Hepatitis C virus clearance correlates with HLA-DR expression on proliferating CD8+ T cells in immune-primed chimpanzees

Biomarkers in Detection of Hepatitis C Virus Infection

The hepatitis C virus (HCV) infection affects 58 million people worldwide. In the United States, the incidence rate of acute hepatitis C has doubled since 2014; during 2021, this increased to 5% from 2020. Acute hepatitis C is defined by any symptom of acute viral hepatitis plus either jaundice or elevated serum alanine aminotransferase (ALT) activity with the detection of HCV RNA, the anti-HCV antibody, or hepatitis C virus antigen(s). However, most patients with acute infection are asymptomatic. In addition, ALT activity and HCV RNA levels can fluctuate, and a delayed detection of the anti-HCV antibody can occur among some immunocompromised persons with HCV infection. The detection of specific biomarkers can be of great value in the early detection of HCV infection at an asymptomatic stage. The high rate of HCV replication (which is approximately 1010 to 1012 virions per day) and the lack of proofreading by the viral RNA polymerase leads to enormous genetic diversity, creating a major challenge for the host immune response. This broad genetic diversity contributes to the likelihood of developing chronic infection, thus leading to the development of cirrhosis and liver cancer. Direct-acting antiviral (DAA) therapies for HCV infection are highly effective with a cure rate of up to 99%. At the same time, many patients with HCV infection are unaware of their infection status because of the mostly asymptomatic nature of hepatitis C, so they remain undiagnosed until the liver damage has advanced. Molecular mechanisms induced by HCV have been intensely investigated to find biomarkers for diagnosing the acute and chronic phases of the infection. However, there are no clinically verified biomarkers for patients with hepatitis C. In this review, we discuss the biomarkers that can differentiate acute from chronic hepatitis C, and we summarize the current state of the literature on the useful biomarkers that are detectable during acute and chronic HCV infection, liver fibrosis/cirrhosis, and hepatocellular carcinoma (HCC).

A comprehensive and visualized analysis of relationship between ferroptosis and tumor using bibliometrics and bioinformatics

This study aimed to summarize the current developments and hub genes in the ferroptosis field using bibliometrics and bioinformatics and provide guidance for future developments. The publications on ferroptosis from 2012 to 2021 were extracted from the Web of Science database. VOSviewer software and CiteSpace software were used to visualize and predict the trend of ferroptosis research. The key genes related to ferroptosis were selected from the Web of Genecards, and Kyoto Encyclopedia of Genes and Genomes (KEGG)/Gene Ontology (GO) analysis was performed. Cytoscape software and online survival curve analysis platform were also used to screen hub genes and analyze their roles. Chinese researchers published the highest number of publications in this field, while American publications exhibited higher quality. In terms of institutions, Central South University and Zhejiang University have the highest number of publications. Cell Death Disease published more studies than other journals. The application of ferroptosis is a major research area, and, importantly, "RCD", "FTH1", and "nomogram" are the keywords. We also found tumor-related pathways of interest in the field of ferroptosis. Sirtuin 3 (SIRT3), Glutathione Peroxidase 4 (GPX4), and transferrin receptor (TFRC) genes were of significance for the prognosis of tumors. The number of publications on ferroptosis may increase in the future. Cooperation among countries and disciplines is particularly important in this regard. Also, the applications of ferroptosis, especially in chemotherapy and immunotherapy for tumors, will be the focus of future research. Keywords "RCD", "FTH1", and "nomogram" is receiving high attention, and in-depth studies on tumor-related genes SIRT3, GPX4, and TFRC may provide new therapeutic targets.

