West Nile Virus Infection Research Articles

West Nile Fever in the Russian Federation in 2022, the Incidence Forecast for 2023

The review presents an analysis of West Nile fever (WNF) epidemiological situation in the Russian Federation in 2022 and the summarized results of monitoring over the pathogen. The following features of the WNF epidemic process in Russia are outlined: the decrease (by 4 times) in the incidence rates compared to the long-term average values against an extremely extensive nature of manifestations (16 constituent entities in 6 federal districts), including the detection of local cases in 5 new territories (Tver, Tambov, Vladimir Regions, Khanty-Mansi Autonomous District, and Karachay-Cherkess Republic), predominant registration of incidence in the Central Federal District (51 %), early start and termination of the epidemic season. There is a decrease in the proportion of neuroinvasive forms in the structure of incidence, prevalence of females and the age group of “60 years and over”, as well as record rate values of people infected at the place of residence in cities, which is associated with the peculiarities of case detection, namely, screening examinations of febrile patients in hospitals by efforts of the Reference Center, according to the results of which 60 % of all registered patients with WNF in Russia were diagnosed. Monitoring studies of the Reference Center in the territory of the Central, Southern and North-Caucasian Federal Districts confirmed the intensive circulation of the pathogen. The low level of officially registered incidence is caused by insufficiently effective identification of patients. Molecular genetic studies have shown that West Nile virus lineage 2 circulated in the European part of Russia, both in epizootic and epidemic cycles. Phylogenetic analysis has revealed that 4 West Nile virus isolates found in Astrakhan, Volgograd Regions, the Republic of Kalmykia and Stavropol Territory in 2022 belong to a new genovariant of the genotype 2, first identified in Russia in 2021. Possible complication of the epidemiological situation in all federal districts of the center and south of the European part of Russia is predicted.

Evaluation of NS4A, NS4B, NS5 and 3'UTR Genetic Determinants of WNV Lineage 1 Virulence in Birds and Mammals.

West Nile virus (WNV) is amplified in an enzootic cycle involving birds as amplifying hosts. Because they do not develop high levels of viremia, humans and horses are considered to be dead-end hosts. Mosquitoes, especially from the Culex genus, are vectors responsible for transmission between hosts. Consequently, understanding WNV epidemiology and infection requires comparative and integrated analyses in bird, mammalian, and insect hosts. So far, markers of WNV virulence have mainly been determined in mammalian model organisms (essentially mice), while data in avian models are still missing. WNV Israel 1998 (IS98) is a highly virulent strain that is closely genetically related to the strain introduced into North America in 1999, NY99 (genomic sequence homology > 99%). The latter probably entered the continent at New York City, generating the most impactful WNV outbreak ever documented in wild birds, horses, and humans. In contrast, the WNV Italy 2008 strain (IT08) induced only limited mortality in birds and mammals in Europe during the summer of 2008. To test whether genetic polymorphism between IS98 and IT08 could account for differences in disease spread and burden, we generated chimeric viruses between IS98 and IT08, focusing on the 3' end of the genome (NS4A, NS4B, NS5, and 3'UTR regions) where most of the non-synonymous mutations were detected. In vitro and in vivo comparative analyses of parental and chimeric viruses demonstrated a role for NS4A/NS4B/5'NS5 in the decreased virulence of IT08 in SPF chickens, possibly due to the NS4B-E249D mutation. Additionally, significant differences between the highly virulent strain IS98 and the other three viruses were observed in mice, implying the existence of additional molecular determinants of virulence in mammals, such as the amino acid changes NS5-V258A, NS5-N280K, NS5-A372V, and NS5-R422K. As previously shown, our work also suggests that genetic determinants of WNV virulence can be host-dependent.

Higher replication potential of West Nile virus governs apoptosis induction in human neuroblastoma cells.

Theextent of neuronal cell damage caused by West Nile virus (WNV) infection governs the disease severity ranging from mild, febrile illness to fatal encephalitis. Availability of naturally occurring genetic variants is helpful to study viral factors governing differential pathogenesis. During WNV infection, apoptosis serves as a virulence determinant positively contributing to viral pathogenesis. We investigated the levels of apoptosis induced by a low neurovirulent WNV lineage 5 strain 804994 and a high neurovirulent lineage 1 strain 68856 in human neuroblastoma cells, IMR-32. Our investigations clearly show the correlation between higher multiplication capacities of 68856 with higher levels of cytopathology induced by apoptosis. We observed activation of both the extrinsic and intrinsic apoptotic pathways during WNV infection. Infection with higher neurovirulent strain resulted in higher upregulation of pro-apoptotic proteins including death receptors (DR), adaptor protein, BH3-only regulatory proteins and higher cleavage of initiator caspases of both pathways. These results suggest that the virulence of a WNV strain may correlate with its higher replication fitness and ability to cause more cellular damage.

