Genomic typing of BK virus in clinical specimens by direct sequencing of polymerase chain reaction products

Two hundred and twelve urine specimens, from several clinical groups, were examined for BK virus (BKV) using the polymerase chain reaction (PCR) to detect the VP1 region of BKV DNA. Positive results were obtained on 14 specimens from 44 post‐transplant patients (31.8%), 10 specimens from 39 pregnant women (25.6%), and 5 specimens from 100 children (5%) but not on any specimens from 29 laboratory staff. Twentyeight of the amplified BKV genomes, 19 from urine specimens, eight from culture fluid of inoculated tissue, and also one from a throat washing were directly sequenced from single‐stranded templates immobilized via a biotinylated primer; it was possible to assign all to one of the four subtypes of BKV which had previously been identified on the basis of variation in nucleotide sequence of the VP1 region. Serological subgroup classification correlated with the genomic subtyping results in 21 of the isolates. The distribution of the BKV subtypes and the clinical status of the infected individuals are discussed.