Elimination of hepatitis C virus (HCV) without the need for medical intervention, known as spontaneous clearance (SC), occurs at a significantly lower rate than in the case of hepatitis B virus infection and only in selected individuals, such as reportedly in Keith Richards, a guitarist of The Rolling Stones. The present paper provides an updated narrative review of the research devoted to the phenomenon in order to identify and discuss the demographic, lifestyle-related, clinical, viral genotype-related, and host genetic factors underpinning the SC occurrence. The body of evidence indicates that the likelihood of SC is decreased in older individuals, men, Black people, HIV-coinfected subjects, and intravenous drug and alcohol users. In turn, HBV coinfection and specific polymorphism of the genes encoding interferon lambda 3 (particularly at rs8099917) and interferon lambda 4 (particularly at rs12979860) and HLA genes increase the odds of SC. Numerous other host-specific genetic factors could be implicated in SC, but the evidence is limited only to certain ethnic groups and often does not account for confounding variables. SC of HCV infection is a complex process arising from a combination of various factors, though a genetic component may play a leading role in some cases. Understanding factors influencing the likelihood of this phenomenon justifies better surveillance of high-risk groups, decreasing health inequities in particular ethnic groups, and may guide the development of a prophylactic vaccine, which at present is not available, or novel therapeutic strategies. Further research is needed to elucidate the exact mechanisms underlying SC and to explore potential interventions that could enhance this natural antiviral response.

While elimination of the hepatitis C virus (HCV) following acute infection is not uncommon, spontaneous clearance once the infection becomes chronic is extremely rare. The mechanisms involved in the clearance of chronic HCV infection without intervening antiviral therapy are not well known. Herein we describe a case of a renal transplant recipient who acquired HCV infection while immunosuppressed, experienced a rapid histological progression, and thereafter cleared the virus spontaneously long after withdrawal of immunosuppression following kidney graft rejection and failure. We review the literature and summarize the reports of spontaneous clearance of chronic HCV infection in various settings.

Re-infection by the hepatitis C virus (HCV) occurs rapidly after liver transplantation (LT), and spontaneous clearance of HCV is rare under immunosuppressive conditions. Here, we report on two patients who underwent LT to treat liver cirrhosis and hepatocellular carcinoma. The immunosuppressants prescribed were short-term corticosteroids, tacrolimus, and mycophenolate mofetil. A 50-year-old woman underwent LT, with her brother as the donor. She acquired HCV of serological type 1 after LT; the HCV RNA level was 6.0 logIU/mL. Corticosteroids were discontinued within 24 days, with a total dose of 669 mg (adjusted) prednisolone (PSL). The serum alanine aminotransferase (ALT) level increased to 700 U/L by day 55 post-LT. Surprisingly, HCV RNA was not detected on day 87. A 52-year-old man underwent LT, with his sister as the donor. He became rapidly re-infected with HCV of serological type 2; the HCV RNA level was 6.9 logIU/mL. Corticosteroids were given for 24 days, with a total dose of 827 mg (adjusted) PSL. The serum ALT level increased continuously and his HCV cleared 115 days after LT. Both donor and recipient had the major IL28B genotype. HCV was eliminated spontaneously, even under immunosuppressive conditions, after PSL discontinuation without interferon treatment. Minimal use of immunosuppressants and the presence of hepatitis may have contributed to HCV clearance. However, it is important to evaluate additional relevant cases.

Hepatitis C virus (HCV)-related cirrhosis remains the most common indication for liver transplantation worldwide. Graft reinfection with HCV is nearly universal, causing significant morbidity and mortality. Spontaneous clearance of HCV after liver transplantation and retransplantation is extremely rare. We report a case of spontaneous clearance of HCV genotype 4 that occurred shortly after 2nd liver transplantation.

