CD11b maintains West Nile virus replication through modulation of immune response in human neuroblastoma cells.

BACKGROUND: West Nile virus (WNV) is a rapidly spreading mosquito-borne virus accounted for neuroinvasive diseases. An insight into WNV-host factors interaction is necessary for development of therapeutic approaches against WNV infection. CD11b has key biological functions and been identified as a therapeutic target for several human diseases. The purpose of this study was to determine whether CD11b was implicated in WNV infection. METHODS: SH-SY5Y cells with and without MEK1/2 inhibitor U0126 or AKT inhibitor MK-2206 treatment were infected with WNV. CD11b mRNA levels were assessed by real-time PCR. WNV replication and expression of stress (ATF6 and CHOP), pro-inflammatory (TNF-α), and antiviral (IFN-α, IFN-ß, and IFN-γ) factors were evaluated in WNV-infected SH-SY5Y cells with CD11b siRNA transfection. Cell viability was determined by MTS assay. RESULTS: CD11b mRNA expression was remarkably up-regulated by WNV in a time-dependent manner. U0126 but not MK-2206 treatment reduced the CD11b induction by WNV. CD11b knockdown significantly decreased WNV replication and protected the infected cells. CD11b knockdown markedly increased TNF-α, IFN-α, IFN-ß, and IFN-γ mRNA expression induced by WNV. ATF6 mRNA expression was reduced upon CD11b knockdown following WNV infection. CONCLUSION: These results demonstrate that CD11b is involved in maintaining WNV replication and modulating inflammatory as well as antiviral immune response, highlighting the potential of CD11b as a target for therapeutics for WNV infection.

West Nile Virus: A Neglected Cause of Bell's Palsy?

The West Nile virus (WNV) is the leading cause of mosquito-borne disease in the United States. Bell's palsy (BP) is a clinical syndrome associated with viral infections, but an association with West Nile virus (WNV) is not well-described, with only two cases reported in the literature. We present a case of a 68-year-old woman presenting with fevers and encephalopathy. Cerebrospinal fluid was positive for WNV. Following improvement, she developed facial weakness and was diagnosed with BP secondary to the WNV infection. Identifying BP associated with WNV infection may have significant clinical implications, but further studies are needed to fully characterize a causative relationship.

Severe West Nile virus and Sars-CoV-2 infections in a patient with thymoma and anti-type I IFN antibodies.

The current study aimed to investigate determinants of severity in a previously healthy patient who experienced two life-threatening infections, from West Nile Virus and SARS-CoV2. During COVID19 hospitalization he was diagnosed with a thymoma, retrospectively identified as already present at the time of WNV infection. Heterozygosity for p.Pro554Ser in the TLR3 gene, which increases susceptibility to severe COVID-19, and homozygosity for CCR5 c.554_585del, associated to severe WNV infection, were found. Neutralizing anti-IFN-α and anti-IFN-ω auto-antibodies were detected, likely induced by the underlying thymoma and increasing susceptibility to both severe COVID-19 pneumonia and West Nile encephalitis.

The West Nile virus genome harbors essential riboregulatory elements with conserved and host-specific functional roles.

West Nile virus (WNV) is an arthropod-borne, positive-sense RNA virus that poses an increasing global threat due to warming climates and lack of effective therapeutics. Like other enzootic viruses, little is known about how host context affects the structure of the full-length RNA genome. Here, we report a complete secondary structure of the entire WNV genome within infected mammalian and arthropod cell lines. Our analysis affords structural insights into multiple, conserved aspects of flaviviral biology. We show that the WNV genome folds with minimal host dependence, and we prioritize well-folded regions for functional validation using structural homology between hosts as a guide. Using structure-disrupting, antisense locked nucleic acids, we then demonstrate that the WNV genome contains riboregulatory structures with conserved and host-specific functional roles. These results reveal promising RNA drug targets within flaviviral genomes, and they highlight the therapeutic potential of ASO-LNAs as both WNV-specific and pan-flaviviral therapeutic agents.

