Cytokine levels in Crimean-Congo hemorrhagic fever

Cytokines as biomarkers of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a potentially severe disease caused by CCHF virus. As in other viral hemorrhagic fevers, it is considered that the course and outcome of the disease depend on the viral load and the balance among the immune response mediators, and that a fatal outcome is the result of a "cytokine storm." The level of 27 cytokines was measured in serum samples taken from 29 patients during the acute phase of the disease. Two cases were fatal. Among survivors, significant differences between severe and non-severe cases were observed in the levels of IP-10, and MCP-1, while the levels of IL-1b, IL-5, IL-6, IL-8, IL-9, IL-10, IL-15, IP-10, MCP-1, TNF-α, and RANTES differed significantly between fatal and non-fatal cases (P < 0.05). RANTES was negatively correlated with the outcome of the disease. A striking similarity with the cytokine patterns seen in Ebola virus disease was observed. A weak Th1 immune response was seen. The viral load was positively correlated with IL-10, IP-10, and MCP-1 levels, and negatively correlated with the ratio IL-12/IL-10. Especially IP-10 and MCP-1 were significantly associated with the viral load, the severity and outcome of the disease, and they could act as biomarkers and, probably, as potential targets for treatment strategies design.

Antibodies to the core proteins of Nairobi sheep disease virus/Ganjam virus reveal details of the distribution of the proteins in infected cells and tissues

Nairobi sheep disease virus (NSDV; also called Ganjam virus in India) is a bunyavirus of the genus Nairovirus. It causes a haemorrhagic gastroenteritis in sheep and goats with mortality up to 90%. The virus is closely related to the human pathogen Crimean-Congo haemorrhagic fever virus (CCHFV). Little is currently known about the biology of NSDV. We have generated specific antibodies against the virus nucleocapsid protein (N) and polymerase (L) and used these to characterise NSDV in infected cells and to study its distribution during infection in a natural host. Due to its large size and the presence of a papain-like protease (the OTU-like domain) it has been suggested that the L protein of nairoviruses undergoes an autoproteolytic cleavage into polymerase and one or more accessory proteins. Specific antibodies which recognise either the N-terminus or the C-terminus of the NSDV L protein showed no evidence of L protein cleavage in NSDV-infected cells. Using the specific anti-N and anti-L antibodies, it was found that these viral proteins do not fully colocalise in infected cells; the N protein accumulated near the Golgi at early stages of infection while the L protein was distributed throughout the cytoplasm, further supporting the multifunctional nature of the L protein. These antibodies also allowed us to gain information about the organs and cell types targeted by the virus in vivo. We could detect NSDV in cryosections prepared from various tissues collected post-mortem from experimentally inoculated animals; the virus was found in the mucosal lining of the small and large intestine, in the lungs, and in mesenteric lymph nodes (MLN), where NSDV appeared to target monocytes and/or macrophages.

Procalcitonin Level and Its Predictive Effect on Mortality in Crimean-Congo Hemorrhagic Fever Patients

Crimean-Congo hemorrhagic fever (CCHF) is a potentially fatal disease which is endemic to Turkey. We aimed to investigate the procalcitonin levels and their prognostic value over fatality in CCHF patients. The sera were harvested from patients who were diagnosed with CCHF within the first 2 days of the onset of their symptoms. The patients were divided into 2 groups according to their survival status: fatal or non-fatal. The biochemical and hematological parameters were studied in the Biochemistry Laboratory of Sorgun City Hospital. The sera were stored at -80℃ until testing for procalcitonin, and the procalcitonin levels were assayed by ELISA at the Biochemistry Laboratory of Kirikkale University. Forty- eight patients were included in the study, with 8 and 40 patients in the fatal and non-fatal groups, respectively. While the procalcitonin level was high in all patients in the fatal group, the same was observed in 30 patients in the non-fatal group (75%). The mean value of procalcitonin was 1.12 ng/ml in the fatal group and was 0.21 ng/ml in the non-fatal group (P = 0.003). According to the results of our study, the procalcitonin levels in the first 2 days of the onset of the symptoms might be helpful for predicting fatality in CCHF patients.

Elevated chemokine levels during adult but not pediatric Crimean-Congo hemorrhagic fever

BACKGROUND

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonosis. Clinical reports indicate the severity of CCHF is milder in children than adults. The chemokines are important chemo-attractant mediators of the host immune system.

OBJECTIVES

The main aim of the study was to identify whether or not there were any differences in chemokine levels between the pediatric and adult patients and control groups, and whether there was any correlation with disease severity.

STUDY DESIGN

The serum levels of select chemokines including chemokine (C-C) ligand 2 (CCL2), CCL3, CCL4, chemokine (C-X-C) ligand 8 (CXCL8), CXCL9, and granulocyte-colony stimulating factor (G-CSF) in 29 adult and 32 pediatric CCHF patients and in 35 healthy children and 40 healthy adult control groups were studied by flow cytometric bead immunoassay method.

RESULTS

Great variability was detected in the serum levels of the chemokines for both the adult and pediatric patients and controls. With the exception of G-CSF, the median serum levels of CCL2, CCL3, CCL4, CXCL8, and CXCL9 were found to be significantly higher in the adult patients compared to adult controls (2364.7 vs. 761 pg/ml; 714.1 vs. 75.2 pg/ml; 88.6 vs. 25.5 pg/ml; 217.9 vs. 18.3 pg/ml; 875 vs. 352.2 pg/ml, respectively, p < 0.0001 for all comparisons). Among the chemokines the median CCL4 and G-CSF levels were significantly higher in the pediatric patients compared to pediatric controls (40.3 vs. 7.1 pg/ml, p < 0.0001; 0.1 vs. 0.1 pg/ml, p = 0.049, respectively).

CONCLUSION

The results of this study showed prominent chemokine raising in adult CCHF patients compared to children CCHF patients.

