F. Lamoury

Adaptation of the bovine spongiform encephalopathy agent to primates and comparison with Creutzfeldt– Jakob disease: Implications for human health

There is substantial scientific evidence to support the notion that bovine spongiform encephalopathy (BSE) has contaminated human beings, causing variant Creutzfeldt–Jakob disease (vCJD). This disease has raised concerns about the possibility of an iatrogenic secondary transmission to humans, because the biological properties of the primate-adapted BSE agent are unknown. We show that (i) BSE can be transmitted from primate to primate by intravenous route in 25 months, and (ii) an iatrogenic transmission of vCJD to humans could be readily recognized pathologically, whether it occurs by the central or peripheral route. Strain typing in mice demonstrates that the BSE agent adapts to macaques in the same way as it does to humans and confirms that the BSE agent is responsible for vCJD not only in the United Kingdom but also in France. The agent responsible for French iatrogenic growth hormone-linked CJD taken as a control is very different from vCJD but is similar to that found in one case of sporadic CJD and one sheep scrapie isolate. These data will be key in identifying the origin of human cases of prion disease, including accidental vCJD transmission, and could provide bases for vCJD risk assessment.

Interferon-γ regulates the proliferation and differentiation of mesenchymal stem cells via activation of indoleamine 2,3 dioxygenase (IDO).

The kynurenine pathway (KP) of tryptophan metabolism is linked to antimicrobial activity and modulation of immune responses but its role in stem cell biology is unknown. We show that human and mouse mesenchymal and neural stem cells (MSCs and NSCs) express the complete KP, including indoleamine 2,3 dioxygenase 1 (IDO) and IDO2, that it is highly regulated by type I (IFN-β) and II interferons (IFN-γ), and that its transcriptional modulation depends on the type of interferon, cell type and species. IFN-γ inhibited proliferation and altered human and mouse MSC neural, adipocytic and osteocytic differentiation via the activation of IDO. A functional KP present in MSCs, NSCs and perhaps other stem cell types offers novel therapeutic opportunities for optimisation of stem cell proliferation and differentiation.

Opposite Effects of Dextran Sulfate 500, the Polyene Antibiotic MS-8209, and Congo Red on Accumulation of the Protease-Resistant Isoform of PrP in the Spleens of Mice Inoculated Intraperitoneally with the Scrapie Agent

ABSTRACT The mode and the site of action of the major antiscrapie drugs have been studied by investigating their effects on the abnormal protease-resistant isoform of PrP (PrPres) and on its accumulation in mouse spleen. Day-by-day PrPres accumulation in the spleen and in other peripheral organs was first monitored to describe the early steps of scrapie pathogenesis. Three phases were identified: the detection of scrapie inoculum on the day of scrapie infection, a clearance phase, and then the peripheral accumulation of PrPres. In a second step, the effects of the polyene antibiotic MS-8209, the polyanion dextran sulfate 500 (DS500), and Congo red were assessed on these phases, after the drugs were coincubated with scrapie inoculum. Highly different mechanisms and sites of action were apparent. MS-8209 had a weak effect on the accumulation of PrPres in spleen, suggesting another site of intervention for this drug. DS500 delayed the beginning of the clearance phase but then blocked PrPres synthesis for a long period of time, probably because of its immunological effects on the spleen. Surprisingly, Congo red suppressed the clearance phase of scrapie inoculum and then increased transiently accumulation of PrPres in spleen. We showed in vitro that this effect was related to a direct enhancement of the protease resistance of PrPres by the drug.

Evaluation of the Xpert HCV Viral Load point-of-care assay from venepuncture-collected and finger-stick capillary whole-blood samples: a cohort study

BACKGROUND Point-of-care hepatitis C virus (HCV) RNA testing offers an advantage over antibody testing (which only indicates previous exposure), enabling diagnosis of active infection in a single visit. In this study, we evaluated the performance of the Xpert HCV Viral Load assay with venepuncture and finger-stick capillary whole-blood samples. METHODS Plasma and finger-stick capillary whole-blood samples were collected from participants in an observational cohort enrolled at five sites in Australia (three drug and alcohol clinics, one homelessness service, and one needle and syringe programme). We compared the sensitivity and specificity of the Xpert HCV Viral Load test for HCV RNA detection by venepuncture and finger-stick collection with the Abbott RealTime HCV Viral Load assay (gold standard). FINDINGS Of 210 participants enrolled between Feb 8, 2016, and July 27, 2016, 150 participants had viral load testing results for the three assays tested. HCV RNA was detected in 45 (30% [95% CI 23-38]) of 150 participants based on Abbott RealTime. Sensitivity of the Xpert HCV Viral Load assay for HCV RNA detection in plasma collected by venepuncture was 100·0% (95% CI 92·0-100·0) and specificity was 99·1% (95% CI 94·9-100·0). Sensitivity of the Xpert HCV Viral Load assay for HCV RNA detection in samples collected by finger-stick was 95·5% (95% CI 84·5-99·4) and specificity was 98·1% (95% CI 93·4-99·8). No adverse events caused by the index test or the reference standard were observed. IMPLICATIONS The Xpert HCV Viral Load test can detect active infection from a finger-stick sample, which represents an advance over antibody-based tests that only indicate past or previous exposure. FUNDING National Health and Medical Research Council (Australia), Cepheid, South Eastern Sydney Local Health District (Australia), and Merck Sharp & Dohme (Australia).

