Serological Evidence of Phleboviruses in Domestic Animals on the Pre-Apennine Hills (Northern Italy).

Phleboviruses are arboviruses transmitted by sand flies, mosquitoes and ticks. Some sand fly-borne phleboviruses cause illnesses in humans, such as the summer fevers caused by the Sicilian and Naples viruses or meningitis caused by the Toscana virus. Indeed, traces of several phleboviral infections have been serologically detected in domestic animals, but their potential pathogenic role in vertebrates other than humans is still unclear, as is the role of vertebrates as potential reservoirs of these viruses. In this study, we report the results of a serological survey performed on domestic animals sampled in Northern Italy, against four phleboviruses isolated from sand flies in the same area. The sera of 23 dogs, 165 sheep and 23 goats were tested with a virus neutralization assay for Toscana virus, Fermo virus, Ponticelli I virus and Ponticelli III virus. Neutralizing antibodies against one or more phleboviruses were detected in four out of 23 dogs, 31 out of 165 sheep and 12 out of 23 goats. This study shows preliminary evidence for the distribution pattern of phleboviral infections in different animal species, highlighting the potential infection of the Toscana virus in dogs and the Fermo virus in goats.

Orthobunyaviruses in the Caribbean: Melao and Oropouche virus infections in school children in Haiti in 2014.

We report the identification of two orthobunyaviruses, Melao virus (MELV) and Oropouche virus (OROV), in plasma specimens from Haitian children with acute febrile illness who presented during outbreaks caused by alpha- and flaviviruses in 2014. Heretofore not described as a human pathogen, MELV was isolated in cell culture from the plasma of five case patients. OROV RNA was detected in the plasma of an additional child, using an unbiased sequencing approach, with phylogenetic inference suggesting a close relationship with strains from Brazil. Abdominal pain was reported by four case patients with MELV infections, with lymphadenopathy noted in two cases. Our findings document the occurrence of these orthobunyaviruses within the Caribbean region and highlight the critical importance of surveillance with viral genome sequence analyses to identify outbreaks caused by these and other emerging viruses.

Oropouche infection a neglected arbovirus in patients with acute febrile illness from the Peruvian coast.

OBJECTIVE: To evaluate the frequency of infection caused by the Oropouche virus (OROV) in 496 patients with acute febrile disease (AFI), whose samples were obtained for the analysis of endemic arboviruses in a previous investigation carried out in 2016. RESULTS: OROV was detected in 26.4% (131/496) of serum samples from patients with AFI. Co-infections with Dengue virus (7.3%), Zika virus (1.8%) and Chikungunya (0.2%) were observed. The most common clinical symptoms reported among the patients with OROV infections were headache 85.5% (112/131), myalgia 80.9% (106/131), arthralgia 72.5% (95/131) and loss of appetite 67.9% (89/131). Headache and myalgia were predominant in all age groups. Both OROV infections and co-infections were more frequent in May, June and July corresponding to the dry season of the region.

The first discovery of severe fever with thrombocytopenia syndrome virus in Taiwan.

Severe fever with thrombocytopenia syndrome (SFTS), an emerging tick-borne zoonosis, has been rapidly spread in many Asian counties since 2010, which raises the great concern in East Asia. Nevertheless, the infection status of SFTS in Taiwan remains unclear. To investigate the existence of SFTSV in Taiwan, a total of 151 serum samples collected from 31 sheep, 63 bovine and 57 dogs were enrolled this study. Furthermore, 360 adult female Rhipicephalus microplus were also included. One-step RT-nested PCR and IgG ELISA were conducted to test SFTSV specific RNA and antibodies, respectively. The result provided the first evidence of the existence of SFTSV RNA and antibodies in ruminants and ticks in Taiwan.

Serologic evidence of widespread Toscana virus infection in Bulgaria.

BACKGROUND: Toscana virus (TOSV) is an emerging sandfly-borne virus that is endemic in Mediterranean countries. METHODS: In order to detect TOSV circulation among the human population of Bulgaria, serum samples from 459 apparently healthy adult individuals, residing in19 out of 28 districts in the country, were tested for the presence of IgG antibodies to TOSV. RESULTS: An overall seroprevalence rate of 24.4% was observed, ranging from 4.4% to 53.5% in the districts. Rates were highest in persons over 60 years of age and residing in the southern districts. CONCLUSION: The results of the first TOSV seroprevalence study in Bulgaria revealed that infection is widespread. Physicians should be aware of the virus circulation during summer and consider the diagnosis in cases of febrile illness, meningitis or meningoencephalitis.

