The effect of viral load on the composition of the gut microbiota in chronic HCV-infection: a metagenomic analysis taking into account the gender and age of patients

Purpose: to identify specific characteristics of the gut microbiota composition associated with high and low viral load in patients with chronic HCV infection, taking into account sex and age.

Materials and methods: a single-center, cross-sectional clinical study was conducted, including 124 patients with chronic HCV infection . The study determined the composition of gut microbial diversity using metagenomic sequencing of 16S rRNA. High-throughput sequencing was performed using the MiSeq genetic analyzer (Illumina, USA) using a protocol based on the analysis of variable regions of the 16S rRNA gene. Data were analyzed using Kraken2. The significance level was set at 0.05.

Results: the features of the gut microbiota in patients with chronic HCV infection , depending on the level of viral load, are described. In the group of patients with low viral load, there was an increase in the diversity of opportunistic bacteria, including representatives of the oral microbiota Prevotella (padj = 0.129) and Gemella (padj = 0.124), inflammatory markers Burkholderia (padj =0.035), Haemophilus (padj = 0.143) and Paraclostridium (padj = 0.035) and delayed motility Sarcina (padj = 0.035). In patients with high viral load, there was a relative increase in the presence of proinflammatory and potentially pathogenic taxa such as Stenotrophomonas (padj = 0.106) and Nitratidesulfovibrio (padj = 0.121).

Conclusions: the study demonstrates that the viral load in chronic HCV infection is associated with qualitatively different shifts in the gut microbiota. The data obtained suggest that at high viral load, changes in the gut microbiota are predominantly mediated by systemic inflammation, while at low viral load they more closely reflect structural changes in the liver.

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