Prediction of tumor recurrence by distinct immunoprofiles in liver transplant patients based on mass cytometry

Recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) is a marker of poor prognosis. However, the reliable biomarkers of post-LT HCC recurrence remain to be identified. In this study, serial peripheral blood samples from the LT recipients with and without HCC recurrence were collected at five time points. Single-cell mass cytomertry (CyTOF) was utilized for the in-depth analysis of peripheral blood monocellular cells (PBMCs). CyTOF analysis showed that at 3 weeks post-LT, the activated immune cell population was increased, while the fraction of immune cells with suppressive functions (myeloid-derived suppressive cells) was reduced. The post-LT immune composition in patients with LT for HCC was enormously different from that in patients with LT for causes other than HCC. Furthermore, at 3 weeks after LT, compared with patients without recurrence, the patients with HCC recurrences were high in two subsets of T cells: CD57⁺ HLA-DR⁺ CD8⁺ and CD28⁺γδ. The CD57⁺ HLA-DR⁺ CD8⁺ T cells presented high levels of perforin, granzyme B, and Ki-67 and displayed a highly cytotoxic and proliferative phenotype, while the CD28⁺γδ T cells had reduced levels of IFN-γ and, hence, were less activated compared to CD28^- cells. Based on these findings, we concluded that analyzing the PBMCs of LT recipients by CyTOF can predict the post-LT HCC recurrence. The distinct immune features can stratify patients with the risk of HCC recurrence at 3 weeks after LT, which will help clinician in further management plan and improve the prognosis of patients.

HIV-1-Specific CD11c+ CD8+ T Cells Display Low PD-1 Expression and Strong Anti-HIV-1 Activity

Exhaustion of HIV-1-specific CD8⁺ T cells prevents optimal control of HIV-1 infection. Identifying unconventional CD8⁺ T cell subsets to effectively control HIV-1 replication is vital. In this study, the role of CD11c⁺ CD8⁺ T cells during HIV-1 infection was evaluated. The frequencies of CD11c⁺ CD8⁺ T cells significantly increased and were negatively correlated with viral load in HIV-1-infected treatment-naïve patients. HIV-1-specific cells were enriched more in CD11c⁺ CD8⁺ T cells than in CD11c^- CD8⁺ T cells, which could be induced by HIV-1-derived overlapping peptides, marking an HIV-1-specific CD8⁺ T cell population. This subset expressed higher levels of activating markers (CD38 and HLA-DR), cytotoxic markers (granzyme B, perforin, and CD107a), and cytokines (IL-2 and TNF-α), with lower levels of PD-1 compared to the CD11c^- CD8⁺ T cell subset. In vitro analysis verified that CD11c⁺ CD8⁺ T cells displayed a stronger HIV-1-specific killing capacity than the CD11c^- counterparts. These findings indicate that CD11c⁺ CD8⁺ T cells have potent immunotherapeutic efficacy in controlling HIV-1 infection.

Integrated immune dynamics define correlates of COVID-19 severity and antibody responses

SARS-CoV-2 causes a spectrum of COVID-19 disease, the immunological basis of which remains ill defined. We analyzed 85 SARS-CoV-2-infected individuals at acute and/or convalescent time points, up to 102 days after symptom onset, quantifying 184 immunological parameters. Acute COVID-19 presented with high levels of IL-6, IL-18, and IL-10 and broad activation marked by the upregulation of CD38 on innate and adaptive lymphocytes and myeloid cells. Importantly, activated CXCR3⁺cT_FH1 cells in acute COVID-19 significantly correlate with and predict antibody levels and their avidity at convalescence as well as acute neutralization activity. Strikingly, intensive care unit (ICU) patients with severe COVID-19 display higher levels of soluble IL-6, IL-6R, and IL-18, and hyperactivation of innate, adaptive, and myeloid compartments than patients with moderate disease. Our analyses provide a comprehensive map of longitudinal immunological responses in COVID-19 patients and integrate key cellular pathways of complex immune networks underpinning severe COVID-19, providing important insights into potential biomarkers and immunotherapies.

