Comprehensive assessment of specific antibodies on infectious activity of tick-borne encephalitis virus

Vaccines for prophylactic immunization provide the most reliable and effective protection against the vast majority of infectious diseases. Tick-borne encephalitis (TBE) represents a high-priority medical issue at the territory of the Eurasian continent. Of great importance is assessing a role of distinct antibody titers especially low titers, observed quite often in vaccinated individuals, sometimes posing obstacles in determining a threshold of seropositivity as well as the level of specific protection against TBE virus. We aimed at obtaining data to assess antiviral activity of virus-specific antibodies with distinct titer levels based on the in vitro, ex vivo and in vivo experimental studies with a highly virulent Far-Eastern strain of tick-borne encephalitis virus. The in vitro, ex vivo and in vivo comprehensive experimental studies with a highly virulent Far-Eastern strain of tick-borne encephalitis virus (TBEV) were conducted and the dynamics of antiviral activity of virus-specific antibodies at variable titers (1:100–1:3200) was measured (timeframe ranged within 1–96 hours p.i.) to provide a rationale for evaluating the antiviral immune response. It was found that the in vitro experiments demonstrated that the IgG at 1:100 titer exerted a weak anti-TBEV neutralizing effect at all time-points examined. The IgG 1:400 titer caused a 2 log PFU/mL decline in TBEV Dal strain yield at 72 h post-infection, whereas at 1:3200 titer it completely suppressed TBEV replication throughout the observation period. The ex vivo experiments with blood serum obtained from vaccinated subjects demonstrating a range of TBEV antibody titers (sera from vaccinated individuals with varying anti-TBEV antibody titers) and in vivo (outinbred white mice) experiments revealed a delayed virus elimination for antibody titers at 1:100 and 1:200 as well as rapid virus elimination (1–2 days p.i.) for antibody titers greater than 1:400. Thus, antibody titer at 1:400 may be considered as the universal anti-TBEV protection threshold. In order to properly conclude regarding the revaccination schedule it is advised to start with testing blood serum for durability of anti-TBEV immune response. Subjects with TBEV antibody titers at 1:100 and 1:200 should be strongly recommended to undergo a mandatory revaccination. Such an approach is believed to be the most effective way toward enhancing efficacy of vaccine-mediated protection against TBE.

Download Full-text

Effect of immature tick-borne encephalitis virus particles on antiviral activity of 5-aminoisoxazole-3-carboxylic acid adamantylmethyl esters

Journal of General Virology ◽

10.1099/jgv.0.001658 ◽

2021 ◽

Vol 102 (9) ◽

Author(s):

Ksenia K. Tuchynskaya ◽

Anastasiia D. Fomina ◽

Nikolai A. Nikitin ◽

Viktoria V. Illarionova ◽

Viktor P. Volok ◽

...

Keyword(s):

Carboxylic Acid ◽

Antiviral Activity ◽

Severe Disease ◽

Experimental Studies ◽

Encephalitis Virus ◽

Viral Population ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus, is common in Europe and Asia and causes a severe disease of the central nervous system. A promising approach in the development of therapy for TBEV infection is the search for small molecule antivirals targeting the flavivirus envelope protein E, particularly its β-n-octyl-d-glucoside binding pocket (β-OG pocket). However, experimental studies of candidate antivirals may be complicated by varying amounts and different forms of the protein E in the virus samples. Viral particles with different conformations and arrangements of the protein E are produced during the replication cycle of flaviviruses, including mature, partially mature, and immature forms, as well as subviral particles lacking genomic RNA. The immature forms are known to be abundant in the viral population. We obtained immature virion preparations of TBEV, characterized them by RT-qPCR, and assessed in vivo and in vitro infectivity of the residual mature virions in the immature virus samples. Analysis of the β-OG pocket structure on the immature virions confirmed the possibility of binding of adamantylmethyl esters of 5-aminoisoxazole-3-carboxylic acid in the pocket. We demonstrated that the antiviral activity of these compounds in plaque reduction assay is significantly reduced in the presence of immature TBEV particles.