Neural transplantation of human MSC and NT2 cells in the twitcher mouse model

BACKGROUND Accumulating evidence has demonstrated that the NT2 embryonal carcinoma cell line and multipotential stem cells found in BM, mesenchymal stromal cells (MSC), have the ability to differentiate into a wide variety of cell types. This study was designed to explore the efficacy of these two human stem cell types as a graft source for the treatment of demyelinating disorders such as Krabbes disease and multiple sclerosis (MS). METHODS We examined the engraftment and in vivo differentiation of adult MSC and NT2 cells after transplantation into two demyelinating environments, the neonatal and postnatal twitcher mouse brain. RESULTS Both types of xenografts led to anatomical integration, without tumor formation, and remained viable in the normal and twitcher mouse brain, showing differentiation into neurons, astrocytes and oligodendrocytes. DISCUSSION This study represents a platform for further stem cell transplantation studies in the twitcher model and potentially has important therapeutic implications.

Phylogenetic clustering of hepatitis C virus among people who inject drugs in Vancouver, Canada

Little is known about factors associated with hepatitis C virus (HCV) transmission among people who inject drugs (PWID). Phylogenetic clustering and associated factors were evaluated among PWID in Vancouver, Canada. Data were derived from the Vancouver Injection Drug Users Study. Participants who were HCV antibody‐positive at enrolment and those with HCV antibody seroconversion during follow‐up (1996 to 2012) were tested for HCV RNA and sequenced (Core‐E2 region). Phylogenetic trees were inferred using maximum likelihood analysis and clusters were identified using ClusterPicker (90% bootstrap threshold, 0.05 genetic distance threshold). Factors associated with clustering were assessed using logistic regression. Among 655 eligible participants, HCV genotype prevalence was: G1a: 48% (n = 313), G1b: 6% (n = 41), G2a: 3% (n = 20), G2b: 7% (n = 46), G3a: 33% (n = 213), G4a: <1% (n = 4), G6a: 1% (n = 8), G6e: <1% (n = 1), and unclassifiable: 1% (n = 9). The mean age was 36 years, 162 (25%) were female, and 164 (25%) were HIV+. Among 501 participants with HCV G1a and G3a, 31% (n = 156) were in a pair/cluster. Factors independently associated with phylogenetic clustering included: age <40 (versus age ≥40, adjusted odds ratio [AOR] = 1.64; 95% confidence interval [CI] 1.03, 2.63), human immunodeficiency virus (HIV) infection (AOR = 1.82; 95% CI 1.18, 2.81), HCV seroconversion (AOR = 3.05; 95% CI 1.40, 6.66), and recent syringe borrowing (AOR 1.59; 95% CI 1.07, 2.36). Conclusion: In this sample of PWID, one‐third demonstrated phylogenetic clustering. Factors independently associated with phylogenetic clustering included younger age, recent HCV seroconversion, prevalent HIV infection, and recent syringe borrowing. Strategies to enhance the delivery of prevention and/or treatment strategies to those with HIV and recent HCV seroconversion should be explored, given an increased likelihood of HCV transmission in these subpopulations. (Hepatology 2014;60:1571–1580)

The Influence of Hepatitis C Virus Genetic Region on Phylogenetic Clustering Analysis

Sequencing is important for understanding the molecular epidemiology and viral evolution of hepatitis C virus (HCV) infection. To date, there is little standardisation among sequencing protocols, in-part due to the high genetic diversity that is observed within HCV. This study aimed to develop a novel, practical sequencing protocol that covered both conserved and variable regions of the viral genome and assess the influence of each subregion, sequence concatenation and unrelated reference sequences on phylogenetic clustering analysis. The Core to the hypervariable region 1 (HVR1) of envelope-2 (E2) and non-structural-5B (NS5B) regions of the HCV genome were amplified and sequenced from participants from the Australian Trial in Acute Hepatitis C (ATAHC), a prospective study of the natural history and treatment of recent HCV infection. Phylogenetic trees were constructed using a general time-reversible substitution model and sensitivity analyses were completed for every subregion. Pairwise distance, genetic distance and bootstrap support were computed to assess the impact of HCV region on clustering results as measured by the identification and percentage of participants falling within all clusters, cluster size, average patristic distance, and bootstrap value. The Robinson-Foulds metrics was also used to compare phylogenetic trees among the different HCV regions. Our results demonstrated that the genomic region of HCV analysed influenced phylogenetic tree topology and clustering results. The HCV Core region alone was not suitable for clustering analysis; NS5B concatenation, the inclusion of reference sequences and removal of HVR1 all influenced clustering outcome. The Core-E2 region, which represented the highest genetic diversity and longest sequence length in this study, provides an ideal method for clustering analysis to address a range of molecular epidemiological questions.

