Commercial real-time reverse transcriptase PCR assays can underestimate or fail to quantify hepatitis delta virus viremia.

BACKGROUND & AIMS: Hepatitis delta virus (HDV) infection causes fulminant hepatitis and increases the severity of chronic hepatitis B virus infection, leading to cirrhosis, liver failure, or hepatocellular carcinoma. There are 8 HDV genotypes (genotypes 1-8). We previously developed a TaqMan real-time reverse transcriptase (RT)-PCR method that is able to quantify viral load of all HDV genotypes (linear from 2 to 8 log(10) copies/mL). We compared its results with those from 3 commercial real-time RT-PCR assays: the Lightmix HDV kit (designed to quantify HDV genotype 1 [HDV-1]), and the RoboGene and the DiaPro HDV RNA quantification kits (designed to quantify all genotypes).
METHODS: We selected RNA from 128 clinical samples of all HDV genotypes except HDV-4, with various HDV viral load values. We also analyzed 5 samples, collected over time, from each of 6 patients infected with strains of different genotypes.
RESULTS: Quantification results from the commercial kits for HDV-1 from European or Asian samples were consistent with those from our method, however, they underestimated (0.5-1 log(10) with Lightmix and DiaPro) and did not detect (1 and 4 samples with Lightmix and DiaPro, respectively) HDV-1 African samples. Moreover, the commercial kits greatly underestimated HDV viral load of almost all non-genotype-1 strains (about 2-3 log(10)), and even did not detect HDV-7 or HDV-8 RNA in several samples with high concentrations of virus.
CONCLUSIONS: Commercial kits accurately quantify HDV-1 in samples from European and Asian patients. However, they can dramatically underestimate or fail to quantify HDV viral load from samples from African patients infected with strains of genotypes 1 and 5 to 8.