Analyses of 184 immune features define kinetics of immune responses to SARS-CoV-2

Circulating T_FH1 cells in acute COVID-19 correlate with antibodies

sIL-6R levels are elevated in severe COVID-19 but do not correlate with IL-6

Elevated IL-6 and IL-18 correlate with immune cell hyperactivation

Herpes Zoster in rheumatoid arthritis patients receiving tofacitinib, a single center experience from Taiwan

In clinical trials of tofacitinib for rheumatoid arthritis (RA), Japanese and Korean patients had higher incidence of herpes zoster (HZ) than subjects from elsewhere; however, post-market data from Asia are lacking. Hence, we investigated the incidence of HZ and its risk factors in Taiwanese RA patients receiving tofacitinib. At a medical center in Taichung, Taiwan, we enrolled patients with active RA treated with tofacitinib between January 4, 2015 and December 9, 2017, following unsuccessful methotrexate therapy and no tofacitinib exposure RA patients as a control group. Demographic characteristics, interferon-gamma levels, and lymphocyte counts were compared. Among 125 tofacitinib-treated RA patients, 7 developed HZ, an incidence rate of 3.6/100 person-years. Patients with HZ had shorter disease duration than those without, but higher frequency of prior HZ. Baseline interferon-gamma levels and HLA-DR activated T cell counts were positively correlated and significantly lower in patients with HZ than without. Strikingly, 5/7 HZ cases occurred within 4 months of starting tofacitinib therapy. Incidence of HZ in tofacitinib-treated Taiwanese RA patients is lower than rates in Japan or Korea, and commensurate with the global average. HZ may occur soon after commencing tofacitinib therapy. The role of interferon-gamma and activated T cells in tofacitinib-related HZ deserves further investigation.

Use of an Outbred Rat Hepacivirus Challenge Model for Design and Evaluation of Efficacy of Different Immunization Strategies for Hepatitis C Virus

BACKGROUND AND AIMS

The lack of immunocompetent small animal models for hepatitis C virus (HCV) has greatly hindered the development of effective vaccines. Using rodent hepacivirus (RHV), a homolog of HCV that shares many characteristics of HCV infection, we report the development and application of an RHV outbred rat model for HCV vaccine development.

APPROACH AND RESULTS

Simian adenovirus (ChAdOx1) encoding a genetic immune enhancer (truncated shark class II invariant chain) fused to the nonstructural (NS) proteins NS3-NS5B from RHV (ChAd-NS) was used to vaccinate Sprague-Dawley rats, resulting in high levels of cluster of differentiation 8-positive (CD8+ ) T-cell responses. Following RHV challenge (using 10 or 100 times the minimum infectious dose), 42% of vaccinated rats cleared infection within 6-8 weeks, while all mock vaccinated controls became infected with high-level viremia postchallenge. A single, 7-fold higher dose of ChAd-NS increased efficacy to 67%. Boosting with ChAd-NS or with a plasmid encoding the same NS3-NS5B antigens increased efficacy to 100% and 83%, respectively. A ChAdOx1 vector encoding structural antigens (ChAd-S) was also constructed. ChAd-S alone showed no efficacy. Strikingly, when combined with ChAd-NS, ChAD-S produced 83% efficacy. Protection was associated with a strong CD8+ interferon gamma-positive recall response against NS4. Next-generation sequencing of a putative RHV escape mutant in a vaccinated rat identified mutations in both identified immunodominant CD8+ T-cell epitopes.

CONCLUSIONS

A simian adenovirus vector vaccine strategy is effective at inducing complete protective immunity in the rat RHV model. The RHV Sprague-Dawley rat challenge model enables comparative testing of vaccine platforms and antigens and identification of correlates of protection and thereby provides a small animal experimental framework to guide the development of an effective vaccine for HCV in humans.

Challenges and Promise of a Hepatitis C Virus Vaccine

An estimated 1.5-2 million new hepatitis C virus (HCV) infections occur globally each year. Critical to the World Health Organization's (WHO) HCV elimination strategy is an 80% reduction in incidence of HCV infections by 2030. However, even among high-income countries, few are on target to achieve the WHO's incident infection-reduction goal. A preventative vaccine could have a major impact in achieving incidence-reduction targets globally. However, barriers to HCV vaccine development are significant and include at-risk populations that are often marginalized: viral diversity, limited options for testing HCV vaccines, and an incomplete understanding of protective immune responses. In part because of those factors, testing of only one vaccine strategy has been completed in at-risk individuals as of 2019. Despite challenges, immunity against HCV protects against chronic infection in some repeated HCV exposures and an effective HCV vaccine could prevent transmission regardless of risk factors. Ultimately, prophylactic vaccines will likely be necessary to achieve global HCV elimination.

