Thrombocytopenia and hemorrhage are seen in this disease. But, the cause of thrombocytopenia is not clear. We hypothesized that endothelium dysfunction may be the cause of thrombocytopenia. We evaluated the endothelium functions by flow-mediated dilatation (FMD) in CCHF.

METHODS

Consecutive children with suspected CCHF who applied to our hospital were evaluated for recruitment into the study. FMD analysis was done in the active and healing period of the disease. Diagnosis was confirmed or ruled out by polymerase chain reaction and/or ELISA test. Basal brachial artery diameter (BBAD) and dilated brachial artery diameter (DBAD) after ischemic period were measured and percent dilatations [(DBAD-BBAD)/BBAD, FMD%] were computed from all subjects.

RESULTS

Fifty-four children (40 male, mean age 12.4 ± 4.4 years) were recruited into the study. CCHF diagnosis was confirmed in 28 children and ruled out in 26 children. Groups were similar for age and gender. FMD% was significantly decreased in CCHF patients when comparing this with the control patients in the active period (2.65 ± 2.76 vs. 13.76 ± 7.95, P < 0.001). FMD% was correlated with platelet count in the active period of the disease (r = 0.599, P = 0.004). FMD% was recovered in the healing period (2.65 ± 2.76 vs. 14.72 ± 2.66, P < 0.001) and was not significantly different from basal values of control patients (P > 0.05).

CONCLUSIONS

FMD is significantly decreased in CCHF and recovers in the healing period. So, endothelium functions are disturbed, and disturbance is correlated with thrombocytopenia in CCHF.