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An intronic GGGGCC repeat expansion in C9orf72 is a common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The repeats are transcribed in both sense and antisense directions to generate distinct dipeptide repeat proteins, of which poly(GA), poly(GR), and poly(PR) have been implicated in contributing to neurodegeneration. Poly(PR) binding to RNA may contribute to toxicity, but analysis of poly(PR)-RNA binding on a transcriptome-wide scale has not yet been carried out. We therefore performed crosslinking and immunoprecipitation (CLIP) analysis in human cells to identify the RNA binding sites of poly(PR). We found that poly(PR) binds to nearly 600 RNAs, with the sequence GAAGA enriched at the binding sites. In vitro experiments showed that poly(GAAGA) RNA binds poly(PR) with higher affinity than control RNA and induces the phase separation of poly(PR) into condensates. These data indicate that poly(PR) preferentially binds to poly(GAAGA)-containing RNAs, which may have physiological consequences.

Objective A GGGGCC repeat expansion in the C9orf72 gene is the most common cause of genetic frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). As potential therapies targeting the repeat expansion are now entering clinical trials, sensitive biomarker assays of target engagement are urgently required. Our objective was to develop such an assay. Methods We used the single molecule array (Simoa) platform to develop an immunoassay for measuring poly(GP) dipeptide repeat proteins (DPRs) generated by the C9orf72 repeat expansion in cerebrospinal fluid (CSF) of people with C9orf72-associated FTD/ALS. Results and conclusions We show the assay to be highly sensitive and robust, passing extensive qualification criteria including low intraplate and interplate variability, a high precision and accuracy in measuring both calibrators and samples, dilutional parallelism, tolerance to sample and standard freeze-thaw and no haemoglobin interference. We used this assay to measure poly(GP) in CSF samples collected through the Genetic FTD Initiative (N=40 C9orf72 and 15 controls). We found it had 100% specificity and 100% sensitivity and a large window for detecting target engagement, as the C9orf72 CSF sample with the lowest poly(GP) signal had eightfold higher signal than controls and on average values from C9orf72 samples were 38-fold higher than controls, which all fell below the lower limit of quantification of the assay. These data indicate that a Simoa-based poly(GP) DPR assay is suitable for use in clinical trials to determine target engagement of therapeutics aimed at reducing C9orf72 repeat-containing transcripts.

Small ruminant lentiviruses (SRLV) cause an incurable multiorganic disease widely spread in sheep and goats that disturbs animal welfare and production. In the absence of a vaccine, control measures have been traditionally based on early diagnosis and breeding with virus-inactivated colostrum with segregation of seropositive animals. However, antigenic heterogeneity, poor antibody production due to low viral load, and single strain design of most available ELISA, pose a threat to SRLV diagnosis. Genome-wide association studies have described TMEM154 E35K polymorphism as a good genetic marker for selection of resistant animals in some American and European breeds. In this study, a multitargeted serological and virological screening of more than 500 animals from four different breeds (latxa, raza Navarra, assaf, and churra) attending to SRLV infection status was performed. Then, animals were genotyped to characterize TMEM154 E35K polymorphism. ELISA procedures, individually considered, only identified a proportion of the seropositive animals, and PCR detected a fraction of seronegative animals, globally offering different animal classifications according to SRLV infection status. TMEM154 allele frequency differed substantially among breeds and a positive association between seroprevalence and TMEM154 genotype was found only in one breed. Selection based on TMEM154 may be suitable for specific ovine breeds or SRLV strains, however generalization to the whole SRLV genetic spectrum, ovine breeds, or epidemiological situation may need further validation.

