A broadly reactive one-step real-time RT-PCR assay for rapid and sensitive detection of hepatitis E virus

Hepatitis E virus (HEV) is transmitted by the fecal-oral route and causes sporadic and epidemic forms of acute hepatitis. Large waterborne HEV epidemics have been documented exclusively in developing countries. At least four major genotypes of HEV have been reported worldwide: genotype 1 (found primarily in Asian countries), genotype 2 (isolated from a single outbreak in Mexico), genotype 3 (identified in swine and humans in the United States and many other countries), and genotype 4 (identified in humans, swine and other animals in Asia). To better detect and quantitate different HEV strains that may be present in clinical and environmental samples, we developed a rapid and sensitive real-time RT-PCR assay for the detection of HEV RNA. Primers and probes for the real-time RT-PCR were selected based on the multiple sequence alignments of 27 sequences of the ORF3 region. Thirteen HEV isolates representing genotypes 1-4 were used to standardize the real-time RT-PCR assay. The TaqMan assay detected as few as four genome equivalent (GE) copies of HEV plasmid DNA and detected as low as 0.12 50% pig infectious dose (PID50) of swine HEV. Different concentrations of swine HEV (120-1.2PID50) spiked into a surface water concentrate were detected in the real-time RT-PCR assay. This is the first reporting of a broadly reactive TaqMan RT-PCR assay for the detection of HEV in clinical and environmental samples.