Schmallenberg virus affects T-bet, Gata3, RoRrγt, Foxp3 and Eomes in mice brain

Schmallenberg virus (SBV), a neurotropic member of the genus Orthobunyavirus, infects ruminants and causes neurological lesions and fetal malformations including cerebellar hypoplasia, hydranencephaly, and porencephaly. The aim of this study is to establish intracerebral (i.c.) infection of SBV in newborn BALB/c mice and to investigate some of the transcription factors in brain. For this aim, brain samples of newborn BALB/c mice which were infected with SBV i.c. were analyzed by plaque titration and real-time RT-PCR for T-bet, Gata3, RoRγt, Foxp3 and Eomes mRNA levels. Study results showed that SBV can replicate in BALB/c mice brain and cause death of newborn mice with generation of infectious viral particles. Analyses of transcription factor mRNA levels indicated up-regulation of T-bet, Gata3, RoRγt, Foxp3 and down-regulation of Eomes. In this report, we introduce preliminary data of T cell transcription factors affected by SBV infection of BALB/c mice. Keywords: Eomes; Foxp3; Gata3; RoRγt; Schmallenberg virus; T-bet.

Hazara nairovirus elicits differential induction of apoptosis and nucleocapsid protein cleavage in mammalian and tick cells

The Nairoviridae family within the Bunyavirales order comprise tick-borne segmented negative-sense RNA viruses that cause serious disease in a broad range of mammals, yet cause a latent and lifelong infection in tick hosts. An important member of this family is Crimean-Congo haemorrhagic fever virus (CCHFV), which is responsible for serious human disease that results in case fatality rates of up to 30 %, and which exhibits the most geographically broad distribution of any tick-borne virus. Here, we explored differences in the cellular response of both mammalian and tick cells to nairovirus infection using Hazara virus (HAZV), which is a close relative of CCHFV within the CCHFV serogroup. We show that HAZV infection of human-derived SW13 cells led to induction of apoptosis, evidenced by activation of cellular caspases 3, 7 and 9. This was followed by cleavage of the classical apoptosis marker poly ADP-ribose polymerase, as well as cellular genome fragmentation. In addition, we show that the HAZV nucleocapsid (N) protein was abundantly cleaved by caspase 3 in these mammalian cells at a conserved DQVD motif exposed at the tip of its arm domain, and that cleaved HAZV-N was subsequently packaged into nascent virions. However, in stark contrast, we show for the first time that nairovirus infection of cells of the tick vector failed to induce apoptosis, as evidenced by undetectable levels of cleaved caspases and lack of cleaved HAZV-N. Our findings reveal that nairoviruses elicit diametrically opposed cellular responses in mammalian and tick cells, which may influence the infection outcome in the respective hosts.

Endothelial activation and dysfunction in severe fever with thrombocytopenia syndrome

Background

Pathogenesis of severe fever with thrombocytopenia syndrome (SFTS) has not been well described yet. Recent studies indicate that SFTSV could replicate in endothelial cells. Here we performed a case-control study to determine whether endothelial activation/dysfunction occurred in SFTSV infection and to identify the biomarkers reflecting endothelial dysfunction.

Methodology/Principal findings

In a case-control study of 134 SFTS patients and 68 healthy controls, serum levels of plasminogen activator inhibitor 1, tissue plasminogen activator, P-selectin, platelet endothelial cell adhesion molecular, CD40 ligand, E-selectin, vascular endothelial growth factor A, serum amyloid antigen 1 (SAA-1) and vascular cell adhesion molecular 1 were significantly enhanced in the patients than the controls (all P<0.05), indicating the occurrence of endothelial activation/dysfunction in SFTS. The intercellular adhesion molecular 1 (ICAM-1) and SAA-1 at the convalescent phase were also significantly associated with severe patients, after adjusting for the potential confounders. The odds ratio was estimated to be 3.364 (95% CI 1.074–10.534) for ICAM-1, and 1.881 (95% CI 1.166–3.034) for SAA-1, respectively. Cutoff value of 1.1×10⁷ pg/mL SAA-1 or 1.2×10⁶ pg/mL ICAM-1 were found to have moderate power of predicting fatal cases.

