# Analysis of genetic evolution and molecular transmission of hepatitis C virus in key areas of the southeast coast of China

## TL;DR

This study analyzes the genetic evolution and transmission of hepatitis C virus in China's southeast coast to support prevention and control strategies.

## Contribution

The paper provides new molecular epidemiological data on HCV genotypes and transmission networks in a specific region of China.

## Key findings

- Genotype 1b was the most prevalent HCV genotype in the study area.
- Molecular transmission clusters were identified with a high clustering rate of 67.80%.
- Transmission clusters of genotype 1b showed closer connections than genotype 2a.

## Abstract

Hepatitis C virus (HCV) infection is prevalent worldwide. The genotype (GT) distribution characteristics and transmission patterns of HCV show regional differences. Currently, the research on HCV genotype characteristics, molecular transmission networks, and associated risk factors in key areas of the southeast coast of China remains limited. This district lacks accurate molecular epidemiological data on HCV, hindering the implementation of prevention and control efforts. This study aims to investigate the epidemiological characteristics and molecular network transmission features of hepatitis C genotypes in key areas of the southeastern coast of China, to provide a reference basis for prevention and control strategies.

The HCV RNA-positive serum samples (88 cases) were collected from sentinel surveillance subjects with hepatitis C in Xiuyu District, Putian City, Fujian Province, China, from October 2022 to April 2023. The Core and NS5b fragments of the HCV genome were amplified by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The PCR products were sent to Sangon Biotech (Shanghai, China) Co., Ltd. for purification and Sanger sequencing. The sequences were assembled and aligned using biological software. The processed sequences were used to construct phylogenetic trees and molecular transmission networks. The Fisher–Freeman–Halton exact test was used to evaluate the significance of differences in demographic characteristics between HCV genotype groups.

A total of 59 sequence samples were obtained from October 2022 to April 2023 (53 in the Core fragment and 45 in the NS5B fragment). Phylogenetic tree analysis showed that the major HCV genotypes were 1b (36/59, 61.02%) and 2a (22/59, 37.29%). One sample showed inconsistent genotyping results between the two genomic fragments. Most HCV strains had similar genetic evolutionary relationships in the Xiuyu District. There was a statistically significant difference in the distribution of HCV genotypes across occupations (p < 0.05), whereas no other factors showed significant differences. At genetic distance thresholds of 0.018 and 0.043, Core and NS5B sequences formed the highest number of transmission clusters. A total of 40 sequences formed the molecular transmission network, with an overall clustering rate of 67.80%. The Core fragment contained 6 clusters, and the NS5b fragment contained 5 clusters. The connection between samples in the GT 1b transmission cluster was closer than in GT 2a. The network transmission figures reflected the potential connections between samples.

In this study, the HCV genotypes in the key areas were predominantly 1b and 2a. Most hepatitis C strains shared a similar evolutionary relationship. It suggested that there might be cluster transmission in this area. However, we still need more detailed epidemiological case investigations and experimental data in the future to obtain an accurate estimate of hepatitis C prevalence. Providing targeted treatment for HCV-infected individuals and intensifying screening among farmers are crucial measures to prevent and control hepatitis C in Xiuyu District.