Search

The coronavirus disease 2019 (COVID-19) pandemic has affected a large portion of the global population, both physically and mentally. Current evidence suggests that the rapidly evolving coronavirus subvariants risk rendering vaccines and antibodies ineffective due to their potential to evade existing immunity, with enhanced transmission activity and higher reinfection rates that could lead to new outbreaks across the globe. The goal of viral management is to disrupt the viral life cycle as well as to relieve severe symptoms such as lung damage, cytokine storm, and organ failure. In the fight against viruses, the combination of viral genome sequencing, elucidation of the structure of viral proteins, and identifying proteins that are highly conserved across multiple coronaviruses has revealed many potential molecular targets. In addition, the timeand cost-effective repurposing of preexisting antiviral drugs or approved/clinical drugs for these targets offers considerable clinical advantages for COVID-19 patients. This review provides a comprehensive overview of various identified pathogenic targets and pathways as well as corresponding repurposed approved/clinical drugs and their potential against COVID-19. These findings provide new insight into the discovery of novel therapeutic strategies that could be applied to the control of disease symptoms emanating from evolving SARS-CoV-2 variants. [ABSTRACT FROM AUTHOR]

Orthoflavivirus encephalitidis, formerly tick-borne encephalitis virus (TBEV), belongs to the Orthoflavivirus genus. TBEV is transmitted by tick bites and infection with TBEV can lead to serious disorders of the central nervous system. In this study, a new protective monoclonal mouse antibody (mAb) FVN-32, with high binding activity to glycoprotein E of TBEV, was selected and examined in post exposure prophylaxis in a mouse model of TBEV infection. BALB/c mice were injected mAb FVN-32 at doses of 200 μg, 50 μg, and 12.5 μg per mouse one day after a TBEV challenge. mAb FVN-32 showed 37.5% protective efficacy when administered at doses of 200 μg and 50 μg per mouse. The epitope for protective mAb FVN-32 was localized in TBEV glycoprotein E domain I+II, using a set of truncated fragments of glycoprotein E. Additionally, the target site recognized by mAb FVN-32 was defined using combinatorial libraries of peptides. Three-dimensional modeling revealed that the site is dspatially close to the fusion loop, but does not come into contact with it, and is localized in a region between 247 and 254 amino acid residues on the envelope protein. This region is conserved among TBEV-like orthoflaviviruses. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis (TBE) is an infectious disease of the central nervous system. The causative agent is the tick-borne encephalitis virus (TBEV), which is most commonly transmitted by tick bites, but which may also be transmitted through the consumption of raw dairy products or, in rare instances, via infected transfusions, transplants, or the slaughter of infected animals. The only effective preventive option is active immunization. Currently, two vaccines are available in Europe—Encepur® and FSME-IMMUN®. In Central, Eastern, and Northern Europe, isolated TBEV genotypes belong mainly to the European subtype (TBEV-EU). In this study, we investigated the ability of these two vaccines to induce neutralizing antibodies against a panel of diverse natural TBEV-EU isolates from TBE-endemic areas in southern Germany and in regions of neighboring countries. Sera of 33 donors vaccinated with either FSME-IMMUN®, Encepur®, or a mixture of both were tested against 16 TBEV-EU strains. Phylogenetic analysis of the TBEV-EU genomes revealed substantial genetic diversity and ancestry of the identified 13 genotypic clades. Although all sera were able to neutralize the TBEV-EU strains, there were significant differences among the various vaccination groups. The neutralization assays revealed that the vaccination using the two different vaccine brands significantly increased neutralization titers, decreased intra-serum variance, and reduced the inter-virus variation. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis (TBE) is a viral infection of the human central nervous system caused by the TBE virus (TBEV). The most effective protective measure against TBE is vaccination. Despite the highly immunogenic vaccine, cases of vaccine breakthroughs (VBTs) occur. One of the first targets of infection is dendritic cells (DC), which represent a fundamental bridge between innate and adaptive immunity through antigen presentation, costimulation, and cytokine production. Therefore, we investigated the activation and maturation of DCs and cytokine production after in vitro TBEV stimulation of peripheral blood mononuclear cells (PBMCs) obtained from VBT and unvaccinated TBE patients. Our results showed that the expression of HLA-DR and CD86 on DCs, was upregulated to a similar extent in both vaccinated and unvaccinated TBE patients but differed in cytokine production after stimulation with TBEV. PBMCs from patients with VBT TBE responded with lower levels of IFN-α and the proinflammatory cytokines IL-12 (p70) and IL-15 after 24- and 48-hour in vitro stimulation with TBEV, possibly facilitating viral replication and influencing the development of cell-mediated immunity. On the other hand, significantly higher levels of IL-6 in addition to an observed trend of higher expression of TNF-α measured after 6 days of in vitro stimulation of PBMC could support disruption of the blood–brain barrier and promote viral and immune cell influx into the CNS, leading to more severe disease in VBT TBE patients. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis virus (TBEV) is one of the most threatening pathogens which affects the human central nervous system (CNS). TBEV circulates widely in Northern Eurasia. According to ECDC, the number of TBE cases increase annually. There is no specific treatment for the TBEV infection, thus vaccination is the main preventive measure. Despite the existence of several inactivated vaccines currently being licensed, the development of new TBEV vaccines remains a leading priority in countries endemic to this pathogen. Here we report new recombinant virus made by infectious subgenomic amplicon (ISA) approach using TBEV and yellow fever virus vaccine strain (YF17DD-UN) as a genetic backbone. The recombinant virus is capable of effective replication in mammalian cells and induce TBEV-neutralizing antibodies in mice. Unlike the original vector based on the yellow fever vaccine strain, chimeric virus became neuroinvasive in doses of 107−106 PFU and can be used as a model of flavivirus neuroinvasiveness, neurotropism and neurovirulence. These properties of hybrid structures are the main factors limiting their practical use as vaccines platforms. [ABSTRACT FROM AUTHOR]

Introduction: Tahyna virus (TAHV), an arbovirus of the genus Orthobunyavirus, is a cause of human diseases and less studied worldwide. In this study, a new strain of TAHV was isolated from Aedes sp. mosquitoes collected in Panjin city, Liaoning province. However, the competent vector of TAHV in China is still unknown. Methods: The genome of newly isolated TAHV was sequenced and phylogenetic analysis is performed. Aedes albopictus and Culex pipiens pallens were orally infected with artificial virus blood meals (1:1 of virus suspension and mouse blood), the virus was detected in the midgut, ovary, salivary gland and saliva of the mosquitoes. Then, the transmission and dissemination rates, vertical transmission and horizontal transmission of the virus by the mosquitoes were assessed. Methods: The genome of newly isolated TAHV was sequenced and phylogenetic analysis is performed. Aedes albopictus and Culex pipiens pallens were orally infected with artificial virus blood meals (1:1 of virus suspension and mouse blood), the virus was detected in the midgut, ovary, salivary gland and saliva of the mosquitoes. Then, the transmission and dissemination rates, vertical transmission and horizontal transmission of the virus by the mosquitoes were assessed. Methods: The genome of newly isolated TAHV was sequenced and phylogenetic analysis is performed. Aedes albopictus and Culex pipiens pallens were orally infected with artificial virus blood meals (1:1 of virus suspension and mouse blood), the virus was detected in the midgut, ovary, salivary gland and saliva of the mosquitoes. Then, the transmission and dissemination rates, vertical transmission and horizontal transmission of the virus by the mosquitoes were assessed. Results: Phylogenetic analysis revealed that the virus shared high similarity with TAHV and was named the TAHV PJ01 strain. After oral infection with virus blood meals, Ae. albopictus showed positive for the virus in all tested tissues with an extrinsic incubation period of 2 days and a fluctuating increasement of transmission and dissemination rates. Whereas no virus was detected in the saliva of Cx. pipiens pallens. Suckling mice bitten by infectious Ae. albopictus developed obvious neurological symptoms, including inactivity, hind-leg paralysis and difficulty turning over, when the virus titer reached 1.70×105 PFU/mL in the brain. Moreover, TAHV was detected in the eggs, larvae and adults of F1 offspring of Ae. albopictus. Discussion: Ae. albopictus is an efficient vector to transmit TAHV but Cx. pipiens pallens is not. Ae. albopictus is also a reservoir host that transmits the virus vertically, which further increases the risk of outbreaks. This study has important epidemiological implications for the surveillance of pathogenic viruses in China and guiding comprehensive vector control strategies to counteract potential outbreaks in future. [ABSTRACT FROM AUTHOR]

