title: Enhanced detection of Coxiella burnetii with a complementary locked primer-based real-time PCR method.
abstract: OBJECTIVE
  Coxiella burnetii is the bacterial causative agent of Q fever in humans. Because Q fever can establish itself with an initial inoculation of fewer than ten C. burnetii cells, a sensitive detection method for C. burnetii infection is needed for early detection. We aimed to evaluate the effectiveness of a complementary locked primer (CLP)-based real-time PCR method for sensitive detection of C. burnetii infection.
  
  
  METHODS
  To evaluate the ability of CLPs to enhance the efficiency of the real-time PCR assay for the C. burnetii IS1111 insertion sequence, the mean threshold cycle values from 20 real-time PCR replicates with either CLPs or conventional primers were determined using tenfold serial dilutions (102-108) of purified C. burnetii Nine Mile genomic DNA. In addition, the cross-reactivity between C. burnetii and 31 non-Coxiella species was examined.
  
  
  RESULTS
  The CLP-based real-time PCR allowed specific and reliable detection of as few as 59 copies of the IS1111 element present in the genome of C. burnetii, which represents approximately 2.96 genome equivalents or three cells of C. burnetii. These results demonstrate the effectiveness of CLP-based real-time PCR for sensitive detection of C. burnetii infection.
  
  
  CONCLUSIONS
  It can be concluded that the CLP-based real-time PCR assay is a more appropriate method for sensitive detection and quantification of C. burnetii than previously reported methods.
authors: Division of Zoonoses, Center for Immunology and Pathology, National Institute of Health, Korea Centers for Disease Control Prevention, Chungcheongbuk-do, Korea.
authors: Eun-Ju
authors: EJ
authors: Kim
authors: Hong Yong
authors: HY
authors: Kang
authors: Kyu-Jam
authors: KJ
authors: Hwang
authors: Sang-Hee
authors: SH
authors: Park
authors: Mi-Yeoun
authors: MY
authors: Park
authors: Sungdo
authors: S
authors: Park
authors: Jin Seok
authors: JS
authors: Yu
authors: Ji Sung
authors: JS
authors: Park
authors: Sang Hyeon
authors: SH
authors: Kang
authors: Hyuk
authors: H
authors: Chu
mesh_terms: D016997:Coxiella burnetii / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D016133:Polymerase Chain Reaction; D011778:Q Fever / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial