Biology subjects

Palacios, G.

Publications and source records attributed to Palacios, G..

12 recordsLinked to original sources

bioRxiv2026

Evaluation of new adjuvants in enhancing the immune response to a candidate of Severe Fever with Thrombocytopenia Syndrome Virus vaccine.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging zoonotic disease caused by the tick-borne bunyavirus SFTSV. SFTSV is primarily transmitted by Haemaphysalis longicornis ticks and can cause a hemorrhagic fever-like illness characterized by high fever, thrombocytopenia, leukopenia, and multiorgan failure, with reported case-fatality rates ranging from 10% to over 30%. Despite its growing public health relevance, no licensed vaccines or specific antiviral therapies are currently available. Here, we evaluated a beta-propiolactone-inactivated SFTSV vaccine candidate based on strain YL1, formulated with benchmark adjuvants (Addavax and Alhydrogel) or experimental innate immune agonists, including Sendai virus-derived defective interfering RNA (SDI), a RIG-I agonist, and imidazoquinoline-poly(ethylene glycol)-cholesterol conjugate (IMDQ-P-C), a TLR7/8 agonist, alone or in combination. Using an extended prime-boost regimen, we examined adjuvant-dependent modulation of humoral immunity, antigen-specific cellular recall, antibody cross-reactivity, and functional protection following passive serum transfer and live-virus challenge in IFNAR-/- mice. All adjuvanted formulations induced detectable humoral responses, with Addavax and SDI eliciting the highest virus-specific binding and neutralizing antibody titers. Antigen-specific analyses identified the nucleoprotein (NP) as the dominant target of vaccine-induced immune memory. NP elicited robust antibody response and the broadest cytokine recall profile following ex vivo stimulation. This response was broader than that induced by the whole inactivated virus and was characterized by mixed Th1-associated, Th2-associated, and proinflammatory-associated features that varied across adjuvant formulations. In contrast, the head domain of the Gn glycoprotein elicited limited cellular recall responses, consistent with its relatively weak humoral immunogenicity after both priming and boosting. Nevertheless, sera from SDI and Addavax-adjuvanted groups displayed cross-reactivity with Gn from a heterologous SFTSV strain, suggesting broader antibody recognition across viral genotypes. Functionally, sera from SDI and Addavax-immunized mice conferred partial protection following passive transfer into IFNAR-/- recipients, as reflected by reduced viral loads, delayed disease onset, and prolonged survival after lethal SFTSV challenge. Together, these findings support the immunogenicity and protective potential of a BPL-inactivated SFTSV vaccine platform and identify NP as a major target of vaccine-induced immune memory. They further highlight the importance of adjuvant selection in shaping the magnitude, antigenic focus, and functional quality of vaccine-induced antiviral immunity.

microbiology↗

bioRxiv2026

Modeling Risk Group 4 virus infection and antiviral treatment in microfluidic lung organ-on-chips in maximum containment laboratories

Development of candidate countermeasures against human pathogens frequently includes nonhuman animal experimentation. Preclinical animal pathogen exposure studies are conducted to model diseases and accumulate preliminary and hypothetically translatable data to inform and justify the design of clinical trial evaluation of countermeasure safety and efficacy. In addition to frequent ethical critiques, challenges associated with animal experimentation include considerable resources needed to achieve statistical power and robustness, replicability and reproducibility concerns, potentially compromised objectivity through lack of blinding, fundamental species-specific biological differences, and risk of unpredictable pathogen adaptation to the experimental animal. Recent U.S. and U.K. government initiatives aim to reduce animal experimentation by complementing or potentially replacing them with new approach methodologies (NAMs), i.e., increasingly sophisticated in silico, in chemico, and in vitro approaches. We piloted development of one type of NAM, organ-on-chips (OOCs), in the highly challenging environment of a maximum (biosafety level 4) containment laboratory. Using a Risk Group 4 virus, Nipah virus (NiV), and two types of lung OOCs seeded with human or porcine cells, we demonstrated the recapitulation of key features of NiV lung infection, including viral infection, replication, and translocation, that are associated with proinflammatory cytokine secretion, immune cell recruitment, and disruption of the air-liquid interface barrier. We reproduced the known anti-NiV activity of remdesivir and evaluated that of another potential antiviral, zotatifin. Our results pave the way for similar applications of advanced microphysiological systems for modeling infections caused by high-consequence viruses.

microbiology↗

bioRxiv2026

A historical cross-border Andes virus lineage reveals the origin of a cruise ship hantavirus pulmonary syndrome outbreak

