SEQUENCE VARIABILITY OF BORNA-DISEASE VIRUS OPEN READING FRAME-II FOUND IN HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS

A cDNA fragment of the Borna disease virus (BDV) open reading frame II (ORF-II), which encodes a 24-kDa phosphoprotein (p24 [P protein]), wa s amplified from total RNA of peripheral blood mononuclear cells (PBMC ) from three psychiatric inpatients. The amplified cDNA fragments mere cloned, sequenced, and analyzed. A total of 15 clones, 5 from each pa tient, were studied. Intrapatient divergencies of the BDV ORF-II nucle otide sequence were 4.2 to 7.3%, 4.8 to 7.3%, and 2.8 to 7.1% for the three patients, leading to differences of 7.7 to 14.5%, 10.3 to 17.1%, and 6.0 to 16.2%, respectively, in the deduced amino acid sequence fo r BDV p24. Interpatient divergencies among the 15 clones were 5.9 to 1 2.7% at the nucleotide level and 12.8 to 28.2% at the amino acid level . Thus, in p24, BDV in human PBMC of the patients undergoes mutation a t high rates in vivo. Additionally, we found that the nucleotide Seque nce of the 15 human BDV ORF-II cDNA clones differed from those of the horse strains V and He/80-1 by 4.2 to 9.3%. However, comparison of the consensus amino acid sequence deduced from the 15 human clones with t hose of the horse strains revealed no human-specific amino acid residu e, suggesting that the BDV infecting humans may be related to that inf ecting horses.