A C9orf72 repeat expansion is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis. One of the suggested pathomechanisms is toxicity from dipeptide repeat proteins (DPRs), which are generated via unconventional translation of sense and antisense repeat transcripts with poly-GA, poly-GP and poly-GR being the most abundant dipeptide proteins. Animal and cellular studies highlight a neurotoxic role of poly-GR and poly-PR and to a lesser degree of poly-GA. Human post-mortem studies in contrast have been much less clear on a potential role of DPR toxicity but have largely focused on immunohistochemical methods to detect aggregated DPR inclusions. This study uses protein fractionation and sensitive immunoassays to quantify not only insoluble but also soluble poly-GA, poly-GP and poly-GR concentrations in brain homogenates of FTD patients with C9orf72 mutation across four brain regions. We show that soluble DPRs are less abundant in clinically affected areas (i.e. frontal and temporal cortices). In contrast, the cerebellum not only shows the largest DPR load but also the highest relative DPR solubility. Finally, poly-GR levels and poly-GP solubility correlate with clinical severity. These findings provide the first cross-comparison of soluble and insoluble forms of all sense DPRs and shed light on the distribution and role of soluble DPRs in the etiopathogenesis of human C9orf72-FTD.

Small ruminant lentiviruses (SRLVs) are endemic in most areas of Europe, causing a chronic infection and a multisystemic disease affecting the udder, carpal joints, lungs, and central nervous system. Due to the lack of treatments and protective vaccination strategies, infection control is focused on the identification of infected animals through serological or molecular techniques. However, antigenic and genetic heterogeneity of SRLVs represent a clear drawback for diagnosis. Infected animals may present lower animal production parameters such as birth weight or milk production and quality, depending on productive systems considered and, likely, to the diagnostic method applied. In this study, four sheep flocks dedicated to dairy or meat production were evaluated using three different ELISA and two PCR strategies to classify animal population according to SRLV infection status. Productive parameters were recorded along one whole lactation or reproductive period and compared between positive and negative animals. SRLV was present in 19% of the total population, being unequally distributed in the different flocks. Less than half of the infected animals were detected by a single diagnostic method, highlighting the importance of combining different diagnostic techniques. Statistical analysis employing animal classification using all the diagnostic methods associated lambing size, lamb weight at birth, and daily weight gain with SRLV infection status in meat flocks. Milk production, somatic cell count, fat, and protein content in the milk were associated with SRLV infection in dairy flocks, to a greater extent in the flock showing higher seroprevalence. A multi-platform SRLV diagnostic strategy was useful for ensuring correct animal classification, thus validating downstream studies investigating production traits.

The objective of this work was to comparatively study the tissue tropism and the associated pathology of 2 autochthonous small ruminant lentivirus (SRLV) field strains using an experimental infection in sheep through the bone marrow. Fifteen male, SRLV-free lambs of the Rasa Aragonesa breed were inoculated with strain 697 (nervous tissue origin, animals A1–A6), with strain 496 (articular origin, animals B1–B6), or with uninfected culture medium (C1–C3). Clinical, serologic, and polymerase chain reaction (PCR) evaluations were performed periodically. Two lambs from each infected group and a control animal were euthanized at 134, 273, and 319 days postinfection. Tissues were analyzed by gross and histopathologic evaluation; immunohistochemistry for CD3, CD4, CD8, CD68, and FoxP3 cell markers; lung morphometric evaluation; and tissue proviral quantification by PCR. All infected animals became positive either by enzyme-linked immunosorbent assay and/or PCR, with group B lambs showing the highest serologic values and more consistently positive PCR reactions. Group A lambs showed representative lung lesions but only mild histopathologic changes in the central nervous system (CNS) or in carpal joints. Contrarily, group B lambs demonstrated intense carpal arthritis and interstitial pneumonia but an absence of lesions in the CNS. Proviral copies in tissues were detected only in group B lambs. Experimental infection with these SRLV strains indicates that strain 496 is more virulent than strain 697 and more prone to induce arthritis, whereas strain 697 is more likely to reproduce encephalitis in Rasa Aragonesa lambs. Host factors as well as viral factors are responsible for the final clinicopathologic picture during SRLV infections.