Andes virus (ANDV) caused a multi-country outbreak of hantavirus pulmonary syndrome among passengers and crew of a cruise ship in 2026. To investigate the origin and evolutionary history of the virus responsible for the outbreak, we analyzed complete ANDV small (S), medium (M), and large (L) genome segment sequences from Chile alongside outbreak-associated and publicly available genome sequences. Across all three segment-specific phylogenies, the outbreak virus clustered within an ANDV Clade III cluster spanning southern Chile and northern Patagonia in Argentina and were most closely related to a human-derived ANDV (p1236) collected in Los Rios Region of Chile in 2012, representing the closest known historical relative of the outbreak-associated virus. Phylogeographic analysis showed that the genetically distinct ANDV Clade V lineage circulating in central Chile was not closely related to the cruise ship outbreak-associated genomes, thereby reducing the likelihood that the index cases acquired infection through zoonotic spillover while traveling through the Maule Region. These findings trace the geographic origin of the outbreak-associated virus to a defined corridor, the Hua Hum Pass, a cross-border zone connecting Province of Neuquen in Argentina with the Los Rios and La Araucania Regions of Chile.

evolutionary biology↗

bioRxiv2026

APOE is a presynaptic protein that accumulates with age and modulates neurotransmitter release

The synaptic vesicle (SV) cycle is the fastest membrane trafficking and protein sorting process in biology. It underlies neuronal communication and cognition, yet synaptic function declines during normal aging, increasing vulnerability to neurologic disease. How the SV cycle is maintained across the lifespan of a complex organism remains unclear. Here, we used wild-type mice (C57BL/6J) to define the age- and sex-stratified molecular landscape of SVs and identified apolipoprotein E (APOE) as an abundant presynaptic protein further enriched in aged female samples. Super-resolution imaging, cell-type selective expression, and protease protection assays demonstrate that APOE originates from astroglia and associates with the cytosolic face of SVs. Using iGluSnFR and pHluorin optophysiology, we find that both decreased and increased APOE levels impair neurotransmission during stimulus trains. Together, these findings place APOE at the synapse and establish it as a cell-nonautonomous regulator of the SV cycle.

neuroscience↗

bioRxiv2024

Rapid metabolic regulation of a novel arginine methylation of KCa3.1 attenuates T cell exhaustion.

T cell receptor (TCR) engagement initiates the activation process, and this signaling event is regulated in multifaceted ways. Nutrient availability in the immediate niche is one such mode of regulation1-3. Here, we investigated how the availability of an essential amino acid methionine (Met) and TCR signaling might interplay in the earliest events of T cell activation to affect subsequent T cell fate and function. We found that limiting Met during only the initial 30 minutes of CD8+ T cell activation increased Ca2+ influx, Ca2+-mediated NFAT1 (Nfatc2) activation, NFAT1 promoter occupancy, and T cell exhaustion. We identified changes in the protein arginine methylome during the initial 30 min of TCR engagement and discovered a novel arginine methylation of a Ca2+-activated potassium transporter, KCa3.1, which regulates Ca2+-mediated NFAT1 signaling to ensure optimal activation. Ablation of arginine methylation in KCa3.1 led to increased NFAT1 activation, rendering T cells dysfunctional in murine tumour and infection models. Furthermore, acute Met supplementation at early stages reduced nuclear NFAT1 in tumour-infiltrating T cells and augmented their anti-tumour activity. Our findings identify a metabolic event occurring early after T cell activation that influences the subsequent fate of the cell.

immunology↗

bioRxiv2023

Mitochondrial proteostasis mediated by CRL5Ozz and Alix maintains skeletal muscle function

High energy-demanding tissues, such as skeletal muscle, require mitochondrial proteostasis to function properly. Two quality-control mechanisms, the ubiquitin proteasome system (UPS) and the release of mitochondria-derived vesicles, safeguard mitochondrial proteostasis. However, whether these processes interact is unknown. Here we show that the E3 ligase CRL5Ozz, a member of the UPS, and its substrate Alix control the mitochondrial concentration of Slc25A4, a solute carrier that is essential for ATP production. The mitochondria in Ozz-/- or Alix-/-skeletal muscle share overt morphologic alterations (they are supernumerary, swollen, and dysmorphic) and have abnormal metabolomic profiles. We found that CRL5Ozz ubiquitinates Slc25A4 and promotes its proteasomal degradation, while Alix facilitates SLC25A4 loading into exosomes destined for lysosomal destruction. The loss of Ozz or Alix offsets steady-state levels of Slc25A4, which disturbs mitochondrial metabolism and alters muscle fiber composition. These findings reveal hitherto unknown regulatory functions of Ozz and Alix in mitochondrial proteostasis.

