Study on Borna disease virus infection in viral encephalitis patients in Ningxia Hui Autonomous Region / 中华传染病杂志

ABSTRACT

Objective To investigate the prevalence of Borna disease virus (BDV) in viral encephalitis patients in Ningxia Hui Autonomous Region and to analyze phylogenetic development of BDV in this area. Methods The gene fragments of BDV were amplified by real time nested reverse transcriptase polymerase chain reaction (PCR) from peripheral blood mononuclear cells (PBMC) of 60viral encephalitis (VE) patients. Enzyme linked immunosorbent assay (ELISA) was applied to detect p40 antibody in the cerebrospinal fluid from those patients who were confirmed as BDV p24 positive in previous study and those patients who were detected as BDV positive by PCR in the present study.The confirmed p40 positive samples were used for BDV gene cloning and sequencing, which were subsequently compared with the sequences of overseas standard strains, including He/80, H1766 and strain V by software MEGA and DnaSP4.0. The virus phylogenetic tree was constructed based on the above data. Results The positive rate of BDV p24 by PCR was 10. 08% (12/119) and the positive rate of BDV p40 by PCR was 5.88% (7/119). The cerebrospinal samples from two patients were detected as nucleoprotein antibody positive by ELISA, which resulted in a positive rate of 1.68%. The results of gene sequence analysis showed that the sequences of 6 cases among the 7 BDV positive patients were exactly same as the sequence of German horse-origin He/80 strain. Only one synonymous mutation was detected in the remaining one case. Reconstructed gene phylogenetic tree showed a hybrid China (Ningxia)- German and Japan branch was formed by the BDV stain isolated from VE patients in Ningxia and the overseas BDV standard stains. Conclusions BDV infection may exist in VE patients in Ningxia Hui Autonomous Region, which may be associated with close contact between human and animals. The gene sequence of stains isolated from patients in Ningxia is highly homological with the overseas standard strain, which suggests that the domestic BDV may come from overseas, while domestic strains with mutations couldn't be excluded.