cis-Acting Element at the 5' Noncoding Region of Tacaribe Virus S RNA Modulates Genome Replication.

Tacaribe virus (TCRV) is the prototype of New World mammarenaviruses, a group that includes several members that cause hemorrhagic fevers in humans. The TCRV genome comprises two RNA segments, named S (small) and L (large). Both genomic segments contain noncoding regions (NCRs) at their 5' and 3' ends. While the 5'- and 3'-terminal 19-nucleotide sequences are known to be essential for promoter function, the role of their neighboring internal noncoding region (iNCR) sequences remains poorly understood. To analyze the relevance of the 5' and 3' iNCRs in TCRV S RNA synthesis, mutant S-like minigenomes and miniantigenomes were generated. Using a minireplicon assay, Northern blotting, and reverse transcription-quantitative PCR, we demonstrated that the genomic 5' iNCR is specifically engaged in minigenome replication yet is not directly involved in minigenome transcription, and we showed that the S genome 3' iNCR is barely engaged in this process. Analysis of partial deletions and point mutations, as well as total or partial substitution of the 5' iNCR sequence, led us to conclude that the integrity of the whole genomic 5' iNCR is essential and that a local predicted secondary structure or RNA-RNA interactions between the 5' and 3' iNCRs are not strictly required for viral S RNA synthesis. Furthermore, we employed a TCRV reverse genetic approach to ask whether manipulation of the S genomic 5' iNCR sequence may be suitable for viral attenuation. We found that mutagenesis of the 5' promoter-proximal subregion slightly impacted recombinant TCRV virulence in vivo. IMPORTANCE The Mammarenavirus genus of the Arenaviridae family includes several members that cause severe hemorrhagic fevers associated with high morbidity and mortality rates, for which no FDA-approved vaccines and limited therapeutic resources are available. We provide evidence demonstrating the specific involvement of the TCRV S 5' noncoding sequence adjacent to the viral promoter in replication. In addition, we examined the relevance of this region in the context of an in vivo infection. Our findings provide insight into the mechanism through which this 5' viral RNA noncoding region assists the L polymerase for efficient viral S RNA synthesis. Also, these findings expand our understanding of the effect of genetic manipulation of New World mammarenavirus sequences aimed at the rational design of attenuated recombinant virus vaccine platforms.

Deconstructing virus condensation.

Viruses have evolved precise mechanisms for using the cellular physiological pathways for their perpetuation. These virus-driven biochemical events must be separated in space and time from those of the host cell. In recent years, granular structures, known for over a century for rabies virus, were shown to host viral gene function and were named using terms such as viroplasms, replication sites, inclusion bodies, or viral factories (VFs). More recently, these VFs were shown to be liquid-like, sharing properties with membrane-less organelles driven by liquid-liquid phase separation (LLPS) in a process widely referred to as biomolecular condensation. Some of the best described examples of these structures come from negative stranded RNA viruses, where micrometer size VFs are formed toward the end of the infectious cycle. We here discuss some basic principles of LLPS in connection with several examples of VFs and propose a view, which integrates viral replication mechanisms with the biochemistry underlying liquid-like organelles. In this view, viral protein and RNA components gradually accumulate up to a critical point during infection where phase separation is triggered. This yields an increase in transcription that leads in turn to increased translation and a consequent growth of initially formed condensates. According to chemical principles behind phase separation, an increase in the concentration of components increases the size of the condensate. A positive feedback cycle would thus generate in which crucial components, in particular nucleoproteins and viral polymerases, reach their highest levels required for genome replication. Progress in understanding viral biomolecular condensation leads to exploration of novel therapeutics. Furthermore, it provides insights into the fundamentals of phase separation in the regulation of cellular gene function given that virus replication and transcription, in particular those requiring host polymerases, are governed by the same biochemical principles.

DDX3 suppresses type I interferons and favors viral replication during Arenavirus infection.

