Rescue and in vitro characterization of a divergent TBEV-Eu strain from the Netherlands

Abstract

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.

Differential susceptibility of geographically distinct Ixodes ricinus populations to tick-borne encephalitis virus and louping ill virus

“…MK007541), a P4 stock of TBEV-Neudoerfl [ 31 ] (GenBank accession no. U27495), and a P3 stock of TBEV-NL [ 32 ] (GenBank accession no. ON502378) were used for infection experiments.…”

Use of Wild Ungulates as Sentinels of TBEV Circulation in a Naïve Area of the Northwestern Alps, Italy

“…A twofold series dilution from 1:8 to 1:2048 was prepared with already inactivated borderline sera from wild ungulates. A virus solution containing 70 plaque-forming units was added in the same volume as the serum dilutions: TBEV 'Salland' [52], WNV (lineage 2, B-956 Uganda strain) and Usutu virus (virus isolate Netherlands 2016). After 1 h of incubation at 37 • C and 5% CO 2 , the virus-serum mixtures were added in duplicate to the 24-well plates.…”