Infectious Encephalitis in Adults: Characteristics, Outcome and Clinical Clues (S25.010)

<h3>Objective:</h3> Clinical characterization and comparison between the major causative agents of acute infectious encephalitis in adults. <h3>Background:</h3> The annual incidence of acute infectious encephalitis in adults is reported between 0.5–16 per 100,000 persons. West Nile virus (WNV) is among the most important causative agents of viral encephalitis. <h3>Design/Methods:</h3> We retrospectively characterize the clinical course of acute infectious encephalitis among adult patients admitted to the Tel-Aviv Medical Center between 2010 and 2020 (n=95), comparing major causative agents and focusing on WNV encephalitis (WNVE, n=31), varicella-zoster virus encephalitis (VZVE, n=30) and herpes simplex 1 virus encephalitis (HSV1E, n=13). <h3>Results:</h3> Patient groups differed in terms of age, with WNVE (median age 73) and VZVE (76) patients significantly older compared with HSV1E patients (51). CSF characteristics differed between groups, with VZVE patients having significant mononuclear white blood cell (WBC) predominance (99%) and HSV1E patients having lower CSF protein (57 mg/dL). Blood inflammation markers also differed significantly, with WBC higher in WNVE and C-reactive protein lower in HSV1E. Functional outcome was the worst in WNVE patients at discharge (median modified Rankin Scale [mRS] score 4) and last follow-up (median mRS score 4), reaching statistical significance when compared with VZVE patients. Differences in functional outcome prevailed when excluding patients with poor functional baseline (mRS score &gt; 2 before presentation). Logistic regression found age as an independent variable associated with worse functional outcome, and age, baseline mRS and WNVE (compared to VZVE) as associated with mortality. <h3>Conclusions:</h3> In odds with previous reports, WNVE and VZVE were far more common than HSV1E. Differences in laboratory characteristics could prove clinically useful early in the presentation of acute encephalitis. In some aspects, WNVE patients had a course resembling a bacterial, rather than viral, CNS infection. The detrimental outcome of WNVE emphasizes the need to promote solutions to WNV infection such as vaccinations and specific drugs. <b>Disclosure:</b> Dr. Maayan Eshed has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bionaut Labs Ltd. Dr. Levinson has nothing to disclose. Dr. Mina has nothing to disclose. Dr. Ashkenazi has nothing to disclose. Dr. Dekel has nothing to disclose. Dr. Cohen-Poradosu has nothing to disclose. Yifat Alcalay has nothing to disclose. Orna Aizenstein Lehavi has nothing to disclose. Yael Paran has nothing to disclose. Dr. Gadoth has received intellectual property interests from a discovery or technology relating to health care.

Concomitant West Nile Virus Encephalitis and Ischemic Strokes – A Case Report and Review of the Literature. (P8-10.004)

<h3>Objective:</h3> We report a case of concomitant West Nile virus (WNV) encephalitis and acute ischemic strokes and review the literature documenting cases of WNV encephalitis with associated cerebrovascular disease. <h3>Background:</h3> Cases of WNV have risen since 2002, but neuroinvasive disease in uncommon, occurring in 1 in 150. The most common presentation of neuroinvasive WNV is a meningo-encephalitis. Cerebrovascular presentations are exceedingly rare. <h3>Design/Methods:</h3> We report a case of concomitant neuro-invasive WNV infection and acute stroke. We include magnetic resonance imaging (MRI), serologic and cerebrospinal fluid (CSF) laboratory data, and electroencephalogram (EEG) findings. We also present a review of PubMed, Embase, and Web of Science databases for cases of WNV encephalitis associated with cerebral infarctions. <h3>Results:</h3> A 70-year-old woman without significant cardiovascular history was admitted with depressed level of consciousness, hypophonia, and inability to participate in examination. MRI and computed tomography angiography demonstrated bilateral corona radiata strokes without obvious large vessel occlusion. Transthoracic echocardiogram demonstrated a patent foramen ovale; lower extremity ultrasound did not reveal any venous thrombosis. Low-density lipoprotein was elevated. Urine toxicology screen was positive for cocaine. Poor mental status could not be explained by the infarcts alone thus further testing was pursued. Testing for toxic and metabolic abnormalities was unrevealing. EEG demonstrated mild generalized delta slowing. CSF testing showed elevated WNV IgM and IgG. Upon discharged to a rehabilitation facility, her examination was unchanged from presentation. A review of the literature yielded 28 cases of WNV encephalitis complicated by cerebrovascular disease. Most cases were multi-territorial ischemic strokes but etiology of infarction appears varied. <h3>Conclusions:</h3> Pursuit of uncommon etiologies is imperative when presenting symptoms and imaging are not explained by routine testing. The association of neurotropic viruses and strokes may be underappreciated, and possible pathophysiologic connections remain unexplained. <b>Disclosure:</b> Dr. Hingorani has nothing to disclose. Dr. Feske has received publishing royalties from a publication relating to health care. Dr. Cervantes-Arslanian has nothing to disclose.

