Search

Tick-borne encephalitis virus (TBEV) infection may cause acute central nervous system inflammation varying in clinical manifestations and severity. A possible correlation of TBEV-specific antibody and cell-mediated immune responses, shortly after infection, with clinical manifestations, severity and long-term outcome has been poorly investigated. In a cohort of thirty early tick-borne encephalitis (TBE) patients, we assessed the magnitude, specificity and functional properties of TBEV-specific T-cell and antibody responses. These responses early during disease were assessed in view of clinical manifestations, severity and long-term outcome. TBEV-specific T-cell responses to C, E, NS1, and NS5 proteins were significantly lower in patients with severe acute illness than in patients with mild TBE. Lower T-cell responses to E, NS1, and NS5 proteins also correlated with the development of meningoencephalomyelitis. Virus-specific antibody titres early after infection did not correlate with disease severity, clinical manifestations, or long-term outcome in this study, possibly due to the small number of patients of which matching serum and peripheral blood mononuclear cells were available. The findings suggest that virus-specific T cells afford a certain degree of protection against the development of severe TBEV-induced disease.

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by RVF virus (RVFV). RVFV infections in humans are usually asymptomatic or associated with mild febrile illness, although more severe cases of haemorrhagic disease and encephalitis with high mortality also occur. Currently, there are no licensed human vaccines available. The safety and efficacy of a genetically engineered four-segmented RVFV variant (hRVFV-4s) as a potential live-attenuated human vaccine has been tested successfully in mice, ruminants, and marmosets though the correlates of protection of this vaccine are still largely unknown. In the present study, we have assessed hRVFV-4s-induced humoral and cellular immunity in a mouse model of RVFV infection. Our results confirm that a single dose of hRVFV-4s is highly efficient in protecting naïve mice from developing severe disease following intraperitoneal challenge with a highly virulent RVFV strain and data show that virus neutralizing (VN) serum antibody titres in a prime-boost regimen are significantly higher compared to the single dose. Subsequently, VN antibodies from prime-boost-vaccinated recipients were shown to be protective when transferred to naïve mice. In addition, hRVFV-4s vaccination induced a significant virus-specific T cell response as shown by IFN-γ ELISpot assay, though these T cells did not provide significant protection upon passive transfer to naïve recipient mice. Collectively, this study highlights hRVFV-4s-induced VN antibodies as a major correlate of protection against lethal RVFV infection.

Tick-borne encephalitis virus (TBEV) vaccine breakthrough (VBT) infections are not uncommon in endemic areas. The clinical and immunological outcomes have been poorly investigated. We assessed the magnitude and specificity of virus-specific antibody and T cell responses after TBE in previously vaccinated subjects and compared the results with those of unvaccinated TBE patients and study subjects that received vaccination without VBT infection. Symptomatic TBEV infection of unvaccinated study subjects induced virus-specific antibody responses to the E protein and non-structural protein 1 (NS1) as well as T cell responses to structural and other non-structural (NS) proteins. After VBT infections, significantly impaired NS1-specific antibody responses were observed, while the virus-specific T cell responses to the NS proteins were relatively strong. VBT infection caused predominantly moderate to severe disease during hospitalization. The level of TBEV EDIII- and NS1-specific antibodies in unvaccinated convalescent patients inversely correlated with TBE severity and neurological symptoms early after infection., (© 2024. The Author(s).)

Tick-borne encephalitis (TBE) is a serious neurological disease caused by TBE virus (TBEV). Because antiviral treatment options are not available, vaccination is the key prophylactic measure against TBEV infections. Despite the availability of effective vaccines, cases of vaccination breakthrough infections have been reported. The multienzymatic non-structural protein 3 (NS3) of orthoflaviviruses plays an important role in polyprotein processing and virus replication. In the present study, we evaluated NS3 of TBEV as a potential vaccine target for the induction of protective immunity. To this end, a recombinant modified vaccinia virus Ankara that drives the expression of the TBEV NS3 gene (MVA-NS3) was constructed. MVA-NS3 was used to immunize C57BL/6 mice. It induced NS3-specific immune responses, in particular T cell responses, especially against the helicase domain of NS3. However, MVA-NS3-immunized mice were not protected from subsequent challenge infection with a lethal dose of the TBEV strain Neudoerfl, indicating that in contrast to immunity to prME and NS1, NS3-specific immunity is not an independent correlate of protection against TBEV in this mouse model.

Introduction: Tick-borne encephalitis virus (TBEV) is one of the most relevant tick-transmitted neurotropic arboviruses in Europe and Asia and the causative agent of tick-borne encephalitis (TBE). Annually more than 10,000 TBE cases are reported despite having vaccines available. In Europe, the vaccines FSME-IMMUN® and Encepur® based on formaldehyde-inactivated whole viruses are licensed. However, demanding vaccination schedules contribute to sub-optimal vaccination uptake and breakthrough infections have been reported repeatedly. Due to its immunogenic properties as well as its role in viral replication and disease pathogenesis, the non-structural protein 1 (NS1) of flaviviruses has become of interest for non-virion based flavivirus vaccine candidates in recent years., Methods: Therefore, immunogenicity and protective efficacy of TBEV NS1 expressed by neuraminidase (NA)-deficient Influenza A virus (IAV) or Modified Vaccinia virus Ankara (MVA) vectors were investigated in this study., Results: With these recombinant viral vectors TBEV NS1-specific antibody and T cell responses were induced. Upon heterologous prime/boost regimens partial protection against lethal TBEV challenge infection was afforded in mice., Discussion: This supports the inclusion of NS1 as a vaccine component in next generation TBEV vaccines., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Beicht, Kubinski, Zdora, Puff, Biermann, Gerlach, Baumgärtner, Sutter, Osterhaus, Prajeeth and Rimmelzwaan.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kubinski, Beicht, Zdora, Biermann, Puff, Gerlach, Tscherne, Baumgärtner, Osterhaus, Sutter, Prajeeth and Rimmelzwaan.)