Small ruminant lentivirus (SRLV) infection causes losses in the small ruminant industry due to reduced animal production and increased replacement rates. Infection of wild ruminants in close contact with infected domestic animals has been proposed to play a role in SRLV epidemiology, but studies are limited and mostly involve hybrids between wild and domestic animals. In this study, SRLV seropositive red deer, roe deer and mouflon were detected through modified ELISA tests, but virus was not successfully amplified using a set of different PCRs. Apparent restriction of SRLV infection in cervids was not related to the presence of neutralizing antibodies. In vitro cultured skin fibroblastic cells from red deer and fallow deer were permissive to the SRLV entry and integration, but produced low quantities of virus. SRLV got rapidly adapted in vitro to blood-derived macrophages and skin fibroblastic cells from red deer but not from fallow deer. Thus, although direct detection of virus was not successfully achieved in vivo, these findings show the potential susceptibility of wild ruminants to SRLV infection in the case of red deer and, on the other hand, an in vivo SRLV restriction in fallow deer. Altogether these results may highlight the importance of surveilling and controlling SRLV infection in domestic as well as in wild ruminants sharing pasture areas, and may provide new natural tools to control SRLV spread in sheep and goats.

The major challenges in diagnosing small ruminant lentivirus (SRLV) infection include early detection and genotyping of strains of epidemiological interest. A longitudinal study was carried out in Rasa Aragonesa sheep experimentally infected with viral strains of genotypes A or B from Spanish neurological and arthritic SRLV outbreaks, respectively. Sera were tested with two commercial ELISAs, three based on specific peptides and a novel combined peptide ELISA. Three different PCR assays were used to further assess infection status.The kinetics of anti-viral antibody responses were variable, with early diagnosis dependent on the type of ELISA used. Peptide epitopes of SRLV genotypes A and B combined in the same ELISA well enhanced the overall detection rate, whereas single peptides were useful for genotyping the infecting strain (A vs. B). The results of the study suggest that a combined peptide ELISA can be used for serological diagnosis of SRLV infection, with single peptide ELISAs useful for subsequent serotyping.

We describe the clinicopathologic features of an arthritis outbreak in sheep induced by small ruminant lentivirus (SRLV), linked to the presence of a new SRLV isolate phylogenetically assigned to caprine arthritis encephalitis virus–like subgroup B2. Thirteen SRLV seropositive Rasa Aragonesa adult ewes were selected from 5 SRLV highly infected flocks (mean seroprevalence, 90.7%) for presenting uni- or bilateral chronic arthritis in the carpal joint. A complete study was performed, including symptomatology, histopathology, immunocytochemistry, immunohistochemistry, in situ hybridization, and microbiology. The carpus was the joint almost exclusively affected, with 10 sheep (76%) showing a moderate increase in carpal joint size (diameter range, 18–20 cm; normal range, 15–16 cm) without signs of locomotion problems and with 3 ewes (23%) showing severe inflammation with marked increase in diameter (21–24 cm), pain at palpation, and abnormal standing position. Grossly, chronic proliferative arthritis was observed in affected joints characterized by an increased thickness of the synovial capsule and synovial membrane proliferation. Microscopically, synovial membrane inflammation and proliferation and hyperplasia of synoviocytes were observed. More positive cases of SLRV infection were detected by immunocytochemistry of articular fluid than of bronchoalveolar lavage fluid. Immunohistochemistry and in situ hybridization also detected positive cells in the subsynovial connective tissue, lung, mediastinal lymph node, mammary gland, and mammary lymph node. All animals were negative for the presence of Mycoplasma or other bacteria in the articular space. The present outbreak likely represents an adaptation of a caprine virus to sheep. Our results underline the importance of the arthritis induced by SRLV in sheep, a clinical form that might be underestimated. © The Author(s) 2014.

