Growth of tick-borne encephalitis virus (European subtype) in cell lines from vector and non-vector ticks

We undertook a comparative study of the susceptibility of different tick cell lines to infection with the European subtype of tick-borne encephalitis virus (TBEV), prototype strain Neudoerfl. The growth of TBEV was investigated in lines derived from vector Ixodes ricinus L. ticks (IRE/CTVM18, 19, and 20), as well as non-vector ticks, namely Ixodes scapularis Say (IDE2), Boophilus microplus Canestrini (BME/CTVM2), Hyalomma anatolicum anatolicum Koch (HAE/CTVM9), Rhipicephalus appendiculatus Neumann (RA-257) and recently established and herein described lines from the argasid tick Ornithodoros moubata Murray (OME/CTVM21 and 22). All the tick cell lines tested were susceptible to infection by TBEV and the virus caused productive infection without any cytopathic effect. However, there was a clear difference between the TBEV growth in vector and non-vector cell lines, since I. ricinus cell lines produced 100-1000-fold higher virus yield than the non-vector cell lines. The lowest virus production was observed in O. moubata and R. appendiculatus cell lines.