Liver transplantation for chronic hepatitis C virus infection in the United States 2002-2014: An analysis of the UNOS/OPTN registry

Current Status of Liver Transplantation in North America

Liver transplantation indications continue to evolve in North America. Several recent changes have occurred in the field with changes in the allocation system, new performance metrics, expansion of transplant oncology, and utilization of ex vivo perfusion devices and techniques. Deceased donor liver transplantation continues to be the primary modality of liver transplantation in North America, with an ongoing focus on advancing the use of living donor liver transplantation, especially in those patients who may not have favorable access to deceased donor allografts.

Successful full-term pregnancy after preterm event in a liver transplant patient: a case report

BACKGROUND

Pregnancy after liver transplantation poses a significant challenge to both the patient and the transplant team.

CASE PRESENTATION

We present the case of a 19-year-old European patient who underwent liver transplantation 5 years previously owing to autoimmune hepatitis. Poor compliance with immunosuppressive therapy and missed follow-up visits during the patient's first pregnancy likely contributed to her liver function deterioration, hospitalization, and failed pregnancy. Owing to the patient's complex medical history, combined immunosuppressive treatment, and risks to the fetus, her second pregnancy was high risk. However, close outpatient monitoring and adherence to treatment led to a successful, uneventful, full-term pregnancy and healthy delivery.

CONCLUSION

Liver transplant recipients who desire to become pregnant require careful planning and management to ensure optimal outcomes for both the mother and the fetus. A personalized strategy is necessary to balance the potential benefits of childbirth with the risks involved in pregnancy after liver transplantation.

Progression of fibrosis in liver transplant recipients with hepatitis C before and after sustained virologic response

BACKGROUND

Liver transplant (LT) recipients with untreated hepatitis C (HCV) are at risk for cirrhosis graft failure. The advent of direct acting antiviral agents (DAA) has improved outcomes in HCV.

AIMS

We aim to examine liver transplant outcomes and allograft fibrosis development/progression after sustained virologic response (SVR).

METHODS

We performed a retrospective cohort study of 226 consecutive liver transplant recipients with HCV from 2007 to 2018. The cohort was split into transplants pre (Group A) and post (Group B) 2014 to reflect the introduction of DAAs. Fibrosis was monitored with liver biopsy and non-invasive imaging.

RESULTS

Group B had significantly improved HCV treatment rates and earlier SVR compared to Group A, with a cumulative incidence rate of SVR at 2 years of 86.7% versus 15.4% (HR = .11, p < .001). Prior to achieving SVR, Group A demonstrated worsening of fibrosis stage per year (+.21, p < .001) whereas Group B showed minimal change on protocol annual biopsy (-.02, p = .80). After SVR, most patients were followed non-invasively and demonstrated stable or improved fibrosis stage over time. Patients undergoing transient elastography showed regression in fibrosis stage per year (-.19, p < .001).

CONCLUSION

HCV patients undergoing LT after 2014 had higher rates of SVR and improved clinically relevant transplant outcomes, namely less graft loss and death relating to HCV. Fibrosis progression halted or improved after SVR in both cohorts, suggesting that LT recipients with SVR do not require fibrosis monitoring even with established fibrosis prior to SVR.

Impact of direct antiviral agents for hepatitis C virus -induced liver diseases on registration, waiting list and liver transplant activity in France

Direct-acting antivirals (DAA) has dramatically improved the prognosis of liver transplantation (LT) candidates for HCV end-stage liver disease (ESLD). We aimed to evaluate the impact of DAA on waiting list (WL) registration and LT activity in France. We evaluated all patients registered to the French WL for HCV ESLD between 2000 and 2018. Timespan was divided into two periods according to DAA availability: 2010-2013 versus 2014-2018. Changes in the indications of LT, outcome on WL were evaluated. Then, we evaluated the activity of LT and outcome for HCV recipients in France. Among 3,173 HCV candidates, registration on WL decreased by 33% between 2013 and 2018. The 1-year waitlist survival increased from 76.9% (95%CI: 74.2%-79.4%) in 2010-2013 to 79.8% (95%CI: 77.2%-82.1%) in 2014-2018 (p < 0.01). Regarding LT activity, the part of HCV ESLD decreased from 26% in 2010 to 16% in 2018. The 1-year graft survival rate in HCV recipients increased from 76.9% (95%CI: 73.7%-79.7%) in 2010-2012 to 84.9% (95%CI: 82.9%-86.7%) in 2013-2018 (p < 0.01). The availability of DAA to treat HCV infection is associated with a significant decrease of registration for LT, death and drop out for worsening condition on the LT. In addition, it has decreased the number of HCV+ LT and improved the 1-year graft survival in France.

