Objective In order to investigate the relationship between Borna disease virus(BDV) and the viral encephalitis,and whether BDV infection exists in Ningxia or not.Methods The p24 fragment of BDV in peripheral blood mononuclear cells(PBMC) and cerebrospinal fluid mononuclear cells(CSFMC) in 52 patients with viral encephalitis and 32 healthy donors were examined by nested reverse transcriptase polymerase chain reaction(RT-PCR) and fluorescence quantitative(FQ) PCR to analysis gene sequence,homogenicity and amino acid sequence of positive products.Results The positive rate of BDV p24 in PBMC and CSFMC in viral encephalitis(9.6%,11.5%) was significantly higher than that in healthy donors(0,P