Overwintering West Nile virus in active Culex pipiens mosquito populations in Greece.

The flavivirus West Nile Virus (WNV), which is transmitted by mosquitoes, poses a significant threat to both humans and animals, and its outbreaks often challenge public health in Europe and other continents. In recent years, there is an increasing trend of WNV incidence rates across several European countries. However, whether there is a year-round circulation or seasonal introduction has yet to be elucidated. Real-time polymerase chain reaction (PCR) identified WNV-positive Culex pipiens mosquitos in 6 out of 146 pools examined in winter 2022 that correspond to three out of the 24 study areas, located in two coastal regions units in Attica, Greece. Spatial dispersion of the six positive pools in the same region suggests a clustered circulation of WNV during the winter of 2022. This is the first study that documents the identification of WNV in Cx. pipiens populations, captured in adult traps during winter period. Our findings underscore the need to extend entomological surveillance programs to include the winter period, specifically in temperate climates and historically affected areas by WNV.

Forecasting West Nile Virus With Graph Neural Networks: Harnessing Spatial Dependence in Irregularly Sampled Geospatial Data.

Machine learning methods have seen increased application to geospatial environmental problems, such as precipitation nowcasting, haze forecasting, and crop yield prediction. However, many of the machine learning methods applied to mosquito population and disease forecasting do not inherently take into account the underlying spatial structure of the given data. In our work, we apply a spatially aware graph neural network model consisting of GraphSAGE layers to forecast the presence of West Nile virus in Illinois, to aid mosquito surveillance and abatement efforts within the state. More generally, we show that graph neural networks applied to irregularly sampled geospatial data can exceed the performance of a range of baseline methods including logistic regression, XGBoost, and fully-connected neural networks.

Spatiotemporally Explicit Epidemic Model for West Nile Virus Outbreak in Germany: An Inversely Calibrated Approach.

Since the first autochthonous transmission of West Nile Virus was detected in Germany (WNV) in 2018, it has become endemic in several parts of the country and is continuing to spread due to the attainment of a suitable environment for vector occurrence and pathogen transmission. Increasing temperature associated with a changing climate has been identified as a potential driver of mosquito-borne disease in temperate regions. This scenario justifies the need for the development of a spatially and temporarily explicit model that describes the dynamics of WNV transmission in Germany. In this study, we developed a process-based mechanistic epidemic model driven by environmental and epidemiological data. Functional traits of mosquitoes and birds of interest were used to parameterize our compartmental model appropriately. Air temperature, precipitation, and relative humidity were the key climatic forcings used to replicate the fundamental niche responsible for supporting mosquito population and infection transmission risks in the study area. An inverse calibration method was used to optimize our parameter selection. Our model was able to generate spatially and temporally explicit basic reproductive number (R0) maps showing dynamics of the WNV occurrences across Germany, which was strongly associated with the deviation from daily means of climatic forcings, signaling the impact of a changing climate in vector-borne disease dynamics. Epidemiological data for human infections sourced from Robert Koch Institute and animal cases collected from the Animal Diseases Information System (TSIS) of the Friedrich-Loeffler-Institute were used to validate model-simulated transmission rates. From our results, it was evident that West Nile Virus is likely to spread towards the western parts of Germany with the rapid attainment of environmental suitability for vector mosquitoes and amplifying host birds, especially short-distance migratory birds. Locations with high risk of WNV outbreak (Baden-Württemberg, Bavaria, Berlin, Brandenburg, Hamburg, North Rhine-Westphalia, Rhineland-Palatinate, Saarland, Saxony-Anhalt and Saxony) were shown on R0 maps. This study presents a path for developing an early warning system for vector-borne diseases driven by climate change.

Spotting Culex pipiens from satellite: modeling habitat suitability in central Italy using Sentinel-2 and deep learning techniques.

