[Use of polymerase chain reaction to reduce the use of animal studies: a project for the expression of the structural proteins of tick-borne meningoencephalitis virus].

Tick-borne encephalitis virus is difficult to propagate because with consecutive passages in cell culture the virus titer will decrease. Stockvirus has to be propagated in young mice. Therefore, every production of virus for research, diagnostic assays or vaccination demands the use of laboratory animals. We decided to clone the part of the viral genome which codes for the structural proteins, and to produce the structural proteins in a suitable expression system. Using reverse transcription, followed by the polymerase chain reaction, we amplified exactly this part of the viral genome, added restriction sites for cloning and a stop-codon. Cloning of this DNA-fragment and expression of the structural proteins of tick-borne encephalitis virus in the baculovirus expression system has thus been possible. Replacement of traditional viral antigen by these recombinant proteins may reduce the need for laboratory animals.