Crimean-Congo hemorrhagic fever: CXCL10 correlates with the viral load

Crimean-Congo hemorrhagic fever (CCHF) is a human disease with high fatality rate. Although its pathogenesis is not elucidated yet, it is considered that cytokines play a significant role in the progression and outcome of the disease. Serum CXCL10 levels were estimated in 35 patients with acute CCHF and were correlated with the viral load, and various demographic and clinical parameters. The mean CXCL10 concentration in the patients' group was higher compared to the respective value in the control group (4421.74 pg/ml vs. 28.47 pg/ml, P < 0.05). A strong positive correlation between CXCL10 and viral load was seen (rs = 0.57, P < 0.001), while the outcome of the disease was related with the viral load (rs = 0.47, P = 0.004) and the presence of hemorrhagic manifestations (P < 0.001). The study provides an insight into the strong correlation between CXCL10 and viral load in acute CCHF cases suggesting that it plays an important role in CCHF pathogenesis.

Can serum ferritin level predict disease severity in patients with crimean-congo hemorrhagic Fever?

OBJECTIVE

Crimean-Congo hemorrhagic fever (CCHF) is an acute viral disease. Several factors have already been suggested to explain the pathogenesis as well as predict the disease severity. In our study we aim to investigate the role of serum ferritin level as a possible predicting factor of disease severity in these patients.

MATERIALS AND METHODS

We evaluated all patients with laboratory confirmed diagnosis of CCHF who were admitted to Boo-Ali Hospital of Zahedan from May 2011 to June 2012. Confirmation of the disease determined using the presence of anti- CCHFV IgM in the serum by enzyme-linked immunosorbent assay (ELISA) or by polymerase chain reaction(PCR). After ethical approval, patients were categorized into two groups of mild and severe disease according to disseminated intravascular coagulation (DIC) severity using the scoring system of International Society on Thrombosis and Hemostasis (ISTH). Serum ferritin levels were evaluated and compared between these two groups. Receiver operating characteristic (ROC) curve analysis was performed to assess the optimal cutoff value of serum ferritin for predicting the disease severity.

RESULTS

A total of 42 patients (36 men, 6 women, age range: 17-78 years) were included in this study, of whom 38% had Persian and 62% had Baloch ethnicity. According to DIC severity score, 54.7% of the patients had severe disease and 45.3% had mild disease. The area under the ROC curve was 0.896 and 95% CI was 0.801-0.991 (p<0.0001). A cut-off point of 1060 ng/dL, had a sensitivity of 78.9%, a specificity of 87%, a positive predictive value of 6% and a negative predictive value of 100%. Positive and negative likelihood ratios for this serum ferritin level were 6.05 and 0.24, respectively.

CONCLUSION

Increased serum ferritin level has a significant positive correlation with disease severity in patients with CCHF and can evaluate the prognosis of these patients with a high sensitivity and specificity.

Crimean-Congo haemorrhagic fever replication interplays with regulation mechanisms of apoptosis

Pathogenesis of viral haemorrhagic fevers is associated with alteration of vascular barrier function and haemorrhage. To date, the specific mechanism behind this is unknown. Programmed cell death and regulation of apoptosis in response to viral infection is an important factor for host or virus survival but this has not been well-studied in the case of Crimean-Congo hemorrhagic fever virus (CCHFV). In this study, we demonstrated that CCHFV infection suppresses cleavage of poly(ADP-ribose) polymerase (PARP), triggered by staurosporine early post-infection. We also demonstrated that CCHFV infection suppresses activation of caspase-3 and caspase-9. Most interestingly, we found that CCHFV N can suppress induction of apoptosis by Bax and inhibit the release of cytochrome c from the inner membrane of mitochondria to cytosol. However, CCHFV infection induces activation of Bid late post-infection, suggesting activation of extrinsic apoptotic signalling. Consistently, supernatant from cells stimulated late post-infection was found to induce PARP cleavage, most probably through the TNF-α death receptor pathway. In summary, we found that CCHFV has strategies to interplay with apoptosis pathways and thereby regulate caspase cascades. We suggest that CCHFV suppresses caspase activation at early stages of the CCHFV replication cycle, which perhaps benefits the establishment of infection. Furthermore, we suggest that the host cellular response at late stages post-infection induces host cellular pro-apoptotic molecules through the death receptor pathway.

Cytokine concentrations in pediatric patients with Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever is a zoonotic disease that can be a severe illness in humans. We investigated concentrations of interleukin (IL)-6, tumor necrosis factor-α and IL-10 in serum samples obtained from 25 pediatric Crimean-Congo hemorrhagic fever cases and 35 control children with no signs of infection. Lower cytokine values in our patients could be a good prognostic factor to for a better outcome.

Recent advances in research on Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is an expanding tick-borne hemorrhagic disease with increasing human and animal health impact. Immense knowledge was gained over the past 10 years mainly due to advances in molecular biology, but also driven by an increased global interest in CCHFV as an emerging/re-emerging zoonotic pathogen. In the present article, we discuss the advances in research with focus on CCHF ecology, epidemiology, pathogenesis, diagnostics, prophylaxis and treatment. Despite tremendous achievements, future activities have to concentrate on the development of vaccines and antivirals/therapeutics to combat CCHF. Vector studies need to continue for better public and animal health preparedness and response. We conclude with a roadmap for future research priorities.

Animal models of viral hemorrhagic fever

The term "viral hemorrhagic fever" (VHF) designates a syndrome of acute febrile illness, increased vascular permeability and coagulation defects which often progresses to bleeding and shock and may be fatal in a significant percentage of cases. The causative agents are some 20 different RNA viruses in the families Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae, which are maintained in a variety of animal species and are transferred to humans through direct or indirect contact or by an arthropod vector. Except for dengue, which is transmitted among humans by mosquitoes, the geographic distribution of each type of VHF is determined by the range of its animal reservoir. Treatments are available for Argentine HF and Lassa fever, but no approved countermeasures have been developed against other types of VHF. The development of effective interventions is hindered by the sporadic nature of most infections and their occurrence in geographic regions with limited medical resources. Laboratory animal models that faithfully reproduce human disease are therefore essential for the evaluation of potential vaccines and therapeutics. The goal of this review is to highlight the current status of animal models that can be used to study the pathogenesis of VHF and test new countermeasures.