Conclusions

The endothelial dysfunction may be one of the pathogenic mechanism of SFTS. The serum levels of ICAM-1 and SAA-1 might be used to predict adverse outcome.

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral disease and first reported in the rural areas of China. Pathogenesis of the disease has not been well described yet. Recent studies indicated that SFTSV replicated in endothelial cells. So, we performed a case-control study to explore whether endothelial activation/dysfunction occurred in SFTSV infection and to identify biomarkers reflecting endothelial dysfunction. We found that the occurrence of endothelial activation/dysfunction in severe fever with thrombocytopenia syndrome and the serum levels of ICAM-1 and SAA-1 might be used to predict adverse outcome.

Pathogens and epidemiologic feature of severe fever with thrombocytopenia syndrome in Hubei province, China

To evaluate the aetiological agents and epidemiologic features of severe fever with thrombocytopenia syndrome (SFTS) in Hubei province, China, sera from patients were collected from January to December 2011. All cases occurred from April to December, and the epidemic peaked from May to August. The ages of patients ranged from 10 to 86 years (median=55years), and the incidence of SFTS increased with age. The female:male ratio of cases was 1.008:1, and 54.6% (77/141) and 1.4% (2/141) of the cases were confirmed by qPCR to be SFTSV and Hantavirus (HV) infection, respectively. No case of simultaneous infection with two or more pathogens was found. The research in this paper showed that some suspected SFTS cases are confused with HV infection due to similar symptoms. The analysis showed that the distribution of SFTSV has a marked regional aggregation in Hubei province.

Exosomes in Viral Disease

Viruses have evolved many mechanisms by which to evade and subvert the immune system to ensure survival and persistence. However, for each method undertaken by the immune system for pathogen removal, there is a counteracting mechanism utilized by pathogens. The new and emerging role of microvesicles in immune intercellular communication and function is no different. Viruses across many different families have evolved to insert viral components in exosomes, a subtype of microvesicle, with many varying downstream effects. When assessed cumulatively, viral antigens in exosomes increase persistence through cloaking viral genomes, decoying the immune system, and even by increasing viral infection in uninfected cells. Exosomes therefore represent a source of viral antigen that can be used as a biomarker for disease and targeted for therapy in the control and eradication of these disorders. With the rise in the persistence of new and reemerging viruses like Ebola and Zika, exploring the role of exosomes become more important than ever.

Association of the Serum Angiotensin II Level with Disease Severity in Severe Fever with Thrombocytopenia Syndrome Patients

OBJECTIVE

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a novel Bunyavirus. Recent data suggest that the physiological balance of multiple proinflammatory cytokines is substantially changed in cases of severe fever with thrombocytopenia syndrome virus (SFTSV) infection, and the inflammatory response probably plays an important role in disease progression. Angiotensin II is an important active substance of the renin-angiotensin system, and studies have demonstrated that angiotensin II is involved in key events in the inflammatory process and can regulate inflammatory cell responses.

METHODS

In order to elucidate the role of angiotensin II in the pathogenesis of SFTS, we collected serum samples from SFTS patients in the acute or convalescent phase and tested the angiotensin II levels using an enzyme-linked immunosorbent assay as well as SFTSV viral RNA with real-time reverse-transcriptase polymerase chain reaction. Furthermore, we explored possible correlations between the angiotensin II levels and clinical parameters in SFTS patients.

RESULTS

Our data showed that the serum level of angiotensin II was significantly increased in the acute phase compared with that seen in the convalescent phase and the healthy controls, while there were no significant differences between the convalescent cases and healthy controls (p>0.05). A correlation analysis demonstrated that the level of angiotensin II positively correlated with the SFTS viral RNA load. The angiotensin II levels were also found to be correlated with clinical parameters indicating impairments in organ functions. Moreover, we also found that the angiotensin II levels were significantly increased in the severe cases versus the non-severe cases (p<0.001).

CONCLUSION

The serum angiotensin II levels in SFTS patients may be used to stratify the disease severity and are possibly predictive of disease outcomes.