Immunopathogenesis of Liver Injury During Hepatitis C Virus Infection

The present report describes current concepts about the mechanism of liver cell injury caused by host immune response against hepatitis C virus (HCV) infection in human beings. This report is based on the observations from experimental studies and follow-up actions on human liver diseases. The results from different investigations suggest that liver injury depends on the presentation of viral antigen and the level of host immune response raised against HCV-related peptides. Both innate and adaptive immunity are triggered to counter the viral onset. During development of host immunity, the cell-mediated immune response involving CD4⁺ Th1 cells and CD8⁺ cytotoxic T-lymphocyte (CTL) cells were found to play a major role in causing liver damage. The hepatic Innate lymphoid cells (ILCs) subsets are involved in the immune regulation of different liver diseases: viral hepatitis, mechanical liver injury, and fibrosis. Humoral immunity and natural killer (NK) cell action also contributed in liver cell injury by antibody-dependent cellular cytotoxicity (ADCC). In fact, immunopathogenesis of HCV infection is a complex phenomenon where regulation of immune response at several steps decides the possibility of viral elimination or persistence. Regulation of immune response was noted starting from viral-host interaction to immune reaction cascade engaged in cell damage. The activation or suppression of interferon-stimulated genes, NK cell action, CTL inducement by regulatory T cells (Treg), B cell proliferation, and so on was demonstrated during HCV infection. Involvement of HLA in antigen presentation, as well as types of viral genotypes, also influenced host immune response against HCV peptides. The combined effect of all these effector mechanisms ultimately decides the progression of viral onset to acute or chronic infection. In conclusion, immunopathogenesis of liver injury after HCV infection may be ascribed mainly to host immune response. Second, it is cell-mediated immunity that plays a predominant role in liver cell damage.

Approaches, Progress, and Challenges to Hepatitis C Vaccine Development

Risk factors for hepatitis C virus (HCV) infection vary, and there were an estimated 1.75 million new cases worldwide in 2015. The World Health Organization aims for a 90% reduction in new HCV infections by 2030. An HCV vaccine would prevent transmission, regardless of risk factors, and significantly reduce the global burden of HCV-associated disease. Barriers to development include virus diversity, limited models for testing vaccines, and our incomplete understanding of protective immune responses. Although highly effective vaccines could prevent infection altogether, immune responses that increase the rate of HCV clearance and prevent chronic infection may be sufficient to reduce disease burden. Adjuvant envelope or core protein and virus-vectored nonstructural antigen vaccines have been tested in healthy volunteers who are not at risk for HCV infection; viral vectors encoding nonstructural proteins are the only vaccine strategy to be tested in at-risk individuals. Despite development challenges, a prophylactic vaccine is necessary for global control of HCV.

Hepatic immunopathology during occult hepacivirus re-infection

Despite drug advances for Hepatitis C virus (HCV), re-infections remain prevalent in high-risk populations. Unfortunately, the role of preexisting viral immunity and how it modulates re-infection is unclear. GBV-B infection of common marmosets is a useful model to study tissue immune responses in hepacivirus infections, and in this study we re-challenged 4 animals after clearance of primary viremia. Although only low-to-absent viremia was observed following re-challenge, GBV-B viral RNA was detectable in liver, confirming re-infection. Microscopic hepatic lesions indicated severe-to-mild lymphocyte infiltration and fibrosis in 3 out of 4 animals. Further, GBV-B-specific T cells were elevated in animals with moderate-to-severe hepatopathology, and up to 3-fold increases in myeloid dendritic and activated natural killer cells were observed after infection. Our data indicate that occult hepacivirus re-infections occur and that new liver pathology is possible even in the presence of anti-hepacivirus T cells and in the absence of high viremia.