Sequential determination of serum viral titers, virus-specific IgG antibodies, and TNF-α, IL-6, IL-10, and IFN-γ levels in patients with Crimean-Congo hemorrhagic fever

BACKGROUND

Although there have been a number of studies on the pathogenesis of Crimean-Congo hemorrhagic fever (CCHF) recently, knowledge on this topic is still insufficient. This study aims to reveal the kinetics of serum CCHF virus (CCHFV) titers, serum levels of anti-CCHFV immunoglobulin (Ig)G, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and interferon (IFN)-γ in CCHF patients.

METHODS

In total, 31 CCHF cases (11 fatal) were studied. Serum samples were obtained daily from all patients from the time of admission and continued for a 7-day hospitalization period for serologic (ELISA), virologic (real-time PCR), and cytokine (ELISA) analysis.

RESULTS

The mean serum CCHFV titer at admission was 5.5E + 09 copies/mL in fatal cases and 5.7E + 08 copies/mL in survivors (p < 0.001). Compared to survivors, both the mean serum levels of IL-6 and TNF-α at admission were found to be significantly increased in fatal cases. The serum levels of IL-6, TNF-α and serum CCHFV titer at admission were significantly and positively correlated with disseminated intravascular coagulation (DIC) scores (r = 0.626, p = 0.0002; r = 0.461, p = 0.009; and r = 0.625, p = 0.003, respectively). When the data obtained from the sequential determination of CCHFV titer and levels of anti-CCHFV IgG, IL-6, TNF-α, IL-10 and IFN-γ were grouped according to the days of illness, the initial serum CCHFV titer of a fatal patient was 5.5E + 09 (copies/mL) and it was 6.1E + 09 (copies/mL) in a survivor on the 2 day of illness. While significant alterations were observed in all cytokines during the monitoring period, IL-6 levels remained consistently higher in fatal cases and TNF-α levels increased in both in fatal and non-fatal CCHF cases.

CONCLUSIONS

The increased CCHFV load and higher concentrations of IL-6 and TNF-α, the presence of DIC, and the absence of CCHFV specific immunity are strongly associated with death in CCHF.

Importance of serum adipokine and ghrelin levels in patients with Crimean-Congo hemorrhagic fever

Crimean-Congo Hemorrhagic Fever (CCHF) may present with a mild clinical course or else exhibit a severe profile with potentially fatal hemorrhaging. The pathogenesis of the disease has not yet been well described. Cytokines have recently been investigated in order to explain the pathogenesis. The latest reports show that adipokines are powerful inflammation modulators. This study investigated the effect of adipokines (resistin, leptin, and adiponectin) and ghrelin on disease severity in CCHF patients by testing their serum levels. This retrospective study was conducted with patients with CCHF hospitalized at the Karadeniz Technical University, Medical Faculty in Turkey. Patients were divided into severe and non-severe groups. Serum adipokine levels of patients with CCHF were measured using enzyme-linked immunosorbent assay (ELISA). Fifty-three patients with confirmed CCHF were investigated. Twenty-five (47.2%) of these patients constituted the severe group. Serum resistin levels in the severe and non-severe groups were 108.9 ± 24.7 ng/ml and 77.5 ± 27.7 ng/ml (P < 0.001), leptin levels 15.5 ± 9.8 and 11.2 ± 5.1 ng/ml (P = 0.074), adiponectin levels 26.8 ± 18.9 and 27.4 ± 16.3 ng/ml (P = 0.903) and ghrelin levels 57.1 ± 48.7 and 200.9 ± 182.7 ng/ml (P = 0.001), all respectively. This study confirms that significant changes in serum levels of resistin and ghrelin take place in severe CCHF.

Evaluation of antiviral efficacy of ribavirin, arbidol, and T-705 (favipiravir) in a mouse model for Crimean-Congo hemorrhagic fever

BACKGROUND

Mice lacking the type I interferon receptor (IFNAR-/- mice) reproduce relevant aspects of Crimean-Congo hemorrhagic fever (CCHF) in humans, including liver damage. We aimed at characterizing the liver pathology in CCHF virus-infected IFNAR-/- mice by immunohistochemistry and employed the model to evaluate the antiviral efficacy of ribavirin, arbidol, and T-705 against CCHF virus.

METHODOLOGY/PRINCIPAL FINDINGS

CCHF virus-infected IFNAR-/- mice died 2-6 days post infection with elevated aminotransferase levels and high virus titers in blood and organs. Main pathological alteration was acute hepatitis with extensive bridging necrosis, reactive hepatocyte proliferation, and mild to moderate inflammatory response with monocyte/macrophage activation. Virus-infected and apoptotic hepatocytes clustered in the necrotic areas. Ribavirin, arbidol, and T-705 suppressed virus replication in vitro by ≥3 log units (IC50 0.6-2.8 µg/ml; IC90 1.2-4.7 µg/ml). Ribavirin [100 mg/(kg×d)] did not increase the survival rate of IFNAR-/- mice, but prolonged the time to death (p<0.001) and reduced the aminotransferase levels and the virus titers. Arbidol [150 mg/(kg×d)] had no efficacy in vivo. Animals treated with T-705 at 1 h [15, 30, and 300 mg/(kg×d)] or up to 2 days [300 mg/(kg×d)] post infection survived, showed no signs of disease, and had no virus in blood and organs. Co-administration of ribavirin and T-705 yielded beneficial rather than adverse effects.