IFN-α as a time-sensitive biomarker during Oropouche virus infection in early and late seroconverters.

In the present study, patients with acute OROV fever were classified as early seroconverters (IgM/IgG positive at baseline) or late seroconverters (IgM/IgG negative at baseline) and the timeline kinetics of the production of chemokines and cytokines were assessed at 1-3, 4-7, 8-10 and ≥11 days after patients have reported the first symptoms. Regardless immunoglobulin profile, all OROV fever patients presented higher levels of CXCL8, and IFN-α and lower levels of TNF and IL-10 at baseline as compared to healthy donors (HD). Lower levels of CCL2, CXCL10, and IFN-γ and higher levels of CCL2, CXCL10, IL-6, and IL-17A were detected in early and late seroconverters, respectively, as compared to HD. While early seroconverters presented the increasing levels of CCL2 along the timeline, late seroconverters displayed decreasing levels of CCL2, CXCL10, and IL-6 following days of disease onset. Noteworthy was that IFN-α was revealed as universal biomarker of human OROV fever, while CXCL8 & IL-5 and CXCL10 & IL-17 were consistently observed in early and late seroconverters, respectively. Thus, our results suggest that the production of IFN-α, CXCL10, and IL-17 precede the seroconversion bringing novel insights on the immunological events triggered by the OROV disease.

Schmallenberg virus neutralising antibody responses in sheep.

BACKGROUND: Schmallenberg virus (SBV) is a midge borne virus of cattle and sheep. Infection is typically asymptomatic in adult sheep but fetal infection during pregnancy can result in abortion, stillbirth, neurological disorders and malformations of variable severity in newborn animals. It was first identified in Germany and the Netherlands in 2011 and then circulated throughout Europe in 2012 and 2013. Circulation in subsequent years was low or non-existent until summer and autumn 2016, leading to an increased incidence of deformed newborn lambs and calves in 2016-17. This study reports SBV circulation in October 2016 within a group of 24 ewes and 13 rams. The ewes were monitored at 3 times points over an 11 week period (September to December 2016). RESULTS: Most ewes displayed an increase in SBV VNT with antibody titre increases greater in older, previously exposed ewes. Two ewes had SBV RNA detectable by RT-qPCR, one on 30/09/16 and one on 04/11/16. Of these ewes, one had detectable serum SBV RNA (indicating viraemia) despite pre-existing antibody. The rams had been previously vaccinated with a commercial inactivated SBV vaccine, they showed minimal neutralising antibody titres against SBV 8 months post-vaccination and all displayed increased titre in October 2016. CONCLUSION: This data suggests that SBV circulated for a minimum period of 5 weeks in September to October 2016 in central England. Ewes previously exposed to virus showed an enhanced antibody response compared to naïve animals. Pre-existing antibody titre did not prevent re-infection in at least one animal, implying immunity to SBV upon natural exposure may not be life-long. In addition, data suggests that immunity provided by killed adjuvanted SBV vaccines only provides short term protection (< 8 months) from virus.

Circulation of Toscana Virus in a Sample Population of Corsica, France.

Sandfly-borne phleboviruses pathogenic to humans, such as Toscana virus (TOSV) and Sandfly Fever Sicilian virus (SFSV), are endemic in the Mediterranean region. In France, several autochthonous cases of TOSV infection have been described, causing either meningitis or encephalitis. The aim of the present study was to investigate the seroprevalence of TOSV and SFSV antibodies in a healthy population from Corsica. In this cross-sectional study, participants were enrolled (i) from a medical staff at the University of Corsica and (ii) from general practitioners of the Corsican Sentinelles Network. The seroprevalence study was based on a virus microneutralization assay. A total of 240 sera were tested. Altogether, 54 sera (22.5%) were confirmed positive for TOSV antibodies, whereas none were positive for SFSV (0/240). The residential district of participants was significantly associated with TOSV seropositivity (p value = 0.005). The rate of the seropositivity against TOSV in our study suggests that the Corsican population is well exposed to the TOSV. These results encourage the implementation of a systematic surveillance system including entomological, microbiological, and medical aspects for the collection of better information on the diseases that are associated with phleboviruses in Corsica and beyond in the regions where these viruses are present.

