Localization of the different hepatitis C virus core gene products expressed in COS-1 cells

In this study we have investigated the subcellular localization in transfected COS-1 cells of the two major forms of the hepatitis C virus core protein: the immature protein of 191 residues (p21) and its proteolytically cleaved product of 173 residues (p19). In this study, and unlike previous investigations, we have been able to distinguish separately the localization of p21 from p19. This was achieved by the addition of a C-terminal HSV Tag to the p21 full coding sequence, and exploiting the fact that it is subsequently lost in the p19 product. In order to obtain an accurate localization of both p21 and p19 we used a mouse anti-HSV Tag MAb together with a human anti-core MAb (B12.F8) to perform double immunofluorescence studies. The results have shown that p21 is always localized around the nuclear envelope. On the other hand, p19 can be found diffused in the cytoplasm to different degrees. These in vivo results reinforce the proposed links between the regulated processing of the hepatitis C virus core protein and the possibility that this may contribute towards the regulation of its diverse biological functions.