The Lived Experience of Patients Utilizing Second-Generation Direct-Acting Antiviral for Treatment of Chronic Hepatitis C Virus Infection: A Phenomenological Analysis

Hepatitis C is a global public health problem, and the aim of this study was to understand the experiences of patients with hepatitis C using second-generation antivirals. In-depth interviews were conducted with ten outpatients, cognitively capable of reporting their experience, followed up at a university clinic. Field diaries kept during the interviews were also used. The researchers carried out a thematic analysis to identify the ways in which individuals experienced their medication; then, these ways were reorganized to encompass the essential structures of the experience. The patients experienced the use of DAAs as providing resolution and it was permeated by: the experience of time-stagnant time, waiting for medication and the cure; the experience of spaces, understood as necessary and imposed spaces; the experience of relationships with others, personified by the support provided by healthcare professionals; the experience of sexuality, when patients developed several coping strategies to deal with the challenges imposed by the treatment. To conclude, increasing the knowledge about the patients' experiences can contribute to improve the healthcare model for hepatitis C, since several patients have severe hepatic impairment, and the eradication of the virus is only one of the stages of patients' treatments.

Gender specific survival rates after deceased donor liver transplantation: A retrospective cohort

Background

According to the literature, there are sex allocation inequalities in liver transplantation (LT). Sex disparities in outcomes after LT have been debated. This study aimed to evaluate sex-specific outcomes after LT, specifically short-term mortality and long-term survival rates.

Methods

A retrospective cohort of the entire LT series from to 2010–2019 in a single center in which the inclusion criteria were adults ≥18 YO age who underwent primary deceased donor LT. Mortality rate was evaluated within 30 days and 6 months. Survival rate was evaluated at 1,3 and 5 years of age.

Results

A total of 240 primary and deceased donor LTs (153 men and 87 women) were included. Mean age 55.2Y men and 51.6Y women (p = 0.02). Hepatocellular carcinoma (HCC) was the direct indication in 32.7% of the men and only 17.4% of the women. The leading primary liver morbidities were viral hepatitis (B, C, and D) in 38.3% (N = 92) and nonalcoholic steatohepatitis (NASH) in 20.8% (N = 50) of patients. Thirty-day mortality was 14%, which was significantly higher in men (18%) than in women (8%). Survival rates after 5 years were 64.9% and 78.3%, respectively. Multivariate analysis through logistic regression that included age, direct indication, MELD, and primary liver morbidity revealed statistically significant female to male Odds-Ratio of 0.4 in 30 days, 6 m mortality and a statistically significant higher long-term survival.

Conclusions

Our observations revealed better female outcomes, namely, lower short-term mortality and higher long-term survival. Given the consistency after stratification and given the multivariate analysis, this is unlikely to be attributable to confounders. Such findings suggesting consistently better female outcomes have not been previously reported; hence, multi center study is encouraged.

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Gender outcome disparities after liver transplantation (LT) is debated.

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We present retrospective cohort of 240 consecutive LT in a single center.

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We found significant lower short-term mortality rates and better long-term survival in women.

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The outcome disparity was consistent in most underlying liver diseases.

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We had not identified factors that may confound sex outcome disparity.

The impact of advanced patient age in liver transplantation: a European Liver Transplant Registry propensity-score matching study

BACKGROUND

The futility of liver transplantation in elderly recipients remains under debate in the HCV eradication era.

METHODS

The aim was to assess the effect of older age on outcome after liver transplantation. We used the ELTR to study the relationship between recipient age and post-transplant outcome. Young and elderly recipients were compared using a PSM method.

RESULTS

A total of 10,172 cases were analysed. Recipient age >65 years was identified as an independent risk factor associated with reduced patient survival (HR:1.42 95%CI:1.23-1.65,p < 0.001). After PSM, 2124 patients were matched, and the same association was found between elderly recipients and patient survival and graft survival (p < 0.001). As hepatocellular carcinoma and alcoholic cirrhosis were independent prognostic factors for patient and graft survival a propensity score-matching was performed for each. Patient and graft survival were significantly worse (p < 0.05) in the alcoholic cirrhosis elderly group. However, patient and graft survival in the hepatocellular carcinoma cohort were similar (p > 0.05) between groups.