First case of laboratory-confirmed severe fever with thrombocytopenia syndrome disease revealed the risk of SFTSV infection in Xinjiang, China.

The Xinjiang Uygur Autonomous Region locating in Northwest of China was not considered the epidemic area of severe fever with thrombocytopenia syndrome (SFTS). Here we report the first laboratory-confirmed SFTS case that a female patient had tick bite in Xinjiang and illness onset after returning to Hainan Province. Laboratory tests identified SFTS virus (SFTSV) infection, and the virus was isolated from the patient's serum sample. Furthermore, SFTSV prevalence among tick groups was identified, and IgM response to SFTSV from febrile patients was identified. The findings suggested that there have been risks of SFTSV infection due to exposure to ticks in Xinjiang.

Experimental infection of golden hamsters with Guama virus (Peribunyaviridae, Orthobunyavirus).

The Guama virus (GMAV) is a member of Peribunyaviridae family, Orthobunyavirus genus. Several strains of the virus were isolated in South and Central Americas from several hosts, such as humans, wild animals, including nonhuman primates, wild rodents and mosquitoes as well as mice used as sentinels. The virus is able to cause febrile disease in humans. Here we describe for the first time pathologic and biochemical findings in golden hamsters (Mesocricetus auratus) infected with the prototype GMAV. Blood and organs of infected and control animals were collected every 24 h after infection from the 1st to the 7th day post infection (dpi) and at 21 dpi when experiment was ended. The tissues were processed for histopathology and immunohistochemistry. The blood and serum were used to determine viremia and biochemical markers plus to detect anti-GMAV antibodies. The viremia was early detected already on the 1st dpi and it was no longer detected on the 3rd dpi. Total anti-GMAV antibodies were detected from the 6th dpi. Hepatic markers as ALT of infected animals were increased and showed statistically significant difference in comparison with control animals, indicating damage of the liver; indeed the liver was the most affected organ, but other organs presented lesions and positive GMAV immunostaining as brain, lung, liver, spleen, and kidney. Our findings indicate that golden hamsters are a good animal model for experimental infection of the GMAV.

Seroprevalence of Severe Fever with Thrombocytopenia Syndrome Phlebovirus in Domesticated Deer in South Korea.

Severe fever with thrombocytopenia syndrome phlebovirus (SFTSV) has a wide host range. Not only has it been found in humans, but also in many wild and domesticated animals. The infection of breeding deer on farms is a particularly worrisome public health concern due to the large amount of human contact and the diverse use of deer products, including raw blood. To investigate the prevalence of breeding domesticated deer, we examined the SFTSV infection rate on deer farms in South Korea from 2015 to 2017. Of the 215 collected blood samples, 0.9% (2/215) were found to be positive for viral RNA by PCR, and sequence analysis showed the highest homology with the KADGH human isolate. Both SFTSV-specific recombinant N and Gn protein-based ELISAs revealed that 14.0% (30/215) and 7.9% (17/215) of collected blood specimens were positive for SFTSV antibody. These results demonstrate that the breeding farm deer are exposed to SFTSV and could be a potential infection source for humans through direct contact or consumption of byproducts.

Viral load and inflammatory cytokine dynamics associated with the prognosis of severe fever with thrombocytopenia syndrome virus infection: An autopsy case.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by a novel bunyavirus. The mechanism underlying disease progression remains unknown, and effective treatment strategy for SFTS is yet to be completely established, making its increasing incidence and subsequent mortality a great concern. Here, we present the autopsy case of a patient with rapidly progressed, fatal SFTS infection. Her viral titer and serum cytokines levels were measured daily and compared with the values of a survivor of the infection. Our findings elucidate the clinical features and pathophysiology of SFTS.

