Infection of Common Marmosets with GB Virus B Chimeric Virus Encoding the Major Nonstructural Proteins NS2 to NS4A of Hepatitis C Virus

Abstract

A lack of immunocompetent-small-primate models has been an obstacle for developing hepatitis C virus (HCV) vaccines and affordable antiviral drugs. In this study, HCV/GB virus B (GBV-B) chimeric virus carrying the major nonstructural proteins NS2 to NS4A (HCV NS2 to -4A chimera) was produced and used to infect common marmosets, since HCV NS2 to NS4A proteins are critical proteases and major antigens. Seven marmosets were inoculated intrahepatically with HCV NS2 to -4A chimera RNA for primary infection or intravenously injected with chimera-containing serum for passage infection. Three animals used as controls were injected with phosphate-buffered saline (PBS) or GBV-B, respectively. Six of seven HCV NS2 to -4A chimera-infected marmosets exhibited consistent viremia and one showed transient viremia during the course of follow-up detection. All six infected animals with persistent circulating viremia presented characteristics typical of viral hepatitis, including viral RNA and proteins in hepatocytes and histopathological changes in liver tissue. Viremia was consistently detected for 5 to 54 weeks of follow-up. FK506 immunosuppression facilitated the establishment of persistent chimera infection in marmosets. An animal with chimera infection spontaneously cleared the virus in blood 7 weeks following the first inoculation, but viral-RNA persistence, low-level viral protein, and mild necroinflammation remained in liver tissue. The specific antibody and T-cell response to HCV NS3 in this viremia-resolved marmoset was boosted by rechallenging, but no viremia was detected during 57 weeks of follow-up. The chimera-infected marmosets described can be used as a suitable small-primate animal model for studying novel antiviral drugs and T-cell-based vaccines against HCV infection. H epatitis C virus (HCV) infection is a global health threat thatcauses chronic hepatitis and is associated with 78% of primary hepatocellular carcinoma (1). Currently, limitations of small-primate models hamper the development of HCV vaccines and affordable antiviral drugs. Chimpanzees have been used as a uniquely reliable animal for HCV infection in past decades (2), significantly contributing to defining the infection natural history, pathogenesis, immune response, and rechallenge of HCV (3-6). However, the utility of chimpanzees has been more and more restricted by ethical concerns, and though rare, the use of this primate model in medical studies is extremely costly (2). The nonprimate animal models simulating HCV infection might potentially be mimicked with rodent hepacivirus (RHV)-infected rats (7,8), canine hepacivirus (CHV)-infected dogs (9), and equine hepacivirus (EHCV) (nonprimate hepacivirus [NPHV])-infected horses (10). HCV infection in immunocompetent mice was reported in genetically humanized mouse CD81 and occludin (OCLN) (11,12). However, the differences in infection courses and immune responses fundamentally separate these mice from HCV-infected patients.Common marmosets (Callithrix jacchus), one of the New World small ...

Hepatitis C: from discovery to cure

“…Recently, Zhu et al . described a marmoset model infected with GBV‐B chimeric virus which supported consistent expression of six major HCV antigens including NS2 to NS4A. This novel small primate model was immunocompetent, providing an alternative model for antiviral drugs evaluation.…”

Animal Models Used in Hepatitis C Virus Research

“…It was further demonstrated that serum from these viremic animals caused infection and hepatic inflammation in naïve marmosets; however, viremia was intermittent, which appeared to correlate with the induction of cellular and humoral immune responses. A GBV-B/HCV chimera carrying HCV NS2 to NS4A caused viremia in marmosets for 20 weeks, and viremia was maintained even longer under immunosuppression [109]. These results from infection studies with GBV-B/HCV chimeras remain to be validated in larger cohorts of animals, to more accurately characterize their replicative capacities, correlates of immunological protection, and virally induced pathogenesis.…”

Utility of Common Marmoset (Callithrix jacchus) Embryonic Stem Cells in Liver Disease Modeling, Tissue Engineering and Drug Metabolism

“…A modest antibody response to HCV core and E2 proteins was also detected [ 81 ]. Marmosets infected with another HCV/GB-V chimeric virus expressing nonstructural proteins NS2 to NS4A of HSC also exhibited viremia with characteristics typical of viral hepatitis [ 82 ]. These findings indicated that common marmosets infected with chimeric viruses are valuable tools in the development of vaccines and antiviral drugs against HCV infection.…”