Introduction: Tick-borne encephalitis virus (TBEV) is an important human pathogen that can cause a serious disease involving the central nervous system (tick-borne encephalitis, TBE). Although approved inactivated vaccines are available, the number of TBE cases is rising, and breakthrough infections in fully vaccinated subjects have been reported in recent years. Methods: In the present study, we generated and characterized a recombinant Modified Vaccinia virus Ankara (MVA) for the delivery of the pre-membrane (prM) and envelope (E) proteins of TBEV (MVA-prME). Results: MVA-prME was tested in mice in comparison with a licensed vaccine FSME-IMMUN® and proved to be highly immunogenic and afforded full protection against challenge infection with TBEV. Discussion: Our data indicate that MVA-prME holds promise as an improved next-generation vaccine for the prevention of TBE. [ABSTRACT FROM AUTHOR]

Since 2018, autochthonous West Nile virus (WNV) infections have been regularly reported in eastern–central Germany. While clinically apparent infections in humans and horses are not frequent, seroprevalence studies in horses may allow the tracing of WNV and related flaviviruses transmission, such as tick-borne encephalitis virus (TBEV) and Usutu virus (USUV), and consequently help to estimate the risk of human infections. Hence, the aim of our study was to follow the seropositive ratio against these three viruses in horses in Saxony, Saxony Anhalt, and Brandenburg and to describe their geographic distribution for the year 2021. In early 2022, i.e., before the virus transmission season, sera from 1232 unvaccinated horses were tested using a competitive pan-flavivirus ELISA (cELISA). In order to estimate the true seropositive ratio of infection with WNV, TBEV, and USUV for 2021, positive and equivocal results were confirmed by a virus neutralization test (VNT). In addition, possible risk factors for seropositivity using questionnaires were analyzed using logistic regression based on questionnaires similar to our previous study from 2020. In total, 125 horse sera reacted positive in the cELISA. Based on the VNT, 40 sera showed neutralizing antibodies against WNV, 69 against TBEV, and 5 against USUV. Three sera showed antibodies against more than one virus, and eight were negative based on the VNT. The overall seropositive ratio was 3.3% (95% CI: 2.38–4.40) for WNV, 5.6% (95% CI: 4.44–7.04) for TBEV, and 0.4% (95% CI: 0.14–0.98) for USUV infections. While age and number of horses on the holding were factors predicting TBEV seropositivity, no risk factors were discovered for WNV seropositivity. We conclude that horses are useful sentinels to determine the flavivirus circulation in eastern–central Germany, as long as they are not vaccinated against WNV. [ABSTRACT FROM AUTHOR]

Japanese encephalitis virus (JEV), a zoonotic flavivirus, is principally transmitted by hematophagous mosquitoes, continually between susceptible animals and incidentally from those animals to humans. For almost a century since its discovery, JEV was geographically confined to the Asia-Pacific region with recurrent sizable outbreaks involving wildlife, livestock, and people. However, over the past decade, it has been detected for the first time in Europe (Italy) and Africa (Angola) but has yet to cause any recognizable outbreaks in humans. JEV infection leads to a broad spectrum of clinical outcomes, ranging from asymptomatic conditions to self-limiting febrile illnesses to life-threatening neurological complications, particularly Japanese encephalitis (JE). No clinically proven antiviral drugs are available to treat the development and progression of JE. There are, however, several live and killed vaccines that have been commercialized to prevent the infection and transmission of JEV, yet this virus remains the main cause of acute encephalitis syndrome with high morbidity and mortality among children in the endemic regions. Therefore, significant research efforts have been directed toward understanding the neuropathogenesis of JE to facilitate the development of effective treatments for the disease. Thus far, multiple laboratory animal models have been established for the study of JEV infection. In this review, we focus on mice, the most extensively used animal model for JEV research, and summarize the major findings on mouse susceptibility, infection route, and viral pathogenesis reported in the past and present, and discuss some unanswered key questions for future studies. [ABSTRACT FROM AUTHOR]

The alimentary route is the second most important route of tick-borne encephalitis infection. In Poland, the last TBE case due to the consumption of unpasteurized milk or dairy products of infected animals was recorded in 2017 as the fourth documented outbreak of TBEV infection in the country. In this study, two patients infected with TBEV through consumption of unpasteurized goat's milk from one source are described from a cluster of eight cases. In August and September 2022, a 63- and 67-year-old woman were hospitalized at the Infectious Diseases Clinic of the Institute of Rural Health (Lublin, Poland). The patients denied been recently bitten by a tick, and neither had been vaccinated against TBEV. The disease had a biphasic course. In the first case, the patient suffered from a fever, spine pain, and muscle weakness and paresis of the lower left limb. The second patient suffered from fever, vertigo, headaches, abdominal pain, and diarrhoea. The results of IgM and IgG antibodies were positive in both cases. After three weeks hospitalization, the patients were discharged in good condition. In one case, slight hearing impairment was observed. Vaccination and avoiding the consumption of unpasteurized milk remain the most effective ways to prevent tick-borne encephalitis. [ABSTRACT FROM AUTHOR]

Viral tropism within the brain and the role(s) of vertebrate immune response to neurotropic flaviviruses infection is largely understudied. We combine multimodal imaging (cm-nm scale) with single nuclei RNA-sequencing to study Langat virus in wildtype and interferon alpha/beta receptor knockout (Ifnar–/–) mice to visualize viral pathogenesis and define molecular mechanisms. Whole brain viral infection is imaged by Optical Projection Tomography coregistered to ex vivo MRI. Infection is limited to grey matter of sensory systems in wildtype mice, but extends into white matter, meninges and choroid plexus in Ifnar–/– mice. Cells in wildtype display strong type I and II IFN responses, likely due to Ifnb expressing astrocytes, infiltration of macrophages and Ifng-expressing CD8+ NK cells, whereas in Ifnar–/–, the absence of this response contributes to a shift in cellular tropism towards non-activated resident microglia. Multimodal imaging-transcriptomics exemplifies a powerful way to characterize mechanisms of viral pathogenesis and tropism. Here the authors combine a multimodal imaging-snRNAseq transcriptomics strategy to provide insight into the distribution of a neurotropic tick-borne flavivirus in the brain, and show that absence of interferon signaling increases infection of resident microglia. [ABSTRACT FROM AUTHOR]