Mechanism of Immune Evasion in Mosquito-Borne Diseases.

In recent decades, mosquito-borne illnesses have emerged as a major health burden in many tropical regions. These diseases, such as malaria, dengue fever, chikungunya, yellow fever, Zika virus infection, Rift Valley fever, Japanese encephalitis, and West Nile virus infection, are transmitted through the bite of infected mosquitoes. These pathogens have been shown to interfere with the host's immune system through adaptive and innate immune mechanisms, as well as the human circulatory system. Crucial immune checkpoints such as antigen presentation, T cell activation, differentiation, and proinflammatory response play a vital role in the host cell's response to pathogenic infection. Furthermore, these immune evasions have the potential to stimulate the human immune system, resulting in other associated non-communicable diseases. This review aims to advance our understanding of mosquito-borne diseases and the immune evasion mechanisms by associated pathogens. Moreover, it highlights the adverse outcomes of mosquito-borne disease.

Analysis Of Preventive Measures for West Nile Virus

The article explores the preventive measures for West Nile disease, starting with the origin of West Nile virus, first introducing the main processes of vaccine development, describing the two main types of vaccines: equine and human vaccines, citing research data showing the success of equine vaccine development, exposing the progress of human vaccine research, the possible problems, to whether there are studies confirming the breakthrough of this problem. The examples of two live attenuated vaccines are used to show the progress of vaccine development at this stage, and the problems and possible solutions to the vaccine are analyzed in light of its cost-effectiveness. Other preventive measures that are available to achieve the preventive effect are further analyzed, which are divided into two categories, the first being regional level protective measures by interfering with the transmission route, and the second being individual level protective measures by reducing contact with the source of transmission. The study data confirmed the need to maintain and strengthen bird monitoring programs, and ranked regional and personal precautions, analyzing the problems with regional precautions and the need for problem-specific ranking.

Species Composition and Geographic Distribution of Culicinae Mosquitoes and Their Possible Infection with West Nile Virus in Hormozgan Province, Southern Iran.

West Nile virus (WNV) is a mosquito-borne virus that causes a febrile disease and may cause a fatal neurological illness in humans. We aimed to investigate the geographic distribution of Culicinae mosquitoes and their possible infection with WNV in Hormozgan Province, southern Iran. Field studies were carried out from June 2017 to May 2019. Different mosquito sampling methods were used monthly to collect mosquitoes from 22 sites. The Real-Time PCR technique was used to detect the virus infection in the mosquitoes. Overall, 6165 mosquitoes were caught. The species were Culex theileri (33.25%), Cx. pipiens (20.45%), Cx. quinquefasciatus (10.51%), Aedes caspius (6.33%), Cx. tritaeniorhynchus (5.82%), Ae. vexans (4.10%), Cx. sinaiticus (3.62%), Cx. antennatus (3.29%), Culiseta longiareolata (2.81%), Cx. perexiguus (2.03%), Cs. subochrea (1.95%), Cx. mimeticus (1.49%), Cx. pusillus (1.38%), Cx. univittatus (1.27%), Cx. modestus (1.14%), and Cx. sitiens (0.57%). The molecular detection of virus infection in mosquitoes found to be negative for WNV. The presence of many species of mosquito vectors and high population traffic increase the risk of disease transmission is very high. Therefore, the way to restrict WNV infection factors is increasing the knowledge for personal protection measures to prevent mosquito bites.

