Rapid detection of varicella-zoster virus infection by a loop-mediated isothermal amplification method.
The reliability of varicella-zoster virus (VZV) loop-mediated isothermal amplification (LAMP) was evaluated for rapid diagnosis of viral infection. VZV-specific primers only amplified VZV DNA; no LAMP products were observed in reactions performed with other viral DNA templates. The specificity of this method was confirmed by two independent determinations, agarose gel electrophoresis and a turbidity assay. The sensitivity of VZV LAMP, determined by agarose gel electrophoresis, were 500 copies/tube. Detection using the turbidity assay, however, gave a sensitivity of 1,000 copies/tube. After these initial validation studies, reliability of VZV LAMP was evaluated for the detection of viral DNA in clinical specimens. Thirty-two swab samples collected from patients with vesicular skin eruptions were tested for VZV DNA. VZV was confirmed in sample numbers 10-32 by VZV real-time PCR, a previously established technique. VZV LAMP products were detected using turbidity from samples 13 to 32 (sensitivity; 87.0%, specificity; 100%, positive predictive value; 100%, negative predictive value; 75%). Although low levels of VZV DNA could be detected in the three samples exhibiting divergent results (samples numbers 10-12), no VZV LAMP product was detected in these samples, indicating a higher detection limit for this assay. Requirement of a DNA extraction step in the VZV LAMP method was examined in next experiment. The turbidity assay detected a VZV LAMP product in all of the 20 positive swab samples (samples numbers 13-32), regardless of DNA extraction.
Department of Medicine, Division of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
Souki
S
Okamoto
Tetsushi
T
Yoshikawa
Masaru
M
Ihira
Kayoko
K
Suzuki
Kaoru
K
Shimokata
Yukihiro
Y
Nishiyama
Yoshizo
Y
Asano
D002644:Chickenpox / Q000175:diagnosis* / Q000821:virology; D017931:DNA Primers; D004279:DNA, Viral / Q000032:analysis* / Q000097:blood / Q000737:chemistry / Q000235:genetics; D005814:Genes, Viral; D014645:Herpesvirus 3, Human / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D021141:Nucleic Acid Amplification Techniques; D012680:Sensitivity and Specificity
D017931:DNA Primers; D004279:DNA, Viral