Culex pipiens, an important vector of many vector borne diseases, is a species capable to feeding on a wide variety of hosts and adapting to different environments. To predict the potential distribution of Cx. pipiens in central Italy, this study integrated presence/absence data from a four-year entomological survey (2019-2022) carried out in the Abruzzo and Molise regions, with a datacube of spectral bands acquired by Sentinel-2 satellites, as patches of 224 × 224 pixels of 20 meters spatial resolution around each site and for each satellite revisit time. We investigated three scenarios: the baseline model, which considers the environmental conditions at the time of collection; the multitemporal model, focusing on conditions in the 2 months preceding the collection; and the MultiAdjacency Graph Attention Network (MAGAT) model, which accounts for similarities in temperature and nearby sites using a graph architecture. For the baseline scenario, a deep convolutional neural network (DCNN) analyzed a single multi-band Sentinel-2 image. The DCNN in the multitemporal model extracted temporal patterns from a sequence of 10 multispectral images; the MAGAT model incorporated spatial and climatic relationships among sites through a graph neural network aggregation method. For all models, we also evaluated temporal lags between the multi-band Earth Observation datacube date of acquisition and the mosquito collection, from 0 to 50 days. The study encompassed a total of 2,555 entomological collections, and 108,064 images (patches) at 20 meters spatial resolution. The baseline model achieved an F1 score higher than 75.8% for any temporal lag, which increased up to 81.4% with the multitemporal model. The MAGAT model recorded the highest F1 score of 80.9%. The study confirms the widespread presence of Cx. pipiens throughout the majority of the surveyed area. Utilizing only Sentinel-2 spectral bands, the models effectively capture early in advance the temporal patterns of the mosquito population, offering valuable insights for directing surveillance activities during the vector season. The methodology developed in this study can be scaled up to the national territory and extended to other vectors, in order to support the Ministry of Health in the surveillance and control strategies for the vectors and the diseases they transmit.

The potential role of the Asian bush mosquito Aedes japonicus as spillover vector for West Nile virus in the Netherlands.

BACKGROUND: In recent years the Asian bush mosquito Aedes japonicus has invaded Europe, including the Netherlands. This species is a known vector for a range of arboviruses, possibly including West Nile virus (WNV). As WNV emerged in the Netherlands in 2020, it is important to investigate the vectorial capacity of mosquito species present in the Netherlands to estimate the risk of future outbreaks and further spread of the virus. Therefore, this study evaluates the potential role of Ae. japonicus in WNV transmission and spillover from birds to dead-end hosts in the Netherlands. METHODS: We conducted human landing collections in allotment gardens (Lelystad, the Netherlands) in June, August and September 2021 to study the diurnal and seasonal host-seeking behaviour of Ae. japonicus. Furthermore, their host preference in relation to birds using live chicken-baited traps was investigated. Vector competence of field-collected Ae. japonicus mosquitoes for two isolates of WNV at two different temperatures was determined. Based on the data generated from these studies, we developed a Susceptible-Exposed-Infectious-Recovered (SEIR) model to calculate the risk of WNV spillover from birds to humans via Ae. japonicus, under the condition that the virus is introduced and circulates in an enzootic cycle in a given area. RESULTS: Our results show that Ae. japonicus mosquitoes are actively host seeking throughout the day, with peaks in activity in the morning and evening. Their abundance in August was higher than in June and September. For the host-preference experiment, we documented a small number of mosquitoes feeding on birds: only six blood-fed females were caught over 4 full days of sampling. Finally, our vector competence experiments with Ae. japonicus compared to its natural vector Culex pipiens showed a higher infection and transmission rate when infected with a local, Dutch, WNV isolate compared to a Greek isolate of the virus. Interestingly, we also found a small number of infected Cx. pipiens males with virus-positive leg and saliva samples. CONCLUSIONS: Combining the field and laboratory derived data, our model predicts that Ae. japonicus could act as a spillover vector for WNV and could be responsible for a high initial invasion risk of WNV when present in large numbers.

