Sensitive and rapid diagnosis of human parvovirus B19 infection by loop-mediated isothermal amplification

BACKGROUND: Human parvovirus B19 (B19) infections exhibit various skin manifestations that are similar to and hence hard to distinguish from many other skin diseases. The virological diagnosis of B19 infection is usually based on time-consuming serological tests and polymerase chain reaction (PCR). OBJECTIVES: In this study, a DNA amplification method, loop-mediated isothermal amplification (LAMP), was used for the diagnosis of B19 infection and was compared with PCR. METHODS: Ten patients with acute B19 infection and 16 patients with other skin diseases were enrolled. Sera and pharyngeal swabs were used directly as the templates in LAMP. The LAMP reaction was carried out at 63 degrees C for 1 h in a heat block. The reaction products were judged visually, by adding SYBR Green I into the tubes, and by gel electrophoresis. RESULTS: B19 DNA was detected by LAMP in 10 sera and all of seven tested pharyngeal swabs of 10 patients with acute B19 infection but not in samples from 16 patients with other skin diseases. The results were in agreement with those obtained by PCR except for one case. The reason for the single discrepancy may be that the sensitivity of LAMP is 10(2) times higher than PCR. CONCLUSIONS: Detection of B19 DNA by LAMP in serum and especially in the pharynx is a rapid and convenient method for the diagnosis of acute B19 infection.