CONCLUSIONS/SIGNIFICANCE

Activated hepatic macrophages and monocyte-derived cells may play a role in the proinflammatory cytokine response in CCHF. Clustering of infected hepatocytes in necrotic areas without marked inflammation suggests viral cytopathic effects. T-705 is highly potent against CCHF virus in vitro and in vivo. Its in vivo efficacy exceeds that of the current standard drug for treatment of CCHF, ribavirin.

The nairovirus nairobi sheep disease virus/ganjam virus induces the translocation of protein disulphide isomerase-like oxidoreductases from the endoplasmic reticulum to the cell surface and the extracellular space

Nairobi sheep disease virus (NSDV) of the genus Nairovirus causes a haemorrhagic gastroenteritis in sheep and goats with mortality up to 90%; the virus is found in East and Central Africa, and in India, where the virus is called Ganjam virus. NSDV is closely related to the human pathogen Crimean-Congo haemorrhagic fever virus, which also causes a haemorrhagic disease. As with other nairoviruses, replication of NSDV takes place in the cytoplasm and the new virus particles bud into the Golgi apparatus; however, the effect of viral replication on cellular compartments has not been studied extensively. We have found that the overall structure of the endoplasmic reticulum (ER), the ER-Golgi intermediate compartment and the Golgi were unaffected by infection with NSDV. However, we observed that NSDV infection led to the loss of protein disulphide isomerase (PDI), an oxidoreductase present in the lumen of the endoplasmic reticulum (ER) and which assists during protein folding, from the ER. Further investigation showed that NSDV-infected cells have high levels of PDI at their surface, and PDI is also secreted into the culture medium of infected cells. Another chaperone from the PDI family, ERp57, was found to be similarly affected. Analysis of infected cells and expression of individual viral glycoproteins indicated that the NSDV PreGn glycoprotein is involved in redistribution of these soluble ER oxidoreductases. It has been suggested that extracellular PDI can activate integrins and tissue factor, which are involved respectively in pro-inflammatory responses and disseminated intravascular coagulation, both of which manifest in many viral haemorrhagic fevers. The discovery of enhanced PDI secretion from NSDV-infected cells may be an important finding for understanding the mechanisms underlying the pathogenicity of haemorrhagic nairoviruses.

Crimean-Congo hemorrhagic fever: history, epidemiology, pathogenesis, clinical syndrome and genetic diversity

Crimean-Congo hemorrhagic fever (CCHF) is the most important tick-borne viral disease of humans, causing sporadic cases or outbreaks of severe illness across a huge geographic area, from western China to the Middle East and southeastern Europe and throughout most of Africa. CCHFV is maintained in vertical and horizontal transmission cycles involving ixodid ticks and a variety of wild and domestic vertebrates, which do not show signs of illness. The virus circulates in a number of tick genera, but Hyalomma ticks are the principal source of human infection, probably because both immature and adult forms actively seek hosts for the blood meals required at each stage of maturation. CCHF occurs most frequently among agricultural workers following the bite of an infected tick, and to a lesser extent among slaughterhouse workers exposed to the blood and tissues of infected livestock and medical personnel through contact with the body fluids of infected patients. CCHFV is the most genetically diverse of the arboviruses, with nucleotide sequence differences among isolates ranging from 20% for the viral S segment to 31% for the M segment. Viruses with diverse sequences can be found within the same geographic area, while closely related viruses have been isolated in far distant regions, suggesting that widespread dispersion of CCHFV has occurred at times in the past, possibly by ticks carried on migratory birds or through the international livestock trade. Reassortment among genome segments during co-infection of ticks or vertebrates appears to have played an important role in generating diversity, and represents a potential future source of novel viruses. In this article, we first review current knowledge of CCHFV, summarizing its molecular biology, maintenance and transmission, epidemiology and geographic range. We also include an extensive discussion of CCHFV genetic diversity, including maps of the range of the virus with superimposed phylogenetic trees. We then review the features of CCHF, including the clinical syndrome, diagnosis, treatment, pathogenesis, vaccine development and laboratory animal models of CCHF. The paper ends with a discussion of the possible future geographic range of the virus. For the benefit of researchers, we include a Supplementary Table listing all published reports of CCHF cases and outbreaks in the English-language literature, plus some principal articles in other languages, with total case numbers, case fatality rates and all CCHFV strains on GenBank.

Can the mild clinical course of crimean-congo hemorrhagic fever in children be explained by cytokine responses?

Cytokines are possibly one of the factors responsible for death due to Crimean-Congo hemorrhagic fever (CCHF). This study aimed to determine the differences between the cytokine levels in children and adult patients with CCHF; the influence of cytokines; and the severity of the course of the disease, which seems to be milder in children. Thirty-four children and 36 adult patients diagnosed with CCHF between 2010 and 2011 were included in this study. Diagnosis was performed by serology or by the polymerase chain reaction for CCHF virus. Levels of IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12 p70, IL-13, IL-17A, and IL-22 were measured in all serum samples. Although the disease had a fatal course in three adult patients, there were no deaths in children. Statistically significant differences were not observed between the cytokine concentrations in the adults and children. No differences were detected between the serum cytokine levels in the children with moderate and those with a severe clinical course of the disease. In the adult patients with fatal outcome, significantly higher serum levels of IL-2, IL-5, IL-9, IL-12 p70, and IL-13 were detected as compared to the cytokine levels in patients who survived the infection. No differences were detected between the serum levels of IFN-γ, IL-1β, IL-17A, IL-22, IL-10, IL-6, IL-4, and TNF-α in the patients who died and those who survived. Thus, the milder clinical course in children with CCHF cannot be explained by the cytokine network alone. The incomplete maturation of the immune system and timing and scale of immune responses could change the outcome dramatically.

