An effective therapeutic vaccine for the treatment of chronic hepatitis C virus (HCV) infection, as an adjunct to newly developed directly-acting antivirals (DAA), or for the prevention of ...reinfection, would significantly reduce the global burden of disease associated with chronic HCV infection. A recombinant chimpanzee adenoviral (ChAd3) vector and a modified vaccinia Ankara (MVA), encoding the non-structural proteins of HCV (NSmut), used in a heterologous prime/boost regimen induced multi-specific, high-magnitude, durable HCV-specific CD4+ and CD8+ T-cell responses in healthy volunteers, and was more immunogenic than a heterologous Ad regimen. We now assess the immunogenicity of this vaccine regimen in HCV infected patients (including patients with a low viral load suppressed with interferon/ribavirin therapy), determine T-cell cross-reactivity to endogenous virus, and compare immunogenicity with that observed previously in both healthy volunteers and in HCV infected patients vaccinated with the heterologous Ad regimen. Vaccination of HCV infected patients with ChAd3-NSmut/MVA-NSmut was well tolerated. Vaccine-induced HCV-specific T-cell responses were detected in 8/12 patients; however, CD4+ T-cell responses were rarely detected, and the overall magnitude of HCV-specific T-cell responses was markedly reduced when compared to vaccinated healthy volunteers. Furthermore, HCV-specific cells had a distinct partially-functional phenotype (lower expression of activation markers, granzyme B, and TNFα production, weaker in vitro proliferation, and higher Tim3 expression, with comparable Tbet and Eomes expression) compared to healthy volunteers. Robust anti-vector T-cells and antibodies were induced, showing that there is no global defect in immunity. The level of viremia at the time of vaccination did not correlate with the magnitude of the vaccine-induced T-cell response. Full-length, next-generation sequencing of the circulating virus demonstrated that T-cells were only induced by vaccination when there was a sequence mismatch between the autologous virus and the vaccine immunogen. However, these T-cells were not cross-reactive with the endogenous viral variant epitopes. Conversely, when there was complete homology between the immunogen and circulating virus at a given epitope T-cells were not induced. T-cell induction following vaccination had no significant impact on HCV viral load. In vitro T-cell culture experiments identified the presence of T-cells at baseline that could be expanded by vaccination; thus, HCV-specific T-cells may have been expanded from pre-existing low-level memory T-cell populations that had been exposed to HCV antigens during natural infection, explaining the partial T-cell dysfunction. In conclusion, vaccination with ChAd3-NSmut and MVA-NSmut prime/boost, a potent vaccine regimen previously optimized in healthy volunteers was unable to reconstitute HCV-specific T-cell immunity in HCV infected patients. This highlights the major challenge of overcoming T-cell exhaustion in the context of persistent antigen exposure.
For two decades the scientific community has sought to understand why some people clear hepatitis C virus (HCV) and others do not. Recently, several large genome-wide association studies have ...identified single nucleotide polymorphisms (SNPs) linked to interferon lambda 3 (IFNλ3) that are associated with the spontaneous resolution and successful treatment of HCV infection. These observations are generating intense research activity; the hope is that IFNλ3 genetic variants may serve as important predictive biomarkers of treatment outcome and offer new insights into the biological pathways involved in viral control. A pharmacogenomic treatment approach for HCV can now be envisaged, with the incorporation of host genetic variants into a predictive treatment algorithm with other factors. The SNPs associated with the clinical outcome of HCV infection are located some distance from the IFNλ3 gene itself, and causal genetic variants have yet to be clearly defined. Locating these causal variants, mapping in detail the IFNλ3 signalling pathways and determining the downstream genetic signature so induced will clarify the role of IFNλ3 in the pathogenesis of HCV. Clinical studies assessing safety and efficacy in the treatment of HCV with exogenous IFNλ3 are currently underway. Early results suggest that IFNλ3 treatment inhibits HCV replication and is associated with a limited side effect profile. However, hepatotoxicity in both healthy volunteers and HCV-infected patients has been described. This review discusses the genetic studies that link IFNλ3 to both the spontaneous resolution and treatment-induced clearance of HCV and the potential impact of this in clinical practice, the biology of IFNλ3 as currently understood and how this may impact on HCV infection, and describes the early studies that assess the role of this cytokine in the treatment of patients with HCV.