CONCLUSION

Liver transplantation is an acceptable and safe curative option for elderly transplant candidates, with worse long-term outcomes compare to young candidates. The underlying liver disease for liver transplantation has a significant impact on the selection of elderly patients.

Nonalcoholic Steatohepatitis: A Rapidly Increasing Indication for Liver Transplantation in India

BACKGROUND AND AIMS

Recently, there has been a considerable increase in patients with nonalcoholic fatty liver disease. Availability of high-efficacy drugs for hepatitis B and hepatitis C virus (HCV) infection may have changed the disease prevalence. We aimed to study the impact of this changing epidemiology in patients undergoing liver transplantation (LT) over a 10-year period.

METHODS

The study population was stratified into Period 1 (2009-2014) and Period 2 (2015-2019). Demographics, indications for LT and changes in the epidemiology between two periods were analysed. Aetiology-based posttransplant survival analysis was carried out.

RESULTS

Indication for LT among 1017 adult patients (277 in Period 1 and 740 in Period 2) showed a significant increase in nonalcoholic steatohepatitis (NASH; 85 [30.7%] and 311 [42%]; P = 0.001), decrease in hepatitis C (49 [17.7%] and 75 [10.1%]; P = 0.002), and increase in hepatocellular carcinoma from Period 1 to Period 2 (13 [26.5%] to 38 [50.7%]; P = 0.009) among HCV patients. Patients transplanted for NASH had a lower 5-year survival compared with viral hepatitis (75.9% vs 87.4%; P = 0.03). There was a strong association between coronary artery disease and NASH (hazard ratio = 1.963, 95% confidence interval, 1.19-3.22).

CONCLUSION

NASH is the leading indication for liver transplantation in India, surpassing viral hepatitis in recent years.

Pregnancy after liver transplant: maternal and perinatal outcomes

BACKGROUND

Liver transplantation is a life-saving and successful therapeutic procedure which is more and more frequent worldwide, also among women of reproductive age. Consequently, there is an increasing number of reports of pregnancy following liver transplantation, but doubts still exist regarding preconception counseling and the optimal method of managing pregnancy. The aim of this study was to report and evaluate pregnancy outcomes in women who had undergone liver transplantation.

METHODS

We retrospectively analyzed female patients after orthotopic liver transplantation who reported pregnancy and were under medical care of a single transplant center.

RESULTS

We identified 14 pregnancies in 10 women who had undergone liver transplantation (12 childbirths, one induced abortion due to fetal death in the first trimester, one pregnancy is still ongoing). Causes of transplantation include congenital or acquired disorders and the most common indication was autoimmune hepatitis (50%). The mean age at the point of transplantation was 28.5 (range 21-36), mean maternal age at pregnancy was 32 (range 26-43), and transplant-to-pregnancy interval was 4.07 years (range 1.5-7). The mean gestational week was 36.67 (range 31-40). Immunosuppression was maintained with combinations of prednisone (n = 11), tacrolimus (n = 13), and azathioprine (n = 8) prior to and during pregnancy. Two pregnancies were unintended, so women took mycophenolate mofetil in the first weeks of gestation. Another two women stopped taking azathioprine due to increasing anemia. Maternal complications included increase of aspartate transaminase and alanine transaminase (n = 2), anemia (n = 4) and hyperthyroidism (n = 2). Among the 12 childbirths, five (41.67%) were preterm. Only five women entered labor spontaneously, while seven (58,33%) had cesarean delivery.

CONCLUSIONS

Pregnancy after liver transplantation can achieve relatively favorable outcomes. Liver transplantation does not influence women's fertility and, during pregnancy, we report low rates of minor graft complications. A multidisciplinary team should be involved in contraceptive, fertility and consequently pregnancy counseling of female transplant recipients.

Quantitative assessment of liver fibrosis by digital image analysis reveals correlation with qualitative clinical fibrosis staging in liver transplant patients