Lyme borreliosis (LB) is not notifiable in many European countries, and accurate data on the incidence are often lacking. This study aimed to determine the seroprevalence of Borrelia burgdorferi sensu lato (s.l.)-specific antibodies in the general population of The Netherlands, and to determine risk factors associated with seropositivity. Sera and questionnaires were obtained from participants (n = 5592, aged 0–88 years) enrolled in a nationwide serosurveillance study. The sera were tested for B. burgdorferi s.l.-specific IgM and IgG antibodies using ELISA and immunoblot. Seroprevalence was estimated controlling for the survey design. Risk factors for seropositivity were analyzed using a generalized linear mixed-effect model. In 2016/2017, the seroprevalence in The Netherlands was 4.4% (95% CI 3.5–5.2). Estimates were higher in men (5.7% [95% CI 4.4–7.2]) than in women (3.1% [95% CI 2.0–4.0]), and increased with age from 2.6% (95% CI 1.4–4.4) in children to 7.7% (95% CI 5.9–7.9) in 60- to 88-year-olds. The seroprevalence for B. burgdorferi s.l. in the general population in The Netherlands was comparable to rates reported in European countries. The main risk factors for seropositivity were increasing age, being male and the tick bite frequency. The dynamics of LB infection are complex and involve variables from various disciplines. This could be further elucidated using infectious disease modelling. [ABSTRACT FROM AUTHOR]

Copyright of Der Nervenarzt is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The family Flaviviridae is comprised of a diverse group of arthropod-borne viruses that are the etiological agents of globally relevant diseases in humans. Among these, infection with several of these flaviviruses—including West Nile virus (WNV), Zika virus (ZIKV), Japanese encephalitis virus (JEV), tick-borne encephalitis virus (TBEV), and Powassan virus (POWV)—can result in neuroinvasive disease presenting as meningitis or encephalitis. Factors contributing to the development and resolution of tick-borne flavivirus (TBEV, POWV) infection and neuropathology remain unclear, though many recently undertaken studies have described the virus–host interactions underlying encephalitic disease. With access to neural tissues despite the selectively permeable blood–brain barrier, T cells have emerged as one notable contributor to neuroinflammation. The goal of this review is to summarize the recent advances in tick-borne flavivirus immunology—particularly with respect to T cells—as it pertains to the development of encephalitis. We found that although T cell responses are rarely evaluated in a clinical setting, they are integral in conjunction with antibody responses to restricting the entry of TBFV into the CNS. The extent and means by which they can drive immune pathology, however, merits further study. Understanding the role of the T cell compartment in tick-borne flavivirus encephalitis is instrumental for improving vaccine safety and efficacy, and has implications for treatments and interventions for human disease. [ABSTRACT FROM AUTHOR]

Background: Lyme borreliosis (LB) is the most common tick-borne disease in Europe, but the burden of disease is incompletely described. Methods: We conducted a systematic review across PubMed, EMBASE, and CABI Direct (Global Health) databases, from January 1, 2005, to November 20, 2020, of epidemiological studies reporting incidence of LB in Europe (PROSPERO, CRD42021236906). Results: The systematic review yielded 61 unique articles describing LB incidence (national or subnational) in 25 European countries. Substantial heterogeneity in study designs, populations sampled, and case definitions restricted data comparability. The European Union Concerted Action on Lyme Borreliosis (EUCALB)–published standardized LB case definitions were used by only 13 (21%) of the 61 articles. There were 33 studies that provided national-level LB incidence estimates for 20 countries. Subnational LB incidence was available from an additional four countries (Italy, Lithuania, Norway, and Spain). The highest LB incidences (>100 cases per 100,000 population per year [PPY]) were reported in Belgium, Finland, the Netherlands, and Switzerland. Incidences were 20–40/100,000 PPY in the Czech Republic, Germany, Poland, and Scotland and <20/100,000 PPY in Belarus, Croatia, Denmark, France, Ireland, Portugal, Russia, Slovakia, Sweden, and the United Kingdom (England, Northern Ireland, and Wales); markedly higher incidences were observed at the subnational level (up to 464/100,000 PPY in specific local areas). Conclusions: Although countries in Northern (Finland) and Western (Belgium, the Netherlands, and Switzerland) Europe reported the highest LB incidences, high incidences also were reported in some Eastern European countries. There was substantial subnational variation in incidence, including high incidences in some areas of countries with low overall incidence. This review, complemented by the incidence surveillance article, provides a comprehensive view into LB disease burden across Europe that may guide future preventive and therapeutic strategies—including new strategies on the horizon. [ABSTRACT FROM AUTHOR]

Background: Lyme borreliosis (LB), a tick bite-transmitted infection caused by Borrelia burgdorferi sensu lato (Bbsl) complex spirochetes, is the most common tickborne disease in Europe. Studies in European countries have reported LB seroprevalence (prevalence of antibodies to Bbsl infection) and diagnostic strategies used for testing. We conducted a systematic literature review to summarize contemporary LB seroprevalence in Europe. Methods: PubMed, Embase, and CABI Direct (Global Health) databases were searched from 2005 to 2020 to identify studies reporting LB seroprevalence in European countries. Reported single-tier and two-tier test results were summarized; algorithms (standard or modified) were used to interpret final test results from studies that used two-tier testing. Results: The search yielded 61 articles from 22 European countries. Studies used a range of diagnostic testing methods and strategies (48% single-tier, 46% standard two-tier, and 6% modified two-tier). In 39 population-based studies, of which 14 were nationally representative, seroprevalence estimates ranged from 2.7% (Norway) to 20% (Finland). There was substantial heterogeneity among studies in terms of design, cohort types, periods sampled, sample sizes, and diagnostics, which limited cross-study comparisons. Nevertheless, among studies that reported seroprevalence in persons with greater exposure to ticks, LB seroprevalence was higher among these groups than in the general population (40.6% vs. 3.9%). Furthermore, among studies that used two-tier testing, general population LB seroprevalence was higher in Western Europe (13.6%) and Eastern Europe (11.1%) than in Northern Europe (4.2%) and Southern Europe (3.9%). Conclusion: Despite variations in LB seroprevalence between and within European subregions and countries, high seroprevalence was observed in certain geographic regions and particular risk groups, suggesting significant disease burden and supporting the need for improved, targeted public health interventions such as vaccination. Harmonized approaches to serologic testing and more nationally representative seroprevalence studies are needed to better understand the prevalence of Bbsl infection in Europe. [ABSTRACT FROM AUTHOR]