Crimean-Congo hemorrhagic fever: an overview

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral infection that is a serious threat to humans. The disease is widely distributed in Africa, Asia, and Europe and has developed into a serious public health concern. Humans become infected through the bites of ticks, by contact with a patient with CCHF, or by contact with blood or tissues from viremic livestock. Microvascular instability and impaired hemostasis are the hallmarks of the infection. Infection in human begins with nonspecific febrile symptoms, but may progress to a serious hemorrhagic syndrome with high mortality rates. Enzyme-linked immunoassay (ELISA) and polymerase chain reaction (PCR) are the most used and specific tests for the diagnosis. The mainstay of treatment is supportive. Although definitive studies are not available, ribavirin is suggested to be effective especially at the earlier phase of the infection. Uses of universal protective measures are the best way to avoid the infection. In this review, all aspects of CCHF are overviewed in light of the current literature.

A case of crimean-congo hemorrhagic Fever in oman

In the summer of June 2011, the first case of Crimean-Congo hemorrhagic fever (CCHF) was observed in Oman since the last fifteen years. The first blood sample using reverse transcriptase polymerase chain reaction (PCR) test were sent looking for CCHF, tick-borne encephalitis, dengue, Japanese encephalitis, Chikungunya and West Nile. All resulted as negative. The repeated serology for CCHF came strongly positive after five days from the initial negative test, and accordingly patient started on ribavirin and he responded to it. His condition improved dramatically.

Animal models of tick-borne hemorrhagic Fever viruses

Tick-borne hemorrhagic fever viruses (TBHFV) are detected throughout the African and Eurasian continents and are an emerging or re-emerging threat to many nations. Due to the largely sporadic incidences of these severe diseases, information on human cases and research activities in general have been limited. In the past decade, however, novel TBHFVs have emerged and areas of endemicity have expanded. Therefore, the development of countermeasures is of utmost importance in combating TBHFV as elimination of vectors and interrupting enzootic cycles is all but impossible and ecologically questionable. As in vivo models are the only way to test efficacy and safety of countermeasures, understanding of the available animal models and the development and refinement of animal models is critical in negating the detrimental impact of TBHFVs on public and animal health.

Lethal Crimean-Congo hemorrhagic fever virus infection in interferon α/β receptor knockout mice is associated with high viral loads, proinflammatory responses, and coagulopathy

Crimean-Congo hemorrhagic fever (CCHF) is a widely distributed viral hemorrhagic fever characterized by rapid onset of flu-like symptoms often followed by hemorrhagic manifestations. CCHF virus (CCHFV), a bunyavirus in the Nairovirus genus, is capable of infecting a wide range of mammalian hosts in nature but so far only causes disease in humans. Recently, immunocompromised mice have been reported as CCHF disease models, but detailed characterization is lacking. Here, we closely followed infection and disease progression in CCHFV-infected interferon α/β receptor knockout (IFNAR(-/-)) mice and age-matched wild-type (WT) mice. WT mice quickly clear CCHFV without developing any disease signs. In contrast, CCHFV infected IFNAR(-/-) mice develop an acute fulminant disease with high viral loads leading to organ pathology (liver and lymphoid tissues), marked proinflammatory host responses, severe thrombocytopenia, coagulopathy, and death. Disease progression closely mimics hallmarks of human CCHF disease, making IFNAR(-/-) mice an excellent choice to assess medical countermeasures.

Ganjam virus/Nairobi sheep disease virus induces a pro-inflammatory response in infected sheep

Partly due to climate change, and partly due to changes of human habitat occupation, the impact of tick-borne viruses is increasing. Nairobi sheep disease virus (NSDV) and Ganjam virus (GV) are two names for the same virus, which causes disease in sheep and goats and is currently known to be circulating in India and East Africa. The virus is transmitted by ixodid ticks and causes a severe hemorrhagic disease. We have developed a real-time PCR assay for the virus genome and validated it in a pilot study of the pathogenicity induced by two different isolates of NSDV/GV. One isolate was highly adapted to tissue culture, grew in most cell lines tested, and was essentially apathogenic in sheep. The second isolate appeared to be poorly adapted to cell culture and retained pathogenicity in sheep. The real-time PCR assay for virus easily detected 4 copies or less of the viral genome, and allowed a quantitative measure of the virus in whole blood. Measurement of the changes in cytokine mRNAs showed similar changes to those observed in humans infected by the closely related virus Crimean Congo hemorrhagic fever virus.

A Syrian golden hamster model recapitulating ebola hemorrhagic fever

Ebola hemorrhagic fever (EHF) is a severe viral infection for which no effective treatment or vaccine is currently available. While the nonhuman primate (NHP) model is used for final evaluation of experimental vaccines and therapeutic efficacy, rodent models have been widely used in ebolavirus research because of their convenience. However, the validity of rodent models has been questioned given their low predictive value for efficacy testing of vaccines and therapeutics, a result of the inconsistent manifestation of coagulopathy seen in EHF. Here, we describe a lethal Syrian hamster model of EHF using mouse-adapted Ebola virus. Infected hamsters displayed most clinical hallmarks of EHF, including severe coagulopathy and uncontrolled host immune responses. Thus, the hamster seems to be superior to the existing rodent models, offering a better tool for understanding the critical processes in pathogenesis and providing a new model for evaluating prophylactic and postexposure interventions prior to testing in NHPs.

Cytokine and chemokine levels in patients with severe fever with thrombocytopenia syndrome virus

Background

Severe fever with thrombocytopenia syndrome virus (SFTSV), which can cause hemorrhagic fever–like illness, is a newly discovered bunyavirus in China. The pathogenesis of SFTSV infection is poorly understood. However, it has been suggested that immune mechanisms, including cytokines and chemokines, play an important role in disease pathogenesis. In the present study, we investigated host cytokine and chemokine profiles in serum samples of patients with SFTSV infection from Northeast China and explored a possible correlation between cytokine levels and disease severity.

