title: Prevalence and distribution of BK virus subtypes in healthy people and immunocompromised patients detected by PCR-restriction enzyme analysis.
abstract: BACKGROUND
  Four antigenic subtypes of BK virus (BKV) have recently been characterised by both genomic subtyping and serological reactivity.
  
  
  OBJECTIVE
  To study the prevalence and distribution of subtypes of BKV in different groups of patients.
  
  
  METHODS
  Urine specimens were collected from 33 bone marrow transplant (BMT) recipients, from 101 HIV-infected patients, from 15 children aged 2-5 and from 40 pregnant women were tested for BKV DNA by polymerase chain reaction (PCR) and subtyped using a PCR-sequencing (PCR-S) and a modified PCR-restriction enzyme analysis (PCR-RE) methods.
  
  
  RESULTS
  BKV DNA was detected in 12/18 (67%) of BMT patients with haematuria and 5/15 (33%) without. Overall BKV DNA was detected in 45% of HIV-infected patients, the prevalence of BKV DNA increased with greater immunosuppression as defined by CD4 cell counts. BKV DNA was detected in urine samples from 27% of children and 47% of pregnant women. Four stable BKV subtypes were detected in these patient groups. Dual infections with more than one subtype were identified in urine samples from HIV-infected patients, children and pregnant women but not in the samples from bone marrow recipients.
  
  
  CONCLUSIONS
  This study has confirmed the high prevalence of BKV infection in immunocompromised patients and suggests that stable BKV subtypes with conserved sequences are circulating in the human population. The techniques of PCR-S and PCR-RE described in this study are sufficiently sensitive for subtyping BKV direct from clinical specimens.
authors.affiliation: Virus Reference Division, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5TH, UK.
authors.forename: L
authors.initials: L
authors.lastname: Jin
authors.forename: V
authors.initials: V
authors.lastname: Pietropaolo
authors.forename: J C
authors.initials: JC
authors.lastname: Booth
authors.forename: K H
authors.initials: KH
authors.lastname: Ward
authors.forename: D W
authors.initials: DW
authors.lastname: Brown