丙型肝炎基因分型进展及其临床意义

Hepatitis C Virus in mainland China with an emphasis on genotype and subtype distribution

Due to the low fidelity of the RNA-dependent RNA polymerase, Hepatitis C virus (HCV) mutates quite frequently. There are seven genetically divergent genotypes (GTs) distributed in the world, each of which contains several closely related subtypes. The peer-reviewed literatures reporting the prevalence rate of HCV GTs in Chinese hospitalized patients were identified by systematic searching of three electronic databases, and the prevalence rates were pooled through 137 qualified studies. The significant difference between HCV GT and HCV viral load and severity of hepatitis were analyzed under Chi-squared or Fisher's exact test. Data from epidemiological studies on hospitalized patients demonstrated that HCV GTs 1-6 have been found in China, of which 1b (62.78%(95% CI: 59.54-66.02%)) and 2a (17.39% (95% CI: 15.67-19.11%)) are the two predominant subtypes. HCV GTs and subtypes exhibits significant regional divergence. In North, Northwest, Northeast, East (except Jiangxi province) and Central China (except Hunan province), HCV-1b, 2a remain the two predominant subtypes; South China shows the most abundant genetic diversity that 14 subtypes were found, and HCV-3 in the Southwest China remains higher prevalent subtype than the other regions. In addition, co-infection in Liaoning province of Northeast China is the most diverse with 10 co-infection types, and Tibet has the highest rate of co-infection. The associations between HCV GTs and patients group, severity of illness and antiviral treatment efficacy were also discussed in this review.

Mechanism of hepatitis C virus infection

About 170 million persons are infected with hepatitis C virus (HCV) around the world, and nearly 80% of infected patients develop chronic liver disease that may eventually lead to liver cirrhosis or hepatocellular carcinoma. The mechanisms underlying the life cycle of HCV in the host are still largely unknown and the efforts made by researchers have been hampered by the absence of a robust system reproducing HCV infection. Moreover, there are no effective vaccines or drugs available to defend or exclude viruses because of frequent viral mutation. In 2005, several research groups have successfully established cell culture systems for HCV, pushing the basic research on HCV to a new stage. This paper will focus on HCV genome diversity, progress in culture models, HCV life cycle, and protein function to highlight the mechanism of HCV infection.