Assessing West Nile virus (WNV) and Usutu virus (USUV) exposure in bird ringers in the Netherlands: a high-risk group for WNV and USUV infection?

IntroductionIn 2020, the first Dutch West Nile virus (WNV) infected birds were detected through risk-targeted surveillance of songbirds. Retrospective testing of patients with unexplained neurological disease revealed human WNV infections in July and August 2020. Bird ringers are highly exposed to mosquito bites and possibly avian excrements during ringing activities. This study therefore investigates whether bird ringers are at higher risk of exposure to WNV and Usutu virus (USUV). MethodsDutch bird ringers were asked to provide a single serum sample (May – September 2021) and to fill out a survey. Sera were screened by protein microarray for presence of specific IgG against WNV and USUV non-structural protein 1 (NS1), followed by focus reduction virus neutralization tests (FRNT). Healthcare workers (2009–2010), the national immunity cohort (2016–2017) and blood donors (2021) were used as control groups without this occupational exposure. ResultsThe majority of the 157 participating bird ringers was male (132/157, 84%) and the median age was 62 years. Thirty-seven participants (37/157, 23.6%) showed WNV and USUV IgG microarray signals above background, compared to 6.4% (6/94) in the community cohort and 2.1% (2/96) in blood donors (p < 0.01). Two seroreactive bird ringers were confirmed WNV or USUV positive by FRNT. The majority of seroreactive bird ringers travelled to EU countries with reported WNV human cases (30/37, 81%) (p = 0.07). No difference was observed between bird ringers with and without previous yellow fever vaccination. DiscussionThe higher frequency of WNV and/or USUV IgG reactive bird ringers indicates increased flavivirus exposure compared to the general population, suggesting that individuals with high-exposure professions may be considered to complement existing surveillance systems. However, the complexity of serological interpretation in relation to location-specific exposure (including travel), and antibody cross-reactivity, remain a challenge when performing surveillance of emerging flaviviruses in low-prevalence settings.

Circulation of West Nile virus in mosquitoes approximate to the migratory bird stopover in West Coast Malaysia.

Being a tropical country with a conducive environment for mosquitoes, mosquito-borne illnesses such as dengue, chikungunya, lymphatic filariasis, malaria, and Japanese encephalitis are prevalent in Malaysia. Recent studies reported asymptomatic infection of West Nile virus (WNV) in animals and humans, but none of the studies included mosquitoes, except for one report made half a century ago. Considering the scarcity of information, our study sampled mosquitoes near migratory bird stopover wetland areas of West Coast Malaysia located in the Kuala Gula Bird Sanctuary and Kapar Energy Venture, during the southward migration period in October 2017 and September 2018. Our previous publication reported that migratory birds were positive for WNV antibody and RNA. Using a nested RT-PCR analysis, WNV RNA was detected in 35 (12.8%) out of 285 mosquito pools consisting of 2,635 mosquitoes, most of which were Culex spp. (species). Sanger sequencing and phylogenetic analysis revealed that the sequences grouped within lineage 2 and shared 90.12%-97.01% similarity with sequences found locally as well as those from Africa, Germany, Romania, Italy, and Israel. Evidence of WNV in the mosquitoes substantiates the need for continued surveillance of WNV in Malaysia.

Vector Competence of Culex quinquefasciatus from Brazil for West Nile Virus.

West Nile virus is characterized as a neurotropic pathogen, which can cause West Nile fever and is transmitted by mosquitoes of the genus Culex. In 2018, the Instituto Evandro Chagas performed the first isolation of a WNV strain in Brazil from a horse brain sample. The present study aimed to evaluate the susceptibility of orally infected Cx. quinquefasciatus from the Amazon region of Brazil to become infected and transmit the WNV strain isolated in 2018. Oral infection was performed with blood meal artificially infected with WNV, followed by analysis of infection, dissemination, and transmission rates, as well as viral titers of body, head, and saliva samples. At the 21st dpi, the infection rate was 100%, the dissemination rate was 80%, and the transmission rate was 77%. These results indicate that Cx. quinquefasciatus is susceptible to oral infection by the Brazilian strain of WNV and may act as a possible vector of the virus since it was detected in saliva from the 21st dpi.

West Nile Virus and Epizootic Hemorrhagic Disease Virus Co-Infection in a Novel Host at the Nashville Zoo.

