Detection of tick-borne encephalitis virus RNA in ticks (Ixodes ricinus) by the polymerase chain reaction.

A polymerase chain reaction for the detection of tick-borne encephalitis virus (TBEV) RNA in ticks was developed. Two pairs of primers for nested PCR were selected from the 5'-NCR and the 5'-terminus of the C protein coding region, which are highly conserved among the TBEV isolates sequenced so far. The sensitivity of the nested PCR was tested by dilution experiments of a TBEV positive brain suspension. The specificity of the PCR products was confirmed by Southern blotting. In a pilot study, 60 homogenates of 7200 ticks (I. ricinus) were examined by PCR. Two homogenates were found positive. The PCR for TBEV RNA appears to be a valuable method to define endemic areas of TBE.