The proportion, origin and pro-inflammation roles of low density neutrophils in SFTS disease.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is a novel emerging viral infectious disease. We explored the percentage, origins and functional roles of low density neutrophils (LDNs), one of the neutrophils subsets, in SFTS. METHODS: The LDNs and normal density neutrophils (NDNs) from blood of SFTS and normal volunteers which were collected separately. The percentage, origins and the phagocytic capability of SFTS viral (SFTSV) of LDNs were investigated by flow cytometry and real time PCR. The capacity of LDNs to secrete cytokines and to damage endothelial cells was assessed by ELISA and flow cytometry. RESULTS: We observed that the proportion of LDNs increased dramatically compared with the healthy donors and became the dominant circulating neutrophil population in SFTS patients. Interestingly, the NDNs from the normal donors could switch to LDNs under the SFTS environment. Moreover, SFTSV load in LDNs was significantly higher than that of NDNs in the severe SFTS patients. In addition, the LDNs secreted much higher levels of pro-inflammatory cytokines than NDNs in SFTS and could induce endothelial cell injury. CONCLUSION: The NDNs can be converted to LDNs. This conversion mechanism could become the source of LDNs. The LDNs in severe SFTS patient could engulf more SFTSV and exhibit pro-inflammation functions. TRIAL REGISTRATION: The Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology (IORG No: IORG0003571) gave a final APPROVAL for the study.

Seroprevalence of Heartland Virus Antibodies in Blood Donors, Northwestern Missouri, USA.

We estimated the seroprevalence of Heartland virus antibodies to be 0.9% (95% CI 0.4%-4.2%) in a convenience sample of blood donors from northwestern Missouri, USA, where human cases and infected ticks have been identified. Although these findings suggest that some past human infections were undetected, the estimated prevalence is low.

Application of therapeutic plasma exchange in patients having severe fever with thrombocytopenia syndrome.

BACKGROUND/AIMS: Severe fever with thrombocytopenia syndrome (SFTS) is a viral hemorrhagic fever with a high fatality rate. However, effective treatments for SFTS cases not responded to supportive therapy have not been established. Herein, we introduced the therapeutic plasma exchange (TPE) in SFTS patients in a tertiary hospital between 2013 and 2015. METHODS: TPE was performed in patients with rapidly progressing SFTS. Clinical, laboratory, and virological parameters were compared before and after TPE. RESULTS: Among 27 confirmed SFTS patients, two patients were treated with TPE and ribavirin combination in May 2013, then, 14 patients with rapidly progressing SFTS patients were treated with only TPE from June 2013 to September 2015: their median age was 58 years (interquartile range, 50 to 70) and eight (57.1%) were male. Body temperature, pressure-adjusted heart rate, white blood cell and platelet counts, coagulation profile, serum creatinine, and multiple organ dysfunction score improved immediately after TPE. In addition, the mean cyclic threshold value of real-time reverse transcriptase polymerase chain reaction for SFTS virus after TPE (mean ± standard deviation, 31.3 ± 2.9) was significantly higher than that before TPE (26.5 ± 2.9; p < 0.001), indicating that serum viral loads decreased after TPE. Finally, 13 of 14 TPE-treated patients (92.8%) recovered from rapidly progressing SFTS without sequelae. CONCLUSION: SFTS patients treated with TPE showed improvements in clinical, laboratory, and virological parameters. These results suggest that TPE would be a therapeutic modality as rescue therapy in patients with rapidly progressing SFTS.

Neutralizing antibodies to Severe Fever with Thrombocytopenia Syndrome Virus in general population, Shandong Province, China.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS virus (SFTSV) in East Asia. The research on seroprevalence of SFTSV in healthy people and risk factors had been detailed. However, the levels of neutralizing antibodies against SFTSV in general population were currently unclear. In the present study, we tested 1375 healthy persons from Penglai County, eastern China, for SFTSV neutralizing antibodies; 0.58% (8/1,375) was positive and the positive rates were not significantly different among people at different age groups, occupations and genders. Besides, a follow-up study was conducted and the titer of neutralizing antibodies decreased over time in all eight people but one, and the neutralizing antibodies of five lasted for the entire study period of seven years. Our results suggesting that subclinical infection or a relatively mild form of SFTS illness is occurring in this population, but a small percentage of sera have neutralizing capacity to SFTSV. Hence, most people are just susceptible to SFTSV infection.

Neutralizing antibodies against Simbu serogroup viruses in cattle and sheep, Nigeria, 2012-2014.