Methods and Principal Findings

Acute phase serum samples from 40 patients, diagnosed with SFTSV infection were included. Patients were divided into two groups – severe or non-severe – based on disease severity. Levels of tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, interleukin-6, interferon (IFN)-γ, IFN- γ-induced protein (IP)-10 and RANTES were measured in the serum samples with commercial ELISAs. Statistical analysis showed that increases in TNF-α, IP-10 and IFN-γ were associated with disease severity.

Conclusions

We suggest that a cytokine-mediated inflammatory response, characterized by cytokine and chemokine production imbalance, might be in part responsible for the disease progression of patients with SFTSV infection.

Serological evaluation of Crimean-Congo hemorrhagic fever in humans with high-risk professions living in enzootic regions of Isfahan province of Iran and genetic analysis of circulating strains

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral disease that is asymptomatic in infected livestock, but causes a serious threat to humans with a mortality rate up to 50%. Although the CCHF virus (CCHFV) is often transmitted by ticks, livestock-to-human and human-to-human transmission also occurs. In the current study, we focused on CCHF in the province of Isfahan, located in the center of Iran and deemed to be the second most infected province. Human and livestock sera and resident ticks in the livestock are collected from different regions of the province and analyzed with specific IgG ELISA and RT-PCR tests. Overall, 12% and 12.7% of studied human and livestock populations were IgG positive, respectively. The genome of CCHFV was detected in 9% of ticks resident in livestock involved in this survey. The CCHFV isolates from infected ticks were genetically examined. Nucleotide sequence of the S-segment revealed that the different isolates were closely related to each other, with nucleotide sequence identities higher than 98%. Phylogenetic analysis demonstrated that a variant isolate clustered with the Iraq strain. This high proportion of IgG-positive sera and nearly high proportion of infected ticks increases the risk of CCHF outbreaks in the province and probably posits a great danger to other provinces.

Crimean-Congo hemorrhagic fever: epidemiological trends and controversies in treatment

Crimean-Congo hemorrhagic fever (CCHF) virus has the widest geographic range of all tick-borne viruses and is endemic in more than 30 countries in Eurasia and Africa. Over the past decade, new foci have emerged or re-emerged in the Balkans and neighboring areas. Here we discuss the factors influencing CCHF incidence and focus on the main issue of the use of ribavirin for treating this infection. Given the dynamics of CCHF emergence in the past decade, development of new anti-viral drugs and a vaccine is urgently needed to treat and prevent this acute, life-threatening disease.

Rift Valley fever virus inhibits a pro-inflammatory response in experimentally infected human monocyte derived macrophages and a pro-inflammatory cytokine response may be associated with patient survival during natural infection

Rift Valley fever virus (RVFV) causes significant morbidity and mortality in humans and livestock throughout Africa and the Middle East. The clinical disease ranges from mild febrile illness, to hepatitis, retinitis, encephalitis and fatal hemorrhagic fever. RVFV NSs protein has previously been shown to interfere in vitro with the interferon response, and RVFV lacking the NSs protein is attenuated in several animal models. Monocytes and macrophages are key players in the innate immune response via expression of various cytokines and chemokines. Here we demonstrate that wild-type RVFV infection of human monocyte-derived macrophages leads to a productive infection and inhibition of the innate immune response via decreased expression of IFN-α2, IFN-β and TNF-α. Using a recombinant virus lacking the NSs protein, we show that this effect is mediated by the viral NSs protein. Finally, analysis of RVF patient samples demonstrated an association between a pro-inflammatory cytokine response and patient survival.

Crimean-Congo haemorrhagic fever: peritoneal and pleural effusion

In Crimean-Congo haemorrhagic fever (CCHF), haemorrhagic manifestations are usually petechiae and ecchymoses on mucous membranes and skin. Rarely, there is bleeding from the nose, gingiva, gastro-intestinal tract, genito-urinary tract, brain and lungs. A 13-year-old boy with CCHF presented with gastro-intestinal bleeding and developed peritoneal and pleural effusion. He made a complete recovery with supportive treatment and ribavirin, without requiring chest or peritoneal fluid drainage. To our knowledge, this is the first report of CCHF associated with peritoneal and pleural fluid.

Crimean-Congo hemorrhagic fever virus activates endothelial cells

Crimean-Congo hemorrhagic fever virus (CCHFV) causes viral hemorrhagic fever with high case-fatality rates and is geographically widely distributed. Due to the requirement for a biosafety level 4 (BSL-4) laboratory and the lack of an animal model, knowledge of the viral pathogenesis is limited. Crimean-Congo hemorrhagic fever (CCHF) is characterized by hemorrhage and vascular permeability, indicating the involvement of endothelial cells (ECs). The interplay between ECs and CCHFV is therefore important for understanding the pathogenesis of CCHF. In a previous study, we found that CCHFV-infected monocyte-derived dendritic cells (moDCs) activated ECs; however, the direct effect of CCHFV on ECs was not investigated. Here, we report that ECs are activated upon infection, as demonstrated by upregulation of mRNA levels for E-selectin, vascular cell adhesion molecule 1 (VCAM1), and intercellular adhesion molecule 1 (ICAM1). Protein levels and cell surface expression of ICAM1 responded in a dose-dependent manner to increasing CCHFV titers with concomitant increase in leukocyte adhesion. Furthermore, we examined vascular endothelial (VE) cadherin in CCHFV-infected ECs by different approaches. Infected ECs released higher levels of interleukin 6 (IL-6) and IL-8; however, stimulation of resting ECs with supernatants derived from infected ECs did not result in increased ICAM1 expression. Interestingly, the moDC-mediated activation of ECs was abrogated by addition of neutralizing tumor necrosis factor alpha (TNF-α) antibody to moDC supernatants, thereby identifying this soluble mediator as the key cytokine causing EC activation. We conclude that CCHFV can exert both direct and indirect effects on ECs.

