Molecular and cellular determinants of cell‐to‐cell transmission of HCV in vitro

Abstract

It was reported previously that HCV can be transmitted from persistently infected human bone-marrow-derived B-lymphoblastoid cells (TO.FE(HCV)) to human hepatoma cells by cell-to-cell contact. The present study confirms and characterize further such type of HCV infection in vitro. TO.FE(HCV) cells were co-cultured with 2.2.15 hepatoma cells, that are not susceptible to cell-free infection by sera containing HCV of 1b genotype. By this co-cultivation system it was demonstrated that HCV transmission to recipient cells requires de novo virus RNA replication. Several factors may favor HCV-transmission, evidence is provided that TO.FE(HCV) cells were able to select HCV-quasispecies. 5'-UTR and core sequence analysis revealed differences in the HCV-quasispecies composition in serum inoculum and in infected TO.FE B-cells at 4 months post-inoculation. It is considered that the latter may be more successful in replicating HCV in vitro and used to express surface molecules which may be involved in cell-to-cell contact. In TO.FE(HCV) cells replicate distinct, or few close related, HCV-variants correlated with those of serum inoculum. Comparative analysis of tetra-spans and integrins expression undertaken by cytofluorimetry displayed higher level of expression for TO.FE cells in comparison to other human bone-marrow-derived B-cell lines. Overall, the observed persistent in vitro HCV replication is mediated by a continuous cell-to-cell reinfection that may be favored by selection of viral variants and expression of molecules involved in cell adhesion. These observations may provide an explanation for the establishment of HCV infection, the occurrence of chronic infection and HCV-related lymphoproliferative diseases.

Apolipoprotein E, but Not Apolipoprotein B, Is Essential for Efficient Cell-to-Cell Transmission of Hepatitis C Virus

“…Although only in vitro evidence is available for in vivo cell-cell transmission (6)(7)(8), this mechanism is supported by the observation that HCV antigen-positive cell clusters are found in the liver of HCV-infected patients (9). Also, in vitro neutralizing antibodies from infected patients can neutralize cell-free HCV infection almost completely, whereas they fail to control infection in vivo (10)(11)(12).…”

A Novel Inhibitor IDPP Interferes with Entry and Egress of HCV by Targeting Glycoprotein E1 in a Genotype-Specific Manner

“…Cell-to-cell transmission, the major route of HCV transmission in the liver, was also efficiently blocked by IDPP (Fig. 3)3233. However, IDPP did not demonstrate any inhibitory effect on intracellular viral RNA replication or viral protein expression (Figs 1E, 4C and E), suggesting that the MOA of IDPP is different from that of the current FDA-approved HCV DAAs.…”

HCV Infection by Cell-to-Cell Transmission: Choice or Necessity?

“…By localized fusion events at cell contact points, the virus can directly enter neighbouring cells, permitting to cells naturally refractory to infection, because totally or partially lacking receptors/co-receptors, to become infected. Thus, the cell-to-cell route of virus transmission allows HCV to spread and thereafter to recruit close naïve cells other than resident hepatocyte, such as B and T lymphocytes [21,114,120,140,141], bone-marrow, spleen, kidney or central nervous system cells [142][143][144]. Though the classical route operates only in the Schematic representation of the molecules involved in membrane contacts and fusion that result in the formation of the so called "virological synapses" and that may also mediate cell-to-cell HCV transmission.…”

“…3) [90,93,114,130]. It is also possible that these processes occur between other cell types, such as macrophages, endothelial and epithelial cells, which all behave as mediators for heterologous cell transmission of HCV.…”

“…Ultrastructural changes occurring at cell surface membranes at cell contacts sites were analyzed in detail and shown to affect replication and expression of HCV in both donor and recipient cells. More recently, Valli et al [114] accurately focused on cellular and molecular factors supporting cell-to-cell virus transmission, suggesting that selection of mutants in viral quasispecies and expression of cell adhesion molecules were able to maintain and propagate virus.…”