Qualitative differences in cellular immunogenicity elicited by hepatitis C virus T-Cell vaccines employing prime-boost regimens

T-cell based vaccines have been considered as attractive candidates for prevention of hepatitis C virus (HCV) infections. In this study we compared the magnitude and phenotypic characteristics of CD8+ T-cells induced by three commonly used viral vectors, Adenovirus-5 (Ad5), Vaccinia virus (VV) and Modified Vaccinia Ankara (MVA) expressing the HCV NS3/4A protein. C57/BL6 mice were primed with DNA expressing NS3/4A and boosted with each of the viral vectors in individual groups of mice. We then tracked the vaccine-induced CD8+ T-cell responses using pentamer binding and cytokine production analysis. Overall, our data indicate that the memory cells induced by Ad5 were inferior to those induced by VV or MVA. We found that Ad5 boosting resulted in rapid expansion and significantly higher frequencies of NS3-specific T-cells compared to VV and MVA boosting. However, the functional profiles, assessed through analysis of the memory cell marker CD127 and the anti-apoptotic molecule Bcl-2 in the blood, spleen, and liver; and measurements of interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 production indicated significantly lower frequencies of long-lived memory T-cells following Ad5 boosting compared to VV and MVA. This same set of analyses suggested that the memory cells induced following boosting with MVA were superior to those induced by both Ad5 and VV. This superiority of the MVA-induced CD8+ T-cells was confirmed following surrogate challenge of mice with a recombinant mouse herpes virus expressing the HCV NS3 protein. Higher levels of NS3-specific CD8+ T-cells displaying the functional markers CD69, Ki67 and Granzyme B were found in the spleens of mice boosted with MVA compared to VV and Ad5, both alone and in combination. These data suggest that MVA may be a more successful viral vector for induction of effective CD8+ T-cell responses against hepatitis C virus.

Rosuvastatin Is Effective to Decrease CD8 T-Cell Activation Only in HIV-Infected Patients With High Residual T-Cell Activation Under Antiretroviral Therapy

OBJECTIVE

The aim of the trial was to evaluate in patients under antiretroviral therapy (ART) the effect of rosuvastatin on cellular and soluble markers of immune activation/inflammation, as well as to identify patients who better benefit from statin administration.

METHODS

IMEA-043-CESAR was a phase II open-label pilot trial that enrolled patients under suppressive ART and CD4 <500/mm. Patients received rosuvastatin (20 mg/d) for 12 weeks. The primary outcome was the variation at week 12 (W12) in the proportion of CD38HLA-DRCD8 T lymphocytes. Secondary outcomes included evolution of other markers of T-cell activation and of inflammatory biomarkers between baseline, W12, and W24.

RESULTS

Fifty patients were enrolled; end points were available for 43 patients. When considering all patients, the proportion of CD38HLA-DRCD8 T cells did not significantly decline throughout the follow-up. However, the proportion of CD38CD8T cells significantly decreased at W12 [median percentage change of -22.2% (-32.3; +1.4)]. Principal component analysis allowed identification of 3 groups of patients based on their baseline activation/inflammation profiles, 1 group with elevated levels of CD8 T-cell activation, and a small group with high levels of systemic inflammation and low levels of T-cell activation. Half of the patients exhibited relatively low levels of inflammation and activation. The proportion of activated CD8 T cells significantly decreased only in the particular group of patients with high baseline CD8 T-cell activation.

CONCLUSIONS

This study shows that combining rosuvastatin with effective ART can result in a sustained decrease in CD8 T-cell activation and highlights the importance of identifying patients who can benefit from specific immunotherapeutic strategies.

IL-10 plays a central regulatory role in the cytokines induced by hepatitis C virus core protein and polyinosinic acid:polycytodylic acid