Several arenaviruses cause hemorrhagic fever (HF) diseases that are associated with high morbidity and mortality in humans. Accordingly, HF arenaviruses have been listed as top-priority emerging diseases for which countermeasures are urgently needed. Because arenavirus nucleoprotein (NP) plays critical roles in both virus multiplication and immune-evasion, we used an unbiased proteomic approach to identify NP-interacting proteins in human cells. DDX3, a DEAD-box ATP-dependent-RNA-helicase, interacted with NP in both NP-transfected and virus-infected cells. Importantly, DDX3 deficiency compromised the propagation of both Old and New World arenaviruses, including the HF arenaviruses Lassa and Junin viruses. The DDX3 role in promoting arenavirus multiplication associated with both a previously un-recognized DDX3 inhibitory role in type I interferon production in arenavirus infected cells and a positive DDX3 effect on arenavirus RNA synthesis that was dependent on its ATPase and Helicase activities. Our results uncover novel mechanisms used by arenaviruses to exploit the host machinery and subvert immunity, singling out DDX3 as a potential host target for developing new therapies against highly pathogenic arenaviruses.

Regulation of Tacaribe Mammarenavirus Translation: Positive 5' and Negative 3' Elements and Role of Key Cellular Factors.

Mammarenaviruses are enveloped viruses with a bisegmented negative-stranded RNA genome that encodes the nucleocapsid protein (NP), the envelope glycoprotein precursor (GPC), the RNA polymerase (L), and a RING matrix protein (Z). Viral proteins are synthesized from subgenomic mRNAs bearing a capped 5' untranslated region (UTR) and lacking 3' poly(A) tail. We analyzed the translation strategy of Tacaribe virus (TCRV), a prototype of the New World mammarenaviruses. A virus-like transcript that carries a reporter gene in place of the NP open reading frame and transcripts bearing modified 5' and/or 3' UTR were evaluated in a cell-based translation assay. We found that the presence of the cap structure at the 5' end dramatically increases translation efficiency and that the viral 5' UTR comprises stimulatory signals while the 3' UTR,specifically the presence of a terminal C+G-rich sequence and/or a stem-loop structure, down-modulates translation. Additionally, translation was profoundly reduced in eukaryotic initiation factor (eIF) 4G-inactivated cells, whereas depletion of intracellular levels of eIF4E had less impact on virus-like mRNA translation than on a cell-like transcript. Translation efficiency was independent of NP expression or TCRV infection. Our results indicate that TCRV mRNAs are translated using a cap-dependent mechanism, whose efficiency relies on the interplay between stimulatory signals in the 5' UTR and a negative modulatory element in the 3' UTR. The low dependence on eIF4E suggests that viral mRNAs may engage yet-unknown noncanonical host factors for a cap-dependent initiation mechanism.IMPORTANCE Several members of the Arenaviridae family cause serious hemorrhagic fevers in humans. In the present report, we describe the mechanism by which Tacaribe virus, a prototypic nonpathogenic New World mammarenavirus, regulates viral mRNA translation. Our results highlight the impact of untranslated sequences and key host translation factors on this process. We propose a model that explains how viral mRNAs outcompete cellular mRNAs for the translation machinery. A better understanding of the mechanism of translation regulation of this virus can provide the bases for the rational design of new antiviral tools directed to pathogenic arenaviruses.

Differential contributions of tacaribe arenavirus nucleoprotein N-terminal and C-terminal residues to nucleocapsid functional activity.

