Abstract: Objective To observe the relationships between the genotypes of hepatitis C virus (HCV) and the severity of disease, and the expression of immune regulatory cytokines in chronic hepatitis C (CHC) patients.Methods Between February 2021 and February 2023, 150 CHC patients treated in Nanyang First People's Hospital were collected in this study, including 92 males and 58 females, aged from 40 to 68 years, with an average age of (45.8±7.2) years. The patients were divided into a mild CHC group (58 cases), a moderate CHC group (48 cases) and a severe CHC group (44 cases) according to the severity of their disease. The HCV genotypes of these patients were determined at the same time. The expression of immunocompetent cells in patients with different severity and genotypes were compared.Results One hundred and thirteen CHC patients were HCV RNA positive and 37 patients were HCV RNA negative. The number of HCV RNA positive and HCV RNA negative cases in CHC patients with different severity was statistically significant (P<0.05). Six HCV genotypes were detected, including 15 cases of type 1a (10.0%), 61 cases of type 1b (40.7%), 59 cases of type 2a (39.3%), 7 cases of type 2b (4.7%), 3 cases of type 3a (2.0%) and 5 cases of type 6 (3.3%). There was no significant difference in the number of cases of CHC patients with different severity (P>0.05). In view of the small number of cases with HCV genotypes 2b, 3a and 6 , the serum IFN-γ. and IL-4 levels were only compared in patients with HCV genotypes 1a, 1b and 2a. The levels of IFN-γ and IL-4 in serum of CHC patients with HCV genotypes 1a, 1b and 2a were significantly different (P<0.05). The levels of serum IFN-γ and IL-4 in patients with mild, moderate and severe CHC were significantly different (P<0.05).Conclusion There are multiple HCV genotypes in CHC patients, and there is a close relationship between subtype 1b and the severity of disease and the expression of Th1/Th2/Th17 cytokines. At the same time, there are significant differences in the expression of immune regulatory cytokines in patients with different severity of the disease.

Key words: Genotype, Chronic hepatitis C, IFN-γ, IL-4, IL-17