Effects of storage and viral load on hepatitis C viral genotyping.

Hepatitis C virus (HCV) genotyping is important for determining the treatment protocol for hepatitis C patients. Since amplified material from the Roche HCV Monitor kit is compatible with the Innogenetics INNO-LiPA HCV II kit (line probe assay), amplicons from the Monitor assay can be used to identify the HCV genotype. The Monitor package insert recommends using amplicons within a 7-day period (at 4 degrees C) following amplification. It was hypothesized that storage of amplicons for 4 weeks and longer (at -20 degrees C) would not affect the sensitivity of the genotyping assay. After denaturation, amplicons from two genotypes were stored for 7-386 days prior to performing the genotyping assay. Storage of amplicons did not hamper the ability to identify the genotype. Additionally, the sensitivity of the assay was evaluated by analyzing five genotypes with low viral loads. HCV genotypes were detected most consistently at viral levels of 10,000 copies/mL. In conclusion, the Innogenetics genotyping assay can use stored amplicons, thus reducing the cost of the assay by avoiding additional PCR reactions. Determining the sensitivity of this assay facilitates the efficient use of this test by incorporating a sensitivity cutoff of >or=10,000 copies/mL.