A protective vaccine against hepatitis C virus (HCV) remains an unmet clinical need. HCV infects millions of people worldwide and is a leading cause of liver cirrhosis and hepatocellular cancer. ...Animal challenge experiments, immunogenetics studies, and assessment of host immunity during acute infection highlight the critical role that effective T cell immunity plays in viral control. In this first-in-man study, we have induced antiviral immunity with functional characteristics analogous to those associated with viral control in natural infection, and improved upon a vaccine based on adenoviral vectors alone. We assessed a heterologous prime-boost vaccination strategy based on a replicative defective simian adenoviral vector (ChAd3) and modified vaccinia Ankara (MVA) vector encoding the NS3, NS4, NS5A, and NS5B proteins of HCV genotype 1b. Analysis used single-cell mass cytometry and human leukocyte antigen class I peptide tetramer technology in healthy human volunteers. We show that HCV-specific T cells induced by ChAd3 are optimally boosted with MVA, and generate very high levels of both CD8(+) and CD4(+) HCV-specific T cells targeting multiple HCV antigens. Sustained memory and effector T cell populations are generated, and T cell memory evolved over time with improvement of quality (proliferation and polyfunctionality) after heterologous MVA boost. We have developed an HCV vaccine strategy, with durable, broad, sustained, and balanced T cell responses, characteristic of those associated with viral control, paving the way for the first efficacy studies of a prophylactic HCV vaccine.
Lynch syndrome is a hereditary cancer syndrome caused by mismatch repair gene mutations, and female carriers are at an increased risk of endometrial and ovarian cancer. The best approach to screening ...is not yet clear and practice varies across countries and centers. We aimed to provide evidence to inform the best approach to screening and risk reduction.
A systematic search of the literature was conducted (Medline, Embase, PubMed). Studies evaluating the following were included: women with Lynch syndrome (by mismatch repair mutation or Amsterdam II criteria), screening methods for endometrial and/or ovarian cancer, intervention included endometrial biopsy, transvaginal ultrasound, or serum cancer antigen 125 (CA-125), outcomes evaluated were number of cancers and/or endometrial hyperplasia.
A total of 18 studies of Lynch syndrome carriers which screened for endometrial cancer using transvaginal ultrasound and/or hysteroscopy/endometrial biopsy revealed an incidence of 3.9% at the time of screening. Most (64.1%) endometrial cancers detected were from screening, with the balance detected in symptomatic women at the first screening visits, regular review, or between screening intervals. In mismatch repair carriers, the overall sensitivity of endometrial screening was 66.7%, and the number needed to screen ranged between 4 and 38 (median 7). The sensitivity of endometrial biopsy was 57.1% and the number needed to screen was 23-380 (median 78). The sensitivity of transvaginal ultrasound was 34.4% and the number needed to screen was 35-973 (median 170). Fourteen studies which screened for ovarian cancer using transvaginal ultrasound and/or CA-125 revealed an incidence of 1.3% at the time of screening and 42.9% of ovarian cancers were detected at asymptomatic screening. The sensitivity of ovarian screening was 54.6%, and the number needed to screen was 9-191 (median 23) in mismatch repair carriers. Thirteen studies reported 5.8% incident endometrial cancers and 0.5% ovarian cancers at time of risk reducing surgery.
There is limited evidence to support screening for endometrial and ovarian cancer in Lynch syndrome and data on mortality reduction are not available. Further prospective, randomized trials comparing targeted screening methods are needed. Risk reducing surgery remains the most reliable way to reduce endometrial and ovarian cancer risk in Lynch syndrome.