Background: Tick-borne encephalitis virus (TBEV) can cause severe neurological disease in humans. Its geographical distribution is expanding in Western Europe with unresolved causes and spatial patterns, necessitating enhanced surveillance. Monitoring the virus in the environment is complicated, as it usually relies on destructive sampling of small rodents to test organs for TBEV, which in addition to ethical considerations also raises issues for long-term monitoring or longitudinal studies. Moreover, even when the virus is not detected in the blood or organs of the rodent, TBEV can still be transmitted from an infected tick to uninfected ticks feeding nearby. This is due to the ability of TBEV to replicate and migrate locally within the epidermis of small mammals, including those that do not appear to have systemic infection. This suggests that the virus may be detectable in skin biopsies, which has been confirmed in experimentally infected laboratory rodents, but it remains unknown if this sample type may be a viable alternative to destructively obtained samples in the monitoring of natural TBEV infection. Here we test ear tissue and dried blood spot (DBS) samples from rodents to determine whether TBEV-RNA can be detected in biological samples obtained non-destructively. Methods: Rodents were live-trapped and sampled at three woodland areas in The Netherlands where presence of TBEV has previously been recorded. Ear tissue (n = 79) and DBSs (n = 112) were collected from a total of 117 individuals and were tested for TBEV-RNA by real-time RT-PCR. Results: TBEV-RNA was detected in five rodents (4.3% of tested individuals), all of which had a TBEV-positive ear sample, while only two out of four of these individuals (for which a DBS was available) had a positive DBS. This equated to 6.3% of ear samples and 1.8% of DBSs testing positive for TBEV-RNA. Conclusions: We provide the first evidence to our knowledge that TBEV-RNA can be detected in samples obtained non-destructively from naturally infected wild rodents, providing a viable sampling alternative suitable for longitudinal surveillance of the virus. [ABSTRACT FROM AUTHOR]

Introduction of point mutations is one of the forces enabling arboviruses to rapidly adapt in a changing environment. The influence of these mutations on the properties of the virus is not always obvious. In this study, we attempted to clarify this influence using an in silico approach. Using molecular dynamics (MD) simulations, we investigated how the position of charge-changing point mutations influences the structure and conformational stability of the E protein for a set of variants of a single TBEV strain. The computational findings were supported by experimental evaluation of relevant properties of virions, such as binding to heparan sulfate, thermostability, and susceptibility of the viral hemagglutinating activity to detergents. Our results also point to relationships between E protein dynamics and viral neuroinvasiveness. [ABSTRACT FROM AUTHOR]

Introduction: Patients with chronic hepatitis B (CHB) have a dynamic disease process and risk of end-stage liver disease. It is critical to unambiguously differentiate the stages of the disease and focus on therapy prior to onset of an irreversible clinical endpoint. Methods: We retrospectively analyzed a wide range of CHB patients at different stages. The predictive power of serum complement component 3 (C3) levels for the development of acute-on-chronic liver failure (ACLF) in patients with decompensated cirrhosis was established and validated. Results: The decrease in serum C3 levels paralleled the severity of diseases related to hepatitis B virus. Patients with decompensated cirrhosis who developed ACLF had significantly lower serum C3 levels than others on admission (0.50 vs. 0.80 g/L, P < 0.001). Data analysis also revealed that low serum C3 was a significant risk factor for developing ACLF (hazard ratio = 0.32, P < 0.01). The area under the receiver operating characteristic curve (auROC) for serum C3 levels that predicted the development of ACLF in patients with decompensated cirrhosis was 0.90, which had sensitivity and specificity of 88.2% and 88.7%, respectively. A similar result was observed in the validation set (auROC = 0.86 for predicting development of ACLF in patients with decompensated cirrhosis). Conclusions: Serum C3 levels are valuable in assessing the severity of CHB-related stages. Low C3 levels signifies the development of ACLF in patients with decompensated cirrhosis. Plain Language Summary: Generally, acute-on-chronic liver failure is a rapidly worsening liver failure syndrome. This disease is intractable and with high mortality. Acute decompensation of the liver is defined as the occurrence of complications of liver disease (i.e., ascites, hepatic encephalopathy, gastrointestinal bleeding, and bacterial infection). Clinically, acute decompensation in hepatitis B virus-related cirrhosis (a result of chronic liver injury by virus) often develops into acute-on-chronic liver failure. In addition, the complement component 3 is a serum protein, which participates in the immune response against virus infection and has been reported to be associated with liver failure. We tried to explore the feature of serum complement component 3 to differentiate the stages of the disease and assess its predictive value for acute-on-chronic liver failure. So, we analyzed the complement component 3 data from a broad range of hepatitis B virus-cirrhosis patients. Through analysis, we found that complement component 3 levels are valuable in assessing the severity of chronic hepatitis B-related stages. Low complement component 3 levels can also signify the development of acute-on-chronic liver failure in patients with decompensated cirrhosis. [ABSTRACT FROM AUTHOR]

Background: Tick-borne encephalitis (TBE) is the most significant tick-borne disease in Europe and Asia, with more than 10,000 cases per year worldwide. A surge of reported TBE cases can be observed despite the availability of highly efficient vaccines. There is little known about the serological immune protection rate of the population in Germany. The seroprotection rate is defined as the presence of neutralizing antibodies. In contrast, the vaccination rate, as defined by public health agencies, may differ from the true protection rate in a population. Materials and Methods: 2220 blood samples from inhabitants of the county Ortenaukreis in the Federal State of Baden-Württemberg in Germany were included in the study. These were tested for anti-TBEV IgG antibodies by an anti-TBEV-IgG-ELISA. Subsequently, all TBEV-IgG positive samples were confirmed for neutralizing antibodies in the micro serum neutralization assay. Results: From the overall 2220 samples, 2104 were included in the comparison because of the selection of specific age groups (ages 20–69). In our sample size, we found an average serological protection rate (presence of neutralizing antibodies) of 57% (518/908) for the female blood donors and of 52% (632/1196) for the male blood donors. Discussion: In this study, we present new findings on a highly endemic region in southern Germany. Additionally, we present current data regarding the serological TBEV protection rates in the Ortenaukreis in southern Germany and compare these with a dataset published by the RKI, which is based on vaccination reports of the primary care providers and health care insurers, and with a self-reporting study conducted by a vaccine manufacturer. Our results significantly exceed the official numbers of average active vaccination status by 23.2% for females and by 21% for males. This might indicate an even longer persistence of TBE-vaccination-induced antibody titers than previously assumed. [ABSTRACT FROM AUTHOR]

Background: Ticks are important medical arthropods that can transmit hundreds of pathogens, such as parasites, bacteria, and viruses, leading to serious public health burdens worldwide. Unexplained fever is the most common clinical manifestation of tick-borne diseases. Since the emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the surge of coronavirus disease 2019 (COVID-19) cases led to the hospital overload and fewer laboratory tests for tick-borne diseases. Therefore, it is essential to review the tick-borne pathogens and further understand tick-borne diseases. Purpose: The geographic distribution and population of ticks in the Northern hemisphere have expanded while emerging tick-borne pathogens have been introduced to China continuously. This paper focused on the tick-borne pathogens that are threatening public health in the world. Their medical significant tick vectors, as well as the epidemiology, clinical manifestations, diagnosis, treatment, prevention, and control measures, are emphasized in this document. Methods: In this study, all required data were collected from articles indexed in English databases, including Scopus, PubMed, Web of Science, Science Direct, and Google Scholar. Results: Ticks presented a great threat to the economy and public health. Although both infections by tick-borne pathogens and SARS-CoV-2 have fever symptoms, the history of tick bite and its associated symptoms such as encephalitis or eschar could be helpful for the differential diagnosis. Additionally, as a carrier of vector ticks, migratory birds may play a potential role in the geographical expansion of ticks and tick-borne pathogens during seasonal migration. Conclusion: China should assess the risk score of vector ticks and clarify the potential role of migratory birds in transmitting ticks. Additionally, the individual and collective protection, vector control, comprehensive surveillance, accurate diagnosis, and symptomatic treatment should be carried out, to meet the challenge. [ABSTRACT FROM AUTHOR]