UNLABELLED: The arenavirus nucleoprotein (NP) is the main protein component of viral nucleocapsids and is strictly required for viral genome replication mediated by the L polymerase. Homo-oligomerization of NP is presumed to play an important role in nucleocapsid assembly, albeit the underlying mechanism and the relevance of NP-NP interaction in nucleocapsid activity are still poorly understood. Here, we evaluate the contribution of the New World Tacaribe virus (TCRV) NP self-interaction to nucleocapsid functional activity. We show that alanine substitution of N-terminal residues predicted to be available for NP-NP interaction strongly affected NP self-association, as determined by coimmunoprecipitation assays, produced a drastic inhibition of transcription and replication of a TCRV minigenome RNA, and impaired NP binding to RNA. Mutagenesis and functional analysis also revealed that, while dispensable for NP self-interaction, key amino acids at the C-terminal domain were essential for RNA synthesis. Furthermore, mutations at these C-terminal residues rendered NP unable to bind RNA both in vivo and in vitro but had no effect on the interaction with the L polymerase. In addition, while all oligomerization-defective variants tested exhibited unaltered capacities to sustain NP-L interaction, NP deletion mutants were fully incompetent to bind L, suggesting that, whereas NP self-association is dispensable, the integrity of both the N-terminal and C-terminal domains is required for binding the L polymerase. Overall, our results suggest that NP self-interaction mediated by the N-terminal domain may play a critical role in TCRV nucleocapsid assembly and activity and that the C-terminal domain of NP is implicated in RNA binding. IMPORTANCE: The mechanism of arenavirus functional nucleocapsid assembly is still poorly understood. No detailed information is available on the nucleocapsid structure, and the regions of full-length NP involved in binding to viral RNA remain to be determined. In this report, novel findings are provided on critical interactions between the viral ribonucleoprotein components. We identify several amino acid residues in both the N-terminal and C-terminal domains of TCRV NP that differentially contribute to NP-NP and NP-RNA interactions and analyze their relevance for binding of NP to the L polymerase and for nucleocapsid activity. Our results provide insight into the contribution of NP self-interaction to RNP assembly and activity and reveal the involvement of the NP C-terminal domain in RNA binding.

Hemodynamic monitoring and echocardiographic evaluation in cardiogenic shock.

Cardiogenic shock (CS) is characterized by the presence of a state of tissue hypoperfusion secondary to ventricular dysfunction. Hemodynamic monitoring allows us to obtain information about cardiovascular pathophysiology that will help us make the diagnosis and guide therapy in CS situations. The most used monitoring system in CS is the pulmonary artery catheter since it provides key hemodynamic variables in CS, such as cardiac output, pulmonary artery pressure, and pulmonary artery occlusion pressure. On the other hand, echocardiography makes it possible to obtain, at the bedside, anatomical and hemodynamic data that complement the information obtained through continuous monitoring devices. CS monitoring can be considered multimodal and integrative by including hemodynamic, metabolic, and echocardiographic parameters that allow describing the characteristics of CS and guiding therapeutic interventions during hemodynamic resuscitation.

Translation cost, quality, and adequacy.

PURPOSE: Although the inclusion of non-native-speaking participants in nursing research is important in every country where nursing research takes place, the literature contains little on the method of achieving quality translation while simultaneously addressing cost containment. We describe a process for evaluating translation adequacy and demonstrate its use in comparing procedures for translating data from non-native-speaking interviews. ORGANIZING CONSTRUCT: This work demonstrates a process for establishing, evaluating, and achieving translation adequacy when conducting qualitative research for cross-cultural comparisons. METHODS: In an ethnographic investigation of disability in Mexican American women, we describe a process for obtaining translation adequacy, defined here as the methodological goal whereby the quality of the translated text meets the needs of the specified study. Using a subset of responses transcribed from Spanish audiotapes into Spanish text, the text was subjected to two separate translation processes, which were compared for adequacy based on error rates and accuracy of meaning, as well as for cost. FINDINGS: The process for discriminating translation adequacy was sensitive to differences in certified versus noncertified translators. While the noncertified translation initially appeared to be seven times less expensive than the certified process, auditing and correcting errors in noncertified translations substantially increased cost. No errors were found with the certified translations. CONCLUSIONS: The level of translation adequacy needed for any qualitative study should be considered before beginning the study itself. Based on a predetermined level, translation choices can be assessed using specified methods, which can also lead to greater transparency in the research process. CLINICAL RELEVANCE: An ongoing process to verify translation outcomes including cost, a component minimally discussed in the current literature, is relevant to nurses worldwide. Awareness of expense and quality issues makes greater methodological transparency possible in the design of translation projects and research studies.

Nuclease Activity of the Junín Virus Nucleoprotein C-Terminal Domain.