Hepatitis C virus (HCV) can cause persistent infection and chronic liver disease, and viral factors are involved in HCV persistence. HCV core protein, a highly conserved viral protein, not only elicits an immunoresponse, but it also regulates it. In addition, HCV core protein interacts with toll-like receptors (TLRs) on monocytes, inducing them to produce cytokines. Polyinosinic acid:polycytodylic acid (polyI:C) is a synthetic analogue of double-stranded RNA that binds to TLR3 and can induce secretion of type I IFN from monocytes. Cytokine response against HCV is likely to affect the natural course of infection as well as HCV persistence. However, possible effects of cytokines induced by HCV core protein and polyI:C remain to be investigated. In this study, we isolated CD14(+) monocytes from healthy donors, cultured them in the presence of HCV core protein and/or polyI:C, and characterized the induced cytokines, phenotypes and mechanisms. We demonstrated that HCV core protein- and polyI:C-stimulated CD14(+) monocytes secreted tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-10, and type I interferon (IFN). Importantly, TNF-α and IL-1β regulated the secretion of IL-10, which then influenced the expression of signal transducer and activator of transcription 1 (STAT1) and interferon regulatory factor 1 (IRF1) and subsequently the production of type I IFN. Interestingly, type I IFN also regulated the production of IL-10, which in turn inhibited the nuclear factor (NF)-κB subunit, reducing TNF-α and IL-1β levels. Therefore, IL-10 appears to play a central role in regulating the production of cytokines induced by HCV core protein and polyI:C.

Immunopathogenesis of Hepatitis C Virus Infection

Despite advances in therapy, hepatitis C virus infection remains a major global health issue with 3 to 4 million incident cases and 170 million prevalent chronic infections. Complex, partially understood, host-virus interactions determine whether an acute infection with hepatitis C resolves, as occurs in approximately 30% of cases, or generates a persistent hepatic infection, as occurs in the remainder. Once chronic infection is established, the velocity of hepatocyte injury and resultant fibrosis is significantly modulated by immunologic as well as environmental factors. Immunomodulation has been the backbone of antiviral therapy despite poor understanding of its mechanism of action.

During Stably Suppressive Antiretroviral Therapy Integrated HIV-1 DNA Load in Peripheral Blood is Associated with the Frequency of CD8 Cells Expressing HLA-DR/DP/DQ

Background

Characterising the correlates of HIV persistence improves understanding of disease pathogenesis and guides the design of curative strategies. This study investigated factors associated with integrated HIV-1 DNA load during consistently suppressive first-line antiretroviral therapy (ART).

Method

Total, integrated, and 2-long terminal repeats (LTR) circular HIV-1 DNA, residual plasma HIV-1 RNA, T-cell activation markers, and soluble CD14 (sCD14) were measured in peripheral blood of 50 patients that had received 1–14 years of efavirenz-based or nevirapine-based therapy.

Results

Integrated HIV-1 DNA load (per 10⁶ peripheral blood mononuclear cells) was median 1.9 log₁₀ copies (interquartile range 1.7–2.2) and showed a mean difference of 0.2 log₁₀ copies per 10 years of suppressive ART (95% confidence interval − 0.2, 0.6; p = 0.28). It was positively correlated with total HIV-1 DNA load and frequency of CD8⁺HLA-DR/DP/DQ⁺ cells, and was also higher in subjects with higher sCD14 levels, but showed no correlation with levels of 2-LTR circular HIV-1 DNA and residual plasma HIV-1 RNA, or the frequency of CD4⁺CD38⁺ and CD8⁺CD38⁺ cells. Adjusting for pre-ART viral load, duration of suppressive ART, CD4 cell counts, residual plasma HIV-1 RNA levels, and sCD14 levels, integrated HIV-1 DNA load was mean 0.5 log₁₀ copies higher for each 50% higher frequency of CD8⁺HLA-DR/DP/DQ⁺ cells (95% confidence interval 0.2, 0.9; p = 0.01).

Conclusions

The observed positive association between integrated HIV-1 DNA load and frequency of CD8⁺DR/DP/DQ⁺ cells indicates that a close correlation between HIV persistence and immune activation continues during consistently suppressive therapy. The inducers of the distinct activation profile warrant further investigation.

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Data from a homogenously treated population with consistent virological suppression

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Integrated HIV-1 DNA load did not vary significantly by duration of therapy

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Integrated HIV-1 DNA load was not associated with markers of recent virus replication

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Integrated HIV-1 DNA load and CD8+HLA-DR/DP/DQ+ frequency were positively associated

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Subjects with top quartile integrated HIV-1 DNA load showed high sCD14 levels

Integrated HIV-1 DNA load remains constant in the peripheral blood of individuals receiving long-term suppressive antiretroviral therapy (ART). However, the mechanisms preventing decay of the reservoir remain unclear. We studied a cross-sectional population, defined by the duration of suppressive ART. Integrated HIV-1 DNA load did not differ significantly according to the duration of suppressive ART, and showed no association with direct or indirect markers of ongoing virus replication. Rather, there was an independent, positive association between integrated HIV-1 DNA load and the frequency of CD8 cells expressing the activation marker HLA-DR/DP/DQ. These cells appear to have important regulatory and effector function. Our findings add to growing evidence that immune activation sustains the HIV-1 reservoir during long-term suppressive ART.