Introduction: Naturally attenuated Langat virus (LGTV) and highly pathogenic tick-borne encephalitis virus (TBEV) share antigenically similar viral proteins and are grouped together in the same flavivirus serocomplex. In the early 1970s, this has encouraged the usage of LGTV as a potential live attenuated vaccine against tick-borne encephalitis (TBE) until cases of encephalitis were reported among vaccinees. Previously, we have shown in a mouse model that immunity induced against LGTV protects mice against lethal TBEV challenge infection. However, the immune correlates of this protection have not been studied., Methods: We used the strategy of adoptive transfer of either serum or T cells from LGTV infected mice into naïve recipient mice and challenged them with lethal dose of TBEV., Results: We show that mouse infection with LGTV induced both cross-reactive antibodies and T cells against TBEV. To identify correlates of protection, Monitoring the disease progression in these mice for 16 days post infection, showed that serum from LGTV infected mice efficiently protected from developing severe disease. On the other hand, adoptive transfer of T cells from LGTV infected mice failed to provide protection. Histopathological investigation of infected brains suggested a possible role of microglia and T cells in inflammatory processes within the brain., Discussion: Our data provide key information regarding the immune correlates of protection induced by LGTV infection of mice which may help design better vaccines against TBEV., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kubinski, Beicht, Zdora, Saletti, Kircher, Petry-Gusmag, Steffen, Puff, Jung, Baumgärtner, Rimmelzwaan, Osterhaus and Prajeeth.)

The hemagglutinin (HA) of A/H3N2 pandemic influenza viruses (IAVs) of 1968 differed from its inferred avian precursor by eight amino acid substitutions. To determine their phenotypic effects, we studied recombinant variants of A/Hong Kong/1/1968 virus containing either human-type or avian-type amino acids in the corresponding positions of HA. The precursor HA displayed receptor binding profile and high conformational stability typical for duck IAVs. Substitutions Q226L and G228S, in addition to their known effects on receptor specificity and replication, marginally decreased HA stability. Substitutions R62I, D63N, D81N and N193S reduced HA binding avidity. Substitutions R62I, D81N and A144G promoted viral replication in human airway epithelial cultures. Analysis of HA sequences revealed that substitutions D63N and D81N accompanied by the addition of N-glycans represent common markers of avian H3 HA adaptation to mammals. Our results advance understanding of genotypic and phenotypic changes in IAV HA required for avian-to-human adaptation and pandemic emergence., Competing Interests: The authors have declared that no competing interests exist.

Tick-borne encephalitis virus (TBEV), a member of the family Flaviviridae , is one of the most important tick-transmitted viruses in Europe and Asia. Being a neurotropic virus, TBEV causes infection of the central nervous system, leading to various (permanent) neurological disorders summarized as tick-borne encephalitis (TBE). The incidence of TBE cases has increased due to the expansion of TBEV and its vectors. Since antiviral treatment is lacking, vaccination against TBEV is the most important protective measure. However, vaccination coverage is relatively low and immunogenicity of the currently available vaccines is limited, which may account for the vaccine failures that are observed. Understanding the TBEV-specific correlates of protection is of pivotal importance for developing novel and improved TBEV vaccines. For affording robust protection against infection and development of TBE, vaccines should induce both humoral and cellular immunity. In this review, the adaptive immunity induced upon TBEV infection and vaccination as well as novel approaches to produce improved TBEV vaccines are discussed.

Multilayering and enzymatic cross-linking of emulsions may cause alterations in the release behavior of encapsulated core material due to changes in thickness, porosity and permeability of the membrane. An interfacial engineering technology based on the layer-by-layer electrostatic deposition of oppositively charged biopolymers onto the surfaces of emulsion droplets in combination with an enzymatic treatment was used to generate emulsions with different droplet interfaces to test this hypothesis. Release behavior of primary, secondary (coated) and laccase-treated secondary emulsions carrying lutein, an oxygenated carotenoid, was characterized and studied. Fish gelatin (FG), whey protein isolate (WPI) and dodecyltrimethylammonium bromide (DTAB) were used as primary emulsifiers under acidic conditions (pH 3.5) to facilitate the adsorption of a negatively charged biopolymer (sugar beet pectin). Laccase was added to promote cross-linking of adsorbed beet pectin. The release of lutein-loaded emulsions was investigated and quantified by UV-Vis spectrophotometry. Primary WPI-stabilized emulsions showed a five times higher release of lutein after 48 h than secondary emulsions (pH 3.5). Primary DTAB-stabilized emulsions released 7.2% of encapsulated lutein within the observation period, whereas beet pectin-DTAB-coated emulsions released only 0.13% of lutein. Cross-linking of adsorbed pectin did not significantly decrease release of lutein in comparison to non-cross-linked secondary emulsions. Additionally, release of lutein was also affected by changes in the pH of the surrounding medium. Results suggest that modulating the interfacial properties of oil-in-water emulsion by biopolymer deposition and/or cross-linking may be a useful approach to generate food-grade delivery systems that have specific release-over-time profiles of incorporated active ingredients.