Download Full-text

Tick-Borne Encephalitis Virus Vaccine-Induced Human Antibodies Mediate Negligible Enhancement of Zika Virus Infection In Vitro and in a Mouse Model

mSphere ◽

10.1128/mspheredirect.00011-18 ◽

2018 ◽

Vol 3 (1) ◽

Cited By ~ 12

Author(s):

James Duehr ◽

Silviana Lee ◽

Gursewak Singh ◽

Gregory A. Foster ◽

David Krysztof ◽

...

Keyword(s):

Mouse Model ◽

Dengue Virus ◽

Human Plasma ◽

Mouse Models ◽

Zika Virus ◽

Encephalitis Virus ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

ABSTRACT Recent reports in the scientific literature have suggested that anti-dengue virus (DENV) and anti-West Nile virus (WNV) immunity exacerbates Zika virus (ZIKV) pathogenesis in vitro and in vivo in mouse models. Large populations of immune individuals exist for a related flavivirus (tick-borne encephalitis virus [TBEV]), due to large-scale vaccination campaigns and endemic circulation throughout most of northern Europe and the southern Russian Federation. As a result, the question of whether anti-TBEV immunity can affect Zika virus pathogenesis is a pertinent one. For this study, we obtained 50 serum samples from individuals vaccinated with the TBEV vaccine FSME-IMMUN (Central European/Neudörfl strain) and evaluated their enhancement capacity in vitro using K562 human myeloid cells expressing CD32 and in vivo using a mouse model of ZIKV pathogenesis. Among the 50 TBEV vaccinee samples evaluated, 29 had detectable reactivity against ZIKV envelope (E) protein by enzyme-linked immunosorbent assay (ELISA), and 36 showed enhancement of ZIKV infection in vitro. A pool of the most highly reacting and enhanced samples resulted in no significant change in the morbidity/mortality of ZIKV disease in immunocompromised Stat2−/− mice. Our results suggest that humoral immunity against TBEV is unlikely to enhance Zika virus pathogenesis in humans. No clinical reports indicating that TBEV vaccinees experiencing enhanced ZIKV disease have been published so far, and though the epidemiological data are sparse, our findings suggest that there is little reason for concern. This study also displays a clear relationship between the phylogenetic distance between two flaviviruses and their capacity for pathogenic enhancement. IMPORTANCE The relationship between serial infections of two different serotypes of dengue virus and more severe disease courses is well-documented in the literature, driven by so-called antibody-dependent enhancement (ADE). Recently, studies have shown the possibility of ADE in cells exposed to anti-DENV human plasma and then infected with ZIKV and also in mouse models of ZIKV pathogenesis after passive transfer of anti-DENV human plasma. In this study, we evaluated the extent to which this phenomenon occurs using sera from individuals immunized against tick-borne encephalitis virus (TBEV). This is highly relevant, since large proportions of the European population are vaccinated against TBEV or otherwise seropositive.

Download Full-text

Inhibition of Tick-Borne Encephalitis Virus Replication with Eprosartan and Ribavirin In Vitro and In Vivo

Antibiotics and Chemotherapy ◽

10.37489/0235-2990-2020-65-9-10-8-12 ◽

2020 ◽

Vol 65 (9-10) ◽

pp. 8-12

Author(s):

G. N. Leonova ◽

O. S. Maistrovskaya ◽

V. A. Lubova

Keyword(s):