Hepatitis C virus: Is it time to say goodbye yet? Perspectives and challenges for the next decade

The majority of individuals exposed to hepatitis C virus (HCV) establish a persistent infection, which is a leading cause of chronic liver disease, cirrhosis and hepatocellular carcinoma. Major progress has been made during the past twenty-five years in understanding the HCV life cycle and immune responses against HCV infection. Increasing evidence indicates that host genetic factors can significantly influence the outcome of HCV infection and the response to interferon alpha-based antiviral therapy. The arrival of highly effective and convenient treatment regimens for patients chronically infected with HCV has improved prospects for the eradication of HCV worldwide. Clinical trials are evaluating the best anti-viral drug combination, treatment doses and duration. The new treatments are better-tolerated and have shown success rates of more than 95%. However, the recent breakthrough in HCV treatment raises new questions and challenges, including the identification of HCV-infected patients and to link them to appropriate health care, the high pricing of HCV drugs, the emergence of drug resistance or naturally occurring polymorphism in HCV sequences which can compromise HCV treatment response. Finally, we still do not have a vaccine against HCV. In this concise review, we will highlight the progress made in understanding HCV infection and therapy. We will focus on the most significant unsolved problems and the key future challenges in the management of HCV infection.

The host HLA-A*02 allele is associated with the response to pegylated interferon and ribavirin in patients with chronic hepatitis C virus infection

Human leukocyte antigen (HLA) alleles are associated with both the progression of chronic hepatitis C (CHC) and the sustained virological response (SVR) to antiviral therapy. HLA-A*02 is the most common HLA allele in people of European/Caucasian descent and the Chinese and Japanese population. Therefore, we investigated whether HLA-A*02 expression is associated with disease outcome in Chinese CHC patients. Three hundred thirty-one treatment-naïve CHC patients were recruited in this study. The expression of HLA-A*02 was tested by FACS and LABType SSO assays. All patients were treated weekly with pegylated interferon plus ribavirin (PEG-IFN/RBV) according to a standard protocol. Virological response was assessed by TaqMan assay at the 4th, 12th, 24th, and 48th week of therapy, and again at the 24th week post-therapy. By the end of the study, 293 CHC patients, including 144 HLA-A*02-positive patients and 149 HLA-A*02-negative patients, were evaluable for analysis. There were no statistical differences in clinicopathological parameters between HLA-A*02-positive and negative patients before antiviral therapy (P > 0.05). The HLA-A*02-positive patients had a higher rapid virological response (RVR, 74.3 % versus 62.4 %, P = 0.03) and SVR (78.5 % versus 64.4 %, P = 0.01) and a lower relapse rate (4.2 % versus 11.9 %, P = 0.03) than HLA-A*02-negative patients. Multivariable logistic regression analysis showed that HLA-A*02 expression, liver fibrosis stages <S3, HCV genotype 2a, IL-28B rs8099917 TT, and RVR were independent predictive factors of SVR (P < 0.05). Host HLA-A*02 allele expression is associated with SVR, highlighting the importance of considering HLA-A*02 as a predictor of the response to PEG-IFN/RBV treatment in the Chinese population with CHC.