Los lentivirus de pequeños rumiantes (SRLV), que incluyen al virus Visna/Maedi (VMV) y al de la artritis encefalitis caprina (CAEV), infectan ovejas y cabras distribuidas por todo el mundo causando un cuadro multisistémico que afecta articulaciones, pulmones, glándula mamaria y sistema nervioso central. Las pérdidas derivadas de la infección van desde el aumento en la tasa de reposición, a un descenso en las producciones animales o en el valor comercial del rebaño. Aunque la enfermedad causada por los SRLV es de carácter lento y generalmente afecta a pulmones y glándula mamaria en nuestro país, se han descrito brotes epidemiológicos causantes de artritis y encefalitis en ovinos que afectan un gran número de animales, causando pérdidas directas. En la actualidad existen 5 genotipos descritos (A-E) que presentan una alta variabilidad genética y biológica. Los genotipos A y B a los que pertenecen las estirpes clásicas de VMV y CAEV respectivamente, están distribuidos mundialmente, mientras que los genotipos C y E están restringidos a zonas geográficas concretas. En ausencia de tratamientos o vacunas totalmente protectoras, las medidas de control se basan en la detección temprana de animales infectados y su posterior eliminación del rebaño. Tras la infección, los animales infectados desarrollan una respuesta de anticuerpos que, si bien no es capaz de eliminar el virus, es indicadora de la infección. Así, empleando métodos de detección serológica podemos diagnosticar la infección indirectamente. Los métodos más eficaces hasta el momento son los ELISAs basados en proteínas recombinantes y péptidos sintéticos. Sin embargo, los métodos disponibles en el comercio están diseñados teniendo en cuenta una única estirpe viral, que sumado a la alta variabilidad antigénica de los SRLV, hace que las medidas disponibles fallen a la hora de controlar todo el espectro antigénico presente. La organización genómica de los lentivirus está bastante conservada entre los miembros del género., a) Aislamiento y caracterización genética de estirpes implicadas en el brote artrítico. En España se han detectado los primeros casos de artritis en ovinos aunque hasta el momento las secuencias encontradas tanto en ovinos como en caprinos son del tipo virus Visna/Maedi (VMV). Teniendo en cuenta que la artritis es un signo más abundante entre cabras infectadas, es importante determinar si la secuencia genética del virus implicado en la artritis ovina es similar al virus de la artritis encefalitis caprina (CAEV). Las secuencias encontradas en los animales afectados se agrupaban en el genotipo B2 de SRLV (tipo CAEV), sugiriendo una posible asociación entre el grupo genético y la patología inducida. Además, se obtuvo un aislado cuyo genoma completo semejaba las estirpes de CAEV siendo sólo la integrasa de tipo VMV. Aunque la región LTR no contenía repeticiones y una deleción en la región R, propuestas como atenuantes de la replicación, el fenotipo observado en cultivos de fibroblastos de piel ovinos fue rápido/alto. El estudio de este brote epidemiológico representa la primera descripción de secuencias de tipo CAEV en ovinos así como la primera estirpe aislada de SRLV en España., b) Aislamiento y caracterización genética de estirpes implicadas en el brote de encefalitis. Se ha descrito un brote extenso en ovinos caracterizado por la presencia de síntomas neurológicos en España. No se conocen las características de los virus implicados y tampoco se dispone de herramientas diagnósticas específicas para dicho brote. Los animales presentaron lesiones en la médula espinal, hecho diferencial del brote, de los que aislamos una estirpe representativa. Las secuencias obtenidas fueron asignadas al genotipo A2/A3 al que pertenecen otras estirpes causantes de encefalitis. La región LTR carecía de repeticiones pero la actividad transcripcional en fibroblastos ovinos resultó ser alta. Sin embargo, los estudios in vitro revelaron que la producción viral fue lenta/baja en fibroblastos ovinos pero alta en macrófagos derivados de monocitos sanguíneos. Así, parece que la replicación viral no puede deducirse de la actividad transcripcional del LTR y su asociación puede no ser correcta. Un análisis de los epitopos inmunodominantes de la envoltura de los SRLV implicados en el brote y de otros descritos, condujo al diseño de un péptido sintético con el que desarrollamos un ELISA capaz de detectar los animales afectados por el brote de encefalitis, pero no los afectados por otras formas de la enfermedad. Así generamos una herramienta diagnóstica específica de interés epidemiológico para controlar la diseminación de estas estirpes altamente patogénicas., c) Caracterización de la restricción de los SRLV por APOBEC3. Los factores intrínsecos de la inmunidad innata incluyen la apolipoprotein B editing enzyme catalytic polypeptide-like 3 (APOBEC3) que inhibe la replicación viral por diferentes mecanismos, incluyendo la desaminación de citosinas del DNA viral. Los ovinos contienen tres genes APOBEC3 que codifican cuatro proteínas (A3Z1, A3Z2, A3Z3, A3Z2Z3) con características antivirales aún desconocidas. Empleando monocitos y macrófagos derivados de monocitos sanguíneos, caracterizamos en este trabajo un descenso acusado en la expresión de A3Z1 que coincide con un aumento significativo de la replicación viral. El análisis de los transcritos de A3Z1 reveló la presencia de variantes derivadas de splicing (A3Z1Tr) que carecían del dominio citidín desaminasa, responsable de la actividad enzimática. Células homólogas (fibroblastos ovinos) transfectadas con A3Z1 mostraron una reducida producción viral tras la infección con SRLV en comparación con A3Z1Tr. A pesar de ello, no se encontraron signos evidentes de desaminación en las secuencias virales obtenidas. Se detectaron variantes derivadas de splicing equivalentes en células humanas y de mono, generalizando la presencia de proteínas A3 truncadas derivadas de splicing en primates. La restricción global mediada por A3Z1 podría estar regulada por la expresión génica de isoformas truncadas derivadas de splicing que carezcan del dominio citidín desaminasa.