Life Expectancy ◽

Treatment Regimen ◽

Active Agent ◽

Encephalitis Virus ◽

In Vivo Model ◽

Control Group ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

Active search for new antiviral substances is currently underway. The purpose of this work is to identify the inhibitory activity of eprosartan medication in comparison with ribavirin in vitro and in vivo in relation to tick-borne encephalitis virus. The value of the half the maximum cytotoxic concentration (CC50) for eprosartan (8.8±1.2 mg/ml) and ribavirin (1.074±0.16 mg/ml) was established. To obtain a medium effective virus-inhibiting concentration (IC50) of the medications, EIA data were used. Using nonlinear regression analysis of the percentage of antigen positive samples, IC50 values of the studied substances were obtained, which for eprosartan was 0.64±0.23 mg/ml in the treatment regimen. The selective index (SI) or chemotherapeutic index (CTI) was 13.7. The IC50 of ribavirin was 0.0067±0.0015 mg/ml, SI or CTI was 160. The suppression of viral reproduction 2.0 log TCID50 occurred in PEK cell culture under the influence of eprosartan at concentrations of 1.2–3.0 mg/ml (treatment regimen), under the influence of ribavirin — 0.2 mg/ml (prophylactic regimen) and 0.2–0.0125 mg/ml (treatment regimen). Samples with eprosartan (1.5 and 0.6 mg/ml) showed an increase in survival of mice by 50% and 20% compared with the virus control group in the in vivo model and, accordingly, an increase in average life expectancy of 5.2 and 2.1 days. Samples with ribavirin (0.05 and 0.025 mg/ml) increased the survival of mice by 60% and 40% and, accordingly, increased the life expectancy by 7.3 and 4.8 days. The data obtained allow recommending eprosartan as an active agent against tick-borne encephalitis virus along with ribavirin.

Download Full-text

Spectrum of antiviral activity of 4-aminopyrimidine N-oxides against a broad panel of tick-borne encephalitis virus strains

Antiviral Chemistry and Chemotherapy ◽

10.1177/2040206620943462 ◽

2020 ◽

Vol 28 ◽

pp. 204020662094346

Author(s):

Evgenia V Dueva ◽

Ksenia K Tuchynskaya ◽

Liubov I Kozlovskaya ◽

Dmitry I Osolodkin ◽

Kseniya N Sedenkova ◽

...

Keyword(s):

Encephalitis Virus ◽

Northern Eurasia ◽

Virus Particles ◽

E Protein ◽

Tick Borne Encephalitis ◽

Tbev Strain ◽

Amino Phenol ◽

Tick Borne Encephalitis Virus ◽

Immature Virus

Tick-borne encephalitis is an important human arbovirus neuroinfection spread across the Northern Eurasia. Inhibitors of tick-borne encephalitis virus (TBEV) strain Absettarov, presumably targeting E protein n-octyl-β-d-glucoside (β-OG) pocket, were reported earlier. In this work, these inhibitors were tested in vitro against seven strains representing three main TBEV subtypes. The most potent compound, 2-[(2-methyl-1-oxido-5,6,7,8-tetrahydroquinazolin-4-yl)amino]-phenol, showed EC50 values lower than 22 µM against all the tested strains. Nevertheless, EC50 values for virus samples of certain strains demonstrated a substantial variation, which appeared to be consistent with the presence of E protein not only in infectious virions, but also in non-infectious and immature virus particles, protein aggregates, and membrane complexes.

Download Full-text

Adaptation of Tick-Borne Encephalitis Virus to BHK-21 Cells Results in the Formation of Multiple Heparan Sulfate Binding Sites in the Envelope Protein and Attenuation In Vivo

Journal of Virology ◽

10.1128/jvi.75.12.5627-5637.2001 ◽

2001 ◽

Vol 75 (12) ◽

pp. 5627-5637 ◽

Cited By ~ 155

Author(s):

Christian W. Mandl ◽

Helga Kroschewski ◽

Steven L. Allison ◽

Regina Kofler ◽

Heidemarie Holzmann ◽

...

Keyword(s):

Heparan Sulfate ◽

Encephalitis Virus ◽

Surface Glycoprotein ◽

Glycoprotein E ◽

Recombinant Viruses ◽

Adult Mice ◽

Tick Borne Encephalitis ◽

Significant Attenuation ◽

Tick Borne Encephalitis Virus

ABSTRACT Propagation of the flavivirus tick-borne encephalitis virus in BHK-21 cells selected for mutations within the large surface glycoprotein E that increased the net positive charge of the protein. In the course of 16 independent experiments, 12 different protein E mutation patterns were identified. These were located in all three of the structural domains and distributed over almost the entire upper and lateral surface of protein E. The mutations resulted in the formation of local patches of predominantly positive surface charge. Recombinant viruses carrying some of these mutations in a defined genetic backbone showed heparan sulfate (HS)-dependent phenotypes, resulting in an increased specific infectivity and binding affinity for BHK-21 cells, small plaque formation in porcine kidney cells, and significant attenuation of neuroinvasiveness in adult mice. Our results corroborate the notion that the selection of attenuated HS binding mutants is a common and frequent phenomenon during the propagation of viruses in cell culture and suggest a major role for HS dependence in flavivirus attenuation. Recognition of this principle may be of practical value for designing attenuated flavivirus strains in the future.