cell biology↗

bioRxiv2022

Genomic accordions may hold the key to Monkeypox Clade IIb's increased transmissibility

The currently expanding monkeypox epidemic is caused by a subclade IIb descendant of a monkeypox virus (MPXV) lineage traced back to Nigeria in 1971. In contrast to monkeypox cases caused by clade I and subclade IIa MPXV, the prognosis of current cases is generally favorable, but person-to-person transmission is much more efficient. MPXV evolution is driven by selective pressure from hosts and loss of virus-host interacting genes. However, there is no satisfactory genetic explanation using single-nucleotide polymorphisms (SNPs) for the observed increased MPXV transmissibility. We hypothesized that key genomic changes may occur in the genomes low-complexity regions (LCRs), which are highly challenging to sequence and have been dismissed as uninformative. Using a combination of highly sensitive techniques, we determined a first high-quality MPXV genome sequence of a representative of the current epidemic with LCRs resolved at unprecedented accuracy. This effort revealed significant variation in short-tandem repeats within LCRs. We demonstrate that LCR entropy in the MPXV genome is significantly higher than that of SNPs and that LCRs are not randomly distributed. In silico analyses indicate that expression, translation, stability, or function of MPXV orthologous poxvirus genes (OPGs) 153, 204, and 208 could be affected in a manner consistent with the established "genomic accordion" evolutionary strategies of orthopoxviruses. Consequently, we posit that genomic studies focusing on phenotypic MPXV clade-/subclade-/lineage-/strain differences should change their focus to the study of LCR variability instead of SNP variability.

genomics↗

bioRxiv2020

Integrated multivariate analysis of transcriptomic data reveals immunological mechanisms in mice after Leishmania infantum infection

Transcriptional analysis of complex biological scenarios has been extensively used, even though sometimes results may prove imprecise or difficult-to interpret due to an overwhelming amount of information. In this study, a large-scale Real-time qPCR experiment was coupled to multivariate statistical analysis to describe the main immunological events underlying the early L. infantum infection in livers of BALB/c mice. High-throughput qPCR was used to evaluate the expression of 223 genes related to immunometabolism 1-, 3-, 5- and 10-days post infection. This integrative analysis showed strikingly different gene signatures at 1- and 10-days post infection, revealing progression of infection in the experimental model based on the upregulation of particular immunological response patterns and mediators. This approach addresses the challenge of integrating large collections of transcriptional data for the identification of candidate biomarkers in experimental models.

microbiology↗

bioRxiv2020

Deployable CRISPR-Cas13a diagnostic tools to detect and report Ebola and Lassa virus cases in real-time

Viral hemorrhagic fevers (VHFs) remain some of the most devastating human diseases, and recent outbreaks of Ebola virus disease (EVD) 1,2 and Lassa fever (LF) 3,4 highlight the urgent need for sensitive, field-deployable tests to diagnose them 5,6. Here we develop CRISPR-Cas13a-based (SHERLOCK) diagnostics targeting Ebola virus (EBOV) and Lassa virus (LASV), with both fluorescent and lateral flow readouts. We demonstrate on laboratory and clinical samples the sensitivity of these assays and the capacity of the SHERLOCK platform to handle virus-specific diagnostic challenges. Our EBOV diagnostic detects both the L and NP genes, thereby eliminating the potential for false positive results caused by the rVSV{Delta}G-ZEBOV-GP live attenuated vaccine. Our two LASV diagnostics together capture 90% of known viral diversity and demonstrate that CRISPR-RNAs (crRNAs) can be effectively multiplexed to provide greater coverage of known viral diversity. We performed safety testing to demonstrate the efficacy of our HUDSON protocol in heat-inactivating and chemically treating VHF viruses before SHERLOCK testing, eliminating the need for an extraction. We developed a user-friendly field protocol and mobile application (HandLens) to report results, facilitating SHERLOCKs use in endemic regions. Finally, we successfully deployed our tests in Sierra Leone and Nigeria in response to recent outbreaks.