Technologies for digitizing tissues provide important quantitative data for liver histopathology investigation. We aimed to assess liver fibrosis degree with quantitative morphometric measurements of histopathological sections utilizing digital image analysis (DIA) and to further investigate if a correlation with histopathologic scoring (Scheuer staging) exists. A retrospective study of patients with at least two post-liver transplant biopsies having a Scheuer stage of ≤ 2 at baseline were gathered. Portal tract fibrotic percentage (%) and size (μm²) were measured by DIA, while clinical fibrosis score was measured by the Scheuer system. Correlations between DIA measurements and Scheuer scores were computed by Spearman correlation analysis. Differences between mean levels of fibrosis (score, size, and percentage) at baseline versus second visit were computed by Student’s t-test. P values < 0.05 were considered significant. Of 22 patients who met the study criteria, 54 biopsies were included for analysis. Average levels ±standard error [S.E.] of portal tract fibrotic percentage (%) and size (μm²) progressed from 46.5 ± 3.6% at baseline to 61.8 ± 3.8% at the second visit (P = 0.005 by Student’s t-test), and from 28,075 ± 3,232 μm² at base line to 67,146 ± 10,639 μm² at the second visit (P = 0.002 by Student’s t-test), respectively. Average levels of Scheuer fibrosis scores progressed from 0.55±0.19 at baseline to 1.14±0.26 at the second visit (P = 0.02 by Student’s t-test). Portal tract fibrotic percentage (%) and portal tract fibrotic size were directly correlated with clinical Scheuer fibrosis stage, with Spearman correlation coefficient and P value computed as r = 0.70, P < 0.0001 and r = 0.41, P = 0.002, respectively. Digital quantitative assessment of portal triad size and fibrosis percentage demonstrates a strong correlation with visually assessed histologic stage of liver fibrosis and complements the standard assessment for allograft monitoring, suggesting the utility of future WSI analysis.

A Comprehensive Analysis of Liver Transplantation Outcomes Among Ethnic Minorities in the United States

GOALS

The aim of this study was to perform a comprehensive assessment of liver transplant (LT) outcomes among US adults with a specific focus on understanding race/ethnicity-specific disparities.

BACKGROUND

Despite improvements in the liver allocation and LT-related care, disparities in LT outcomes persist.

STUDY

Using data from the 2005 to 2016 United Networks for Organ Sharing LT registry, we evaluated waitlist survival, probability of receiving LT, and post-LT survival among US adults stratified by race/ethnicity and liver disease etiology. Kaplan-Meier methods evaluated unadjusted waitlist and post-LT outcomes, and multivariate regression models evaluated adjusted waitlist and post-LT outcomes.

RESULTS

Among 88,542 listed for LT patients (41.3% hepatitis C virus, 25.3% alcoholic liver disease, 22.3% nonalcoholic steatohepatitis, 11.1% hepatitis C virus/alcoholic liver disease), significant race/ethnicity-specific disparities were observed. Compared with non-Hispanic whites, Hispanics had a significantly lower risk of waitlist death [hazard ratio (HR)=0.84, 95% confidence interval (CI): 0.79-0.90, P<0.001]. Compared with non-Hispanic whites, significantly lower likelihood of receiving LT was observed in African Americans (HR=0.94, 95% CI: 0.91-0.98, P<0.001), Hispanics (HR=0.70, 95% CI: 0.68-0.73, P<0.001) and Asians (HR=0.74, 95% CI: 0.69-0.80, P<0.001). Compared with non-Hispanic whites, African Americans had a significantly higher risk of 5-year post-LT death (HR=1.31, 95% CI: 1.23-1.39, P<0.001).

CONCLUSION

Among US adults awaiting LT, significant race/ethnicity-specific disparities in LT outcomes were observed. Despite evaluating an era after implementation of the Model for End-Stage Liver Disease, ethnic minorities continue to demonstrate a lower probability of receiving LT, and significantly higher risk of death post-LT in African Americans.

Elimination of Hepatitis C in Portugal: An Urban Legend?

The burden of hepatitis C virus infection remains very high despite huge progress in the cure of the infection. The high prevalence of hepatitis C, especially in vulnerable groups and particularly drug users, may compromise the achievement of the 2030 WHO targets with a 90% reduction in new infections and a 65% reduction in mortality. Therapy with the latest pangenotypic direct-acting antivirals provides cure rates in the order of 97% with short-term oral treatment (8-12 weeks) and with an excellent safety and tolerability profile. Curing the infection causes significant health gains derived from preventing complications from cirrhosis, especially hepatocellular carcinoma, and from liver transplantation. Elimination of hepatitis seems feasible with the implementation of a massive therapy program, focusing particularly on vulnerable populations, through micro-elimination strategies, and in the general population with age-based screening. The reduction of the virus reservoir (humans are the only reservoir) is a determining factor in eradicating the virus.