Functional Analysis of Oligoadenylate Synthetase in the Emu (Dromaius novaehollandiae).

2'-5'-oligoadenylate synthetase (OAS) is one of the proteins that act as a defense mechanism against foreign RNA in cells. OAS has two functions: an antiviral effect against a wide range of virus species via the OAS/RNase L pathway with synthesized oligoadenylates and inhibition of viral replication specific to viruses of the genus Flavivirus, which is independent of enzymatic activity. Several birds have been reported to possess only one type of OAS family member, OASL, which has both enzymatic activity and inhibitory effects on flaviviral replication. However, the ostrich has two types of OASs, OAS1 and OASL, which show different functions-enzymatic and anti-flaviviral activities, respectively. In this study, emu OASs were cloned to investigate their sequence and function and elucidate the role of OASs in emus. The cloning results showed that emus had OAS1 and OASL, suggesting that emu OASs were more closely related to ostrich than to other birds. Functional investigations showed that emu OAS1 and OASL had enzymatic and anti-flaviviral activities, respectively, similar to those of the ostrich. Emus and ostriches are evolutionarily different from most birds and may be more closely related to mammalian OAS diversity.

Undetection of vector-borne viruses in equids of Galapagos Islands.

Domestic species, including equids, were introduced in the Galapagos Islands in the XIX century. Equine vector-borne diseases are circulating in South America but their occurrence in the Galapagos Island was unknown. The objective of this study was to detect the occurrence of West Nile virus (WNV), Usutu virus (USUV) and equine infectious anemia virus (EIAV) in the four Galapagos Islands raising equids if they were present at a prevalence >1%. Serum samples were collected from 411 equids belonging to 124 owners from April to July 2019. All the results were negative to the ELISA tests used suggesting that WNV, USUV and EIAV are not circulating in the equine population of the Galapagos Islands.

Exploring Climate-Disease Connections in Geopolitical Versus Ecological Regions: The Case of West Nile Virus in the United States.

Many infectious disease forecasting models in the United States (US) are built with data partitioned into geopolitical regions centered on human activity as opposed to regions defined by natural ecosystems; although useful for data collection and intervention, this has the potential to mask biological relationships between the environment and disease. We explored this concept by analyzing the correlations between climate and West Nile virus (WNV) case data aggregated to geopolitical and ecological regions. We compared correlations between minimum, maximum, and mean annual temperature; precipitation; and annual WNV neuroinvasive disease (WNND) case data from 2005 to 2019 when partitioned into (a) climate regions defined by the National Oceanic and Atmospheric Administration (NOAA) and (b) Level I ecoregions defined by the Environmental Protection Agency (EPA). We found that correlations between climate and WNND in NOAA climate regions and EPA ecoregions were often contradictory in both direction and magnitude, with EPA ecoregions more often supporting previously established biological hypotheses and environmental dynamics underlying vector-borne disease transmission. Using ecological regions to examine the relationships between climate and disease cases can enhance the predictive power of forecasts at various scales, motivating a conceptual shift in large-scale analyses from geopolitical frameworks to more ecologically meaningful regions.

Modeling the velocity of evolving lineages and predicting dispersal patterns.

Accurate estimation of the dispersal velocity or speed of evolving organisms is no mean feat. In fact, existing probabilistic models in phylogeography or spatial population genetics generally do not provide an adequate framework to define velocity in a relevant manner. For instance, the very concept of instantaneous speed simply does not exist under one of the most popular approaches that models the evolution of spatial coordinates as Brownian trajectories running along a phylogeny [30]. Here, we introduce a new family of models - the so-called "Phylogenetic Integrated Velocity" (PIV) models - that use Gaussian processes to explicitly model the velocity of evolving lineages instead of focusing on the fluctuation of spatial coordinates over time. We describe the properties of these models and show an increased accuracy of velocity estimates compared to previous approaches. Analyses of West Nile virus data in the U.S.A. indicate that PIV models provide sensible predictions of the dispersal of evolving pathogens at a one-year time horizon. These results demonstrate the feasibility and relevance of predictive phylogeography in monitoring epidemics in time and space.

