5.5. HCV Virion Budding and Secretion
Budding and secretion are other steps not completely elucidated. However, cellular proteins seem to
play a central role during these processes. The Golgi-localized PI4P and the PI4P-binding protein
GOLPH3 have been shown to have a role in HCV secretion. More precisely, GOLPH3 is involved invesicle budding thanks to its interaction with the myosin MYO18A. Silencing of both these proteins
leads to intracellular accumulation of viral particles and reduction of HCV secretion, suggesting a role
in HCV budding [204]. The hepatocellular transcription factor Hepatocyte nuclear factor 4 (HNF4) is
responsible for lipid metabolism and VLDL-mediated lipid transport. Downregulation of HNF4 or its
downstream target phospholipase A2 GXIIB (PLA2GXIIB) also evidenced an impairment of HCV
secretion [205]. In addition, other studies evidenced the colocalization of the Heat Shock Cognate
Protein 70 (HSC70) with both E2 and core on the LD and its association with virions. Moreover, HSC70
downregulation determines an impairment of viral release, as well as a decrease of the volume of LDs [206].