Frequency of whole-organ in lieu of split-liver transplantation over the last decade: Children experienced increased wait time and death

Organ shortage is a barrier to liver transplantation (LT). Split LT (SLT) increases organ utilization, saving 2 recipients. A simulation of Organ Procurement and Transplantation Network/United Network for Organ Sharing data (2007-2017) was performed to identify whole-organ LT grafts (WLT) that met the criteria for being splittable to 2 recipients. Waitlist consequences presented. Deceased donor (DD) livers transplanted as whole organs were evaluated for suitability to split. Of these DD organs, we identified the adolescent and adult recipients of WLT who were suitable for SLT. Pediatric candidates suitable to share the SLT were ascertained from DD match-run lists, and 1342 splittable DD organs were identified; 438 WLT recipients met the criteria for accepting a SLT. Review of the 438 DD match-run lists identified 420 children next on the list suitable for SLT. Three hundred thirty-three children (79%) underwent LT, but had longer wait-times compared to 591 actual pediatric SLT recipients (median 147 days vs 44 days, P  < 0.001). Thirty-three of 420 children died on waitlist after a mean 206 days (standard deviation 317). Sharing organs suitable for splitting increases the number of LT, saving more lives. With careful patient selection, SLT will not be a disadvantage to the adult recipients. With a children-first allocation scheme, SLT will naturally increase the number of allografts because adult organs are too large for small children.

Liver steatosis is a major predictor of poor outcomes in chronic hepatitis C patients with sustained virological response

Sustained virological response (SVR) results in reduced incidence of hepatocellular carcinoma (HCC) and mortality among chronic hepatitis C (CHC) patients with advanced fibrosis. Since both advanced fibrosis and liver steatosis (LS) may coexist in CHC patients, we evaluated their individual effects on a composite outcome of all-cause mortality and HCC in CHC patients with SVR following direct-acting antivirals (DAA) treatment. We retrospectively evaluated inception cohort of 515 CHC patients who achieved SVR following treatment with DAA, with a mean follow-up of 24 months. Baseline liver fibrosis was assessed by transient elastography, and LS was validated by at least three independent ultrasonographic examinations. 211 of 515 patients (41%) had baseline LS. Patients with LS had a higher cumulative rate of all-cause mortality and HCC at 2 years of follow-up compared to patients without LS (15.75% and 2.79%, respectively, P < 0.001), although they did not have increased incidence of advanced fibrosis or cirrhosis. Consistently, multivariate analysis showed that LS was associated with a significant 7.5-fold increased risk of all-cause mortality and HCC (HR 7.51, 95% C.I 3.61-13.36, P < 0.001) even upon adjustment to components of the metabolic syndrome, whereas advanced fibrosis showed only a trend towards statistical significance (HR 2.32, 95% C.I 0.97-6.59, P = 0.06). In conclusion, LS is a major predictor of all-cause mortality and HCC in patients who achieved SVR following DAA treatment regardless of fibrosis stage. These patients should be rigorously screened for HCC.

Pregnancy after liver transplantation: a case series and review of the literature

OBJECTIVE

To evaluate maternal and perinatal outcomes in pregnant women after liver transplantation with a case series and literature systematic review.

METHODS

This was a single-center case-series study performed at University of Naples Federico II. All consecutive women with liver transplantation who reported pregnancy at our institution were included in a dedicated database. In addition, a systematic literature review was performed, including case series, population-based studies, and national registries, including maternal and perinatal outcomes of pregnant women with liver transplant. Studies with fewer than 10 cases and surveys were excluded. The primary outcome was perinatal death, defined as either stillbirth (defined as intrauterine fetal death after 20 weeks of gestation) or neonatal death (death of a live-born infant within the first 28 d of life).

RESULTS

During the study period, two women who underwent liver transplantation had a pregnancy in our Institution. Both of them underwent liver transplantation for biliary atresia at 1 year of age. One of them received cyclosporin as immunosuppressive regime during pregnancy, while the other one received tacrolimus. Both of them had a pregnancy with no major complications and delivered by cesarean section at term a baby with normal weight. One of them developed thrombocytopenia. Seventeen articles were included in this systematic review. Preterm birth at less than 37 weeks of gestations occurred in 279 women (33.6%). One-hundred women (14.9%) experienced preeclampsia, and 206 women (49.2%) delivered by cesarean delivery. Graft rejection related to pregnancy occurred in 73 women (8.3%). 117 women (12.9%) experienced miscarriage, and 22 (2.3%) IUFD. Fifty-two women (9.52%) underwent elective I-TOP. 195 fetuses (33.4%) were LBW. Eight neonatal deaths were recorded (1.3%).

CONCLUSION

The maternal and perinatal outcome is usually favorable, but with an increased risk of preeclampsia, preterm birth, and perinatal morbidity and mortality. However, appropriate counseling about risks and complications is essential but women shouldn't be advised against pregnancy.

