Application of two RNA extraction methods prior to amplification of hepatitis E virus nucleic acid by the polymerase chain reaction.

Amplification of the enterically-transmitted non-A, non-B hepatitis virus (HEV) RNA using conventional reverse transcriptase reactions followed by the polymerase chain reaction (PCR) of the cDNA has not been successful. However, after application of two different RNA capture/extraction methods we were able to amplify HEV nucleic acid from clinical samples and specimens from experimentally infected animals. The first procedure, adapted from an immune electron microscopy (IEM) technique, incorporated an immunocapture step with concentration of the virus-antibody complexes by pelleting in a Beckman airfuge. In the second method, glass powder (or size-fractionated silicon dioxide) was used to capture the RNA from its surrounding milieu by adsorption of the nucleic acid to the silicate particles. Since conventional immunoassays for HEV antigen or antibody are not currently available, the use of these RNA extraction methods, coupled with PCR techniques, will be valuable in screening clinical specimens and in further defining the course of disease using animal infectivity studies.