Download Full-text

Antiviral Properties of Water Extracts of Mycelium Inonotus rheades (Pers.) P. Karst. (1882) against the Virus of Tick-Borne Encephalitis Virus in vitro

Acta biomedica scientifica ◽

10.29413/abs.2021-6.1.8 ◽

2021 ◽

Vol 6 (1) ◽

pp. 55-59

Author(s):

M. A. Khasnatinov ◽

T. G. Gornostai ◽

I. S. Solovarov ◽

M. S. Polyakova ◽

G. A. Danchinova ◽

...

Keyword(s):

Antiviral Activity ◽

Antiviral Agents ◽

Encephalitis Virus ◽

Water Soluble ◽

Xylotrophic Basidiomycetes ◽

Tick Borne Encephalitis ◽

Wood Polysaccharides ◽

Tick Borne Encephalitis Virus ◽

The Relationship

Background. Tick-borne encephalitis virus is dangerous and widespread pathogen that is transmitted to humans through the bites of hard ticks. Wild fungi, such as xylotrophic basidiomycetes, are widely used in traditional medicine to treat the infectious diseases and are promising natural sources of new antiviral agents. It was previously shown that aqueous extracts from the mycelium of the Inonotus rheades (Pers.) P. Karst. (1882) fungus exhibit significant antiviral activity against tick-borne encephalitis virus, however, the mechanisms of this activity remain unclear.Aim. To analyze the relationship between the virucidal properties of I. rheades extract and the substrate on which the cultivation was carried out.Materials and methods. The mycelium was grown either in a standard liquid medium with wort or on wooden disks from birch. Extracts of water-soluble polysaccharides were prepared from both mycelium samples. The concentration of infectious tick-borne encephalitis virus was determined using the method of titration of plaque-forming components (PFU). Approximately 30 000 PFU of tick-borne encephalitis virus was mixed with an equal volume of corresponding I. rheades extract at concentration of 8 mg/mL and incubated for 30 min at 37 °C. Afterwards, the residual infectivity of tick-borne encephalitis virus was determined using the identical virus sample incubated with sterile water as a reference.Results. It was found that treatment of tick-borne encephalitis virus with extracts from I. rheades mycelium resulted in inhibition of the infectivity of the virus in the cell culture. However, the same strain of I. rheades, grown on medium with wort, did not exhibit antiviral properties.Conclusions. Virucidal substances are likely to be not the main metabolites of the mycelium of I. rheades, but are rather metabolized wood polysaccharides. Further research is needed to more accurately identify the active ingredients and assess their antiviral activity.

Download Full-text

Alimentary Infections by Tick-Borne Encephalitis Virus

Viruses ◽

10.3390/v14010056 ◽

2021 ◽

Vol 14 (1) ◽

pp. 56

Author(s):

Martina Ličková ◽

Sabína Fumačová Havlíková ◽

Monika Sláviková ◽

Boris Klempa

Keyword(s):

Experimental Data ◽

Neurological Disease ◽

Preventive Measures ◽

Experimental Studies ◽

Raw Milk ◽

Encephalitis Virus ◽

Relevant Factor ◽

Milk Products ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

Tick-borne encephalitis virus (TBEV) causes serious the neurological disease, tick-borne encephalitis (TBE). TBEV can be transmitted to humans by ticks as well as by the alimentary route, which is mediated through the consumption of raw milk products from infected ruminants such as sheep, goats, and cows. The alimentary route of TBEV was recognized in the early 1950s and many important experimental studies were performed shortly thereafter. Nowadays, alimentary TBEV infections are recognized as a relevant factor contributing to the overall increase in TBE incidences in Europe. This review aims to summarize the history and current extent of alimentary TBEV infections across Europe, to analyze experimental data on virus secretion in milk, and to review possible alimentary infection preventive measures.