The mammarenavirus Junín (JUNV) is the causative agent of Argentine hemorrhagic fever, a severe disease of public health concern. The most abundant viral protein is the nucleoprotein (NP), a multifunctional, two-domain protein with the primary role as structural component of the viral nucleocapsids, used as template for viral polymerase RNA synthesis activities. Here, we report that the C-terminal domain (CTD) of the attenuated Candid#1 strain of the JUNV NP can be purified as a stable soluble form with a secondary structure in line with known NP structures from other mammarenaviruses. We show that the JUNV NP CTD interacts with the viral matrix protein Z in vitro, and that the full-length NP and Z interact with each other in cellulo, suggesting that the NP CTD is responsible for this interaction. This domain comprises an arrangement of four acidic residues and a histidine residue conserved in the active site of exoribonucleases belonging to the DEDDh family. We show that the JUNV NP CTD displays metal-ion-dependent nuclease activity against DNA and single- and double-stranded RNA, and that this activity is impaired by the mutation of a catalytic residue within the DEDDh motif. These results further support this activity, not previously observed in the JUNV NP, which could impact the mechanism of the cellular immune response modulation of this important pathogen.

Cardiogenic shock code 2023. Expert document for a multidisciplinary organization that allows quality care.

Despite the efforts made to improve the care of cardiogenic shock (CS) patients, including the development of mechanical circulatory support (MCS), the prognosis of these patients continues to be poor. In this context, CS code initiatives arise, based on providing adequate, rapid, and quality care to these patients. In this multidisciplinary document we try to justify the need to implement the SC code, defining its structure/organization, activation criteria, patient flow according to care level, and quality indicators. Our specific purposes are: a) to present the peculiarities of this condition and the lessons of infarction code and previous experiences in CS; b) to detail the structure of the teams, their logistics and the bases for the management of these patients, the choice of the type of MCS, and the moment of its implantation, and c) to address challenges to SC code implementation, including the uniqueness of the pediatric SC code. There is an urgent need to develop protocolized, multidisciplinary, and centralized care in hospitals with a large volume and experience that will minimize inequity in access to the MCS and improve the survival of these patients. Only institutional and structural support from the different administrations will allow optimizing care for CS.

Molecular determinants of arenavirus Z protein homo-oligomerization and L polymerase binding.

The arenavirus Z is a zinc-binding RING protein that has been implicated in multiple functions during the viral life cycle. These roles of Z involve interactions with viral and cellular proteins that remain incompletely understood. In this regard, Z inhibits viral RNA transcription and replication through direct interaction with the viral L polymerase. Here, we defined the L-binding domain of Tacaribe virus (TCRV) Z protein and the structural requirements mediating Z homo-oligomerization. By using site-directed mutagenesis, coimmunoprecipitation, and functional assays, we showed that residues R37, N39, W44, L50, and Y57, located around the zinc coordination site I, play a critical role in the Z-L interaction. We also found that Z protein from either TCRV or the pathogenic Junin virus (JUNV) self-associates into oligomeric forms in mammalian cells. Importantly, mutation of the myristoylation site, the strictly conserved residue G at position 2, severely impaired the ability of both TCRV Z and JUNV Z to self-interact as well as their capacity to accumulate at the plasma membrane, strongly suggesting that Z homo-oligomerization is associated with its myristoylation and cell membrane targeting. In contrast, disruption of the RING structure or substitution of W44 or N39, which are critical for L protein recognition, did not affect Z self-binding. Overall, the data presented here indicate that homo-oligomerization is not a requirement for Z-L interaction or Z-mediated polymerase activity inhibition.

Identification of two functional domains within the arenavirus nucleoprotein.

Tacaribe virus (TCRV) belongs to the Arenaviridae family. Its bisegmented negative-stranded RNA genome encodes the nucleoprotein (N), the precursor of the envelope glycoproteins, the polymerase (L), and a RING finger matrix (Z) protein. The 570-amino-acid N protein binds to viral RNA, forming nucleocapsids, which are the template for transcription and replication by the viral polymerase. We have previously shown that the interaction between N and Z is required for assembly of infectious virus-like particles (VLPs) (J. C. Casabona et al., J. Virol. 83:7029-7039, 2009). Here, we examine the functional organization of TCRV N protein. A series of deletions and point mutations were introduced into the N-coding sequence, and the ability of the mutants to sustain heterotypic (N-Z) or homotypic (N-N) interactions was analyzed. We found that N protein displays two functional domains. By using coimmunoprecipitation studies, VLP incorporation assays, and double immunofluorescence staining, the carboxy-terminal region of N was found to be required for N-Z interaction and also necessary for incorporation of N protein into VLPs. Moreover, further analysis of this region showed that the integrity of a putative zinc-finger motif, as well as its amino-flanking sequence (residues 461 to 489), are critical for Z binding and N incorporation into VLPs. In addition, we provide evidence of an essential role of the amino-terminal region of N protein for N-N interaction. In this regard, using reciprocal coimmunoprecipitation analysis, we identified a 28-residue region predicted to form a coiled-coil domain (residues 92 to 119) as a newly recognized molecular determinant of N homotypic interactions.

