Virus concentration using polyethyleneimine-conjugated magnetic beads for improving the sensitivity of nucleic acid amplification tests.

To enhance the sensitivity of virus detection by polymerase chain reaction (PCR) and reverse-transcriptional (RT)-PCR, we developed a novel virus concentration method using polyethyleneimine (PEI)-conjugated magnetic beads. PEI-magnetic beads adsorbed efficiently the enveloped viruses Sindbis virus and Herpes simplex 1 virus, and the nonenveloped virus SV-40, but not the nonenveloped viruses porcine parvovirus (PPV) or poliovirus, based on the PCR detection data. Furthermore, the infectivity in the supernatant of former viruses was reduced markedly after incubation with PEI-magnetic beads. Both real-time PCR and RT-PCR revealed that the DNA viruses were concentrated to a maximum of about 100 times the expected value, whereas the RNA viruses were concentrated over a thousand times, which was significantly more than expected. It was concluded that the PEI-magnetic beads are a superior novel means of concentrating viruses, with the exception of some non-enveloped viruses. The present method was found to enhance the sensitivity of virus detection by PCR and RT-PCR.