A single broadly reactive standard ELISA is commonly applied to control small ruminant lentivirus (SRLV) spread, but type specific ELISA strategies are gaining interest in areas with highly prevalent and heterogeneous SRLV infections. Short (15-residue) synthetic peptides (n= 60) were designed in this study using deduced amino acid sequence profiles of SRLV circulating in sheep from North Central Spain and SRLV described previously. The corresponding ELISAs and two standard ELISAs were employed to analyze sera from sheep flocks either controlled or infected with different SRLV genotypes. Two outbreaks, showing SRLV-induced arthritis (genotype B2) and encephalitis (genotype A), were represented among the infected flocks. The ELISA results revealed that none of the assays detected all the infected animals in the global population analyzed, the assay performance varying according to the genetic type of the strain circulating in the area and the test antigen. Five of the six highly reactive (57-62%) single peptide ELISAs were further assessed, revealing that the ELISA based on peptide 98M (type A ENV-SU5, consensus from the neurological outbreak) detected positives in the majority of the type-A specific sera tested (Se: 86%; Sp: 98%) and not in the arthritic type B outbreak. ENV-TM ELISAs based on peptides 126M1 (Se: 82%; Sp: 95%) and 126M2 0,65 0.77 (Se: 68%; Sp: 88%) detected preferentially caprine arthritis encephalitis (CAEV, type B) and visna/maedi (VMV, type A) virus infections respectively, which may help to perform a preliminary CAEV vs. VMV-like typing of the flock. The use of particular peptide ELISAs and standard tests individually or combined may be useful in the different areas under study, to determine disease progression, diagnose/type infection and prevent its spread. © 2013 Elsevier B.V.

Thirty-one sheep naturally infected with small ruminant lentiviruses (SRLV) of known genotype (A or B), and clinically affected with neurological disease, pneumonia or arthritis were used to analyse mannose receptor (MR) expression (transcript levels) and proviral load in virus target tissues (lung, mammary gland, CNS and carpal joints). Control sheep were SRLV-seropositive asymptomatic (n = 3), seronegative (n = 3) or with chronic listeriosis, pseudotuberculosis or parasitic cysts (n = 1 in each case). MR expression and proviral load increased with the severity of lesions in most analyzed organs of the SRLV infected sheep and was detected in the affected tissue involved in the corresponding clinical disease (CNS, lung and carpal joint in neurological disease, pneumonia and arthritis animal groups, respectively). The increased MR expression appeared to be SRLV specific and may have a role in lentiviral pathogenesis.

