Lymphotropic HCV strain can infect human primary naïve CD4⁺ cells and affect their proliferation and IFN-γ secretion activity

Background: Lymphotropic hepatitis C virus (HCV) infection of B and T cells might play an important role in the pathogenesis of hepatitis C. Recently, we showed that a lymphotropic HCV (SB strain) could infect established T-cell lines and B-cell lines. However, whether HCV replication interferes with cell proliferation and function in primary T lymphocytes is still unclear. Aim: The aim of this study was to analyze whether HCV replication in primary T lymphocytes affected their development, proliferation, and Th1 commitment. Methods: SB strain cell culture supernatant (2 × 10⁴ copies/ml HCV) was used to infect several kinds of primary lymphocyte subsets. Mock, UV-irradiated SB-HCV, JFH-1 strain, and JFH-1 NS5B mutant, which could not replicate in T cells, were included as negative controls. Carboxyfluorescein succinimidyl ester (CFSE) and CD45RA double staining was used to evaluate the proliferative activity of CD4⁺CD45RA⁺CD45RO^- naïve CD4⁺ cells. Interferon (IFN)-γ and interleukin (IL)-10 secretion assays magnetic cell sorting (MACS) were carried out. Results: Negative strand HCV RNA was detected in CD4⁺, CD14⁺, and CD19⁺ cells. Among CD4⁺ cells, CD4⁺CD45RA ⁺RO^- cells (naïve CD4⁺ cells) were most susceptible to replication of the SB strain. The levels of CFSE and CD45RA expression gradually declined during cell division in uninfected cells, while HCV-infected naïve CD4⁺ cells expressed higher levels of CFSE and CD45RA than Mock or UV-SB infected naïve CD4⁺ cells. Moreover, the production of IFN-γ was significantly suppressed in SB-infected naïve CD4⁺ cells. Conclusions: Lymphotropic HCV replication suppressed proliferation and development, including that towards Th1 commitment, in human primary naïve CD4⁺ cells.