High-sensitivity detection of fruit tree viruses using bacterial magnetic particles.

Prunus necrotic ring spot virus (PNRSV) and grapevine fanleaf virus (GFLV) were detected by fluoroimmunoassay using bacterial magnetic particles (BMPs), and a double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA). For the fluoroimmunoassay, fluorescein isothiocyanate labeled anti-PNRSV antibody or anti-GFLV antibody was conjugated onto BMPs of Magnetospirillum gryphiswaldense MSR-1. With this method, a very low minimum antigen concentration (1 x 10(6) dilution of the original sample concentration) could be detected. Using DAS-ELISA, the minimum antigen detection concentration was the original sample concentration. Thus, comparing these two methods, a BMP-based method could increase the sensitivity up to six orders of magnitude (10(6)) higher than an ELISA-based method of detection PNRSV and GFLV.