Network Analysis of the Chronic Hepatitis C Virome Defines Hypervariable Region 1 Evolutionary Phenotypes in the Context of Humoral Immune Responses.

UNLABELLED: Hypervariable region 1 (HVR1) of hepatitis C virus (HCV) comprises the first 27 N-terminal amino acid residues of E2. It is classically seen as the most heterogeneous region of the HCV genome. In this study, we assessed HVR1 evolution by using ultradeep pyrosequencing for a cohort of treatment-naive, chronically infected patients over a short, 16-week period. Organization of the sequence set into connected components that represented single nucleotide substitution events revealed a network dominated by highly connected, centrally positioned master sequences. HVR1 phenotypes were observed to be under strong purifying (stationary) and strong positive (antigenic drift) selection pressures, which were coincident with advancing patient age and cirrhosis of the liver. It followed that stationary viromes were dominated by a single HVR1 variant surrounded by minor variants comprised from conservative single amino acid substitution events. We present evidence to suggest that neutralization antibody efficacy was diminished for stationary-virome HVR1 variants. Our results identify the HVR1 network structure during chronic infection as the preferential dominance of a single variant within a narrow sequence space. IMPORTANCE: HCV infection is often asymptomatic, and chronic infection is generally well established in advance of initial diagnosis and subsequent treatment. HVR1 can undergo rapid sequence evolution during acute infection, and the variant pool is typically seen to diverge away from ancestral sequences as infection progresses from the acute to the chronic phase. In this report, we describe HVR1 viromes in chronically infected patients that are defined by a dominant epitope located centrally within a narrow variant pool. Our findings suggest that weakened humoral immune activity, as a consequence of persistent chronic infection, allows for the acquisition and maintenance of host-specific adaptive mutations at HVR1 that reflect virus fitness.

Intensive temporal mapping of hepatitis C hypervariable region 1 quasispecies provides novel insights into hepatitis C virus evolution in chronic infection.

Hepatitis C virus (HCV) is an RNA virus which exists as swarms of closely related viruses known as quasispecies (QS). A number of studies have demonstrated associations between QS hypervariable region 1 (HVR1) characteristics (diversity and complexity) and treatment success. We investigated HCV QS change in chronic infection over intervals of 2-4 weeks in 23 chronically infected individuals to describe the natural history of virus evolution and establish whether HCV QS characteristics could be used to individualize treatment regimens at a molecular level. HVR1 QS diversity, complexity and divergence continue to change in an unpredictable fashion in chronic infection even where there is little phylogenetic change, which is likely to preclude the use of these features in treatment individualization. Our phylogenetic analysis identified no change in the HVR1 QS in 12 subjects, minor change in four subjects and we describe a time-ordered phylogeny for the first time over a period as short as 16 weeks in seven subjects. We identified the existence of multiple subpopulation infections using partitioned analysis of QS and illustrated how subpopulations were sequentially replaced in a number of subjects. We illustrated marked variation in the nucleotide substitution per codon position between patients with sequence change and those without change in the phylogenetic tree. Analysis of codon-specific selection pressures identified a number of codons under purifying selection, suggesting that these code for structurally conserved amino acids. We also identified sections of the HVR1 under positive selection with marked sequence heterogeneity, suggesting that these may be potential epitope-binding sites.

Treatment of Hereditary Haemorrhagic Telangiectasia with Bevacizumab - What More Needs to be Known?

Introduction: Hereditary haemorrhagic telangiectasia (HHT) is a rare multi-organ vascular disease. It is characterised by mucocutaneous telangiectasia, epistaxis, and arteriovenous malformations. Some 70% of patients with HHT are thought to have issues with gastrointestinal (GI) bleeding. Traditional management of GI bleeding in HHT includes monitoring for iron deficiency anaemia, iron replacement, antifibrinolytic therapy and control of identifiable bleeding sites with argon photocoagulation during gastrointestinal endoscopy. Blood transfusion may also be required. Case description: Our case describes a man in his 40s with confirmed HHT, with transfusion-dependent anaemia secondary to GI bleeding. He was commenced on fortnightly bevacizumab (5 mg/kg) for 12 weeks in an attempt to reduce his blood transfusion requirement and manage his anaemia. In the months prior to starting bevacizumab, our patient's transfusion requirement ranged from 3-5 units of packed red cells per month to maintain an Hb >8 g/dl. He had a marked improvement in his symptoms within the first month of treatment and did not require any further blood transfusion during the three months of treatment. He was given one further IV iron infusion in the final month of his 3-month bevacizumab treatment and did not experience any adverse side effects from bevacizumab. Discussion: HHT results from alterations to genes which encode proteins involved in blood vessel formation. This provides the rationale for using anti VEGF drugs such as bevacizumab. Current evidence for this treatment approach is limited. Conclusion: Bevacizumab can be an effective treatment option in patients with HHT refractory to traditional management. LEARNING POINTS: Gastrointestinal bleeding in hereditary haemorrhagic telangiectasia can be difficult to treat.Bevacizumab, an anti-vascular endothelial growth factor, can be used to treat refractory anaemia secondary to gastrointestinal bleeding in hereditary haemorrhagic telangiectasia.

Efficacy of rituximab in difficult-to-manage autoimmune hepatitis: Results from the International Autoimmune Hepatitis Group.

Treatment options remain limited for patients with autoimmune hepatitis (AIH), while there are still concerns over the consequences of long-term corticosteroid use. A few studies have suggested a role for B cell-driven autoimmune liver injury in AIH. This multicentre, international retrospective cohort study from the International Autoimmune Hepatitis Group aims to evaluate the clinical efficacy and safety of rituximab in difficult-to-manage AIH. METHODS: Clinical data from 22 patients who received rituximab between 2007 and 2017 were collected from centres in the United Kingdom, Germany and Canada. Clinical response was assessed using changes in biochemical and immunological parameters up to 24 months post-rituximab infusion. In addition, we compared the doses of prednisolone used 3 months before and 12 months after treatment, and assessed freedom from AIH flares over the post-treatment period. RESULTS: Twenty-two patients with type-1 AIH were included, with a median age of 40 years at diagnosis (range 19-79); 15/22 (68%) were female and 18/22 (82%) were Caucasian. The median period from diagnosis to the end of follow-up in these patients was 11 years (range 3-28). Values of alanine aminotransferase, aspartate aminotransferase and albumin improved significantly following rituximab therapy, and were sustained for up to 2 years (all p ≪0.001). Prednisolone doses were significantly reduced by 12 months post-treatment (p = 0.003), with 13/21 (62%) patients having a dose reduction. Over a median post-treatment follow-up period of 6 years (range 1-10), 5 patients developed AIH flares at a median of 22 months post-treatment, giving an estimated 71% freedom from AIH flare at 2 years. Four of these patients received a second course of treatment, of whom 2 had subsequent further flares. No serious adverse events attributable to rituximab were recorded. CONCLUSION: In patients with difficult-to-manage AIH, rituximab appears to be clinically effective and well tolerated. Rituximab was associated with sustained improvements in serum liver tests, an absence of clinical disease flares, and a reduction in prednisolone dose. Controlled trials are warranted to further evaluate B cell-targeting therapies in patients with AIH. LAY SUMMARY: Autoimmune hepatitis is an autoimmune condition of the liver, usually treated with medications that suppress the immune system, such as steroids. However, some patients do not respond to this treatment. We analysed the safety and efficacy of rituximab in patients who were not responding to first- or second-line therapies. Rituximab was safe and improved liver blood tests in 70% of patients over a 2-year follow-up period, while enabling steroid doses to be reduced in two-thirds of patients, which is a very positive clinical outcome.