Alimentary Infections by 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.

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

Russian Journal of Infection and Immunity ◽

10.15789/2220-7619-2019-3-4-559-567 ◽

2019 ◽

Vol 9 (3-4) ◽

pp. 559-567

Author(s):

G. N. Leonova ◽

O. S. Majstrovskaya ◽

V. A. Lubova ◽

N. B. Sanina

Keyword(s):

Ex Vivo ◽

Experimental Studies ◽

Encephalitis Virus ◽

Virus Elimination ◽

Specific Antibodies ◽

Tick Borne Encephalitis ◽

Antibody Titers ◽

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.

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Tick-borne encephalitis virus (TBEV) antibodies in animal sera – occurrence in goat flocks in Germany, longevity and ability to recall immunological information after more than six years

BMC Veterinary Research ◽

10.1186/s12917-019-2157-5 ◽

2019 ◽

Vol 15 (1) ◽

Cited By ~ 1

Author(s):

Christine Klaus ◽

Ute Ziegler ◽

Donata Hoffmann ◽

Franziska Press ◽

Christine Fast ◽

...

Keyword(s):

Immunological Memory ◽

Raw Milk ◽

Blood Samples ◽

Milk Products ◽

Federal States ◽

Tick Borne Encephalitis ◽

Antibody Titers ◽

Tick Borne Encephalitis Virus ◽

First Contact ◽

Tbev Infection

Abstract Background TBE is an important tick-borne viral zoonosis in Europe and some parts of Asia. Humans can become infected by tick bite and in some cases also by consumption of nonpasteurized raw milk and raw milk products from ruminants. Serological investigations of milking flocks can help to assess the risk of TBEV infection for humans. 735 blood samples from 50 goat flocks from four federal states of Germany were tested by TBEV-VNT to assess a potential risk for TBEV infection. There are some gaps in the knowledge about immunity in animals, for example with regard to the longevity of TBEV immunity. Two goats and two sheep were immunized and TBEV antibody titers could be detected for up to 7 years. Furthermore, nothing is known about a possible long-lasting immunological memory that could quickly be reactivated by an additional contact to TBEV. Seven years after the first immunization two goats and two sheep as well as two naïve goats and two sheep were boostered and TBEV antibody titers followed. Results Only one sample in each of the three states was TBEV-antibody positive (VNT), albeit with low titers. However, in Baden-Württemberg seven samples were positive, among them four goats of the same flock. TBEV-antibody positive titers were detected in goats for up to 6 years and 10 months, in sheep for up to 4 years and 7 months. Seven years after immunization a clear immunological recall occurred in response to administration of one dose of vaccine in two goats and two sheep. Conclusion It can be concluded that in the tested flocks the risk of an alimentary TBEV infection was low. However, in one single flock a considerably higher risk must be assumed. Antibody titers in goats and sheep can last very long after contact to TBEV, albeit at a low level. This should be taken into consideration in cases where the risk of an alimentary infection is assessed in a flock by serological investigations. The immunological recall gives rise to the suspicion that the immunological memory after a first contact to TBEV lasts for many years, probably lifelong.

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Complete Genome Sequence of a Low-Virulence Tick-Borne Encephalitis Virus Strain

Genome Announcements ◽

10.1128/genomea.01145-16 ◽

2016 ◽

Vol 4 (5) ◽

Cited By ~ 8

Author(s):

G. Dobler ◽

M. Bestehorn ◽

M. Antwerpen ◽

A. Överby-Wernstedt

Keyword(s):

Genome Sequence ◽

Ixodes Ricinus ◽

Virus Strain ◽

Complete Genome Sequence ◽

Neurological Disease ◽

Complete Genome ◽

Encephalitis Virus ◽

Natural Focus ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

We report here the complete genome sequence (GenBank accession no. KX268728) of tick-borne encephalitis strain HB171/11, isolated from an Ixodes ricinus tick from a natural focus where human neurological disease is rare. The strain shows unique characteristics in neuroinvasiveness and neurovirulence.

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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.

