Genotype 3 diversity and quantification of hepatitis E virus RNA.
Genotype 3 hepatitis E viruses (HEVs) are distributed across the world and are now considered to be an emerging public health concern in industrialized countries. At least 10 genotype 3 subtypes have been identified in humans and animals worldwide. It was recently reported that the sensitivities of HEV RNA assays differ greatly. We have assessed the influence of genotype 3 diversity on the performances of two HEV RNA assays: one targeting the ORF3 gene and the other targeting the ORF2 gene. We tested a panel of 5 HEV-positive reference samples of genotypes 3a, 3b, 3c, 3e, and 3f at 10-fold serial dilutions. The HEV RNA concentrations obtained with both reverse transcription (RT)-PCRs were correlated, but the RT-PCR based on ORF2 underestimated the HEV RNA concentrations. The mean [ORF3 - ORF2] difference was 1.41 log copies/ml. We also tested 34 clinical specimens of genotypes 3c (n = 15), 3e (n = 4), and 3f (n = 15), representing the most prevalent subtypes in Europe. The mean [ORF3 - ORF2] differences were 1.41 log copies/ml for genotype 3c, 0.96 log copies/ml for genotype 3e, and 0.70 log copies/ml for genotype 3f. The bias between the 2 RT-PCR assays was significantly greater for genotype 3c than for genotype 3f (P = 0.007). We therefore recommend the use of an RT-PCR protocol based on ORF3 to quantify HEV RNA of genotype 3 strains.
INSERM, U1043, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France.abravanel.f@chu-toulouse.fr
Florence
F
Abravanel
Karine
K
Sandres-Saune
Sebastien
S
Lhomme
Martine
M
Dubois
Jean-Michel
JM
Mansuy
Jacques
J
Izopet
D000818:Animals; D005060:Europe; D014644:Genetic Variation; D005838:Genotype; D016751:Hepatitis E / Q000821:virology; D016752:Hepatitis E virus / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D012367:RNA, Viral / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods*; D014764:Viral Proteins / Q000235:genetics
C400971:ORF2 protein, Hepatitis E virus; C400973:ORF3 protein, Hepatitis E virus; D012367:RNA, Viral; D014764:Viral Proteins