In-Host HEV Quasispecies Evolution Shows the Limits of Mutagenic Antiviral Treatments

Abstract

Deep sequencing; Mutagens; Quasispecies

Seqüenciació profunda; Mutàgens; Quasiespècie

Secuenciación profunda; Mutágenos; Cuasiespecie

Here, we report the in-host hepatitis E virus (HEV) quasispecies evolution in a chronically infected patient who was treated with three different regimens of ribavirin (RBV) for nearly 6 years. Sequential plasma samples were collected at different time points and subjected to RNA extraction and deep sequencing using the MiSeq Illumina platforms. Specifically, we RT-PCR amplified a single amplicon from the core region located in the open-reading frame 2 (ORF2). At the nucleotide level (genotype), our analysis showed an increase in the number of rare haplotypes and a drastic reduction in the frequency of the master (most represented) sequence during the period when the virus was found to be insensitive to RBV treatment. Contrarily, at the amino acid level (phenotype), our study revealed conservation of the amino acids, which is represented by a high prevalence of the master sequence. Our findings suggest that using mutagenic antivirals concomitant with high viral loads can lead to the selection and proliferation of a rich set of synonymous haplotypes that express the same phenotype. This can also lead to the selection and proliferation of conservative substitutions that express fitness-enhanced phenotypes. These results have important clinical implications, as they suggest that using mutagenic agents as a monotherapy treatment regimen in the absence of sufficiently effective viral inhibitors can result in diversification and proliferation of a highly diverse quasispecies resistant to further treatment. Therefore, such approaches should be avoided whenever possible.

This study was partially supported by Plan Estratègic de Recerca i Innovació en Salut (PERIS)—Direcció General de Recerca i Innovació en Salut (DGRIS), Catalan Health Ministry, Generalitat de Catalunya; Centro para el Desarrollo Tecnológico Industrial (CDTI) from the Spanish Ministry of Economy and Business, grant number IDI-20200297, Grant PID2021-126447OB-I00 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe; Projects PI19/00301 and PI22/00258 funded by Instituto de Salud Carlos III (ISCIII) and cofounded by the European Union; and Gilead’s biomedical research project GLD21/00006. S.C.-C has received support from Spanish Ministry of Education, grant FPU21/04150. M.I.-L. received the support of a fellowship from the “la Caixa” Foundation (ID 100010434), whose code is “LCF/BQ/DR23/12000020”.