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Tick-Borne Encephalitis Virus, Coxiella burnetii & Brucella spp. in Milk, Kazakhstan

Online Journal of Public Health Informatics ◽

10.5210/ojphi.v8i1.6535 ◽

2016 ◽

Vol 8 (1) ◽

Author(s):

John Hay ◽

Christina Farris ◽

Phil Elzer ◽

Alexei Andrushchenko ◽

Sue Hagius ◽

...

Keyword(s):

Coxiella Burnetii ◽

Q Fever ◽

Raw Milk ◽

Encephalitis Virus ◽

Western Kazakhstan ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus ◽

Species Specific ◽

Positive Results ◽

Positive Controls

Raw milk was collected from cows in western Kazakhstan in winter 2014-2015. Samples were defatted and frozen at -20C, then tested as follows. For tick-borne encephalitis virus, 65 samples were tested using the VectorBest TBEV antigen capture kit, with 9% positive. For Coxiella burnetii, 50 samples were assayed using a species-specific qPCR assay and all were negative, though positive controls were consistently positive. For Brucella spp., PCR, ELISA and FPA testing is ongoing, with some positive results. These data suggest that consumption of raw cow's milk in western Kazakhstan is a risk factor for tick-borne encephalitis and brucellosis. The risk for Q fever appears to be small during winter, but may be present at other times of the year.

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Contact-dependent transmission of Langat and tick-borne encephalitis virus in type I interferon receptor-1 deficient mice.

Journal of Virology ◽

10.1128/jvi.02039-20 ◽

2021 ◽

Author(s):

Sarah Schreier ◽

Kristin Cebulski ◽

Andrea Kröger

Keyword(s):

Interferon Alpha ◽

Close Contact ◽

Encephalitis Virus ◽

Interferon Α ◽

Type I ◽

Milk Products ◽

Tick Borne Encephalitis ◽

Contact Transmission ◽

Tick Borne Encephalitis Virus ◽

Close Contact Transmission

Tick-borne encephalitis virus (TBEV) is primarily transmitted to humans through tick bites or oral consumption of accordingly contaminated unpasteurized milk or milk products. The detection of TBEV RNA in various body fluids in immunosuppressed human patients is documented. However, the risk of direct contact exposure remains unclear. Interferon-alpha receptor-1 deficient (Ifnar1-/-) mice, which are lacking the interferon-α/β responses, develop neurologic manifestations after infection with TBEV and Langat virus (LGTV). We showed that subcutaneous, intranasal, and peroral infection of LGTV lead to disease, whereas mice with intragastric application of LGTV showed no disease signs. With LGTV infected mice exhibit seroconversion and significant viral RNA levels was detected in saliva, eye smear, feces and urine. As a result, TBEV and LGTV are transmitted between mice from infected to naïve co-caged sentinel animals. Although intranasal inoculation of LGTV is entirely sufficient to establish the disease in mice, the virus is not transmitted by aerosols. These pooled results from animal models highlight the risks of exposure to TBEV contaminants and the possibility for close contact transmission of TBEV in interferon-alpha receptor-1 deficient laboratory mice. Importance Tick-borne encephalitis is a severe disease of the central nervous system caused by the tick-borne encephalitis virus (TBEV). Every year between 10,000-12,000 people become infected with this flavivirus. The TBEV is usually transmitted to humans via the bite of a tick, but infections due to consumption of infectious milk products are increasingly being reported. Since there is no therapy for an TBEV infection and mechanisms of virus persistence in reservoir animals are unclear, it is important to highlight the risk of exposure to TBEV contaminants and know possible routes of transmission of this virus. The significance of our research is in identifying other infection routes of TBEV and LGTV, and the possibility of close contact transmission.

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TBE in South Korea

Tick-borne encephalitis - The Book ◽

10.33442/978-981-14-0914-1_12b-31 ◽

2019 ◽

Author(s):

Joon Young Song

Keyword(s):

South Korea ◽

Human Case ◽

Encephalitis Virus ◽

Surveillance Studies ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus

Although no human case of tick-borne encephalitis (TBE) has been documented in South Korea to date, surveillance studies have been conducted to evaluate the prevalence of tick-borne encephalitis virus (TBEV) in wild ticks.

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