Hepatitis C virus vaccine candidates inducing protective neutralizing antibodies

Hepatitis C: Review of the Epidemiology, Clinical Care, and Continued Challenges in the Direct Acting Antiviral Era

PURPOSE OF REVIEW

This review highlights key studies and recently published data, policies, and recommendations related to hepatitis C virus (HCV) epidemiology, transmission, and treatment.

RECENT FINDINGS

HCV is a leading cause of liver-related deaths, cirrhosis, and hepatocellular carcinoma. Since 2011 and accelerating since 2013, new, safe, tolerable, and curative therapies have considerably altered clinical and public health frameworks related to the prevention, control and clinical management of HCV. Nevertheless, there are several populations in the United States that are important to consider because of disparities in HCV prevalence and transmission risk. Adults born during 1945-1965 have an estimated anti-HCV antibody prevalence of ~3%, which is six times higher than among other adults, are often unaware of their infections, and are at increased risk of having HCV-associated morbidity and mortality from decades of chronic infection. Since the early 2000s, increasing incidence of acute HCV infections among young, white, non-urban people who inject drugs have been reported. Despite promising therapeutic advances, significant challenges remain for reducing HCV-associated morbidity and mortality.

SUMMARY

The high burden of HCV and significant health consequences associated with chronic infection make HCV a critical public health priority. Advances in HCV treatment have created new opportunities for reducing HCV-associated morbidity and mortality. These treatments are safe, well-tolerated, and highly effective; however, benefits cannot be realized without a significant increase in the number of persons tested for HCV so that all chronically infected individuals can be aware of their diagnosis and linked to appropriate clinical care.

Hepatitis C-related hepatocellular carcinoma in the era of new generation antivirals

Hepatitis C virus infection is a major cause of hepatocellular carcinoma worldwide. Interferon has been the major antiviral treatment, yielding viral clearance in approximately half of patients. New direct-acting antivirals substantially improved the cure rate to above 90%. However, access to therapies remains limited due to the high costs and under-diagnosis of infection in specific subpopulations, e.g., baby boomers, inmates, and injection drug users, and therefore, hepatocellular carcinoma incidence is predicted to increase in the next decades even in high-resource countries. Moreover, cancer risk persists even after 10 years of viral cure, and thus a clinical strategy for its monitoring is urgently needed. Several risk-predictive host factors, e.g., advanced liver fibrosis, older age, accompanying metabolic diseases such as diabetes, persisting hepatic inflammation, and elevated alpha-fetoprotein, as well as viral factors, e.g., core protein variants and genotype 3, have been reported. Indeed, a molecular signature in the liver has been associated with cancer risk even after viral cure. Direct-acting antivirals may affect cancer development and recurrence, which needs to be determined in further investigation.

Viral evasion and challenges of hepatitis C virus vaccine development

Hepatitis C virus (HCV) is a major global disease burden, often leading to chronic liver diseases, cirrhosis, cancer, and death in those infected. Despite the recent approval of antiviral therapeutics, a preventative vaccine is recognized as the most effective means to control HCV globally, particularly in at-risk and developing country populations. Here we describe the efforts and challenges related to the development of an HCV vaccine, which after decades of research have not been successful. Viral sequence variability poses a major challenge, yet recent research has provided unprecedented views of the atomic structure of HCV epitopes and immune recognition by antibodies and T cell receptors. This, coupled with insights from deep sequencing, robust neutralization assays, and other technological advances, is spurring research toward rationally HCV designed vaccines that preferentially elicit responses toward conserved epitopes of interest that are associated with viral neutralization and clearance.