Download Full-text

No neutralizing effect of pre-existing tick-borne encephalitis virus antibodies against severe acute respiratory syndrome coronavirus-2: a prospective healthcare worker study

Scientific Reports ◽

10.1038/s41598-021-03685-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Philipp Kohler ◽

Hulda R. Jonsdottir ◽

Lorenz Risch ◽

Pietro Vernazza ◽

Rahel Ackermann-Gäumann ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Healthcare Worker ◽

Current Knowledge ◽

Encephalitis Virus ◽

Live Virus ◽

Tick Borne Encephalitis ◽

Antibody Titers ◽

Tick Borne Encephalitis Virus ◽

Reduced Risk

AbstractCertain immunizations including vaccination against tick-borne encephalitis virus (TBEV) have been suggested to confer cross-protection against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Within a prospective healthcare worker (HCW) cohort, we assessed the potentially protective role of anti-TBEV antibodies against SARS-CoV-2 infection. Among 3352 HCW, those with ≥ 1 previous TBEV vaccination (n = 2018, 60%) showed a reduced risk of SARS-CoV-2 seroconversion (adjusted odds ratio: 0.8, 95% CI: 0.7–1.0, P = 0.02). However, laboratory testing of a subgroup of 26 baseline and follow-up samples did not demonstrate any neutralizing effect of anti-TBEV antibodies against SARS-CoV-2 in live-virus neutralization assay. However, we observed significantly higher anti-TBEV antibody titers in follow-up samples of participants with previous TBEV vaccination compared to baseline, both TBEV neutralizing (p = 0.001) and total IgG (P < 0.0001), irrespective of SARS-CoV-2 serostatus. Based on these data, we conclude that the observed association of previous TBEV vaccination and reduced risk of SARS-CoV-2 infection is likely due to residual confounding factors. The increase in TBEV follow-up antibody titers can be explained by natural TBEV exposure or potential non-specific immune activation upon exposure to various pathogens, including SARS-CoV-2. We believe that these findings, although negative, contribute to the current knowledge on potential cross-immunity against SARS-CoV-2 from previous immunizations.

Download Full-text

Anti-Tick-Borne Encephalitis Virus Activity of Novel Uridine Glycoconjugates Containing Amide or/and 1,2,3-Triazole Moiety in the Linker Structure

Pharmaceuticals ◽

10.3390/ph13120460 ◽

2020 ◽

Vol 13 (12) ◽

pp. 460

Author(s):

Gabriela Brzuska ◽

Gabriela Pastuch-Gawolek ◽

Monika Krawczyk ◽

Boguslaw Szewczyk ◽

Ewelina Krol

Keyword(s):

Antiviral Treatment ◽

Encephalitis Virus ◽

In Vitro Assays ◽

Strong Activity ◽

Tick Borne Encephalitis ◽

Ic50 Values ◽

Low Cytotoxicity ◽

Tick Borne Encephalitis Virus ◽

Further Development

Tick-borne encephalitis virus (TBEV) transmitted by ticks is a pathogen of great medical importance. As still no effective antiviral treatment is available, in the present study, a series of uridine glycoconjugates containing amide or/and 1,2,3-triazole moiety in the linker structure was synthesized and evaluated for the antiviral activity against two strains of TBEV: a highly virulent Hypr strain and less virulent Neudoerfl strain, using standardized previously in vitro assays. Our data have shown that four compounds from the series (18–21) possess strong activity against both TBEV strains. The half maximal inhibitory concentration (IC50) values of compounds 18–21 were between 15.1 and 3.7 μM depending on the virus strain, which along with low cytotoxicity resulted in high values of the selectivity index (SI). The obtained results suggest that these compounds may be promising candidates for further development of new therapies against flaviviruses.

Download Full-text