Evidence of vascular endothelial damage in Crimean-Congo hemorrhagic fever

BACKGROUND

Endothelial infection has an important role in the pathogenesis of Crimean-Congo hemorrhagic fever (CCHF). In this study, we investigated the causes of vascular endothelial damage in patients with CCHF.

METHODS

This prospective case-controlled study was carried out at Ankara Numune Education and Research Hospital between April and September 2007. Seventy-five patients with a laboratory-confirmed diagnosis of CCHF and 88 healthy controls were enrolled in the study. Serum levels of soluble cell adhesion molecules (sICAM-1, sVCAM-1, sE-selectin, sP-selectin, sL-selectin), vascular endothelial growth factor (VEGF), and macrophage migration inhibitory factor (MIF) were investigated in these patients by quantitative sandwich ELISA technique.

RESULTS

In the patient group, serum levels of sVCAM-1, sL-selectin and MIF were significantly higher than in the control group; serum levels of sICAM-1, sP-selectin, sE-selectin, and VEGF were significantly lower than in the control group. Serum levels of sVCAM-1 and sICAM-1 were significantly higher in severe cases than in non-severe cases, whereas the serum level of VEGF was significantly lower. sVCAM-1 was significantly higher in non-survivors than in survivors, while serum VEGF was significantly lower in non-survivors. The optimum cut-offs of sVCAM-1 and VEGF for the prediction of mortality were 205 ng/ml and 125 ng/ml, respectively. At these cut-offs, sVCAM-1 and VEGF had a sensitivity of 100% and specificity of 42.5% and 54.5%, respectively, in identifying CCHF patients who would die from the disease. The positive predictive values were 19% and 23%, respectively; negative predictive values were 100% for both.

CONCLUSION

Endothelial activation can affect the course of CCHF, and vascular endothelial damage is probably indirect. Further studies are needed for general conclusions to be drawn.

Recent progress in the treatment of Crimean–Congo hemorrhagic fever and future perspectives

Crimean–Congo hemorrhagic fever (CCHF) caused by the CCHF virus, a member of the family Bunyaviridae, genus Nairovirus, is a tick-borne acute viral hemorrhagic fever with a high case–fatality rate. Ribavirin has been used as a treatment for patients with CCHF. Although the efficacy of ribavirin in the treatment of CCHF has not yet been proven conclusively, its use in the early stage of the disease is recommended. A number of clinical and virological insights into CCHF have been revealed. Virus-associated hemophagocytic syndrome has been found to contribute to the exacerbation of CCHF in some patients, and the administration of methylprednisolone at high doses was observationally undertaken in patients with CCHF and virus-associated hemophagocytic syndrome, with promising results. It is expected that effective therapeutics and preventive measures will be developed in the future.

Pathogenesis and immune response of Crimean-Congo hemorrhagic fever virus in a STAT-1 knockout mouse model

Tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV) causes a severe hemorrhagic syndrome in humans but not in its vertebrate animal hosts. The pathogenesis of the disease is largely not understood due to the lack of an animal model. Laboratory animals typically show no overt signs of disease. Here, we describe a new small-animal model to study CCHFV pathogenesis that manifests clinical disease, similar to that seen in humans, without adaptation of the virus to the host. Our studies revealed that mice deficient in the STAT-1 signaling molecule were highly susceptible to infection, succumbing within 3 to 5 days. After CCHFV challenge, mice exhibited fever, leukopenia, thrombocytopenia, and highly elevated liver enzymes. Rapid viremic dissemination and extensive replication in visceral organs, mainly in liver and spleen, were associated with prominent histopathologic changes in these organs. Dramatically elevated proinflammatory cytokine levels were detected in the blood of the animals, suggestive of a cytokine storm. Immunologic analysis revealed delayed immune cell activation and intensive lymphocyte depletion. Furthermore, this study also demonstrated that ribavirin, a suggested treatment in human cases, protects mice from lethal CCHFV challenge. In conclusion, our data demonstrate that the interferon response is crucial in controlling CCHFV replication in this model, and this is the first study that offers an in-depth in vivo analysis of CCHFV pathophysiology. This new mouse model exhibits key features of fatal human CCHF, proves useful for the testing of therapeutic strategies, and can be used to study virus attenuation.

Determination of serum adenosine deaminase and xanthine oxidase levels in patients with crimean-congo hemorrhagic fever

OBJECTIVE

Crimean-Congo hemorrhagic fever is an acute viral hemorrhagic fever with a high mortality rate. Despite increasing knowledge about hemorrhagic fever viruses, little is known about the pathogenesis of Crimean-Congo hemorrhagic fever. In this study, we measured serum adenosine deaminase and xanthine oxidase levels in Crimean-Congo hemorrhagic fever patients.

METHODS

Serum adenosine deaminase levels were measured with a sensitive colorimetric method described by Giusti and xanthine oxidase levels by the method of Worthington in 30 consecutive hospitalized patients (mean age 42.6 +/- 21.0). Laboratory tests confirmed their diagnoses of Crimean-Congo hemorrhagic fever. Thirty-five subjects (mean age 42.9 +/- 19.1) served as the control group.

RESULTS

There was a significant difference in adenosine deaminase and xanthine oxidase levels between cases and controls (p<0.05). However, neither adenosine deaminase nor xanthine oxidase levels varied with the severity of disease in the cases assessed (p>0.05).

CONCLUSION

Adenosine deaminase and xanthine oxidase levels were increased in patients with Crimean-Congo hemorrhagic fever. Elevated serum xanthine oxidase activity in patients with Crimean-Congo hemorrhagic fever may be associated with reactive oxygen species generated by the xanthine/xanthine oxidase system during inflammatory responses. In addition, elevated lipid peroxidation may contribute to cell damage and hemorrhage. The association of cell damage and hemorrhage with xanthine oxidase activity should be further investigated in large-scale studies.