Sequencing of the Hepatitis C Virus: A Systematic Review

Since the identification of hepatitis C virus (HCV), viral sequencing has been important in understanding HCV classification, epidemiology, evolution, transmission clustering, treatment response and natural history. The length and diversity of the HCV genome has resulted in analysis of certain regions of the virus, however there has been little standardisation of protocols. This systematic review was undertaken to map the location and frequency of sequencing on the HCV genome in peer reviewed publications, with the aim to produce a database of sequencing primers and amplicons to inform future research. Medline and Scopus databases were searched for English language publications based on keyword/MeSH terms related to sequence analysis (9 terms) or HCV (3 terms), plus “primer” as a general search term. Exclusion criteria included non-HCV research, review articles, duplicate records, and incomplete description of HCV sequencing methods. The PCR primer locations of accepted publications were noted, and purpose of sequencing was determined. A total of 450 studies were accepted from the 2099 identified, with 629 HCV sequencing amplicons identified and mapped on the HCV genome. The most commonly sequenced region was the HVR-1 region, often utilised for studies of natural history, clustering/transmission, evolution and treatment response. Studies related to genotyping/classification or epidemiology of HCV genotype generally targeted the 5′UTR, Core and NS5B regions, while treatment response/resistance was assessed mainly in the NS3–NS5B region with emphasis on the Interferon sensitivity determining region (ISDR) region of NS5A. While the sequencing of HCV is generally constricted to certain regions of the HCV genome there is little consistency in the positioning of sequencing primers, with the exception of a few highly referenced manuscripts. This study demonstrates the heterogeneity of HCV sequencing, providing a comprehensive database of previously published primer sets to be utilised in future sequencing studies.

Inhibiting scrapie neuroinvasion by polyene antibiotic treatment of SCID mice

The polyene antibiotic MS-8209 is currently one of the most effective drugs in the treatment of experimental scrapie. However, its mechanism of action and its site of intervention in the pathogenetical process of scrapie infection are largely unknown. It has been shown previously that the infection of immunodeficient SCID mice by the peripheral route provides a reliable model for direct scrapie neuroinvasion, bypassing the lymphoreticular system. Indeed, a proportion of SCID mice develop scrapie after a similar time to immunocompetent mice, despite their severe immune impairment. This model is now used to clarify the targets of MS-8209. In SCID mice, MS-8209 treatment protected against infection but did not prolong survival time. In SCID mice immunologically reconstituted prior to inoculation, the drug delayed the disease without an effect on the attack rate. These findings strongly suggest that MS-8209 acts by hampering the first step of the neuroinvasion process, i.e. the uptake of the infectious agent by peripheral nerve endings. The mechanism leading to the inhibition of agent propagation to nervous cells is discussed with regard to the properties of polyene antibiotics.

A Comparison of Seminal Hepatitis C Virus (HCV) RNA Levels During Recent and Chronic HCV Infection in HIV-Infected and HIV-Uninfected Individuals

BACKGROUND We aimed to characterize seminal hepatitis C virus (HCV) RNA dynamics in human immunodeficiency virus (HIV)-positive men with acute HCV infection given its potential role in sexual transmission of HCV. METHODS Men with acute HCV infection (duration, ≤12 months) or chronic HCV infection (duration, >12 months) were prospectively recruited. Paired semen and blood samples were assayed for HCV RNA levels. Results were analyzed using χ(2), Fisher exact, Mann-Whitney U, and Kruskal-Wallis tests. RESULTS Eighteen men (27.3%) had acute HCV and HIV coinfection, 22 (33.3%) had chronic HCV infection and HIV coinfection, and 26 (39.4%) had chronic HCV monoinfection. HCV RNA was detected in semen specimens from 29 of 66 men (43.9%). The median HCV RNA level in blood was 4.0 log IU/mL higher than that in semen. HCV RNA levels were correlated in semen and blood (r(2) = 0.142). Neither HIV positivity nor acute HCV infection was associated with an increased frequency of seminal HCV RNA detection. Among men with acute HCV and HIV coinfection, the median HCV RNA level in blood specimens from those with seminal HCV RNA was higher than that in blood specimens from those without seminal HCV RNA (P = .001). Seminal HCV RNA was detected in ≥1 sample for 26 of 35 men (74.3%) attending follow up. CONCLUSIONS HCV RNA was detected in semen during both acute and chronic HCV infection. This was unaffected by HIV positivity or the phase of HCV infection. Elevated seminal HCV RNA levels could contribute to sexual transmission of HCV, but other factors, including high-risk behaviors, may be the main drivers for HCV transmission in HIV-infected individuals.