The key role of Spain in the traffic of West Nile virus lineage 1 strains between Europe and Africa.

BACKGROUND: West Nile Virus (WNV) is a zoonotic arbovirus worldwide spread. Seasonal WNV outbreaks occur in the Mediterranean basin since the late 1990's with ever-increasing incidence. In Southern Spain WNV is endemic, as disease foci - caused by WNV lineage 1 (WNV-L1) strains - occur every year. On the contrary, WNV-L2 is the dominant lineage in Europe, so most European WNV sequences available belong to this lineage, WNV-L1 sequences being still scarce. METHODS: To fill this gap, this study reports the genetic characterisation of 27 newly described WNV-L1 strains, involved in outbreaks affecting wild birds and horses during the last decade in South-Western Spain. RESULTS: All strains except one belong to the Western Mediterranean-1 sub-cluster (WMed-1), related phylogenetically to Italian, French, Portuguese, Moroccan and, remarkably, Senegalese strains. This sub-cluster persisted, spread and evolved into three distinguishable WMed-1 phylogenetic groups that co-circulated, notably, in the same province (Cádiz). They displayed different behaviours: from long-term persistence and rapid spread to neighbouring regions within Spain, to long-distance spread to different countries, including transcontinental spread to Africa. Among the different introductions of WNV in Spain revealed in this study, some of them succeeded to get established, some extinguished from the territory shortly afterwards. Furthermore, Spain's southernmost province, Cádiz, constitutes a hotspot for virus incursion. CONCLUSION: Southern Spain seems a likely scenario for emergence of exotic pathogens of African origin. Therefore, circulation of diverse WNV-L1 variants in Spain prompts for an extensive surveillance under a One Health approach.

Phylogenetic analysis and molecular genetic characteristics of West Nile virus lineage 2 isolates circulating in the Russian Federation.

Since its initial detection in Africa, the West Nile virus has disseminated widely across all continents, becoming endemic in numerous countries, including the Russian Federation. A substantial expansion of the West Nile virus range was observed in the European part of the Russian territory in 1999. In light of this epidemiological trend, research endeavours focusing on monitoring West Nile virus circulation activity in endemic regions of the country have gained paramount significance. A substantial dataset has been accrued from 2007 onwards regarding genomic variability and dissemination dynamics across the country throughout the entire monitoring period for the West Nile fever pathogen. The objective of this study was to characterise West Nile virus isolates that have been circulating in the Russian Federation and identify their molecular and genetic characteristics. A phylogenetic analysis of 55 complete genome sequences revealed that the West Nile virus population within the Russian Federation is genetically heterogeneous and is represented by four major clades. One of these clades is currently exhibiting extensive spread into new regions of the country.

Serosurvey of Blood Donors to Assess West Nile Virus Exposure, South-Central Spain.

We analyzed West Nile Virus (WNV) exposure from 1,222 blood donors during 2017-2018 from an area of south-central Spain. Results revealed WNV seroprevalence of 0.08% (95% CI 0.004%-0.4%) in this population. Our findings underscore the need for continued surveillance and research to manage WNV infection in this region.

West Nile Virus Seroprevalence in Wild Birds and Equines in Madrid Province, Spain.