A 32-year-old female patient received a cadaveric liver transplant for HCV-related cirrhosis in 2007. She was not treated for HCV before transplantation. The patient developed biopsy-proven HCV recurrence with elevated transaminases and 65,553 IU/mL HCV RNA, genotype 4. She could not tolerate interferon-based treatment. The patient's condition progressively worsened and required a 2nd cadaveric liver transplantation in March 2013. Immunosuppression initially included steroids and Prograf, which was then switched to cyclosporine after the patient developed seizure. She developed acute cellular rejection which was readily treated with immunosuppression adjustment. HCV RNA became negative in April, which was confirmed in May 2013.

Spontaneous clearance of hepatitis C rarely occurs after liver transplantation and is extremely rare after retransplantation. This finding may be explained by alterations in the host immune responses to HCV after transplantation. To our knowledge, this is the first case of spontaneous clearance of HCV genotype 4 after liver retransplantation.

The IL28B genotype has been found to have a strong influence on spontaneous clearance of acute HCV both in HCV mono- and HIV/ the HCV co-infected patients. Spontaneous clearance of chronic HCV without HCV treatment is rare. Here, we report on three chronic HCV cases co-infected with HIV with spontaneous clearance of their HCV infection, all with the IL28B CC genotype. These cases were derived from a surveillance of the total HIV/HCV co-infected cohort in Sweden (n =4 66). The estimated frequency of spontaneous clearance of chronic HCV infection in our cohort was calculated to be 0.6-4.7%. Our cases lend some support to the initiation of ART prior to HCV treatment in HIV/HCV co-infected patients. Furthermore, HCV-RNA testing should be recommended immediately before initiation of HCV treatment, to find the subset of HIV/HCV co-infected patients with IL28B CC that may have cleared their chronic infection spontaneously.

Genetic polymorphisms adjacent to IL28B have been previously associated with spontaneous clearance of hepatitis C virus (HCV) and a higher rate of sustained virological response to interferon-based treatment in HCV genotype 1-infected patients. A recent study has shown that patients with the CC genotype of the rs12979860 single nucleotide polymorphism upstream from the IL28B gene are more likely to clear HCV spontaneously relative to the CT or TT genotype. In the liver transplant cohort, HCV recurs almost universally in patients with detectable HCV RNA at the time of transplantation. The spontaneous clearance of HCV infection after transplant is very rare. We report two cases of spontaneous clearance of HCV genotype 1 infection after liver transplantation from homozygous IL28B CC donors. This finding may be explained by alterations in the host immune responses to HCV after transplantation with a CC donor liver, which has potential implications for donor selection in HCV-positive recipients.

Spontaneous clearance of hepatitis C virus (HCV) after orthotopic liver transplantation (OLT) is a rare occurrence. Here, we present detailed immunological analysis of an interferon naive OLT recipient receiving uninterrupted immunosuppression who cleared HCV spontaneously 2 years after transplantation.

Enzyme-linked immunospot assay analysis of peripheral T-cell interferon gamma (IFN-γ), interleukin (IL)-10, and IL-17 response to HCV core and nonstructural antigen 4 and enzyme-linked immunosorbent assay (ELISA) to collagen (Col) subtypes I, II, IV, and V were performed in the index patient at the time of viral clearance and compared with an OLT cohort with persistent viremia matched for time from OLT, immunosuppression, and histology. Enzyme-linked immunospot assay and ELISA analysis were repeated on the patient 4 years after OLT. Transcription-mediated amplification assays were used to confirm viral clearance.

Compared with a cohort of post-OLT and nontransplanted viremic HCV patients, the index patient with HCV clearance demonstrated higher IL-17, IL-10, and lower IFN-γ response to nonstructural antigen 4 and core antigen and a higher titer of antibodies (Abs) to Col subtypes I, II, and V during clearance. On follow-up 2 years later, HCV-specific IFN-γ was increased in the index patient, with a decline in IL-17 and IL-10 response and Col I, II, and V Ab titer.

