Quantification of hepatitis A virus in shellfish by competitive reverse transcription-PCR with coextraction of standard RNA

To quantify hepatitis A virus (HAV) in experimentally contaminated mussels, we developed an internal standard RNA with a 7-nucleotide deletion for com petitive reverse transcription (RT)-PCR. Deposited directly into the sample , this standard was used both as extraction control and as quantification t ool. After coextraction and competitive RT-PCR standard and wild-type produ cts were detected by differential hybridization with specific probes and a DNA enzyme immunoassay. The quantifiable range with this reproducible metho d was 10(4) to 10(7) copies of HAV/gram or 300 to 10(6) 50% tissue culture infective doses/ml.