The Virus-Host Interplay in Junín Mammarenavirus Infection.

Junín virus (JUNV) belongs to the Arenaviridae family and is the causative agent of Argentine hemorrhagic fever (AHF), a severe human disease endemic to agricultural areas in Argentina. At this moment, there are no effective antiviral therapeutics to battle pathogenic arenaviruses. Cumulative reports from recent years have widely provided information on cellular factors playing key roles during JUNV infection. In this review, we summarize research on host molecular determinants that intervene in the different stages of the viral life cycle: viral entry, replication, assembly and budding. Alongside, we describe JUNV tight interplay with the innate immune system. We also review the development of different reverse genetics systems and their use as tools to study JUNV biology and its close teamwork with the host. Elucidating relevant interactions of the virus with the host cell machinery is highly necessary to better understand the mechanistic basis beyond virus multiplication, disease pathogenesis and viral subversion of the immune response. Altogether, this knowledge becomes essential for identifying potential targets for the rational design of novel antiviral treatments to combat JUNV as well as other pathogenic arenaviruses.

Desulfoluna spp. form a cosmopolitan group of anaerobic dehalogenating bacteria widely distributed in marine sponges.

Host-specific microbial communities thrive within sponge tissues and this association between sponge and associated microbiota may be driven by the organohalogen chemistry of the sponge animal. Several sponge species produce diverse organobromine secondary metabolites (e.g. brominated phenolics, indoles, and pyrroles) that may function as a chemical defense against microbial fouling, infection or predation. In this study, anaerobic cultures prepared from marine sponges were amended with 2,6-dibromophenol as the electron acceptor and short chain organic acids as electron donors. We observed reductive dehalogenation from diverse sponge species collected at disparate temperate and tropical waters suggesting that biogenic organohalides appear to enrich for populations of dehalogenating microorganisms in the sponge animal. Further enrichment by successive transfers with 2,6-dibromophenol as the sole electron acceptor demonstrated the presence of dehalogenating bacteria in over 20 sponge species collected from temperate and tropical ecoregions in the Atlantic and Pacific Oceans and the Mediterranean Sea. The enriched dehalogenating strains were closely related to Desulfoluna spongiiphila and Desulfoluna butyratoxydans, suggesting a cosmopolitan association between Desulfoluna spp. and various marine sponges. In vivo reductive dehalogenation in intact sponges was also demonstrated. Organobromide-rich sponges may thus provide a specialized habitat for organohalide-respiring microbes and D. spongiiphila and/or its close relatives are responsible for reductive dehalogenation in geographically widely distributed sponge species.

Immunomodulation of Oxidative Stress during Organ Donation Process: Preliminary Results.

The objective was to quantify oxidative stress resulting from ischemia during the donation process, using malondialdehyde (MDA) measurement, and its modulation by the administration of melatonin. We designed a triple-blind clinical trial with donors randomized to melatonin or placebo. We collected donors by donation after brain death (DBD) and controlled donation after circulatory death (DCD), the latter maintained by normothermic regional perfusion (NRP). Melatonin or placebo was administered prior to donation or following limitation of therapeutic effort (LTE). Demographic variables and medical history were collected. We also collected serial measurements of MDA, at 60 and 90 min after melatonin or placebo administration. A total of 53 donors were included (32 from DBD and 21 from DCD). In the DBD group, 17 donors received melatonin, and 15 placebo. Eight DCD donors were randomized to melatonin and 13 to placebo. Medical history and cause for LTE were similar between groups. Although MDA values did not differ in the DBD group, statistical differences were observed in DCD donors during the 0-60 min interval: -4.296 (-6.752; -2.336) in the melatonin group and -1.612 (-2.886; -0.7445) in controls. Given the antioxidant effect of melatonin, its use could reduce the production of oxidative stress in controlled DCD.