Infection with the tick-borne encephalitis virus (TBEV) can cause meningitis, meningoencephalitis and myelitis in humans. TBEV is an enveloped RNA virus of the family Flaviviridae, which is mostly transmitted via tick bites. However, transmission by consumption of virus-contaminated goat raw milk and goat raw milk products has also been described. Only a few methods have been reported for the detection of TBEV in food so far. Here, we compare different virus extraction methods for goat raw milk and goat raw milk cream cheese and subsequent detection of TBEV-RNA by RT-qPCR. Langat virus (LGTV), a naturally attenuated TBEV strain, was used for artificial contamination experiments. Mengovirus and the human coronavirus 229E were compared to assess their suitability to serve as internal process controls. Out of three tested extraction protocols for raw milk, sample centrifugation followed by direct RNA extraction from the aqueous interphase yielded the best results, with a recovery rate (RR) of 31.8 ± 4.9% for LGTV and a detection limit of 6.7 × 103 LGTV genome copies/ml. Out of two methods for cream cheese, treatment of the samples with TRI Reagent® and chloroform prior to RNA extraction showed the best RR of 4.7 ± 1.6% for LGTV and a detection limit of 9.4 × 104 LGTV genome copies/g. RRs of Mengovirus and LGTV were similar for both methods; therefore, Mengovirus is suggested as internal process control virus. The developed methods may be useful for screening or surveillance studies, as well as in outbreak investigations. [ABSTRACT FROM AUTHOR]

The recent COVID-19 pandemic has resulted in the massive discard of pandemic-related plastic wastes, causing serious ecological harm and a high societal burden. Most single-use face masks are made of synthetic plastics, thus their careless disposal poses a direct threat to wildlife as well as potential ecotoxicological effects in the form of microplastics. Here, we introduce a 1D magnetic photoactive microswarm capable of actively navigating, adhering to, and accelerating the degradation of the polypropylene microfiber of COVID-19 face masks. 1D microrobots comprise an anisotropic magnetic core (Fe3O4) and photocatalytic shell (Bi2O3/Ag), which enable wireless magnetic maneuvering and visible-light photocatalysis. The actuation of a programmed rotating magnetic field triggers a fish schooling-like 1D microswarm that allows active interfacial interactions with the microfiber network. The follow-up light illumination accelerates the disruption of the polypropylene microfiber through the photo-oxidative process as corroborated by morphological, compositional, and structural analyses. The active magnetic photocatalyst microswarm suggests an intriguing microrobotic solution to treat various plastic wastes and other environmental pollutants. Most single-use face masks are made of synthetic plastics, thus their disposal poses a direct threat to wildlife as well as potential ecotoxicological effects in the form of microplastics. Here, the authors introduce a 1D magnetic photoactive microswarm capable of actively navigating, adhering to, and accelerating the degradation of the polypropylene microfiber of single-use face masks. [ABSTRACT FROM AUTHOR]

Usutu virus (USUV) is an emerging zoonotic arbovirus that has caused an increasing number of animal and human cases in Europe in recent years. Understanding the vector species and avian hosts involved in the USUV enzootic cycle in an area of active circulation is vital to anticipate potential outbreaks. Mosquitoes were captured in 2020, while wild birds were sampled in both 2020 and 2021 in Extremadura, southwestern Spain. The presence of USUV in the mosquito vectors was assessed by a real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay and confirmed by sequencing amplicons from two generic RT-PCR sets for flaviviruses. Sequences were analysed phylogenetically. Bird sera were screened for flavivirus antibodies with a blocking ELISA kit and subsequently tested for virus-specific antibodies with a micro-virus-neutralization test. Overall, 6,004 mosquitoes belonging to 13 species were captured, including some well-known flavivirus vectors (Culex pipiens, Cx. perexiguus, and Cx. univittatus). Of the 438 pools tested, USUV was detected in two pools of Cx. pipiens. Phylogenetic analysis using a fragment of the NS5 gene assigned the USUV detected the Africa 3 lineage. Out of 1,413 wild birds tested, USUV-specific antibodies were detected in 17 birds (1.2%, 10 males and 7 females) from eight species. The first detection of USUV Africa 3 lineage in mosquitoes from Spain, together with serologically positive resident wild birds in urban and rural areas, indicates active circulation and a possible risk of exposure for the human population, with necessity to establish specific surveillance plans. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis virus (TBEV) may cause tick-borne encephalitis (TBE), a potential life-threatening infection of the central nervous system in humans. Phylogenetically, TBEVs can be subdivided into three main subtypes, which differ in endemic region and pathogenic potential. In 2016, TBEV was first detected in the Netherlands. One of two detected strains, referred to as Salland, belonged to the TBEV-Eu subtype, yet diverged ≥ 2% on amino acid level from other members of this subtype. Here, we report the successful rescue of this strain using infectious subgenomic amplicons and its subsequent in vitro characterization by comparison to two well-characterized TBEV-Eu strains; Neudoerfl and Hypr. In the human alveolar epithelial cell line A549, growth kinetics of Salland were comparable to the high pathogenicity TBEV-Eu strain Hypr, and both strains grew considerably faster than the mildly pathogenic strain Neudoerfl. In the human neuroblastoma cell line SK-N-SH, Salland replicated faster and to higher infectious titers than both reference strains. All three TBEV strains infected primary human monocyte-derived dendritic cells to a similar extent and interacted with the type I interferon system in a similar manner. The current study serves as the first in vitro characterization of the novel, divergent TBEV-Eu strain Salland. [ABSTRACT FROM AUTHOR]

