Evaluation of synthetic peptides on hepatitis C virus direct inhibition

Hepatitis C is the liver inflammation arising from Hepatitis C virus (HCV) infection, frequently it evolves to chronic conditions, and has been considered the major world cause of cirrhosis and hepatocellular carcinoma. Is estimated that around 71 million people are chronically infected by this virus and 2 million of new cases arise by year. The main pathway of transmission is parenteral and current treatments are based on second and third generation of direct-acting antivirals (DAAs), associated or not to pegylated interferon and ribavirin. These treatments present many side-effects, high cost and resistant mutants have been reported. Therefore, new effective treatments with low costs, major spectrum and less side effects have been sought. Thus, the aim of this study was to develop a prodrug with direct action to HCV-infected cells and efficient for more than one step of virus replication cycle. For this, an initial screening was performed testing six synthetic peptides concerning its toxicity and its effect on HCV subgenomic replicons SGR-Feo JFH1 (genotype 2) and S52/SG (genotype 3) replication, stably expressed in the hepatoma cell line Huh-7.5. The most efficient peptide, GA-Hecate was assessed in the HCV complete replicons J6/JFH-1 RLUC and JFH-1 for all steps of viral infectious cycle and then modeled to produce a prodrug based on HCV protease NS3/4A cleavage site VVCCDD. Peptide GA-Hecate presented at its maximum safe concentration, inhibition of 85%, 95%, 50% and 99% for replication, entry, release and infectivity respectively. Its mechanism of action was associated with alteration in membrane fluidity, redistribution and reduction of lipid droplets quantity, as well as, dsRNA intercalation. The prodrug development prevented the toxicity in non-HCV-infected cells and induced the virus inhibition, but was not absolutely inactive in the presence of free virus particles and erythrocytes. The proposed study proves the concept that the use of NS3 protease cleavage site as a drug carrier. However, more studies are still needed for reaching a prodrug completely inert in non-infected cells. (AU)