The RING domain and the L79 residue of Z protein are involved in both the rescue of nucleocapsids and the incorporation of glycoproteins into infectious chimeric arenavirus-like particles.

Arenaviruses, such as Tacaribe virus (TacV) and its closely related pathogenic Junin virus (JunV), are enveloped viruses with a bipartite negative-sense RNA genome that encodes the nucleocapsid protein (N), the precursor of the envelope glycoprotein complex (GP), the polymerase (L), and a RING finger protein (Z), which is the driving force of arenavirus budding. We have established a plasmid-based system which allowed the successful packaging of TacV-like nucleocapsids along with Z and GP of JunV into infectious virus-like particles (VLPs). By coexpressing different combinations of the system components, followed by biochemical analysis of the VLPs, the requirements for the assembly of both N and GP into particles were defined. We found that coexpression of N with Z protein in the absence of minigenome and other viral proteins was sufficient to recruit N within lipid-enveloped Z-containing VLPs. In addition, whereas GP was not required for the incorporation of N, coexpression of N substantially enhanced the ratio of GP to Z into VLPs. Disruption of the RING structure or mutation of residue L79 to alanine within Z protein, although it had no effect on Z self-budding, severely impaired VLP infectivity. These mutations drastically altered intracellular Z-N interactions and the incorporation of both N and GP into VLPs. Our results support the conclusion that the interaction between Z and N is required for assembly of both the nucleocapsids and the glycoproteins into infectious arenavirus budding particles.

Development of a Reverse Genetic System to Generate Recombinant Chimeric Tacaribe Virus that Expresses Junín Virus Glycoproteins.

Mammarenaviruses are enveloped and segmented negative-stranded RNA viruses that comprise several pathogenic members associated with severe human hemorrhagic fevers. Tacaribe virus (TCRV) is the prototype for the New World group of mammarenaviruses and is not only naturally attenuated but also phylogenetically and antigenically related to all South American pathogenic mammarenaviruses, particularly the Junín virus (JUNV), which is the etiological agent of Argentinian hemorrhagic fever (AHF). Moreover, since TCRV protects guinea pigs and non-human primates from lethal challenges with pathogenic strains of JUNV, it has already been considered as a potential live-attenuated virus vaccine candidate against AHF. Here, we report the development of a reverse genetic system that relies on T7 polymerase-driven intracellular expression of the complementary copy (antigenome) of both viral S and L RNA segments. Using this approach, we successfully recovered recombinant TCRV (rTCRV) that displayed growth properties resembling those of authentic TCRV. We also generated a chimeric recombinant TCRV expressing the JUNV glycoproteins, which propagated similarly to wild-type rTCRV. Moreover, a controlled modification within the S RNA 5' non-coding terminal sequence diminished rTCRV propagation in a cell-type dependent manner, giving rise to new perspectives where the incorporation of additional attenuation markers could contribute to develop safe rTCRV-based vaccines against pathogenic mammarenaviruses.

Right Ventricular Assist Devices After Heart Transplantation.

BACKGROUND: Severe right ventricular failure (RVF) has a significant incidence among cardiac transplant patients. It is a serious complication and an independent risk factor for postoperative mortality. In this setting, ventricular assist devices (VADs) must be considered if conservative medical management fails. This study sought to examine our series of patients with early RVF after heart transplantation requiring VAD support. METHOD: We analyzed consecutive, adult heart transplant recipients at a third level intensive care unit who underwent transplantation from January 2011 to March 2019 requiring post-transplant mechanical circulatory support for RVF. Demographic characteristics, clinical data, complications, and survival rates were collected. RESULTS: Ten patients were included. Median age was 50 years (range, 31.7-57). Eight patients (80%) were male. The most frequent indication for heart transplantation was ischemic heart disease (4 patients) followed by dilated cardiomyopathy and congenital heart disease (2 patients). Preoperative pulmonary hypertension was present in 6 patients. Three patients required a VAD before transplant. Whole survival rate was 60%. After heart transplantation, 7 patients required renal replacement therapy, 2 patients suffered a hemorrhagic stroke, and 5 patients needed a tracheostomy for long-term ventilation. CONCLUSION: Patients who develop RVF after transplantation have an increased incidence of complications and high mortality after surgery. VADs could be implanted immediately after heart transplantation in high-risk patients.