Viral diversity is a challenge to the development of a hepatitis C virus (HCV) vaccine. Following vaccination of humans with adenoviral vectors, we determined the capacity of T cells to target common ...viral variants at immundominant epitopes ex vivo. We identified two major variants for epitopes NS31073 and NS31446, and multiple variants for epitope NS31406 that occurred in >5% of genotype 1 and 3 sequences at a population level. Cross‐reactivity of vaccine‐induced T cells was determined using variant peptides in IFN‐γ ELISPOT assays. Vaccine‐induced T cells targeted approximately 90% of NS31073 genotype 1 sequences and 50% of NS31446 genotype 1 and 3 sequences. For NS31406, 62% of subtype‐1b sequences were targeted. Next, we assessed whether an in vitro priming system, using dendritic cells and T cells from healthy donors, could identify a variant of NS31406 that was maximally cross‐reactive. In vitro priming assays showed that of those tested the NS31406 vaccine variant was the most immunogenic. T cells primed with genotype 1 variants from subtype 1a or 1b were broadly cross‐reactive with other variants from the same subtype. We conclude that immunization with candidate HCV adenoviral vaccines generates cross‐reactive T cells at immunodominant epitopes. The degree of cross‐reactivity varies between epitopes and may be HCV‐subtype specific.
Adenoviral vectors encoding hepatitis C virus (HCV) nonstructural (NS) proteins induce multispecific, high‐magnitude, durable CD4+ and CD8+ T‐cell responses in healthy volunteers. We assessed the ...capacity of these vaccines to induce functional HCV‐specific immune responses and determine T‐cell cross‐reactivity to endogenous virus in patients with chronic HCV infection. HCV genotype 1‐infected patients were vaccinated using heterologous adenoviral vectors (ChAd3‐NSmut and Ad6‐NSmut) encoding HCV NS proteins in a dose escalation, prime‐boost regimen, with and without concomitant pegylated interferon‐α/ribavirin therapy. Analysis of immune responses ex vivo used human leukocyte antigen class I pentamers, intracellular cytokine staining, and fine mapping in interferon‐γ enzyme‐linked immunospot assays. Cross‐reactivity of T cells with population and endogenous viral variants was determined following viral sequence analysis. Compared to healthy volunteers, the magnitude of HCV‐specific T‐cell responses following vaccination was markedly reduced. CD8+ HCV‐specific T‐cell responses were detected in 15/24 patients at the highest dose, whereas CD4+ T‐cell responses were rarely detectable. Analysis of the host circulating viral sequence showed that T‐cell responses were rarely elicited when there was sequence homology between vaccine immunogen and endogenous virus. In contrast, T cells were induced in the context of genetic mismatch between vaccine immunogen and endogenous virus; however, these commonly failed to recognize circulating epitope variants and had a distinct partially functional phenotype. Vaccination was well tolerated but had no significant effect on HCV viral load. Conclusion: Vaccination with potent HCV adenoviral vectored vaccines fails to restore T‐cell immunity except where there is genetic mismatch between vaccine immunogen and endogenous virus; this highlights the major challenge of overcoming T‐cell exhaustion in the context of persistent antigen exposure with implications for cancer and other persistent infections. (Hepatology 2016;63:1455‐1470)
Hepatitis C virus (HCV) is a major global pathogen estimated to infect over 170 million people worldwide. A recent study has shown that vaccination with adenoviral vectors, based on rare human and ...simian serotypes encoding the non-structural (NS) proteins of HCV, induces highly potent, multi-specific and durable T cell responses in healthy human volunteers. In this thesis I assess the safety and immunogenicity of these vaccines (ChAd3–NSmut and Ad6-NSmut), for the first time in HCV infected patients. This work also explores whether vaccine-induced T cell responses target in vivo circulating HCV antigens and common naturally occurring epitope variants. Patients with treatment naive chronic genotype 1 HCV infection were vaccinated (i.m.) with ChAd3-NSmut and Ad6-NSmut in a heterologous prime boost schedule, either with or without current IFN and ribavirin (IFN/RBV). Epitope-specific T cell responses were defined by fine mapping using HCV peptides. Circulating viral genomic sequence was determined in vaccinated patients at baseline and at any point of viral relapse. Cross-reactivity of vaccine-induced T cell responses was determined in T cell assays, using peptides corresponding to both circulating host virus and common population HCV epitope variants. An in vitro dendritic cell /T cell priming model was used to identify possible candidates for a cross-reactive vaccine immunogen at the most immunodominant epitope, NS31406. 33 patients were vaccinated. Vaccination was well tolerated. At the highest vaccine dose (2.5 x 1010vp) vaccine-induced T cell responses were detectable in 11/20 patients receiving concurrent IFN/RBV and 2/4 patients receiving vaccination alone. In total 14 antigenic targets were identified, 2 of which have not previously been described. However, T cell responses were of lower magnitude and more narrowly focused than those observed in healthy volunteers vaccinated with the same regimen. Analysis of viral sequence showed that in many cases vaccine-induced T cells did not target the circulating virus. At the most immunodominant epitope (NS31406), T cells induced by vaccination failed to target common circulating genotype 1 HCV variants. An in vitro model suggested that in order to target all genotype 1 sequences at this epitope, it would be necessary to insert both a genotype 1a and 1b version of this epitope into a vaccine immunogen. Vaccination with adenoviral vectors induces T cell responses in patients with chronic HCV infection, however immune responses are attenuated compared with healthy volunteers. Ultimately a successful therapeutic or prophylactic vaccine strategy will rely on inducing responses that target conserved or cross-reactive epitopes.
