ERVW-1 and hepatocellular carcinoma: To investigate the neutralizing activity of the aptamers against CHIKV, we established a cell assay system using CHIKVpp with the envelope proteins of the West African strain 37997 expressing the firefly luciferase gene to estimate CHIKV entry into a virus-permissive hepatocellular carcinoma (HCC) cell line Huh7 cells (Fig. 2A and B).