Evaluating Prognostic Factors for Liver Transplantation Among United States Patients With Hereditary Transthyretin-Mediated (hATTR) Amyloidosis Using National Registry Data

INTRODUCTION

Orthotopic liver transplantation has been used as a treatment for hereditary transthyretin-mediated (hATTR) amyloidosis, a rare, progressive, and multisystem disease.

RESEARCH QUESTION

The objective is to evaluate survival outcomes post-liver transplantation in patients with hATTR amyloidosis in the United States and assess whether previously published prognostic factors of patient survival in hATTR amyloidosis are generalizable to the US population.

DESIGN

This cohort study examined patients with hATTR amyloidosis undergoing liver transplant in the United States (N = 168) between March 2002 and March 2016 using data reported to the Organ Procurement and Transplantation Network (UNOS)/United Network for Organ Sharing (OPTN).

RESULTS

A multivariable Cox hazards regression model showed among all factors tested, only modified body mass index (kg/m² × g/L) at the time of transplant was significantly associated with survival. Higher modified BMI was associated with lower risk of death relative to a reference population (<600) with historically poor post-transplant outcomes. Patients with modified BMI 1000 to <1200 (hazard ratio [HR] = 0.27; 95% confidence interval [CI] = 0.10-0.73), 1200 to <1400 (HR = 0.20; 95% CI = 0.06-0.75), and ≥1400 (HR = 0.15; 95% CI = 0.04-0.61) exhibited improved adjusted 5-year post-transplant survival of 74%, 80%, and 85%, respectively, versus 33% in the reference population.

DISCUSSION

The association between a higher modified BMI threshold at the time of transplant and improved post-transplant survival suggests that the previously published patient selection criterion for modified BMI may not be applicable to the US population.

Decreasing frequency and improved outcomes of hepatitis C-related liver transplantation in the era of direct-acting antivirals - a retrospective cohort study

Benefit of direct-acting antivirals (DAA) for hepatitis C virus (HCV) on clinical outcomes is unclear. We examined temporal trends in liver transplant (LT) listings, receipt of LT, re-LT, and survival between pre-DAA (2009-2012) and DAA era (2013-2016) using UNOS database. Of 32 319 first adult LT, 15 049 (47%) were performed for HCV. Trends on listing, first LT, and of re-LT for HCV showed 23%, 20%, and 21% decrease in DAA compared to pre-DAA era (P < 0.0001). One-year liver graft and patient survival among HCV LT improved in DAA era (90% vs. 86% and 92% vs. 88%, respectively, P < 0.0001). Non-HCV LT showed no improvement in survival (89% vs. 89% and 92% vs. 92.4%, P = NS). On cox regression, compared to non-HCV LTs in DAA era, LT for HCV in pre-DAA era had worse patient survival (HR 1.56 [1.04-2.35]). The outcome was similar when compared to LTs for HCV in DAA era and for non-HCV in pre-DAA era. Burden of HCV-related LT waitlist and LT is declining in DAA era, with improved post-transplant outcomes, more so in later than earlier DAA era. Our findings negate recent Cochrane meta-analysis on DAA therapy and encourage studies to examine HCV clinical outcomes outside LT setting.

Hepatitis C Virus Envelope Glycoproteins: A Balancing Act of Order and Disorder

Chronic hepatitis C virus infection often leads to liver cirrhosis and primary liver cancer. In 2015, an estimated 71 million people were living with chronic HCV. Although infection rates have decreased in many parts of the world over the last several decades, incidence of HCV infection doubled between 2010 and 2014 in the United States mainly due to increases in intravenous drug use. The approval of direct acting antiviral treatments is a necessary component in the elimination of HCV, but inherent barriers to treatment (e.g., cost, lack of access to healthcare, adherence to treatment, resistance, etc.) prevent dramatic improvements in infection rates. An effective HCV vaccine would significantly slow the spread of the disease. Difficulties in the development of an HCV culture model system and expression of properly folded- and natively modified-HCV envelope glycoproteins E1 and E2 have hindered vaccine development efforts. The recent structural and biophysical studies of these proteins have demonstrated that the binding sites for the cellular receptor CD-81 and neutralizing antibodies are highly flexible in nature, which complicate vaccine design. Furthermore, the interactions between E1 and E2 throughout HCV infection is poorly understood, and structural flexibility may play a role in shielding antigenic epitopes during infection. Here we discuss the structural complexities of HCV E1 and E2.