molecular biology↗

bioRxiv2020

Characteristic and quantifiable COVID-19-like abnormalities in CT- and PET/CT-imaged lungs of SARS-CoV-2-infected crab-eating macaques (Macaca fascicularis)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing an exponentially increasing number of coronavirus disease 19 (COVID-19) cases globally. Prioritization of medical countermeasures for evaluation in randomized clinical trials is critically hindered by the lack of COVID-19 animal models that enable accurate, quantifiable, and reproducible measurement of COVID-19 pulmonary disease free from observer bias. We first used serial computed tomography (CT) to demonstrate that bilateral intrabronchial instillation of SARS-CoV-2 into crab-eating macaques (Macaca fascicularis) results in mild-to-moderate lung abnormalities qualitatively characteristic of subclinical or mild-to-moderate COVID-19 (e.g., ground-glass opacities with or without reticulation, paving, or alveolar consolidation, peri-bronchial thickening, linear opacities) at typical locations (peripheral>central, posterior and dependent, bilateral, multi-lobar). We then used positron emission tomography (PET) analysis to demonstrate increased FDG uptake in the CT-defined lung abnormalities and regional lymph nodes. PET/CT imaging findings appeared in all macaques as early as 2 days post-exposure, variably progressed, and subsequently resolved by 6-12 days post-exposure. Finally, we applied operator-independent, semi-automatic quantification of the volume and radiodensity of CT abnormalities as a possible primary endpoint for immediate and objective efficacy testing of candidate medical countermeasures.

microbiology↗

bioRxiv2018

Human, Nonhuman Primate, and Bat Cells Are Broadly Susceptible to Tibrovirus Particle Cell Entry

In 2012, the genome of a novel rhabdovirus, Bas-Congo virus, was discovered in the acute-phase serum of a Congolese patient with presumed viral hemorrhagic fever. In the absence of a replicating virus isolate, fulfilling Kochs postulates to determine whether Bas-Congo virus is indeed a human virus and/or pathogen has been impossible. However, experiments with vesiculoviral particles pseudotyped with Bas-Congo glycoprotein suggested that Bas-Congo virus particles can enter cells from multiple animals, including humans. In 2015, genomes of two related viruses, Ekpoma virus 1 and Ekpoma virus 2, were detected in human sera in Nigeria. Isolates could not be obtained. Phylogenetic analyses led to the classification of Bas-Congo virus, Ekpoma virus 1, and Ekpoma virus 2 in the same genus, Tibrovirus, together with five biting midge-borne rhabdoviruses (i.e., Beatrice Hill virus, Bivens Arm virus, Coastal Plains virus, Sweetwater Branch virus, and Tibrogargan virus) not known to infect humans. Using individual recombinant vesiculoviruses expressing the glycoproteins of all eight known tibroviruses and more than 75 cell lines representing different animal species, we demonstrate that the glycoproteins of all tibroviruses can mediate vesiculovirus particle entry into human, bat, nonhuman primate, cotton rat, boa constrictor, and Asian tiger mosquito cells. Using four of five isolated authentic tibroviruses (i.e., Bivens Arm virus, Coastal Plains virus, Sweetwater Branch virus, and Tibrogargan virus), our experiments indicate that many cell types may be partially resistant to tibrovirus replication after virion cell entry. Consequently, experimental data solely obtained from experiments using tibrovirus surrogate systems (e.g., vesiculoviral pseudotypes, recombinant vesiculoviruses) cannot be used to predict whether Bas-Congo virus, or any other tibrovirus, infects humans.

microbiology↗

bioRxiv2018

International travelers and genomics uncover a ‘hidden’ Zika outbreak

The ongoing Zika epidemic in the Americas has challenged public health surveillance, response, and control systems. Even as the epidemic appears to be near its end in the Americas, it is unclear whether substantial Zika virus transmission may still be ongoing. This issue is exacerbated by large discrepancies in local case reporting and significant delays in detecting outbreaks due to surveillance gaps. To uncover locations with lingering outbreaks in the Americas, we investigated travel-associated Zika cases diagnosed in the United States and Europe to identify signatures of transmission dynamics that were not captured by local reporting. We found that a large and unreported Zika outbreak occurred in Cuba during 2017, a year after peak transmission in neighboring countries, with cases still appearing in 2018. By sequencing Zika virus from infected travelers, we show that the 2017 outbreak in Cuba was sparked by long-lived lineages of Zika virus introduced from multiple places in the Americas a year prior. Our data suggest that while aggressive mosquito control in Cuba may initially have been effective at mitigating Zika virus transmission, in the absence of vaccines, herd immunity, or strong international coordination, such control measures may need to be maintained to be effective. Our study highlights how Zika virus may still be silently spreading in the Americas and provides a framework for more accurately understanding outbreak dynamics.

epidemiology↗