Expression, immunogenicity and diagnostic value of envelope proteins from an Egyptian hepatitis C virus isolate

The present work aimed at 1) characterization of the E1 and E2 proteins (HCV-E) from an Egyptian hepatitis C virus genotype 4a (HCV-4a) isolate at the molecular and immunological level, 2) in silico identification of the B- and T-cell epitopes responsible for the immunogenicity of HCV-E, and 3) evaluation of the diagnostic potential of both the recombinant HCV-E and antibodies raised using mammalian expression constructs encoding the protein. The region encoding the E1 and E2 proteins was amplified by RT-PCR from RNA isolated from blood of a human infected with HCV-4 and cloned into the pSC-TA plasmid, and the sequence was verified and used to construct a neighbor-joining phylogenetic tree. The translated nucleotide sequence was used to predict the HCV-E secondary structure using the PREDICT-PROTEIN server and PSI-PRED. A 3D model of HCV-E was generated using the online tool 3Dpro. B- and T-cell epitopes were predicted using the online tools BCPred and Epijen v1.0, respectively. The HCV-E-encoding sequence was later subcloned into the mammalian expression plasmid pQE, and the constructs that were generated were used to immunize mice in the absence and presence of adjuvants of plant origin. The maximum sequence identity obtained by nucleotide and protein BLAST analysis with previously published HCV-E sequences was 85 and 77 %, respectively. The B-cell epitope CFTPSPVVV at position 203 and the T-cell epitope ALSTGLIHL at position 380 were found to be highly conserved among all HCV genotypes. Both ELISA and Western blotting experiments on crude and purified recombinant HCV envelope proteins using mouse antisera raised using the HCV-E mammalian expression construct confirmed the specific antigenicity of the expressed protein. The antibodies raised in mice using the HCV-E-encoding construct could efficiently capture circulating antigens in patients' sera with good sensitivity that correlated with liver enzyme levels (r = 0.4052, P < 0.0001 for ALT; r = -0.5439, P = 0.0019 for AST). Moreover, combining the HCV-E-encoding construct with extracts prepared from Echinacea purpurea and Nigella sativa prior to immunizing mice significantly (P < 0.05) increased both the humoral (14.9- to 20-fold increase in antibodies) and the cellular (CD4(+) and cytotoxic CD8(+)- T lymphocytes) responses compared to mice that received the DNA construct alone or PBS-treated mice. Both recombinant HCV-E protein preparations and antibodies raised using the HCV-E-encoding mammalian expression construct represent useful diagnostic tools that can report on active HCV infection. Also, the immunostimulatory effects induced by the two plant extracts used at the cellular and humoral level highlight the potential of natural products for inducing protection against HCV infection. The neutralizing capacity of the induced antibodies is a subject of future investigations. Furthermore, the predicted B- and T-cell epitopes may be useful for tailoring future diagnostics and candidate vaccines against various HCV genotypes.

Immune mechanisms of vaccine induced protection against chronic hepatitis C virus infection in chimpanzees

Hepatitis C virus (HCV) infection is characterized by a high propensity for development of life-long viral persistence. An estimated 170 million people suffer from chronic hepatitis caused by HCV. Currently, there is no approved prophylactic HCV vaccine available. With the near disappearance of the most relevant animal model for HCV, the chimpanzee, we review the progression that has been made regarding prophylactic vaccine development against HCV. We describe the results of the individual vaccine evaluation experiments in chimpanzees, in relation to what has been observed in humans. The results of the different studies indicate that partial protection against infection can be achieved, but a clear correlate of protection has thus far not yet been defined.

Will there be a vaccine to prevent HCV infection?

Prevention of hepatitis C virus (HCV) infection by vaccination has been a priority since discovery of the virus and the need has not diminished over the past 25 years. Infection rates are increasing in developed countries because of intravenous drug use. Reducing transmission will be difficult without a vaccine to prevent persistence of primary infections, and also secondary infections that may occur after cure of chronic hepatitis C with increasingly effective direct-acting antiviral (DAA) regimens. Vaccine need is also acute in resource poor countries where most new infections occur and DAAs may be unaffordable. Spontaneous resolution of HCV infection confers durable protection, but mechanisms of immunity remain obscure and contested in the context of vaccine design. A vaccine must elicit a CD4+ helper T cell response that does not fail during acute infection. The need for neutralizing antibodies versus cytotoxic CD8+ T cells is unsettled and reflected in the design of two very different vaccines evaluated in humans for safety and immunogenicity. Here we review the status of vaccine development and the scientific and practical challenges that must be met if the burden of liver disease caused by HCV is to be reduced or eliminated.