Hepatic immunopathology during occult hepacivirus re-infection

Equine Hepacivirus: A Systematic Review and a Meta-Analysis of Serological and Biomolecular Prevalence and a Phylogenetic Update

Simple Summary

This is a comprehensive review containing the most up-to-date information on Equine Hepacivirus, one of the recently discovered hepatic equine viruses, together with an analysis of serological and biomolecular presence presented in apreviously published papers, and an update on its genetic relationship within the species and with similar species. Extensive description of the EqHV features is included, and results are presented with several tables and figures, providing a valuable reference guide for further studies.

Abstract

Viral hepatitis has recently assumed relevance for equine veterinary medicine since a variety of new viruses have been discovered. Equine Hepacivirus (EqHV) is an RNA virus belonging to the Flaviviridae family that can cause subclinical hepatitis in horses, occasionally evolving into a chronic disease. EqHV, to date, is considered the closest known relative of human HCV. EqHV has been reported worldwide therefore assessing its features is relevant, considering both the wide use of blood products and transfusions in veterinary therapies and its similitude to HCV. The present review resumes the actual knowledge on EqHV epidemiology, risk factors and immunology, together with potential diagnostics and good practices for prevention. Moreover, adhering to PRISMA guidelines for systematic reviews a meta-analysis of serological and biomolecular prevalence and an updated phylogenetic description is presented as a benchmark for further studies.

Occult Infection with Hepatitis C Virus: Looking for Clear-Cut Boundaries and Methodological Consensus

The sustained virologic response and elimination of HCV is widely viewed as a true cure of chronic hepatitis C as it associates with amelioration of histological liver damage and improved clinical outcomes. Therefore, the existence and clinical burden of occult HCV infection (OCI) has been a controversial issue for many years. In this review, we summarize recently published data that adds new information on the molecular and clinical background of OCI and its epidemiological significance. We also identify and discuss the most important methodological pitfalls, which can be a source of inconsistency between studies. Data that have accumulated so far, strongly support the existence of extrahepatic HCV replication in individuals negative for serum HCV-RNA by conventional clinical tests. OCI emerges as a condition where the immune system is unable to fully resolve infection but it is continuously stimulated by low levels of HCV antigens, leading to progression of liver pathology and extrahepatic HCV-related complications. Moreover, the development of monitoring strategies or management guidelines for OCI is still hampered by the lack of clear definition and the confusion regarding its clinical significance. Careful study design and the introduction of uniform protocols for the detection of low-level HCV-RNA are crucial for obtaining reliable data on OCI.

Development of hepatic pathology in GBV-B-infected red-bellied tamarins (Saguinus labiatus)

GB virus B (GBV-B) is a new world monkey-associated flavivirus used to model acute hepatitis C virus (HCV) infection. Critical for evaluation of antiviral or vaccine approaches is an understanding of the effect of HCV on the liver at different stages of infection. In the absence of longitudinal human tissue samples at defined time points, we have characterized changes in tamarins. As early as 2 weeks post-infection histological changes were noticeable, and these were established in all animals by 6 weeks. Despite high levels of liver-associated viral RNA, there was reversal of hepatic damage on clearance of peripheral virus though fibrosis was demonstrated in four tamarins. Notably, viral RNA burden in the liver dropped to near undetectable or background levels in all animals which underwent a second viral challenge, highlighting the efficacy of the immune response in removing foci of replication in the liver. These data add to the knowledge of GBV-B infection in New World primates which can offer attractive systems for the testing of prophylactic and therapeutic treatments and the evaluation of their utility in preventing or reversing liver pathology.

Detection of residual HCV-RNA in patients who have achieved sustained virological response is associated with persistent histological abnormality

BACKGROUND

Whether achieving sustained virological response (SVR) in patients with hepatitis C attains complete elimination of hepatitis C virus (HCV) is unknown, because occult HCV infection (OCI), defined as the detection of HCV-RNA in hepatocytes or peripheral blood mononuclear cells (PBMC) in absence of serum HCV-RNA, may occur. We thus investigated the prevalence and clinical relevance of OCI.

