Antiretroviral therapy promotes an inflammatory-like pattern of human T-cell lymphotropic virus type 1 (HTLV-1) replication in human immunodeficiency virus type 1/HTLV-1 co-infected individuals.

Upon antiretroviral therapy (ART) human immunodeficiency virus (HIV)/human T-cell lymphotropic virus type 1 (HTLV-1) co-infected individuals frequently develop neurological disorders through hitherto unknown mechanisms. Here, we show that effective anti-HIV ART increases HTLV-1 proviral load through a polyclonal integration pattern of HTLV-1 in both CD4(+) and CD8(+) T-cell subsets that is reminiscent of that typically associated with HTLV-1-related inflammatory conditions. These data indicate that preventing ART-triggered clonal expansion of HTLV-1-infected cells in co-infected individuals deserves investigation.

Functional characterization of Negri bodies (NBs) in rabies virus-infected cells: Evidence that NBs are sites of viral transcription and replication.

Rabies virus infection induces the formation of cytoplasmic inclusion bodies that resemble Negri bodies found in the cytoplasm of some infected nerve cells. We have studied the morphogenesis and the role of these Negri body-like structures (NBLs) during viral infection. The results indicate that these spherical structures (one or two per cell in the initial stage of infection), composed of the viral N and P proteins, grow during the virus cycle before appearing as smaller structures at late stages of infection. We have shown that the microtubule network is not necessary for the formation of these inclusion bodies but is involved in their dynamics. In contrast, the actin network does not play any detectable role in these processes. These inclusion bodies contain Hsp70 and ubiquitinylated proteins, but they are not misfolded protein aggregates. NBLs, in fact, appear to be functional structures involved in the viral life cycle. Specifically, using in situ fluorescent hybridization techniques, we show that all viral RNAs (genome, antigenome, and every mRNA) are located inside the inclusion bodies. Significantly, short-term RNA labeling in the presence of BrUTP strongly suggests that the NBLs are the sites where viral transcription and replication take place.

A dose-effect relationship for deltaretrovirus-dependent leukemogenesis in sheep.

BACKGROUND: Retrovirus-induced tumors develop in a broad range of frequencies and after extremely variable periods of time, from only a few days to several decades, depending mainly on virus type. For hitherto unexplained reasons, deltaretroviruses cause hematological malignancies only in a minority of naturally infected organisms and after a very prolonged period of clinical latency. RESULTS: Here we demonstrate that the development of malignancies in sheep experimentally infected with the deltaretrovirus bovine leukemia virus (BLV) depends only on the level of BLV replication. Animals were experimentally infected with leukemogenic or attenuated, but infectious, BLV molecular clones and monitored prospectively through 8 months for viral replication. As early as 2 weeks after infection and subsequently at any time during follow-up, leukemogenic viruses produced significantly higher absolute levels of reverse transcription (RT), clonal expansion of infected cells, and circulating proviruses with RT- and somatic-dependent mutations than attenuated viruses. These differences were only quantitative, and both kinds of viruses triggered parallel temporal fluctuations of host lymphoid cells, viral loads, infected cell clonality and proliferation. CONCLUSION: Deltaretrovirus-associated leukemogenesis in sheep appears to be a two-hit process over time depending on the amounts of first horizontally and then vertically expanded viruses.

[Virus-induced compartimentalization: aggresomes, cytoplasmic inclusions and viral factories]. / Compartimentalisation cellulaire viro-induite: agrésomes, inclusions virales et usines virales.

Some viruses induce, in the infected cells, the formation of cytoplasmic inclusions that are known to contain viral proteins. These viral inclusions that share some characteristics of aggresomes have been considered as sideproducts of the infectious process without any role and resulting from the accumulation and aggregation of large quantities of proteins produced in excess during infection. However, recent results obtained on some viral families suggest that these inclusions have different functions: they can be sites of specific degradation of antiviral proteins or viral factories where essential viral steps (transcription/replication, translation, viral assembly) take place. It is supposed that the viruses-induced compartimentalization is the result of cellular defense mechanisms, which would be diverted by virus for their own replication.

Cardiac Propagation Pattern Mapping With Vector Field for Helping Tachyarrhythmias Diagnosis With Clinical Tridimensional Electro-Anatomical Mapping Tools.