Fatal Severe Fever with Thrombocytopenia Syndrome: An Autopsy Case Report

As of June 2014, among six patients who had severe fever with thrombocytopenia syndrome (SFTS) at our hospital, an 83-year-old man died despite receiving appropriate critical care. An autopsy revealed extensive ischemic damage of the intra-abdominal organs, including the liver, spleen, stomach and gut, due to severe celiac atherosclerotic stenosis and superior mesenteric arterial thrombosis. Many SFTS virus nucleoprotein antigen-immunoreactive cells were detected in a paraaortic node, where necrotizing lymphadenitis was seen, and in the spleen. Fewer such cells were seen in the liver, bone marrow and adrenals.

CONCLUSION

Atherosclerosis, in addition to hemophagocytic lymphohistiocytosis syndrome, can be lethal in elderly SFTS patients.

In vitro and in vivo studies of ribavirin action on Brazilian Orthobunyavirus

Oropouche, Caraparu, Guama, Guaroa, and Tacaiuma are viruses (genus Orthobunyavirus) that cause human febrile illnesses and encephalitis. The goal of this study was to evaluate the antiviral action of ribavirin on these orthobunyaviruses to achieve a therapeutical agent to treat the diseases caused by these viruses. In vitro results showed that ribavirin (50 microg/mL) had antiviral activity only on the Tacaiuma virus. Addition of guanosine in the culture reversed the antiviral effect of ribavirin on Tacaiuma virus, suggesting that ribavirin inhibited this virus by reducing the intra-cellular guanosine pool. Moreover, ribavirin was not an effective drug in vivo because it was unable to inhibit the death of the mice or virus replication in the brain. The results suggest that ribavirin has no antiviral activity on the Oropouche, Caraparu, Guama, Guaroa, or Tacaiuma viruses; consequently, ribavirin would not be a good therapeutical agent to treat these arboviruses.

Sandfly fever virus outbreak in Cyprus

A major outbreak of febrile syndrome occurred during 2002 among the Greek Army forces in Cyprus. Serological and molecular investigations revealed that the causative agent was a Sicilian-like phlebovirus. A virus strain was isolated from a blood sample taken on the first day of the disease. Phylogenetic analysis of partial L RNA segment sequences revealed that the strain from Cyprus differed from sandfly Sicilian virus by 6.7% at the nucleotide level.

Loss of milk yield due to Akabane disease in dairy cows

Akabane disease is an infection with clinical signs of congenital malformation and abortion in ruminants. Abnormal parturitions caused by Akabane disease result in great economic loss. The purpose of this study is to estimate the reduction in the milk yield from abnormal parturition due to Akabane disease. The data were collected from 33 Holstein cows on 11 farms. The animals had abnormal parturitions during the period from September 1998 to March 1999, and were diagnosed as having Akabane disease. The mean and standard deviation of the rate of reduction in the milk yield of 33 cows after abnormal parturition caused by Akabane disease was -11.4 +/- 14.9%. The means and standard deviations of the rate of reduction of four cows calving abnormally at 220-239 days of gestation, nine cows calving abnormally at 240-270 days of gestation, and 20 cows calving abnormally at 271-300 days of gestation were -26.6 +/- 24.7%, -14.7 +/- 11.0%, and -6.9 +/- 12.3%, respectively. In this study, we demonstrated that the rate of reduction in the milk yield in cows affected by Akabane disease was -11.4 +/- 14.9%, but values as high as -26.6 +/- 24.7% were reached in the comparison with the milk yield obtained after normal parturition.

Development of a mouse model for the study of Toscana virus pathogenesis

Toscana virus (TOSV) has recently been recognized as an emerging virus transmitted by phlebotomus vectors, responsible for acute neurological diseases in Mediterranean countries. In our study, we demonstrated that adult Balb/c mice were susceptible to TOSV when infected intracerebrally (i.c.) or subcutaneously (s.c.) with a neuroadapted strain of the virus. We have shown that by performing serial passages of a wild type human isolate of TOSV in mouse brains, selection occurs for a highly virulent variant which replicates efficiently in the central nervous system (CNS) of i.c.-injected mice, causing acute encephalitis and death. Immunohistochemical analysis and TUNEL assay of post-mortem organs showed that TOSV replication was highly restricted to neurons in which it induced apoptotic death; however, virus antigen-positivity was also observed in the spleen and lymph nodes. In s.c.-injected mice, virus was detectable in the spleen and lymph nodes, whereas only few meningeal cells and neurons were affected, allowing for the mouse survival the infection. The presence of TOSV in spleen and lymph node cells in both s.c.- and i.c.-treated mice suggests their possible involvement in the diffusion of the infection. This animal model may be helpful for the development of prophylactic measures against TOSV infections.