Neuroinfections of the central nervous system (CNS) can be triggered by various pathogens. Viruses are the most widespread and have the potential to induce long-term neurologic symptoms with potentially lethal outcomes. In addition to directly affecting their host cells and inducing immediate changes in a plethora of cellular processes, viral infections of the CNS also trigger an intense immune response. Regulation of the innate immune response in the CNS depends not only on microglia, which are fundamental immune cells of the CNS, but also on astrocytes. These cells align blood vessels and ventricle cavities, and consequently, they are one of the first cell types to become infected after the virus breaches the CNS. Moreover, astrocytes are increasingly recognized as a potential viral reservoir in the CNS; therefore, the immune response initiated by the presence of intracellular virus particles may have a profound effect on cellular and tissue physiology and morphology. These changes should be addressed in terms of persisting infections because they may contribute to recurring neurologic sequelae. To date, infections of astrocytes with different viruses originating from genetically distinct families, including Flaviviridae, Coronaviridae, Retroviridae, Togaviridae, Paramyxoviridae, Picomaviridae, Rhabdoviridae, and Herpesviridae, have been confirmed. Astrocytes express a plethora of receptors that detect viral particles and trigger signaling cascades, leading to an innate immune response. In this review, we summarize the current knowledge on virus receptors that initiate the release of inflammatory cytokines from astrocytes and depict the involvement of astrocytes in immune functions of the CNS. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 betacoronavirus pandemic has claimed more than 6.5 million lives and, despite the development and use of COVID-19 vaccines, remains a major global public health problem. The development of specific drugs for the treatment of this disease remains a very urgent task. In the context of a repurposing strategy, we previously screened a library of nucleoside analogs showing different types of biological activity against the SARS-CoV-2 virus. The screening revealed compounds capable of inhibiting the reproduction of SARS-CoV-2 with EC50 values in the range of 20–50 µM. Here we present the design and synthesis of various analogs of the leader compounds, the evaluation of their cytotoxicity and antiviral activity against SARS-CoV-2 in cell cultures, as well as experimental data on RNA-dependent RNA polymerase inhibition. Several compounds have been shown to prevent the interaction between the SARS-CoV-2 RNA-dependent RNA polymerase and the RNA substrate, likely inhibiting virus replication. Three of the synthesized compounds have also been shown to inhibit influenza virus. The structures of these compounds can be used for further optimization in order to develop an antiviral drug. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis virus is an enveloped, pathogenic, RNA virus in the family Flaviviridae, genus Flavivirus. Viral particles are formed when the nucleocapsid, consisting of an RNA genome and multiple copies of the capsid protein, buds through the endoplasmic reticulum membrane and acquires the viral envelope and the associated proteins. The coordination of the nucleocapsid components to the sites of assembly and budding are poorly understood. Here, we investigate the interactions of the wild-type and truncated capsid proteins with membranes with biophysical methods and model membrane systems. We show that capsid protein initially binds membranes via electrostatic interactions with negatively-charged lipids, which is followed by membrane insertion. Additionally, we show that membrane-bound capsid protein can recruit viral genomic RNA. We confirm the biological relevance of the biophysical findings by using mass spectrometry to show that purified virions contain negatively-charged lipids. Our results suggest that nucleocapsid assembly is coordinated by negatively-charged membrane patches on the endoplasmic reticulum and that the capsid protein mediates direct contacts between the nucleocapsid and the membrane. Author summary: Tick-borne encephalitis virus (TBEV) causes a life-threatening neurological disease. The incidence of the disease is increasing despite the availability of efficient vaccines. The virus particles contain a nucleocapsid consisting of the viral RNA genome and multiple copies of the capsid protein. The nucleocapsid is surrounded by an envelope derived from host membranes and two viral surface protein species are embedded into it. The assembly of TBEV virions is poorly understood despite its medical significance. Here, we have used a large combination of biophysical methods to study the interactions of the capsid protein with artificial lipid membranes. We show that the capsid protein requires negatively-charged lipids for membrane binding and that the capsid protein is capable of inserting into the membranes in the presence of such lipids. Once membrane-bound, the capsid protein is able to recruit TBEV genomic RNA onto the membrane. Our results suggest that the initial events of TBEV assembly are mediated by the specific binding of the capsid protein to negatively-charged lipids, allowing for the recruitment of the genome. This is further supported by our characterization of the lipid composition of purified TBEV particles, which shows that the TBEV envelope contains negatively-charged lipids. [ABSTRACT FROM AUTHOR]

The genetic diversities of mammalian tick-borne flaviviruses are poorly understood. We used next-generation sequencing (NGS) to deep sequence different viruses and strains belonging to this group of flaviviruses, including Central European tick-borne encephalitis virus (TBEV-Eur), Far Eastern TBEV (TBEV-FE), Langat (LGTV), Powassan (POWV), Deer Tick (DTV), Kyasanur Forest Disease (KFDV), Alkhurma hemorrhagic fever (AHFV), and Omsk hemorrhagic fever (OHFV) viruses. DTV, AHFV, and KFDV had the lowest genetic diversity, while POWV strains LEIV-5530 and LB, OHFV, TBEV-Eur, and TBEV-FE had higher genetic diversities. These findings are compatible with the phylogenetic relationships between the viruses. For DTV and POWV, the amount of genetic diversity could be explained by the number of tick vector species and amplification hosts each virus can occupy, with low diversity DTV having a more limited vector and host pool, while POWV with higher genetic diversities has been isolated from different tick species and mammals. It is speculated that high genetic diversity may contribute to the survival of the virus as it encounters these different environments. [ABSTRACT FROM AUTHOR]

Flaviviruses are present on every continent and cause significant morbidity and mortality. In many instances, severe cases of infection with flaviviruses involve the invasion of and damage to the central nervous system (CNS). Currently, there are several mechanisms by which it has been hypothesized flaviviruses reach the brain, including the disruption of the blood–brain barrier (BBB) which acts as a first line of defense by blocking the entry of many pathogens into the brain, passing through the BBB without disruption, as well as travelling into the CNS through axonal transport from peripheral nerves. After flaviviruses have entered the CNS, they cause different neurological symptoms, leading to years of neurological sequelae or even death. Similar to neuroinvasion, there are several identified mechanisms of neuropathology, including direct cell lysis, blockage of the cell cycle, indication of apoptosis, as well as immune induced pathologies. In this review, we aim to summarize the current knowledge in the field of mechanisms of both neuroinvasion and neuropathogenesis during infection with a variety of flaviviruses and examine the potential contributions and timing of each discussed pathway. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis (TBE) is Eurasia's most important tick-borne viral disease. Rodents play an important role as natural hosts. Longitudinal studies on the dynamics of the seroprevalence rates in wild rodents in natural foci over the year are rare, and the dynamics of the transmission cycle still need to be understood. To better understand the infection dynamics, rodents were captured in a capture-mark-release-recapture-study in two natural foci in Bavaria, Germany, monthly from March 2019 to October 2022. Overall, 651 blood and thoracic lavage samples from 478 different wild rodents (Clethrionomys glareolus and Apodemus flavicollis) were analyzed for antibodies against tick-borne encephalitis virus (TBEV) by indirect immunofluorescence assay (IIFA) and confirmed using a serum neutralization test (SNT). Furthermore, a generalized linear mixed model (GLMM) analysis was performed to investigate ecological and individual factors for the probability of infection in rodents. Clethrionomys glareolus (19.4%) had a higher seroprevalence than A. flavicollis (10.5%). Within Cl. glareolus, more males (40.4%) than females (15.6%) were affected, and more adults (25.4%) than juveniles (9.8%). The probability of infection of rodents rather depends on factors such as species, sex, and age than on the study site of a natural focus, year, and season. The high incidence rates of rodents, particularly male adult bank voles, highlight their critical role in the transmission cycle of TBEV in a natural focus and demonstrate that serologically positive rodents can be reliably detected in a natural focus regardless of season or year. In addition, these data contribute to a better understanding of the TBEV cycle and thus could improve preventive strategies for human infections. [ABSTRACT FROM AUTHOR]