Transplantation in Congenital Heart Disease: A Challenge.

BACKGROUND: Heart failure is the leading cause of death in grown-up congenital heart disease patients (GUCH). Although heart transplantation (OHT) remains the gold standard in end-stage heart failure, the ratio of GUCH patients undergoing this procedure remains low. OBJECTIVE: Describe the cohort of GUCH patients undergoing heart transplantation at a third-level hospital. METHODS: A retrospective review of GUCH patients undergoing OHT between 1997 and 2019 was conducted at a single tertiary university hospital. We included different preoperative (demographic and clinical data, cardiac catheterization data from the last routine hemodynamic monitoring) and postoperative variables (complications, survival). RESULTS: Fourteen patients were enrolled. The median age was 25.5 years (range, 20.7-32.2). Eight patients (57.1%) were male. The median preoperative left ventricular ejection fraction was 37% (range, 22.5%-55%). As for preoperative hemodynamic evaluation, the median for the mean arterial pulmonary pressure was 19 mm Hg (range, 12-22.5), for the capillary wedge pressure was 16 mm Hg (range, 13.5-19.5), and for pulmonary vascular resistance was 1.83 Wood units (range, 1-4). After OHT, 6 patients (42.9%) suffered an infection, the most common of which was respiratory (3 out of 6). Four patients (28.6%) needed renal replacement therapy, and 4 patients (28.6%) presented liver failure. Four patients (28.6%) developed graft failure, thus requiring mechanical support with extracorporeal membrane oxygenation during a median of 6 days (range, 1-17.5). Survival rate of patients under extracorporeal membrane oxygenation was 50%, and overall survival rate was 78.6%. CONCLUSION: OHT represents a good option for GUCH patients, with good overall survival rates.

Mapping of the tacaribe arenavirus Z-protein binding sites on the L protein identified both amino acids within the putative polymerase domain and a region at the N terminus of L that are critically involved in binding.

Tacaribe virus (TacV) is the prototype of the New World group of arenaviruses. The TacV genome encodes four proteins: the nucleoprotein (N), the glycoprotein precursor, the polymerase (L), and a RING finger protein (Z). Using a reverse genetics system, we demonstrated that TacV N and L are sufficient to drive transcription and replication mediated by TacV-like RNAs and that Z is a powerful inhibitor of these processes (Lopez et al., J. Virol. 65:12241-12251, 2001). More recently, we provided the first evidence of an interaction between Z and L and showed that Z's inhibitory activity was dependent on its ability to bind to L (Jácamo et al., J. Virol. 77:10383-10393, 2003). In the present study, we mapped the TacV Z-binding sites on the 2,210-amino-acid L polymerase. To that end, we performed deletion analysis and point mutations of L and studied the Z-L interaction by coimmunoprecipitation with specific sera. We found that the C-terminal region of L was not essential for the interaction and identified two noncontiguous regions that were critical for binding: one at the N-terminus of L between residues 156 and 292 and a second one in the polymerase domain (domain III). The importance of domain III in binding was revealed by substitutions in D1188 and H1189 within motif A and in each residue of the conserved SDD sequence (residues 1328, 1329, and 1330) within motif C. Our results showed that of the substituted residues, only H1189 and D1329 appeared to be critically involved in binding Z.

Virus⁻Host Interactions Involved in Lassa Virus Entry and Genome Replication.

Lassa virus (LASV) is the causative agent of Lassa fever, a human hemorrhagic disease associated with high mortality and morbidity rates, particularly prevalent in West Africa. Over the past few years, a significant amount of novel information has been provided on cellular factors that are determinant elements playing a role in arenavirus multiplication. In this review, we focus on host proteins that intersect with the initial steps of the LASV replication cycle: virus entry and genome replication. A better understanding of relevant virus⁻host interactions essential for sustaining these critical steps may help to identify possible targets for the rational design of novel therapeutic approaches against LASV and other arenaviruses that cause severe human disease.