On August 30, 2017, one of five bontebok in a mixed-species exhibit at the Nashville Zoo at Grassmere exhibited acute hind-limb ataxia and altered demeanor. Pathological examination demonstrated meningoencephalitis and spinal myelitis. Coinfection of West Nile virus (WNV) and epizootic hemorrhagic disease virus (EHDV) was revealed by quantitative real-time and traditional reverse transcription-polymerase chain reaction assays and virus isolation/whole genome sequencing from brain tissue, respectively. Whole genome sequencing was conducted for EHDV. Mosquito testing from September 19 to October 13, 2017, demonstrated a higher WNV infection rate in mosquitoes at the zoo compared with the rest of Nashville-Davidson County. EHDV is endemic in wild white-tailed deer (family Cervidae) in Tennessee, and the prevalence in wildlife depends on environmental influences. This case illustrates the potential susceptibility of exotic zoo animals to endemic domestic arthropod-borne viruses (arboviruses) and reinforces the importance of cooperative antemortem and postmortem surveillance strategies among human, wildlife, and domestic animal health agencies.

Temporal tracking of microglial and monocyte single-cell transcriptomics in lethal flavivirus infection

As the resident parenchymal myeloid population in the central nervous system (CNS), microglia are strategically positioned to respond to neurotropic virus invasion and have been implicated in promoting both disease resolution and progression in the acute and post-infectious phase of virus encephalitis. In a mouse model of West Nile virus encephalitis (WNE), infection of the CNS results in recruitment of large numbers of peripheral immune cells into the brain, the majority being nitric oxide (NO)-producing Ly6Chi inflammatory monocyte-derived cells (MCs). In this model, these cells enhance immunopathology and mortality. However, the contribution of microglia to this response is currently undefined. Here we used a combination of experimental tools, including single-cell RNA sequencing (scRNA-seq), microglia and MC depletion reagents, high-dimensional spectral cytometry and computational algorithms to dissect the differential contribution of microglia and MCs to the anti-viral immune response in severe neuroinflammation seen in WNE. Intriguingly, analysis of scRNA-seq data revealed 6 unique microglia and 3 unique MC clusters that were predominantly timepoint-specific, demonstrating substantial transcriptional adaptation with disease progression over the course of WNE. While microglia and MC adopted unique gene expression profiles, gene ontology enrichment analysis, coupled with microglia and MC depletion studies, demonstrated a role for both of these cells in the trafficking of peripheral immune cells into the CNS, T cell responses and viral clearance. Over the course of infection, microglia transitioned from a homeostatic to an anti-viral and then into an immune cell-recruiting phenotype. Conversely, MC adopted antigen-presenting, immune cell-recruiting and NO-producing phenotypes, which all had anti-viral function. Overall, this study defines for the first time the single-cell transcriptomic responses of microglia and MCs over the course of WNE, demonstrating both protective and pathological roles of these cells that could potentially be targeted for differential therapeutic intervention to dampen immune-mediated pathology, while maintaining viral clearance functions.

Optimization of scientifico-practical aspects of West Nile fever causative agent’s monitoring (by the example of the Volgograd region)

Objective: to assess the quality and effectiveness of West Nile fever (WNF) causative agent’s monitoring in the Volgograd region and to develop a set of measures to its optimization. Materials and methods: data on the detection of WNV cases, results of serological and zooentomological monitoring in 2009–2021. A comprehensive methodological approach was applied, including statistical and epidemiological methods. Results: based on the assessment of WNF causative agent’s monitoring key aspects in the Volgograd region, it was shown that one of the priority problems is the insufficient and untimely detection of cases among the population. Among the urgent problems of serological monitoring are the lack of a clearly established frequency of serological examination in the population of the region’s administrative territories and the termination of one of the indicator population groups examination, regulated by the current regulatory and methodological documents. An assessment of the parameters of monitoring studies of the external environment indicates an insufficient territorial coverage and a decrease in the volume of studies, primarily in relation to the main carriers of the West Nile virus, which determines the overall low detection rate of West Nile virus markers. Conclusion: recommendations are proposed for optimizing monitoring, which will enhance the efficiency of WNF epidemiological surveillance and develop a scientifically based forecast of the development of the epidemiological situation.

Interleukins, Chemokines, and Tumor Necrosis Factor Superfamily Ligands in the Pathogenesis of West Nile Virus Infection.