Ventricular (VT) and atrial (AT) tachycardias are some of the most common clinical cardiac arrhythmias. For ablation of tachycardia substrates, two clinical diagnosis methods are used: invasive electroanatomical mapping for an accurate diagnosis using electrograms (EGMs) acquired with intracardiac catheters, and localized on the surface mesh of the studied cavities; and noninvasive electrocardiographic imaging (ECGi) for a global view of the arrhythmia, with EGMs mathematically reconstructed from body surface electrocardiograms using 3-D cardio-thoracic surface meshes obtained from CT-scans. In clinics, VT and AT are diagnosed by studying activation time maps that depict the propagation of the activation wavefront on the cardiac mesh. Nevertheless, slow conduction areas-a well-known proarrhythmic feature for tachycardias-and tachycardia specific propagation patterns are not easily identifiable with these maps. Therefore, local characterization of the activation wavefront propagation can be helpful for improving VT and AT diagnoses. The purpose of this study is to develop a method to locally characterize the activation wavefront propagation for clinical data. For this, a conduction velocity vector field is estimated and analyzed using divergence and curl mathematical operators. The workflow was first validated on a simulated database from computer models, and then applied to a clinical database obtained from ECGi to improve AT diagnosis. The results show the relevancy and the efficacy of the proposed method to guide ablation of tachyarrhythmias.

Early and transient reverse transcription during primary deltaretroviral infection of sheep.

BACKGROUND: Intraindividual genetic variability plays a central role in deltaretrovirus replication and associated leukemogenesis in animals as in humans. To date, the replication of these viruses has only been investigated during the chronic phase of the infection when they mainly spread through the clonal expansion of their host cells, vary through a somatic mutation process without evidence for reverse transcriptase (RT)-associated substitution. Primary infection of a new organism necessary involves allogenic cell infection and thus reverse transcription. RESULTS: Here we demonstrate that the primary experimental bovine leukemia virus (BLV) infection of sheep displays an early and intense burst of horizontal replicative dissemination of the virus generating frequent RT-associated substitutions that account for 69% of the in vivo BLV genetic variability during the first 8 months of the infection. During this period, evidence has been found of a cell-to-cell passage of a mutated sequence and of a sequence having undergone both RT-associated and somatic mutations. The detection of RT-dependent proviral substitution was restricted to a narrow window encompassing the first 250 days following seroconversion. CONCLUSION: In contrast to lentiviruses, deltaretroviruses display two time-dependent mechanisms of genetic variation that parallel their two-step nature of replication in vivo. We propose that the early and transient RT-based horizontal replication helps the virus escape the first wave of host immune response whereas somatic-dependent genetic variability during persistent clonal expansion helps infected clones escape the persistent and intense immune pressure that characterizes the chronic phase of deltaretrovirus infection.

Noninvasive Assessment of Atrial Fibrillation Complexity in Relation to Ablation Characteristics and Outcome.

Background: The use of surface recordings to assess atrial fibrillation (AF) complexity is still limited in clinical practice. We propose a noninvasive tool to quantify AF complexity from body surface potential maps (BSPMs) that could be used to choose patients who are eligible for AF ablation and assess therapy impact. Methods: BSPMs (mean duration: 7 ± 4 s) were recorded with a 252-lead vest in 97 persistent AF patients (80 male, 64 ± 11 years, duration 9.6 ± 10.4 months) before undergoing catheter ablation. Baseline cycle length (CL) was measured in the left atrial appendage. The procedural endpoint was AF termination. The ablation strategy impact was defined in terms of number of regions ablated, radiofrequency delivery time to achieve AF termination, and acute outcome. The atrial fibrillatory wave signal extracted from BSPMs was divided in 0.5-s consecutive segments, each projected on a 3D subspace determined through principal component analysis (PCA) in the current frame. We introduced the nondipolar component index (NDI) that quantifies the fraction of energy retained after subtracting an equivalent PCA dipolar approximation of heart electrical activity. AF complexity was assessed by the NDI averaged over the entire recording and compared to ablation strategy. Results: AF terminated in 77 patients (79%), whose baseline AF CL was 177 ± 40 ms, whereas it was 157 ± 26 ms in patients with unsuccessful ablation outcome (p = 0.0586). Mean radiofrequency emission duration was 35 ± 21 min; 4 ± 2 regions were targeted. Long-lasting AF patients (≥12 months) exhibited higher complexity, with higher NDI values (≥12 months: 0.12 ± 0.04 vs. <12 months: 0.09 ± 0.03, p < 0.01) and short CLs (<160 ms: 0.12 ± 0.03 vs. between 160 and 180 ms: 0.10 ± 0.03 vs. >180 ms: 0.09 ± 0.03, p < 0.01). More organized AF as measured by lower NDI was associated with successful ablation outcome (termination: 0.10 ± 0.03 vs. no termination: 0.12 ± 0.04, p < 0.01), shorter procedures (<30 min: 0.09 ± 0.04 vs. ≥30 min: 0.11 ± 0.03, p < 0.001) and fewer ablation targets (<4: 0.09 ± 0.03 vs. ≥4: 0.11 ± 0.04, p < 0.01). Conclusions: AF complexity can be noninvasively quantified by PCA in BSPMs and correlates with ablation outcome and AF pathophysiology.

Fate of premalignant clones during the asymptomatic phase preceding lymphoid malignancy.

