Objective   To identify the cellular localization of Borna disease virus (BDV) P24 by in situ RT-PCR in different periods after transfection and explore the mechanism of BDV latent infection.    Methods   Oligodendrocyte (OL cells) were transfected by plasmid BDV GFP-P24

and then tested by RT- PCR and ELISA in different periods after transfection in order to compare different expressions of nucleic acid and protein. In situ RT-PCR and fluorescence microscopy were used to identity cellular localization of BDV P24 nucleic acid and protein in different periods.    Results   BDV P24 transfected OL model was successfully constructed. The expression of BDV P24 nucleic acid and protein showed there was no statistics difference (P0.05) in different periods in 20 passages. The BDV P24 gene was located in the cellular nucleus but BDV P24 protein in the cellular nucleus first and then in both nucleus and cytoplasm after 15 passages.    Conclusion   BDV P24 gene functions in the cellular nucleus and P24 protein can transport to the cytoplasm of OL cells at 15 passages or so after transfection.