Molecular biology and pathogenesis of Crimean–Congo hemorrhagic fever virus

Over the last several years, we have experienced an increase of large outbreaks of Crimean–Congo hemorrhagic fever virus in European countries and neighboring areas. This disease poses a great threat to public health owing to its high mortality rate, modes of transmission and geographical distribution. Clinical symptoms of infection commonly include hemorrhage, myalgia and fever. The complexity of the technical and facility requirements, in combination with the sporadic outbreaks and consequent lack of clinical specimens has resulted in very limited research of Crimean–Congo hemorrhagic fever virus. To date, there is no vaccine available and a selective antiviral drug for the treatment of the disease is not expected in the near future. Here, we review the most recent findings on the Crimean–Congo hemorrhagic fever virus molecular biology and pathogenesis, including aspects of virus–host cell interactions.

A clear and present danger: tick-borne diseases in Europe

Ticks can transmit a variety of viruses, bacteria or parasites that can cause serious infections or conditions in humans and animals. While tick-borne diseases are becoming an increasing and serious problem in Europe, tick-borne diseases are also responsible for major depressions in livestock production and mortality in sub-Saharan Africa, Latin America and Asia. This review will focus on the most important circulating tick-transmitted pathogens in Europe (Borrelia spp., Anaplasma phagocytophilum, Babesia spp., tick-borne encephalitis virus, Rickettsia spp. and Crimean-Congo hemorrhagic fever virus).

Crimean-Congo hemorrhagic fever: risk for emergence of new endemic foci in Europe?

During recent years, new foci of Crimean-Congo hemorrhagic fever (CCHF) have emerged in several Balkan countries, southwest Russia, and Turkey. Starting in 2002, Turkey experiences the largest ever recorded outbreak with more than 2500 cases. Potential reasons for the emergence or re-emergence of CCHF include climate changes which may have a significant impact on the reproduction rate of the vector Hyalomma ticks, as well as anthropogenic factors (e.g. changes in agricultural and hunting activities). Given the abundance of its vector, the numerous animals that can serve as hosts, and the favorable climate and ecologic parameters in other southern Europe Mediterranean countries, CCHF is an example of a vector-borne disease which may be knocking the door in this area. There are models which show probability of CCHF extending to other countries around the Mediterranean basin suggesting that the vector, veterinarian, and human surveillance should be enhanced.

Interacting roles of immune mechanisms and viral load in the pathogenesis of crimean-congo hemorrhagic fever

Until now, the pathogenesis of Crimean-Congo hemorrhagic fever (CCHF) has not been well described. However, it has been hypothesized that it could be a result of the direct injury of virus-infected tissues in combination with the indirect effects of host immune responses, including cytokines. To shed more light on the role of viral load and cytokines, differential influences of CCHF virus (CCHFV) RNA load, antibody response, and cytokine production on severity and outcome of the disease were studied in sera of 46 patients with confirmed acute CCHF from Kosovo. In this study, viral load proved to be strongly related to the severity and outcome of the disease, with higher viral loads detected in patients with fatal outcomes than in surviving patients. Also, patients with fatal outcome had on average a weaker antibody response, if one was present at all. High levels of interleukin-10 (IL-10), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) were associated with poor outcome, since detected concentrations were highest in patients with fatal outcome and lowest in patients with moderate disease course. Additionally, a positive linear dependence between viral load and these cytokines was observed. Interestingly, reduced levels of IL-12 were detected in all CCHF patients. Our study favors the hypothesis that CCHF could be a result of a delayed and downregulated immune response caused by IL-10, which leads to an increased replication and spread of CCHFV throughout the body. This consequently triggers increased production of IFN-gamma and TNF-alpha, cytokines mediating vascular dysfunction, disseminated intravascular coagulation, organ failure, and shock.

High-dose methylprednisolone in children with Crimean-Congo haemorrhagic fever

Treatment options for Crimean-Congo haemorrhagic fever (CCHF) are limited and based on general supportive managements. Thrombocytopenia is the major risk factor of CCHF. We report our experience with high-dose methylprednisolone (HDMP). This study included five patients with CCHF. Patients were given HDMP if there were findings compatible with virus-associated haemophagocytic syndrome and the effects of HDMP were evaluated. Following this, HDMP fever subsided and platelet counts increased within 24 hours. Leukocyte counts began to increase and visceral bleedings were improved. HDMP treatment was discontinued within approximately five days. After HDMP, only one patient required blood products. HDMP is effective in CCHF, especially on fever and platelet counts. Dependency on blood products was decreased. Further controlled randomized studies with large series are needed in order to analyse the timing and duration of HDMP treatment and its effect on outcome.

Differential activation profiles of Crimean-Congo hemorrhagic fever virus- and Dugbe virus-infected antigen-presenting cells

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic, tick-borne member of the family Bunyaviridae and the genus Nairovirus. To better elucidate the pathogenesis of CCHFV, we analysed the host innate immune response induced in antigen-presenting cells (APCs) infected in vitro by CCHFV. Monocyte-derived dendritic cells (DCs) and macrophages (MPs) were both shown to be permissive for CCHFV and to replicate the virus, as monitored by genomic and antigenomic strand quantification. Virus replication was, however, controlled, corroborating an efficient alpha interferon-induced response. The upregulation of CD-83 and CD-86 indicated that CCHFV induced a partial maturation of DCs, which were also shown to activate the secretion of interleukin (IL)-6 and IL-8, but no tumour necrosis factor alpha (TNF-alpha). On the other hand, in MPs, CCHFV infection elicited a high IL-6 and TNF-alpha response and a moderate chemokine response. Nevertheless, when we compared these APC responses with those seen after infection with Dugbe virus (DUGV), a mildly pathogenic virus genetically close to CCHFV, we found that, in spite of some similarities, DUGV induced a higher cytokine/chemokine response in MPs. These results suggest that CCHFV is able to inhibit the activation of inflammatory mediators selectively in infection in vitro and that these differences could be relevant in pathogenesis.