DETECTION OF TICK-BORNE ENCEPHALITIS-VIRUS BY SAMPLE TRANSFER, PLAQUE-ASSAY AND STRAND-SPECIFIC REVERSE-TRANSCRIPTASE POLYMERASE CHAIN-REACTION - WHAT DO WE DETECT

Experimental inoculation of mice provides a well characterized model f or studying infection with tick-borne encephalitis virus (TBEV), a fla vivirus pathogenic for humans. Conflicting data on the kinetics of vir emia and the development of virus titers in the brain, however, were o nly recently shown to have resulted from the use of assay systems with different levers of sensitivity in the titration of TBEV, i.e. plaque assay or sample transfer into naive recipient mice. Theoretically, RT -PCR could extend further the detectability to antibody-neutralized vi rus and when undertaken strand-specifically discriminate active replic ation from the mere presence of TBEV. We have compared the conventiona l methods for detection of TBEV with a newly devised RT-PCR method. As expected, RT-PCR, in contrast to the infectivity assays, detected ant ibody-neutralized virus. Furthermore, the mere presence or active repl ication of the virus could be differentiated by strand-specific RT-PCR . Plaque assay and sample transfer, in contrast, both detected only in fectious virus. However, whereas sample transfer provides higher sensi tivity for detection of TBEV from solid organs, the plaque assay is le ss costly and considering animals welfare more convenient. Thus, the n ewly devised method may allow the resolution of unanswered questions, while both the traditional infectivity assays retain their benefits in certain situations. (C) 1997 Elsevier Science B.V.