Immune-escape mutations and stop-codons in HBsAg develop in a large proportion of patients with chronic HBV infection exposed to anti-HBV drugs in Europe

Luna Colagrossi, Lucas E. Hermans, Romina Salpini, Domenico Di Carlo, Suzan D. Pas, Marta Alvarez, Ziv Ben-Ari, Greet Boland, Bianca Bruzzone, Nicola Coppola, Carole Seguin-Devaux, Tomasz Dyda, Federico Garcia, Rolf Kaiser, Sukran Köse, Henrik Krarup, Ivana Lazarevic, Maja M. Lunar, Sarah Maylin, Valeria Micheli, Orna Mor, Simona Paraschiv, Dimitros Paraskevis, Mario Poljak, Elisabeth Puchhammer-Stöckl, François Simon, Maja Stanojevic, Kathrine Stene-Johansen, Nijaz Tihic, Pascale Trimoulet, Jens Verheyen, Adriana Vince, Snjezana Zidovec Lepej, Nina Weis, Tülay Yalcinkaya, Charles A. B. Boucher, Annemarie M. J. Wensing, Carlo F. Perno, Valentina Svicher, on behalf of the HEPVIR working group of the European Society for translational antiviral research (ESAR)

HBsAg immune-escape mutations can favor HBV-transmission also in vaccinated individuals, promote immunosuppression-driven HBV-reactivation, and increase fitness of drug-resistant strains. Stop-codons can enhance HBV oncogenic-properties. Furthermore, as a consequence of the overlapping structure of HBV genome, some immune-escape mutations or stop-codons in HBsAg can derive from drug-resistance mutations in RT. This study is aimed at gaining insight in prevalence and characteristics of immune-associated escape mutations, and stop-codons in HBsAg in chronically HBV-infected patients experiencing nucleos(t)ide analogues (NA) in Europe. This study analyzed 828 chronically HBV-infected European patients exposed to ≥ 1 NA, with detectable HBV-DNA and with an available HBsAg-sequence. The immune-associated escape mutations and the NA-induced immune-escape mutations sI195M, sI196S, and sE164D (resulting from drug-resistance mutation rtM204 V, rtM204I, and rtV173L) were retrieved from literature and examined. Mutations were defined as an aminoacid substitution with respect to a genotype A or D reference sequence. At least one immune-associated escape mutation was detected in 22.1% of patients with rising temporal-trend. By multivariable-analysis, genotype-D correlated with higher selection of ≥ 1 immune-associated escape mutation (OR[95%CI]:2.20[1.32-3.67], P = 0.002). In genotype-D, the presence of ≥ 1 immune-associated escape mutations was significantly higher in drug-exposed patients with drug-resistant strains than with wild-type virus (29.5% vs 20.3% P = 0.012). Result confirmed by analysing drug-naïve patients (29.5% vs 21.2%, P = 0.032). Strong correlation was observed between sP120T and rtM204I/V (P < 0.001), and their co-presence determined an increased HBV-DNA. At least one NA-induced immune-escape mutation occurred in 28.6% of patients, and their selection correlated with genotype-A (OR[95%CI]:2.03[1.32-3.10],P = 0.001). Finally, stop-codons are present in 8.4% of patients also at HBsAg-positions 172 and 182, described to enhance viral oncogenic-properties. Immune-escape mutations and stop-codons develop in a large fraction of NA-exposed patients from Europe. This may represent a potential threat for horizontal and vertical HBV transmission also to vaccinated persons, and fuel drug-resistance emergence.