Virus-induced activation of Th-17 cells may contribute to HCV clearance post-OLT. Maintenance of viral suppression may be facilitated by restoration of Th1 (IFN-γ) responses. Modulation of Th17 immunity deserves further attention as a therapeutic strategy in the treatment of HCV recurrence post-OLT.

HCV infection has a severe course of disease in HIV/HCV co-infection and in liver transplant recipients. However, the mechanisms involved remain unclear. Here, we evaluated functional profiles of HCV-specific T-cell responses in 86 HCV mono-infected patients, 48 HIV/HCV co-infected patients and 42 liver transplant recipients. IFN-gamma and IL-2 production and ability of CD4 and CD8 T cells to proliferate were assessed after stimulation with HCV-derived peptides. We observed that HCV-specific T-cell responses were polyfunctional in HCV mono-infected patients, with presence of proliferating single IL-2-, dual IL-2/IFN-gamma and single IFN-gamma-producing CD4+ and dual IL-2/IFN-gamma and single IFN-gamma-producing CD8+ cells. In contrast, HCV-specific T-cell responses had an effector profile in HIV/HCV co-infected individuals and liver transplant recipients with absence of single IL-2-producing HCV-specific CD4+ and dual IL-2/IFN-gamma-producing CD8+ T cells. In addition, HCV-specific proliferation of CD4+ and CD8+ T cells was severely impaired in HIV/HCV co-infected patients and liver transplant recipients. Importantly, "only effector" T-cell responses were associated with significantly higher HCV viral load and more severe liver fibrosis scores. Therefore, the present results suggest that immune-based mechanisms may contribute to explain the accelerated course of HCV infection in conditions of HIV-1 co-infection and liver transplantation.

Recurrent hepatitis C infection (HCV) following liver transplantation causes accelerated allograft cirrhosis. Here we characterized HCV-specific immunity in adult liver transplant recipients (n = 74) with and without allograft cirrhosis. Patients were divided into hepatic inflammation/no cirrhosis (METAVIR scores 0-2, HIN) and hepatic cirrhosis (score 3-4, HFC). As control, 20 normal subjects and 10 non-HCV liver transplant patients were included. Twenty-five different serum cytokines were analyzed using LUMINEX. Frequency of T-cells specific to HCV-derived proteins (NS3, NS4, NS5, Core) was characterized using ELISPOT immunoassays. There was no difference in clinical characteristics between HIN (n = 49) and HFC (n = 25) groups. HIN group had high serum IFN-gamma and IL-12 while HFC demonstrated elevated IL-4, IL-5 and IL-10 (p < 0.01). HCV (NS3, NS4, NS5, Core)-specific IFN-gamma-producing CD4+ T-cells were elevated in the HIN group whereas the HFC patients showed predominance of HCV-specific IL-5 and IL-10-producing CD4+ T-cells.

Lack of HCV-specific Th1-type T-cell immunity is observed in liver transplant recipients with advanced allograft cirrhosis.

Spontaneous resolution of chronic hepatitis C virus (HCV) infection is exceedingly rare and poorly understood. As HCV and human immunodeficiency virus (HIV) have shared routes of transmission, HCV coinfection is estimated to affect 15%-30% of the HIV-positive population. We report 2 patients with HCV-HIV coinfection who underwent orthotopic liver transplantation at our center and had spontaneous clearance of their chronic HCV infection after transplantation without any anti-HCV treatment. Both patients showed no evidence of HCV recurrence for more than 3 years despite long-term immunosuppressant therapy. Spontaneous clearance of chronic HCV infection can occur in HIV-HCV-coinfected patients after liver transplantation. The mechanism of this phenomenon remains unclear.

Immunosuppression is a main determinant for the increased Hepatitis C Virus (HCV) replication after liver transplantation and the accelerated course of recurrent HCV liver disease. We present two patients both with diabetes, renal dysfunction with proteinuria converted to sirolimus therapy, who cleared serum HCV RNA without antiviral treatment. This is a potentially important observation that should stimulate study into factors that may help viral clearance from blood.