BACKGROUND: Simbu serogroup viruses of the Orthobunyavirus genus (Family Peribunyaviridae) include teratogenic pathogens that cause severe economic losses, abortions, stillbirths and congenital abnormalities in ruminants worldwide. Although they were initially isolated from ruminants and Culicoides biting midges about five decades ago in Nigeria, there is no current information on their prevalence and geographical distribution despite reports of abortions and congenital malformations in the country's ruminant population. Here, apparently healthy cattle and sheep obtained from eight states in the three major vegetation zones of Nigeria were screened for the presence of specific neutralizing antibodies against Schmallenberg virus (SBV), Simbu virus (SIMV) and Shamonda virus (SHAV). RESULTS: Using a cross-sectional design, 490 cattle and 165 sheep sera were collected between 2012 and 2014 and tested by a commercial SBV ELISA kit which enables the detection of antibodies against various Simbu serogroup viruses. The seropositivity rates for cattle and sheep were 91.2% and 65.4%, respectively. In cattle, there was no association between ELISA seropositivity and vegetation zone. However, the prevalence of anti-Simbu serogroup antibodies was significantly higher in Ebonyi State compared to other states in the rainforest vegetation zone. The seroprevalence was significantly higher in sheep obtained from live animal markets compared to farms (OR = 5.8). Testing of 20 selected ELISA-positive sera by serum neutralisation test showed that all were positive for one or more of SBV, SIMV and SHAV with the highest titres obtained for SHAV. Antibodies to SBV or a closely related virus were detected in the Sudan savannah and rainforest zones, anti-SIMV antibodies were detected only in the rainforest zone, while anti-SHAV antibodies were found in the three vegetation zones. CONCLUSION: The findings of this study reveal that following the early isolation of Simbu serogroup viruses in Nigeria in the 1960s, members of this virus group are still circulating in the country. Specifically, SBV, SIMV and SHAV or closely related viruses infect cattle and sheep across the three vegetation zones of Nigeria suggesting that insect vector activity is extensive in the country. The exact vegetation zone where the animals became exposed to the viruses could, however, not be determined in this study.

Arginine deficiency is involved in thrombocytopenia and immunosuppression in severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) caused by a recently identified bunyavirus, SFTSV, is an emerging infectious disease with extensive geographical distribution and high mortality. Progressive viral replication and severe thrombocytopenia are key features of SFTSV infection and fatal outcome, whereas the underlying mechanisms are unknown. We revealed arginine deficiency in SFTS cases by performing metabolomics analysis on two independent patient cohorts, suggesting that arginine metabolism by nitric oxide synthase and arginase is a key pathway in SFTSV infection and consequential death. Arginine deficiency was associated with decreased intraplatelet nitric oxide (Plt-NO) concentration, platelet activation, and thrombocytopenia. An expansion of arginase-expressing granulocytic myeloid-derived suppressor cells was observed, which was related to T cell CD3-ζ chain down-regulation and virus clearance disturbance, implicating a role of arginase activity and arginine depletion in the impaired anti-SFTSV T cell function. Moreover, a comprehensive measurement of arginine bioavailability, global arginine bioavailability ratio, was shown to be a good prognostic marker for fatal prediction in early infection. A randomized controlled trial demonstrated that arginine administration was correlated with enhanced Plt-NO concentration, suppressed platelet activation, and elevated CD3-ζ chain expression and eventually associated with an accelerated virus clearance and thrombocytopenia recovery. Together, our findings revealed the arginine catabolism pathway-associated regulation of platelet homeostasis and T cell dysregulation after SFTSV infection, which not only provided a functional mechanism underlying SFTS pathogenesis but also offered an alternative therapy choice for SFTS.

Deficient humoral responses and disrupted B-cell immunity are associated with fatal SFTSV infection.

Severe Fever with Thrombocytopenia Syndrome (SFTS), an emerging infectious disease caused by a novel phlebovirus, is associated with high fatality. Therapeutic interventions are lacking and disease pathogenesis is yet to be fully elucidated. The anti-viral immune response has been reported, but humoral involvement in viral pathogenesis is poorly understood. Here we show defective serological responses to SFTSV is associated with disease fatality and a combination of B-cell and T-cell impairment contribute to disruption of anti-viral immunity. The serological profile in deceased patients is characterized by absence of specific IgG to viral nucleocapsid and glycoprotein due to failure of B-cell class switching. Expansion and impairment of antibody secretion is a signature of fatal SFTSV infection. Apoptosis of monocytes in the early stage of infection diminishes antigen-presentation by dendritic cells, impedes differentiation and function of T follicular helper cells, and contributes to failure of the virus-specific humoral response.