Tick-borne Encephalitis Virus (TBEV) is an emerging flavivirus that causes neurological disorders including viral encephalitis of varying severity. Whilst secondary RNA structures within the 5′ untranslated regions (UTRs) of many flaviviruses determine both virus replication and pathogenic outcomes in humans, these elements have not been systematically investigated for TBEV. In this study, we investigated the role of predicted RNA secondary elements of the first 107 nucleotides (nts) of the viral genome forming the stem-loop A (SLA). Experiments were performed in replicons and infectious TBEV system. This region comprises three distinct structures: 5' stem 0 (S0), stem-loop 1 (SL1) and stem-loop 2 (SL2). S0 was found to be essential for virus infection as mutations in the lower stem of this region significantly reduced virus replication. Point mutations in SL1 that preserved the Y-shape confirmation delayed viral RNA replication but did not abolish virus infectivity. Deletion of SL2 did not abolish infectivity but had a negligible effect on virus propagation. No correlation was observed between in vitro translation efficiency and virus infectivity, suggesting that the 5'UTR functions independently to virus translation. Together, these findings reveal distinct RNA elements within the 5′UTR that are essential for the stability and replication of viral RNA. We further identify changes in RNA folding that lead to altered TBEV infectivity and pathogenesis. Author summary: Tick-borne Encephalitis Virus (TBEV) is becoming endemic in regions previously unreported, including large areas of Europe and Asia. TBEV was also isolated in the UK in 2019, highlighting its potential as a concern to public health. TBEV is spread by ticks and causes severe and often fatal tick-borne encephalitis (TBE). No effective anti-TBEV therapeutics are available. TBEV circulates as three major subtypes that cause disease of varying severity. The reasons for the disparity in disease outcome are largely unknown. TBEV subtypes show high levels of nucleotide conservation at the 5′ non-coding (NC) region that folds to form a Y-shaped stem-loop A (SLA), which is conserved for all flaviviruses. Herein, we describe the identification of stem-loop regions in the SLA that are required for RNA replication and virus infectivity in cell culture, but do not influence viral translation. The observed virus attenuation suggested that the 5′ SLA likely serves as an essential regulatory element for binding to host factors that support viral replication and pathogenicity. These data highlight the complex interactions within specific TBEV viral RNA conformations and reveal new targets for the development of much needed anti-TBEV therapeutics. [ABSTRACT FROM AUTHOR]

Tick-borne encephalitis (TBE) is an emerging zoonosis that may cause long-term neurological sequelae or even death. Thus, there is a growing interest in understanding the factors of TBE pathogenesis. Viral genetic determinants may greatly affect the severity and consequences of TBE. In this study, nonstructural protein 1 (NS1) of the tick-borne encephalitis virus (TBEV) was tested as such a determinant. NS1s of three strains with similar neuroinvasiveness belonging to the European, Siberian and Far-Eastern subtypes of TBEV were studied. Transfection of mouse cells with plasmids encoding NS1 of the three TBEV subtypes led to different levels of NS1 protein accumulation in and secretion from the cells. NS1s of TBEV were able to trigger cytokine production either in isolated mouse splenocytes or in mice after delivery of NS1 encoding plasmids. The profile and dynamics of TNF-α, IL-6, IL-10 and IFN-γ differed between the strains. These results demonstrated the involvement of TBEV NS1 in triggering an immune response and indicated the diversity of NS1 as one of the genetic factors of TBEV pathogenicity. [ABSTRACT FROM AUTHOR]

Copyright of Epidemiological Review / Przegląd Epidemiologiczny is the property of National Institute of Public Health - National Institute of Hygiene and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Zika virus (ZIKV) is a Flavivirus from the Flaviviridae family and a positive-sense single strand RNA virus. ZIKV infection can cause a mild infection to the mother but can be vertically transmitted to the developing fetus, causing congenital anomalies. The prevalence of ZIKV infections was relatively insignificant with sporadic outbreaks in the Asian and African continents until 2006. However, recent epidemic in the Caribbean showed significant increased incidence of Congenital Zika Syndrome. ZIKV infection results in placental pathology which plays a crucial role in disease transmission from mother to fetus. Currently, there is no Food and Drug Administration (FDA) approved vaccine or therapeutic drug against ZIKV. This review article summarizes the recent advances on ZIKV transmission and diagnosis and reviews nutraceuticals which can protect against the ZIKV infection. Further, we have reviewed recent advances related to the novel therapeutic nutrient molecules that have been shown to possess activity against Zika virus infected cells. We also review the mechanism of ZIKV-induced endoplasmic reticulum and apoptosis and the protective role of palmitoleate (nutrient molecule) against ZIKV-induced ER stress and apoptosis in the placental trophoblasts. [ABSTRACT FROM AUTHOR]

Mosquitoes are vectors of various pathogens that cause diseases in humans and animals. To prevent the outbreak of mosquito-borne diseases, it is essential to control vector populations, as treatment or vaccination for mosquito-borne diseases are often unavailable. Insect-specific viruses (ISVs) have previously been described as being potentially helpful against arboviral disease outbreaks. In this study, we present the first in vivo characterization of the ISV Culex Y virus (CYV). CYV was first isolated from free-living Culex pipiens mosquitoes in 2010; then, it was found in several mosquito cell lines in a further study in 2018. For mammalian cells, we were able to confirm that CYV does not replicate as it was previously described. Additionally, we found that CYV does not replicate in honey bees or locusts. However, we detected replication in the Culex pipiens biotype molestus, Aedes albopictus, and Drosophila melanogaster, thus indicating dipteran specificity. We detected significantly higher mortality in Culex pipiens biotype molestus males and Drosophila melanogaster, but not in Aedes albopictus and female Culex pipiens biotype molestus. CYV could not be transmitted transovarially to offspring, but we detected venereal transmission as well as CYV in mosquitos' saliva, indicating that an oral route of infection would also be possible. CYV's dipteran specificity, transmission routes, and killing effect with respect to Culex males may be used as powerful tools with which to destabilize arbovirus vector populations in the future. [ABSTRACT FROM AUTHOR]

Understanding of the nucleation process's fundamental principles in saturated solutions is an urgent task. To do this task, it is necessary to control the formation of polymorphic forms of biologically active compounds. In certain cases, a compound can exist in a single polymorphic form, but have several solvates which can appear in different crystal forms, depending on the medium and conditions of formation, and show different pharmaceutical activity. In the present paper, we report on the analysis of Arbidol conformational preferences in two solvents of different polarities—deuterated chloroform and dimethyl sulfoxide—at 25 °C, using the 2D NOESY method. The Arbidol molecule has various solvate forms depending on the molecular conformation. The method based on the nuclear Overhauser effect spectroscopy was shown to be efficient in the analysis of complex heterocyclic compounds possessing conformation-dependent pseudo-polymorphism. It is one of the types of polymorphism observed in compounds forming crystal solvates. Combined use of NMR methods and X-ray data allowed determining of conformer populations of Arbidol in CDCl3 and DMSO-d6 which were found to be 8/92% and 37/63%, respectively. The preferred conformation in solution is the same that appears in stable crystal solvates of Arbidol. [ABSTRACT FROM AUTHOR]

Objective: Suckling mouse inoculation is an important method that has been used for years to isolate viruses from ticks; however, this method has usually been briefly described in the literature on a case-by-case basis upon successful isolation rather than providing extensive details. Methods: This study describes the procedure from preparation of tick homogenates to identification of virus isolation using the suckling mouse inoculation method. The transient and persistent features were characterized and the incidence of manifestations that developed in the suckling mice, especially in mice from which viruses were isolated, is reported. Results: We identified 22 symptoms that developed in mice, including 13 transient symptoms that recovered by the end of the observation period and 7 persistent symptoms that the mice suffered from throughout the observation period. Persistent symptoms (lateral positioning and dead) and transient symptoms (malaise, emaciation, and difficulty turning over) were the main symptoms based on the high overall incidence. Moreover, we showed that mice from which viruses were isolated had a concentrated period and advanced days of disease onset. Conclusion: This study provides detailed information necessary for better use of suckling mouse inoculation to isolate viruses from ticks, which may benefit optimization of this method to identify, discover, and acquire tick-borne viruses. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) is an emerging flavivirus that is associated with neurological complications, such as neuroinflammatory Guillain Barré Syndrome in adults and microcephaly in newborns, and remains a potentially significant and international public health concern. The World Health Organization is urging the development of novel antiviral therapeutic strategies against ZIKV, as there are no clinically approved vaccines or drugs against this virus. Given the public health crisis that is related to ZIKV cases in the last decade, efficient strategies should be identified rapidly to combat or treat ZIKV infection. Several promising strategies have been reported through drug repurposing studies, de novo design, and the high-throughput screening of compound libraries in only a few years. This review summarizes the genome and structure of ZIKV, viral life cycle, transmission cycle, clinical manifestations, cellular and animal models, and antiviral drug developments, with the goal of increasing our understanding of ZIKV and ultimately defeating it. [ABSTRACT FROM AUTHOR]