Hepatitis C virus (HCV) is a major global pathogen estimated to infect over 170 million people worldwide. A recent study has shown that vaccination with adenoviral vectors, based on rare human and ...simian serotypes encoding the non-structural (NS) proteins of HCV, induces highly potent, multi-specific and durable T cell responses in healthy human volunteers. In this thesis I assess the safety and immunogenicity of these vaccines (ChAd3–NSmut and Ad6-NSmut), for the first time in HCV infected patients. This work also explores whether vaccine-induced T cell responses target in vivo circulating HCV antigens and common naturally occurring epitope variants. Patients with treatment naive chronic genotype 1 HCV infection were vaccinated (i.m.) with ChAd3-NSmut and Ad6-NSmut in a heterologous prime boost schedule, either with or without current IFN and ribavirin (IFN/RBV). Epitope-specific T cell responses were defined by fine mapping using HCV peptides. Circulating viral genomic sequence was determined in vaccinated patients at baseline and at any point of viral relapse. Cross-reactivity of vaccine-induced T cell responses was determined in T cell assays, using peptides corresponding to both circulating host virus and common population HCV epitope variants. An in vitro dendritic cell /T cell priming model was used to identify possible candidates for a cross-reactive vaccine immunogen at the most immunodominant epitope, NS31406. 33 patients were vaccinated. Vaccination was well tolerated. At the highest vaccine dose (2.5 x 1010vp) vaccine-induced T cell responses were detectable in 11/20 patients receiving concurrent IFN/RBV and 2/4 patients receiving vaccination alone. In total 14 antigenic targets were identified, 2 of which have not previously been described. However, T cell responses were of lower magnitude and more narrowly focused than those observed in healthy volunteers vaccinated with the same regimen. Analysis of viral sequence showed that in many cases vaccine-induced T cells did not target the circulating virus. At the most immunodominant epitope (NS31406), T cells induced by vaccination failed to target common circulating genotype 1 HCV variants. An in vitro model suggested that in order to target all genotype 1 sequences at this epitope, it would be necessary to insert both a genotype 1a and 1b version of this epitope into a vaccine immunogen. Vaccination with adenoviral vectors induces T cell responses in patients with chronic HCV infection, however immune responses are attenuated compared with healthy volunteers. Ultimately a successful therapeutic or prophylactic vaccine strategy will rely on inducing responses that target conserved or cross-reactive epitopes.
Zoonotic and related infections pose an enormous health threat to the world's second-most populous continent. Despite the challenges faced by drug discovery scientists in Africa, recent progress ...toward identifying potential medicines across diverse disease areas is a cause for optimism and an indicator of progress in African-led scientific initiatives.
Evidence suggests that there is usually a long delay between noticing first signs of dementia and seeking medical help. We conducted a systematic review of what people experience and how they make ...decisions during this time, and used a meta-ethnographic approach to synthesise the findings. Screening and quality assessment resulted in nine studies eligible for inclusion. People with dementia mainly report experiencing memory lapses, while carers focus on more subtle changes in personality. People respond to these changes in one of three ways: 1) they discount them as normal; 2) they reserve judgement as to their cause and significance, or 3) they misattribute them. Pivotal events can finally trigger help seeking. Active reflection and seeking of further evidence may lead to earlier recognition of the possibility of dementia and the need to seek help; it also reduces the risk of a pivotal event. Public education should aim to improve recognition of more subtle signs and to encourage repeated evaluation and reflection.
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