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Hepatology, vol. 77, pp. E21

Abstract

Dr. Abulaiti et al. pointed out that using an Alu‐RT‐PCR for the detection of transcription of integrated HBV limits the detection of chimeric transcripts. They show that only 15% of the chimeric transcripts obtained by RNA sequencing of liver samples from HBV‐related HCC patients contain an Alu sequence. Although we used a different patient population (chronic HBV patients without HCC), it is very likely that a proportion of chimeric transcripts lack an Alu sequence and are not detected by our Alu‐RT‐PCR.1 HBV integration occurs randomly across the whole genome.2 Alu sequences are also randomly distributed throughout the genome,3 and therefore we believe that quantification of chimeric HBV transcripts containing an Alu sequence may serve as a proxy of the transcriptional activity of integrated HBV. We agree with Abulaiti et al. that transcripts containing the ORF S and ORF X most likely arise from the same integrated HBV. In the total group of chronic HBV patients, we observed similar levels of S ORF and ORF X transcription (Figure 3).1 Our assay does not discriminate between integrants that either contain ORF S/X or ORF X alone, and transcriptional activity is expressed as ORF X transcripts corrected for the total amount of integrants containing X (Figure 4F). This may explain why no difference in ORF S and ORF X levels were observed. However, differences in transcriptional activity between patient subgroups (HBeAg‐negative CH, HBeAg‐positive CH, and HBeAg‐negative ChI) were observed for ORF S and ORF X (Figure 4C,F), which could be explained by differences in the epigenetic modification of integrated HBV between the different stages of disease.4

Authors 5

1. Vladimir V. Loukachov

   Amsterdam UMC Location University of Amsterdam · Amsterdam University Medical Centers · University of Amsterdam

   Affiliation as printed

   Department of Experimental Immunology, Amsterdam UMC, Location AMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, The Netherlands

2. Karel A. van Dort

   Amsterdam UMC Location University of Amsterdam · Amsterdam University Medical Centers · University of Amsterdam

   Affiliation as printed

   Department of Experimental Immunology, Amsterdam UMC, Location AMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, The Netherlands

3. Robin Erken

   Amsterdam UMC Location University of Amsterdam · Amsterdam University Medical Centers · Amsterdam Gastroenterology Endocrinology Metabolism

   Affiliation as printed

   Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands

4. Henk W. Reesink Aachen Department of Gastroenterology and Hepatology

   Leiden University Medical Center

   Affiliation as printed

   Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands

5. Neeltje A. Kootstra corresponding

   Amsterdam UMC Location University of Amsterdam · Amsterdam University Medical Centers · University of Amsterdam

   Affiliation as printed

   Department of Experimental Immunology, Amsterdam UMC, Location AMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, The Netherlands