title: False-positive PCR detection of cyclovirus Malawi strain VS5700009 in human cerebrospinal fluid.
abstract: BACKGROUND
  Cyclovirus (CyCV) Malawi strain VS5700009 has recently been discovered and reported in clinical cerebrospinal fluid (CSF) samples. Further epidemiological and case-control studies are warranted. The availability of a highly sensitive and specific detection assay for this new virus is thus crucial.
  
  
  OBJECTIVE
  To evaluate the performance of the first and the only available PCR assay for CyCV-VS5700009.
  
  
  METHODS
  A total of 100 CSF samples collected during January-December 2010 were selected for PCR detection of CyCV-VS5700009. Positive PCR amplicons were subjected to sequencing confirmation and BLAST analysis.
  
  
  RESULTS
  Initial PCR screening for CyCV-VS5700009 identified one sample, showing a PCR band of expected size (380 bp). Sequencing and BLAST analysis, however, indicated that the band was 364 bp in length and showed >99% nucleotide homology to a human gene known as nuclear receptor coactivator 6 (NCOA6). Pairwise sequence alignment confirmed that both the forward and reverse PCR primers used had significant homology (>70%) to NCOA6. None of the CSF samples tested were positive for CyCV-VS5700009.
  
  
  CONCLUSIONS
  The original PCR assay for CyCV-VS5700009 detection may have potential cross-reactivity with contaminating human genomic DNA. The assay may be of little diagnostic use on clinical specimens that are rich in host DNA such as biopsy tissues.
authors.affiliation: Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Martin C W
authors.initials: MC
authors.lastname: Chan
authors.affiliation: Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Serena W Y
authors.initials: SW
authors.lastname: Kwok
authors.affiliation: Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: paulkschan@cuhk.edu.hk.
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002555:Cerebrospinal Fluid / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D018136:Circoviridae / Q000235:genetics / Q000302:isolation & purification*; D018173:Circoviridae Infections / Q000175:diagnosis*; D018792:Encephalitis, Viral / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008295:Malawi; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D055815:Young Adult
keywords: CSF; Cerebrospinal fluid; Circovirus; Cyclovirus; Diagnosis