METHODS

Subjects from three hospitals who had achieved serum HCV clearance, including 60 of Direct-acting antiviral agents (DAAs) induced SVR, 50 of pegylated interferon plus ribavirin (PR) induced SVR, and 30 of spontaneous resolution, were subjected to detect HCV-RNA in liver by robust RNAscope assay and PBMC by qPCR. Paired liver biopsies at baseline and at SVR24 were analyzed.

RESULTS

OCI was detected in 16 of 140 subjects (11.4%), with 15.0% in DAA-based group, 10.0% in PR group and 6.7% in spontaneously resolved group. In DAA-based subgroups, the incidence of OCI was gradually increased in group of solely DAA(s) therapy, combining DAA and PR therapy and combining DAA and ribavirin therapy. OCI is more frequent in patients with genotype 3. No correlation between baseline viral load, interleukin-28B genotype, baseline transaminases, post-SVR transaminases and OCI were found. However, OCI was significantly linked with severity of fibrosis and active inflammation at post-SVR, even considering basal fibrosis status. In addition, both the magnitude and the frequency of fibrosis regression were lower in patients with OCI than in those without OCI. In the multivariate analysis, PR therapy was identified an independent negative prognostic factor for both hepatic inflammation (P = .022) and fibrosis regression (P = .015). Importantly, we found HCV relapse in one of the OCI patients at 48 weeks after the end of PR treatment.

CONCLUSIONS

HCV-RNA can persist in hepatocytes and/or PBMC in a certain of patients who achieved spontaneous or treatment-induced HCV RNA clearance from serum and associated with persistent histological abnormality. Our findings provide new insights into cure of HCV and could influence the following-up scenario after SVR.

Comparative Analysis of Electrochemiluminescence Assay and Chemiluminescent Microparticle Immunoassay for the Screening of Hepatitis C

The primary objective of the study was to identify a highly sensitive and specific screening technique for the detection of Hepatitis C infection in healthy blood donors in a low prevalence area for HCV. In this study, two of the most commonly used methods for Anti-HCV screening, i.e., Electrochemiluminescence Immunoassay (ECLIA) and Chemiluminescent Microparticle Immunoassay (CMIA) were performed among 517 selected healthy blood donors. The clinical performance of ECLIA and CMIA was compared on the basis of their operational variables, i.e., Sensitivity, Specificity, Accuracy, Youden's J index, Positive and Negative predictive values and False discovery, False positive and False negative rate, etc., Both ECLIA and CMIA are highly sensitive (100%) and specific (98%) in terms of anti HCV detection among the blood donors. According to the clinical performance of ECLIA and CMIA, both are efficient in detecting anti-HCV antibodies among the asymptomatic population of healthy blood donors. But as both of them are associated with false positive results, it is recommended to have Polymerase chain reaction on the reactive samples to detect the HCV RNA.

Cytokine-Mediated Tissue Injury in Non-human Primate Models of Viral Infections

Viral infections trigger robust secretion of interferons and other antiviral cytokines by infected and bystander cells, which in turn can tune the immune response and may lead to viral clearance or immune suppression. However, aberrant or unrestricted cytokine responses can damage host tissues, leading to organ dysfunction, and even death. To understand the cytokine milieu and immune responses in infected host tissues, non-human primate (NHP) models have emerged as important tools. NHP have been used for decades to study human infections and have played significant roles in the development of vaccines, drug therapies and other immune treatment modalities, aided by an ability to control disease parameters, and unrestricted tissue access. In addition to the genetic and physiological similarities with humans, NHP have conserved immunologic properties with over 90% amino acid similarity for most cytokines. For example, human-like symptomology and acute respiratory syndrome is found in cynomolgus macaques infected with highly pathogenic avian influenza virus, antibody enhanced dengue disease is common in neotropical primates, and in NHP models of viral hepatitis cytokine-induced inflammation induces severe liver damage, fibrosis, and hepatocellular carcinoma recapitulates human disease. To regulate inflammation, anti-cytokine therapy studies in NHP are underway and will provide important insights for future human interventions. This review will provide a comprehensive outline of the cytokine-mediated exacerbation of disease and tissue damage in NHP models of viral infections and therapeutic strategies that can aid in prevention/treatment of the disease syndromes.