Viruses of the Bunya- and Togaviridae families: potential as bioterrorism agents and means of control

When considering viruses of potential importance as tools for bioterrorism, several viruses in the Bunya- and Togaviridae families have been cited. Among those in the Bunyaviridae family are Rift Valley fever, Crimean-Congo hemorrhagic fever, hanta, and sandfly fever viruses, listed in order of priority. Those particularly considered in the Togaviridae family are Venezuelan, eastern and western equine encephalitis viruses. Factors affecting the selection of these viruses are the ability for them to induce a fatal or seriously incapacitating illness, their ease of cultivation in order to prepare large volumes, their relative infectivity in human patients, their ability to be transmitted by aerosol, and the lack of measures available for their control. Each factor is fully considered in this review. Vaccines for the control of infections induced by these viruses are in varying stages of development, with none universally accepted to date. Viruses in the Bunyaviridae family are generally sensitive to ribavirin, which has been recommended as an emergency therapy for infections by viruses in this family although has not yet been FDA-approved. Interferon and interferon inducers also significantly inhibit these virus infections in animal models. Against infections induced by viruses in the Togaviridae family, interferon-alpha would appear to currently be the most useful for therapy.

Jatobal virus is a reassortant containing the small RNA of Oropouche virus

Jatobal (JAT) virus was isolated in 1985 from a carnivore (Nasua nasua) in Tucuruí, Pará state, Brazil and was classified as a distinct member of the Simbu serogroup of the Bunyavirus genus, family Bunyaviridae on the basis of neutralization tests. On the basis of nucleotide sequencing, we have found that the small (S) RNA of JAT virus is very similar (>95% identity) to that of Oropouche (ORO) virus, in particular, the Peruvian genotype of ORO virus. In comparison, limited nucleotide sequencing of the G2 protein gene, encoded by the middle (M) RNA, of JAT and ORO viruses, revealed relatively little identity (<66%) between these two viruses. Neutralization tests confirmed the lack of cross-reactivity between the viruses. These results suggest that JAT virus is a reassortant containing the S RNA of ORO virus. JAT virus was attenuated in hamsters compared to ORO virus suggesting that the S RNA of ORO virus is not directly involved in hamster virulence.

Role of Anopheles quadrimaculatus and Coquillettidia perturbans (Diptera: Culicidae) in the transmission cycle of Cache Valley virus (Bunyaviridae: Bunyavirus) in the midwest, USA

Midwestern populations of Coquillettidia perturbans (Walker) and Anopheles quadrimaculatus (Say) were tested for their ability to transmit Cache Valley virus (CV), a recognized human and animal pathogen. Field-collected mosquitoes were fed artificial blood meals containing 5.2-6.2 log10 pfu/ml of CV. After 9-23 d at 28 degrees C, 75-93% of blood-fed Cq. perturbans had disseminated infections and 6-62% transmitted the virus to suckling mice. However, when infected with a lower virus titer (3.3 log10 pfu/ml), only 10-36% of the mosquitoes had disseminated infections and 0-10% transmitted the virus to suckling mice. A similar infection rate (21%) was observed in Cq. perturbans fed on viremic (3.2 log10 pfu/ml) hamsters. An. quadrimaculatus were infected (81-100%) by both doses used, with transmission rates ranging from 13-67% after 16-23 d of incubation. Transmission rates for the laboratory strain An. quadrimaculatus SAVANNAH ranged from 20 to 33% after 7-14 d of incubation. Our data show that although An. quadrimaculatus is more susceptible to CV infections than Cq. perturbans, both mosquito species could be involved in the midwestern transmission cycle of the virus.