West Nile virus (WNV) is a re-emerging flavivirus, primarily circulating among avian hosts and mosquito vectors, causing periodic outbreaks in humans and horses, often leading to neuroinvasive disease and mortality. Spain has reported several outbreaks, most notably in 2020 with seventy-seven human cases and eight fatalities. WNV has been serologically detected in horses in the Community of Madrid, but to our knowledge, it has never been reported from wild birds in this region. To estimate the seroprevalence of WNV in wild birds and horses in the Community of Madrid, 159 wild birds at a wildlife rescue center and 25 privately owned equines were sampled. Serum from thirteen birds (8.2%) and one equine (4.0%) tested positive with a WNV competitive enzyme-linked immunosorbent assay (cELISA) designed for WNV antibody detection but sensitive to cross-reacting antibodies to other flaviviruses. Virus-neutralization test (VNT) confirmed WNV antibodies in four bird samples (2.5%), and antibodies to undetermined flavivirus in four additional samples. One equine sample (4.0%) tested positive for WNV by VNT, although this horse previously resided in a WN-endemic area. ELISA-positive birds included both migratory and resident species, juveniles and adults. Two seropositive juvenile birds suggest local flavivirus transmission within the Community of Madrid, while WNV seropositive adult birds may have been infected outside Madrid. The potential circulation of flaviviruses, including WNV, in birds in the Madrid Community raises concerns, although further surveillance of mosquitoes, wild birds, and horses in Madrid is necessary to establish the extent of transmission and the principal species involved.

The historical ecological background of West Nile virus in Portugal indicates One Health opportunities.

West Nile (WNV) is a zoonotic arbovirus with an expanding geographical range and epidemic activity in Europe. Not having yet experienced a human-associated epidemic, Portugal remains an outlier in the Mediterranean basin. In this study, we apply ecological niche modelling informed by WNV historical evidence and a multitude of environmental variables from across Portugal. We identify that ecological backgrounds compatible with WNV historical circulation are mostly restricted to the south, characterized by a warmer and drier climate, high avian diversity, specific avian species and land types. We estimate WNV ecological suitability across the country, identifying overlaps with the distributions of the three relevant hosts (humans, birds, equines) for public and animal health. From this, we propose a category-based spatial framework providing first of a kind valuable insights for WNV surveillance in Portugal under the One Health nexus. We forecast that near future climate trends alone will contribute to pushing adequate WNV ecological suitability northwards, towards regions with higher human density. This unique perspective on the past, present and future ecology of WNV addresses existing national knowledge gaps, enhances our understanding of the evolving emergence of WNV, and offers opportunities to prepare and respond to the first human-associated epidemic in Portugal.

Disseminated cerebral cryptococcosis after silent West Nile virus infection in a patient with polycythemia vera: A case report and review of the literature.

Although disseminated cryptococcosis can occur occasionally, it is most commonly seen in immunodeficient patients. In 2005, a 43-year-old man was diagnosed with polycythemia vera. Following in 2018, he experienced an unknown-cause fever and headache. To establish the source of the symptoms, a magnetic resonance imaging scan of the brain was performed, which indicated meningeal and gyral-leptomeningeal thickening and several localized T2 hyperintense lesions measuring up to 10 × 14 mm in diameter. Cryptococcus neoformans was then cultivated from cerebrospinal fluid. Serum IgM antibodies against West Nile Virus were positive. After 8 weeks of treatment with amphotericin B and fluconazole, the overall condition improved, and the cerebrospinal fluid control culture became negative. The symptoms returned shortly after discontinuing antifungal therapy, necessitating the reintroduction of fluconazole. Currently, the patient is stable and responding positively to ruxolitinib. Here, it is demonstrated how a patient with polycythemia vera due to immunological weakness might develop disseminated cryptococcosis of the brain after West Nile virus infection.

Denial.

A 51-year-old man presented with decreased vision, fever, confusion, headaches, agitation, nausea, vomiting and diarrhea. Magnetic resonance imaging of the brain demonstrated bilateral T2 hyperintense lesions in the region of the mesial temporal lobe and optic radiations. There was a predominantly polymorphonuclear leukocyte pleocytosis in the cerebrospinal fluid (CSF) with hyperproteinorachia. A meningoencephalitis was diagnosed. Intravenous fluorescein angiography (IVFA) demonstrated a multifocal chorioretinitis that was in a linear pattern in the left eye. CSF enzyme-linked immunosorbent assay was positive for West Nile virus (WNV) IgM. We review the clinical manifestations of WNV disease and highlight the value of IVFA in determining the diagnosis.