An extensive outbreak characterized by the appearance of neurological symptoms in small ruminant lentivirus (SRLV) infected sheep has been identified in Spain, but the genetic characteristics of the strain involved and differential diagnostic tools for this outbreak remain unexplored. In this work, 23 Visna-affected naturally infected animals from the outbreak, 11 arthritic animals (both groups presenting anti-Visna/Maedi virus serum antibodies), and 100 seronegative animals were used. Eight of the Visna-affected animals were further studied post-mortem by immunohistochemistry. All had lesions in spinal cord, being the most affected part of the central nervous system in six of them. A representative strain of the outbreak was isolated. Together with other proviral sequences from the outbreak the virus was assigned to genotype A2/A3. In vitro culture of the isolate revealed that viral production was slow/low in fibroblast-like cells but it was high in blood monocyte-derived macrophages. The long terminal repeat (LTR) of the viral genome of this isolate lacked an U3-duplication, but its promoter activity in fibroblast-like cells was normal compared to other strains. Thus, viral production could not be inferred from the LTR promoter activity in this isolate. Analysis of the viral immunodominant epitopes among SRLV sequences of the outbreak and other known sequences allowed the design of a synthetic SU peptide ELISA that detected the Visna affected animals, representing a tool of epidemiological interest to control viral spread of this highly pathogenic strain.

[Background] A central nervous system (CNS) disease outbreak caused by small ruminant lentiviruses (SRLV) has triggered interest in Spain due to the rapid onset of clinical signs and relevant production losses. In a previous study on this outbreak, the role of LTR in tropism was unclear and env encoded sequences, likely involved in tropism, were not investigated. This study aimed to analyze heterogeneity of SRLV Env regions - TM amino terminal and SU V4, C4 and V5 segments - in order to assess virus compartmentalization in CNS., [Results] Eight Visna (neurologically) affected sheep of the outbreak were used. Of the 350 clones obtained after PCR amplification, 142 corresponded to CNS samples (spinal cord and choroid plexus) and the remaining to mammary gland, blood cells, bronchoalveolar lavage cells and/or lung. The diversity of the env sequences from CNS was 11.1-16.1% between animals and 0.35-11.6% within each animal, except in one animal presenting two sequence types (30% diversity) in the CNS (one grouping with those of the outbreak), indicative of CNS virus sequence heterogeneity. Outbreak sequences were of genotype A, clustering per animal and compartmentalizing in the animal tissues. No CNS specific signature patterns were found., [Conclusions] Bayesian approach inferences suggested that proviruses from broncoalveolar lavage cells and peripheral blood mononuclear cells represented the common ancestors (infecting viruses) in the animal and that neuroinvasion in the outbreak involved microevolution after initial infection with an A-type strain. This study demonstrates virus compartmentalization in the CNS and other body tissues in sheep presenting the neurological form of SRLV infection.

The presence of proviral DNA, mRNA transcripts and/or viral proteins in small ruminant lentiviral infections may be intermittent. The aim of this study was to identify methods of avoiding small ruminant lentivirus (SRLV) transmission to ewes when using infected rams in artificial insemination (AI). Semen from rams, seropositive and PCR-positive in blood but consistently negative for both proviral DNA and viral protein expression in semen, was used to artificially inseminate 19 ewes. Follow-up investigation of these ewes and of two of their offspring indicated that under the study conditions virus transmission through insemination did not occur. These preliminary findings suggest that semen from SRLV-infected rams could be used for AI without the risk of transmitting virus to susceptible ewes or their lambs. Further larger studies will be required to confirm this finding. © 2010 Elsevier Ltd.