First Isolation and Phylogenetic Analyses of Tick-Borne Encephalitis Virus in Lower Saxony, Germany

Abstract

Tick-borne encephalitis (TBE) is the most important tick-borne arboviral disease in Europe. Presently, the main endemic regions in Germany are located in the southern half of the country. Although recently, sporadic human TBE cases were reported outside of these known endemic regions. The detection and characterization of invading TBE virus (TBEV) strains will considerably facilitate the surveillance and assessment of this important disease. In 2018, ticks were collected by flagging in several locations of the German federal state of Lower Saxony where TBEV-infections in humans (diagnosed clinical TBE disease or detection of TBEV antibodies) were reported previously. Ticks were pooled according to their developmental stage and tested for TBEV-RNA by RT-qPCR. Five of 730 (0.68%) pools from Ixodes spp. ticks collected in the areas of “Rauher Busch” and “Barsinghausen/Mooshuette” were found positive for TBEV-RNA. Phylogenetic analysis of the whole genomes and E gene sequences revealed a close relationship between the two TBEV isolates, which cluster with a TBEV strain from Poland isolated in 1971. This study provides first data on the phylogeny of TBEV in the German federal state of Lower Saxony, outside of the known TBE endemic areas of Germany. Our results support the hypothesis of an east-west invasion of TBEV strains in Western Europe.

The Stable Matching Problem in TBEV Enzootic Circulation: How Important Is the Perfect Tick-Virus Match?

“…The TBEV-foci were located in close proximity to each other: Barsinghausen-Mooshütte versus Rauher Busch 35 km beeline and Haselmühl versus Heselbach 27 km beeline. However, the virus isolates from Lower Saxony Rauher Busch P19 and Barsinghausen P51, although being phylogenetically more closely related to each other than to other German isolates, show 10 aa exchanges [ 18 ]. A similar relationship is true for the virus isolates from Haselmühl and Heselbach, which exhibit 19 aa exchanges.…”

“…Each virus isolate was obtained from ticks sampled in the respective TBEV-focus. Two strains were isolated from I. ricinus ticks collected in TBEV-foci in Lower Saxony [ 18 ]. The other strains of Bavarian TBEV-foci were kindly provided by the Bundeswehr Institute of Microbiology (Munich, Germany).…”

“…To gain first insights into this relationship, we chose four virus isolates and tick populations from TBEV-foci in Germany. Two of the selected foci are located in close proximity to each other in Bavaria (Haselmühl and Heselbach) and a similar pair of foci was recently discovered in Lower Saxony (Barsinghausen-Mooshütte and Rauher Busch [ 18 ]). The genetic analysis of selected TBEV isolates from different endemic foci showed exchanges of 10 amino acids (aa) for the TBEV-foci Barsinghausen-Mooshütte and Rauher Busch and 19 aa difference for the TBEV-foci Haselmühl and Heselbach.…”

Tick-Borne Encephalitis Virus: A Quest for Better Vaccines against a Virus on the Rise

“…During the last decades, the incidence of TBE has been fluctuating annually with a general upward trend in several European countries (reviewed in [ 21 ]). Additionally, TBEV and its vectors have invaded novel regions and countries, such as the Netherlands and the United Kingdom, as well as higher altitudes observed in an Austrian alpine region 1500 m above sea level [ 16 , 22 , 23 , 24 , 25 , 26 ]. Possible reasons are a complex interplay of abiotic and biotic factors, combined with socio-economic circumstances and anthropogenic factors [ 26 , 27 , 28 ].…”

Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin

“…TBEV causes a severe neuroinfection known as tick-borne encephalitis, which affects thousands of people across Eurasia annually [2,3]. In recent years, an increase in TBEV infection rates in affected countries and in its geographical distribution has been observed, involving previously unaffected areas such as Switzerland and northern Germany [4][5][6]. Although the disease is not always fatal (mortality rate of 1-2%), a high percentage of patients (35-58%) suffer from permanent sequelae, such as cognitive or neuropsychiatric afflictions, balance disorders, headaches, dysphasia, hearing defects, and spinal paralysis after overcoming the main symptoms [2,7].…”