The blood brain barrier (BBB) is a multicellular microenvironment that plays an important role in regulating bidirectional transport to and from the central nervous system (CNS). Infections by many acutely infectious viruses such as alphaviruses and flaviviruses are known to impact the integrity of the endothelial lining of the BBB. Infection by Venezuelan Equine Encephalitis Virus (VEEV) through the aerosol route causes significant damage to the integrity of the BBB, which contributes to long-term neurological sequelae. An effective therapeutic intervention strategy should ideally not only control viral load in the host, but also prevent and/or reverse deleterious events at the BBB. Two dimensional monocultures, including trans-well models that use endothelial cells, do not recapitulate the intricate multicellular environment of the BBB. Complex in vitro organ-on-a-chip models (OOC) provide a great opportunity to introduce human-like experimental models to understand the mechanistic underpinnings of the disease state and evaluate the effectiveness of therapeutic candidates in a highly relevant manner. Here we demonstrate the utility of a neurovascular unit (NVU) in analyzing the dynamics of infection and proinflammatory response following VEEV infection and therapeutic effectiveness of omaveloxolone to preserve BBB integrity and decrease viral and inflammatory load. [ABSTRACT FROM AUTHOR]

In this work, we presented data from a two-year study of flavi-, flavi-like, and phenuiviruses circulation in the population of ixodid ticks in the Chelyabinsk region. We isolated three tick-borne encephalitis virus (TBEV) strains from I. persulcatus, which was not detected in the ticks of the genus Dermacentor. The virus prevalence ranged from 0.66% to 2.28%. The Yanggou tick virus (YGTV) is widespread in steppe and forest-steppe zones and is mainly associated with ticks of the genus Dermacentor. We isolated 26 strains from D. reticulatus, D. marginatus, and I. persulcatus ticks in the HAE/CTVM8 tick cell line. The virus prevalence ranged from 1.58% to 4.18% in D. reticulatus, ranged from 0.78% to 3.93% in D. marginatus, and was 0.66% in I. persulcatus. There was combined focus of TBEV and YGTV in the territory of the Chelyabinsk region. The Alongshan virus (ALSV) was found to be associated with I. persulcatus ticks and is spread in forest zone. We detected 12 amplicons and isolated 7 strains of ALSV in tick cells. The virus prevalence ranged from 1.13% to 6.00%. The phlebovirus Gomselga and unclassified phenuivirus Stavropol were associated with I. persulcatus and D. reticulatus ticks, respectively. Virus prevalence of the unclassified phenuivirus Stavropol in the Chelyabinsk region is lower than that in neighbouring regions. [ABSTRACT FROM AUTHOR]

The tick-borne encephalitis virus (TBEV) causes a most important viral life-threatening illness transmitted by ticks. The interactions between the virus and ticks are largely unexplored, indicating a lack of experimental tools and systematic studies. One such tool is recombinant reporter TBEV, offering antibody-free visualization to facilitate studies of transmission and interactions between a tick vector and a virus. In this paper, we utilized a recently developed recombinant TBEV expressing the reporter gene mCherry to study its fitness in various tick-derived in vitro cell cultures and live unfed nymphal Ixodes ricinus ticks. The reporter virus was successfully replicated in tick cell lines and live ticks as confirmed by the plaque assay and the mCherry-specific polymerase chain reaction (PCR). Although a strong mCherry signal determined by fluorescence microscopy was detected in several tick cell lines, the fluorescence of the reporter was not observed in the live ticks, corroborated also by immunoblotting. Our data indicate that the mCherry reporter TBEV might be an excellent tool for studying TBEV-tick interactions using a tick in vitro model. However, physiological attributes of a live tick, likely contributing to the inactivity of the reporter, warrant further development of reporter-tagged viruses to study TBEV in ticks in vivo. [ABSTRACT FROM AUTHOR]

Central nervous system (CNS) infection is a serious illness that can lead to death. CNS infections include meningitis, encephalitis, brain abscesses and myelitis. these diseases are caused by causative agents like bacteria, fungi, parasites, and protozoa, but most commonly by viral infections. to combat this issue, accurate diagnosis of etiological agents at an early stage is crucial for appropriate treatment, control of the disease and prevent from becoming life-threatening to the patients. this review paper summarises the main laboratory diagnostic methods for CNS infections caused by viruses ranging from conventional to molecular methods. Conventional isolation methods are considered the 'gold standard' as they provide accurate evidence, but require highly skilled personnel, are time-consuming, critical in cell type selection and are useless for non-cultivable viruses. electron microscopy allows recognition of viral morphology and ultrastructural details as the principle of virus identification through negative staining or thin section technique (suitable for tissue or cell specimens). However, it offers low sensitivity and requires at least 106 virions per millilitre or milligram in the specimen to be detectable by microscopy. Immunological-based methods have been extensively applied for viral diagnosis by detecting the antiviral antibodies or viral antigens in clinical samples. While these methods provided high sensitivity and specificity, the incubation and window period of an infection may give false-negative results. lastly, molecular detections have many advantages such as high sensitivity, specificity, rapid, require a small amount of sample, simultaneous detection of multiple different viruses, and produce both qualitative and quantitative results. [ABSTRACT FROM AUTHOR]

Flaviviruses are a heterogeneous group of viruses that may induce broad antigenic cross-reactivity. We present a patient who was admitted to the infectious disease department with symptoms suggestive of aseptic meningitis. During the clinical workup, the patient reported a tick bite two weeks before the disease onset. High titers of IgM and IgG antibodies to tick-borne encephalitis virus (TBEV) were found in both serum and cerebrospinal fluid (CSF) samples, indicating acute TBEV infection. West Nile virus (WNV) and Usutu virus (USUV) IgM and/or IgG antibodies were also detected, and a virus neutralization test (VNT) was performed. A high titer of TBEV neutralizing (NT) antibodies (640) was detected, which confirmed acute TBE. However, NT antibodies to WNV and USUV were also detected (titer 80 for both viruses). After TBEV and WNV IgG avidity evaluation, previous flavivirus infection was highly suspected (avidity index 82% and 89%, respectively). Blood, CSF, and urine samples were negative for respective viruses' RNA. The presented case highlights the challenges in flavivirus serodiagnosis. In the published literature, different degrees of cross-reactivity or cross-neutralization between TBEV and dengue, louping ill, Omsk hemorrhagic fever, Langat, and Powassan virus were also observed. Therefore, the serology results should be interpreted with caution, including the possibility of cross-reactivity. In areas where several flaviviruses co-circulate VNT is recommended for disease confirmation. [ABSTRACT FROM AUTHOR]