West Nile virus (WNV) is a mosquito-borne pathogen that can lead to encephalitis and death in susceptible hosts. Cytokines play a critical role in inflammation and immunity in response to WNV infection. Murine models provide evidence that some cytokines offer protection against acute WNV infection and assist with viral clearance, while others play a multifaceted role WNV neuropathogenesis and immune-mediated tissue damage. This article aims to provide an up-to-date review of cytokine expression patterns in human and experimental animal models of WNV infections. Here, we outline the interleukins, chemokines, and tumor necrosis factor superfamily ligands associated with WNV infection and pathogenesis and describe the complex roles they play in mediating both protection and pathology of the central nervous system during or after virus clearance. By understanding of the role of these cytokines during WNV neuroinvasive infection, we can develop treatment options aimed at modulating these immune molecules in order to reduce neuroinflammation and improve patient outcomes.

A sero-epidemiological investigation of West Nile virus among patients without any records of their symptoms from three different hospitals from Tunisia

West Nile virus is one of the most known arboviruses around the world, along with Dengue virus, Toscana virus, Chikungunya (CHIK). In Tunisia, many epidemics of WNV had occurred in the past. The last one dated from 2018. The aim of our work was to perform a sero-epidemiological investigation on WNV without any records of their symptoms from three different hospitals from Tunisia. Patients without any records of their symptoms of the infection of West Nile Virus (WNV) infection were included in the period from October 2017 to January 2020 from three different Virology departments in the country (the Military Hospital in Tunis, Fattouma Bourguiba Hospital in Monastir and Sahloul Hospital in Sousse). A venous blood sample was taken from all patients at the bend of the elbow using a sterile syringe under aseptic conditions. Serological investigation for WNV was conducted through ELISA and IFI assays. RT-PCR was used to confirm the infection. The study included 353 patients. Twenty-eighty percent (28.8%) of the population were tested positive for IgM antibodies, males were having less positive antibodies than women (24.6% vs. 36.3%, p<0.05). In the city of Sousse, positive IgM were found more than in the other cities. As for IgG, 19.2% of the patients were having positive antibodies. No significant association was found between genders (p>0.05). One quarter of the IgM antibodies were tested positive using IFI technique, with no difference between genders (p>0.05). Only 9.2% of the samples were positive by PCR. Our results highlight the importance of establishing sustainable entomological systems and effective clinical ones and of promoting appropriate biological control strategies to optimize the limitation of the circulation of WNV as well as other arboviruses to inhibit their harmful effects on health.

Native Wolbachia infection and larval competition stress shape fitness and West Nile virus infection in Culex quinquefasciatus mosquitoes.

Wolbachia transinfections established in key mosquito vectors, including Aedes aegypti are typically associated with pathogen blocking-reduced susceptibility to infection with key pathogens and reduced likelihood those pathogens are transmitted to new hosts. Host-symbiont-virus interactions are less well understood in mosquitoes like Culex quinquefasciatus, which naturally harbor Wolbachia, with pathogen blocking observed in some populations but not others, potentially due to innate differences in their Wolbachia load. In nature, mosquito larvae are often subject to developmental stresses associated with larval competition, which can lead to reduced body size and differential susceptibility to arbovirus infection. In this study, we sought to understand whether competition stress and Wolbachia infection in Cx. quinquefasciatus combine to impact host fitness and susceptibility to infection with West Nile virus. We reared Wolbachia-infected and uninfected Cx. quinquefasciatus larvae under three competition stress levels, increasing larval density without increasing the amount of food supplied. We then monitored larval development and survival, measured wing length and quantified Wolbachia density in adults, and then challenged mosquitoes from each treatment group orally with West Nile virus. We observed that high competition stress extended development time, decreased the likelihood of eclosion, decreased body size, and increased susceptibility to West Nile virus (WNV) infection. We also observed that Wolbachia infection reduced WNV load under low competition stress, and significantly improved the rate of survival for larval reared under higher competition stress. Consequently, our data suggest that native Wolbachia infection in Cx. quinquefasciatus has differential consequences for host fitness and susceptibility to WNV infection depending on competition stress.

Pharmacological Elevation of Cellular Dihydrosphingomyelin Provides a Novel Antiviral Strategy against West Nile Virus Infection.