Toscana virus infections of the central nervous system in children: a report of 14 cases

OBJECTIVE

To evaluate the pathogenicity of a recently discovered arthropod-transmitted bunyavirus (Toscana virus) on the CNS in children and to provide information on the epidemiologic and clinical aspects of Toscana virus infection.

STUDY DESIGN

Case-series analysis of children hospitalized with clinical and cerebrospinal fluid examination compatible with a CNS disease of viral origin.

METHODS

Cerebrospinal fluid, acute, and convalescent sera were investigated for conventional neurotropic viruses and for Toscana and tickborne encephalitis viruses. A clinical-epidemiologic analysis was carried out on confirmed Toscana virus cases to clarify the profile of Toscana virus infection in children.

RESULTS

The study indicates that (1) Toscana virus has been endemic in the Siena province for at least 15 years; (2) the virus is responsible for at least 80% of acute viral infections of the CNS in children throughout the summertime; (3) the clinical signs and symptoms range from aseptic meningitis to meningoencephalitis; (4) infected children resided habitually or temporarily in rural or suburban areas of the Siena province, where ecological characteristics allow arthropods to be peridomestic in human settlements.

CONCLUSIONS

Toscana virus is the most common viral agent involved in acute infections of CNS in children in central Italy.

Hantavirus pulmonary syndrome: a clinical description of 17 patients with a newly recognized disease. The Hantavirus Study Group

BACKGROUND

In May 1993 an outbreak of severe respiratory illness occurred in the southwestern United States. A previously unknown hantavirus was identified as the cause. In Asia hantaviruses are associated with hemorrhagic fever and renal disease. They have not been known as a cause of human disease in North America.

METHODS

We analyzed clinical, laboratory, and autopsy data on the first 17 persons with confirmed infection from this newly recognized strain of hantavirus.

RESULTS

The mean age of the patients was 32.2 years (range, 13 to 64); 61 percent were women, 72 percent were Native American, 22 percent white, and 6 percent Hispanic. The most common prodromal symptoms were fever and myalgia (100 percent), cough or dyspnea (76 percent), gastrointestinal symptoms (76 percent), and headache (71 percent). The most common physical findings were tachypnea (100 percent), tachycardia (94 percent), and hypotension (50 percent). The laboratory findings included leukocytosis (median peak cell count, 26,000 per cubic millimeter), often with myeloid precursors, an increased hematocrit, thrombocytopenia (median lowest platelet count, 64,000 per cubic millimeter), prolonged prothrombin and partial-thromboplastin times, an elevated serum lactate dehydrogenase concentration, decreased serum protein concentrations, and proteinuria. Rapidly progressive acute pulmonary edema developed in 15 of the 17 patients (88 percent), and 13 patients, all of whom had profound hypotension, died (case fatality rate, 76 percent). Increases in the hematocrit and partial-thromboplastin time were predictive of death.

CONCLUSIONS

Infection with a newly described hantavirus causes the hantavirus pulmonary syndrome, which is characterized by a brief prodromal illness followed by rapidly progressive, noncardiogenic pulmonary edema.

Centers for Disease Control and Prevention (CDC). Outbreak of acute illness--southwestern United States, 1993

Beginning in May 1993, cases of acute illness characterized by fever, myalgias, headache, and cough, followed by rapid development of respiratory failure, have been reported to the New Mexico Department of Health (NMDOH), Arizona Department of Health Services (ADHS), Colorado Department of Health (CDH), and Utah Department of Health (UDH). This report presents preliminary findings from an ongoing investigation of this problem, which suggest this illness is associated with a previously unrecognized hantavirus.

The surface charge of L-A9 cells and Aedes albopictus cells infected with Marituba (Bunyaviridae) virus

The surface charge of Marituba virus infected L-A9 cells and Aedes albopictus cells was estimated by direct measurement of their electrophoretic mobilities. Uninfected L-A9 cells and A. albopictus cells have mean electrophoretic mobilities of -1.083 microns/s X cm/V and -1.019 microns/s X cm/V, respectively. In Marituba virus infected L-A9 cells a progressive decline in the electrophoretic mobility was observed. In contrast, in Marituba virus infected A. albopictus cells the electrophoretic mobility of the cell surface was unaltered.