Direct detection of human herpesvirus 6 DNA in serum by the loop-mediated isothermal amplification method.

BACKGROUND: A more rapid and easier method is needed for monitoring human herpesvirus 6 (HHV-6) infections. The loop-mediated isothermal amplification method (LAMP) can detect viral DNA with high specificity, efficiency, and speed under isothermal conditions. LAMP requires only simple equipment that is available in hospital laboratories. OBJECTIVES: We evaluated LAMP as a means of detecting HHV-6 DNA directly from patients' sera. RESULTS: The sensitivity of the HHV-6 LAMP protocol without heat denaturation was 1000 copies/tube; with heat denaturation 10 copies/tube were detected. Three hundred serum samples from children with fever were analyzed. Using HHV-6 isolation as a definition of HHV-6 infection, the sensitivity, specificity, positive predictive value, and negative predictive value of the HHV-6 LAMP method without DNA extraction were 95.5%, 95.2%, 94.0%, and 96.4%, respectively. CONCLUSION: Direct detection of HHV-6 DNA in serum with a modified HHV-6 LAMP could be used for rapid diagnosis of exanthem subitum (ES).