Almost all cancers are preceded by a prolonged period of clinical latency during which a combination of cellular events helps move carcinogen-exposed cells towards a malignant phenotype. Hitherto, investigating the fate of premalignant cells in vivo remained strongly hampered by the fact that these cells are usually indistinguishable from their normal counterparts. Here, for the first time, we have designed a strategy able to reconstitute the replicative history of the bona fide premalignant clone in an animal model, the sheep experimentally infected with the lymphotropic bovine leukemia virus. We have shown that premalignant clones are early and clearly distinguished from other virus-exposed cells on the basis of their degree of clonal expansion and genetic instability. Detectable as early as 0.5 month after the beginning of virus exposure, premalignant cells displayed a two-step pattern of extensive clonal expansion together with a mutation load approximately 6 times higher than that of other virus-exposed cells that remained untransformed during the life span of investigated animals. There was no fixation of somatic mutations over time, suggesting that they regularly lead to cellular death, partly contributing to maintain a normal lymphocyte count during the prolonged premalignant stage. This equilibrium was finally broken after a period of 18.5 to 60 months of clinical latency, when a dramatic decrease in the genetic instability of premalignant cells coincided with a rapid increase in lymphocyte count and lymphoma onset.

Complexity and Distribution of Drivers in Relation to Duration of Persistent Atrial Fibrillation.

BACKGROUND: The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood. OBJECTIVES: This study sought to investigate the complexity and distribution of AF drivers in PsAF of varying durations. METHODS: Of 135 consecutive patients with PsAF, 105 patients referred for de novo ablation of PsAF were prospectively recruited. Patients were divided into 3 groups according to AF duration: PsAF presenting in sinus rhythm (AF induced), PsAF <12 months, and PsAF >12 months. Patients wore a 252-electrode vest for body surface mapping. Localized drivers (re-entrant or focal) were identified using phase-mapping algorithms. RESULTS: In this patient cohort, the most prominent re-entrant driver regions included the pulmonary vein (PV) regions and inferoposterior left atrial wall. Focal drivers were observed in 1 or both PV regions in 75% of patients. Comparing between the 3 groups, with longer AF duration AF complexity increased, reflected by increased number of re-entrant rotations (p < 0.05), number of re-entrant rotations and focal events (p < 0.05), and number of regions harboring re-entrant (p < 0.01) and focal (p < 0.05) drivers. With increased AF duration, a higher proportion of patients had multiple extra-PV driver regions, specifically in the inferoposterior left atrium (p < 0.01), superior right atrium (p < 0.05), and inferior right atrium (p < 0.05). Procedural AF termination was achieved in 70% of patients, but decreased with longer AF duration. CONCLUSIONS: The complexity of AF drivers increases with prolonged AF duration. Re-entrant and focal drivers are predominantly located in the PV antral and adjacent regions. However, with longer AF duration, multiple drivers are distributed at extra-PV sites. AF termination rate declines as patients progress to longstanding PsAF, underscoring the importance of early intervention.

Persistent Atrial Fibrillation From the Onset: A Specific Subgroup of Patients With Biatrial Substrate Involvement and Poorer Clinical Outcome.

OBJECTIVES: This study sought to characterize the clinical characteristics, atrial substrate, and prognosis in a subgroup of patients with persistent atrial fibrillation (AF) from the onset (PsAFonset). BACKGROUND: Patients with AF frequently progress from trigger-driven paroxysmal arrhythmias to substrate-dependent persistent arrhythmias. METHODS: Patients referred for persistent AF (PsAF) ablation were enrolled from 3 centers. Consecutive patients with PsAFonset (n = 129) were compared with patients with PsAF that progressed from paroxysmal AF (n = 231). In addition, 90 patients (30 patients with PsAFonset and 60 control subjects) were studied with noninvasive mapping to characterize the AF drivers. The degree of fractionation and endocardial voltages were assessed invasively. RESULTS: Patients with PsAFonset were younger (p = 0.047) and more obese (p < 0.001); there were more men (p = 0.034), more patients with hypertension (p = 0.044), and these patients had larger left (p < 0.05) and right atria (p < 0.05). Baseline AF cycle length was shorter in the PsAFonset group (p < 0.01); the degree of fractionation was higher (p < 0.001 for both atria), and the endocardial voltage was lower (p < 0.05 for both atria). Patients with PsAFonset had higher a number of re-entrant driver regions (p < 0.001) and extrapulmonary vein regions that had re-entrant drivers (p < 0.05), whereas control subjects displayed more focal driver regions (p = 0.029). The acute AF termination rate was lower in the PsAFonset group (42% vs. 81%; p < 0.001). During a mean follow-up of 17 ± 11 months from the last procedure, patients with PsAFonset had significantly higher AF, atrial tachycardia (AT), and AF/AT recurrence rates (p < 0.01). CONCLUSIONS: Patients with PsAFonset represent a distinct subgroup defined by specific demographics, underlying diffuse biatrial substrate disease, and worse clinical outcome. The findings highlight the importance of defining criteria for early detection of atrial substrate disease.