The flavivirus life cycle is strictly dependent on cellular lipid metabolism. Polyphenols like gallic acid and its derivatives are promising lead compounds for new therapeutic agents as they can exert multiple pharmacological activities, including the alteration of lipid metabolism. The evaluation of our collection of polyphenols against West Nile virus (WNV), a representative medically relevant flavivirus, led to the identification of N,N'-(dodecane-1,12-diyl)bis(3,4,5-trihydroxybenzamide) and its 2,3,4-trihydroxybenzamide regioisomer as selective antivirals with low cytotoxicity and high antiviral activity (half-maximal effective concentrations [EC50s] of 2.2 and 0.24 μM, respectively, in Vero cells; EC50s of 2.2 and 1.9 μM, respectively, in SH-SY5Y cells). These polyphenols also inhibited the multiplication of other flaviviruses, namely, Usutu, dengue, and Zika viruses, exhibiting lower antiviral or negligible antiviral activity against other RNA viruses. The mechanism underlying their antiviral activity against WNV involved the alteration of sphingolipid metabolism. These compounds inhibited ceramide desaturase (Des1), promoting the accumulation of dihydrosphingomyelin (dhSM), a minor component of cellular sphingolipids with important roles in membrane properties. The addition of exogenous dhSM or Des1 blockage by using the reference inhibitor GT-11 {N-[(1R,2S)-2-hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyl]octanamide} confirmed the involvement of this pathway in WNV infection. These results unveil the potential of novel antiviral strategies based on the modulation of the cellular levels of dhSM and Des1 activity for the control of flavivirus infection.

Characteristics of the manifestations of the epidemic process of actual natural focal infections in the Samara region

Features of the landscape and geographical conditions of the Samara region, the rich world of flora and fauna create favorable conditions for the existence of natural foci of infectious and parasitic diseases. The high population density, the presence of megacities (Samara, Togliatti), the passion of the inhabitants of the region for country recreation, together with developed agriculture, determine a high risk of infection of people with pathogens of natural focal infections.Objectives: to analyze the manifestations of the epidemic and epizootic processes of natural focal infections in the Samara region for its zoning according to the degree of danger of infection of the population with actual zoonoses.Methods. We used information on the incidence of the population (form No. 2 "Information on infectious and parasitic diseases") for the period from 2019 to 2021, data from an immunological examination of residents of municipalities using enzyme immunoassay, results of examination of environmental objects in natural foci (indication of genomes and antigens of viruses and bacteria) in vertebrates and their pellets (litter), arthropods using polymerase chain reaction and enzyme immunoassay. Cluster analysis was performed using the Statgraphics plus for Windows application program for a personal computer.Results. Territories with high, moderate and low risk of infection of the population of the Samara region with hemorrhagic fever with renal syndrome, viral tick-borne encephalitis, tularemia, leptospirosis, Q fever and West Nile fever were identified. It is shown that the most relevant zoonosis is hemorrhagic fever with renal syndrome.Discussion. Compiled cartographic mapping of the administrative formations of the Samara region with different risks of infection and disease of people with natural focal infections is relevant for planning preventive measures.

Structural Motifs and Spatial Structures of Helicase (NS3) and RNA-dependent RNA-polymerase (NS5) of a Flavi-like Kindia tick virus (unclassified Flaviviridae)

Kindia tick virus (KITV) is a novel segmented unclassified flavi-like virus of the Flaviviridae family. This virus is associated with ixodes ticks and is potentially pathogenic to humans. The main goal of this work was to search for structural motifs of viral polypeptides and to develop a 3D-structure for viral proteins of the flavi-like KITV. The complete genome sequences for KITV, Zika, dengue, Japanese encephalitis, West Nile and yellow fever viruses were retrieved from GenBank. Bioinformatics analysis was performed using the different software packages. Analysis of the KITV structural proteins showed that they have no analogues among currently known viral proteins. Spatial models of NS3 and NS5 KITV proteins have been obtained. These models had a high level of topological similarity to the tick-borne encephalitis and dengue viral proteins. The methyltransferase and RNA-dependent RNA-polymerase domains were found in the NS5 KITV. The latter was represented by fingers, palm and thumb subdomains, and motifs A-F. The helicase domain and its main structural motifs IVI were identified in NS3 KITV. However, the protease domain typical of NS3 flaviviruses was not detected. The highly conserved amino acid motives were detected in the NS3 and NS5 KITV. Also, eight amino acid substitutions characteristic of KITV/2018/1 and KITV/2018/2 were detected, five of them being localized in alpha-helix and three in loops of nonstructural proteins. Nonstructural proteins of KITV have structural and functional similarities with unsegmented flaviviruses. This confirms their possible evolutionary and taxonomic relationships.