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IN VITRO INFECTIVITY OF HEPATITIS C VIRUS FROM PLASMA AND LYMPHOID CELLS OF PATIENTS WITH THERAPY-INDUCED RESOLUTION OF HEPATITIS C
SA Macparland, TNQ Pham, TI Michalak
Molecular Virology and Hepatology Research, Faculty of Medicine Memorial University, St John’s, Newfoundland
Background and AIM: Low levels of HCV persist for years in serum and lymphoid cells of patients with apparent complete resolution of hepatitis C (JVI 2004;78:5867; JVH 2007;14:537). Also, HCV propagates in vivo and in vitro in human T cells (JGV 2006;87:3577). The aim of this study was to determine whether residual HCV persisting after apparent complete clinical clearance remains infectious in a lymphoid cell-based HCV in vitro infection system.
METHODS: Naive, normal human T cells were exposed to plasma or culture supernatant from PBMC of patients with long-term follow-up after achieving sustained virological response (SVR) to interferon alpha and Ribavirin. HCV RNA positive and replicative strands were evaluated by RT-PCR/ nucleic acid hybridization (RT-PCR/NAH). Clonal sequencing characterized genomes of HCV detected in plasma and in in vitro infected T cells. Immunogold electron microscopy (IEM) with anti-E2 mAb examined HCV particles produced by in vitro infected T cells.
RESULTS: Nine patients followed for up to 60 months after achieving SVR as defined by the current criteria were studied. HCV RNA positive strand was detected in 8/9 T cell cultures infected with plasma and HCV RNA replicative strand in 3/9. Clonal sequencing revealed differences between HCV in plasma and in the T cells. IEM analysis of the culture supernatant from the de novo infected T cells identified enveloped virion particles. In 4 of the 9 cases, supernatant from PBMC was tested for infectivity in cultured T cells. HCV RNA positive strand was detected in 4/4 T cell cultures infected and HCV RNA replicative strand in 1 of 4.
CONCLUSIONS: Residual HCV persisting after therapy-induced resolution of hepatitis C can remain infectious in some individuals. These data may have important implications with respect to the epidemiology of HCV infection and mechanisms of HCV persistence.