Search Results (193)

Metastatic pancreatic ductal adenocarcinoma (PDAC) is typically treated with fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) or gemcitabine plus nab-paclitaxel (GnP), but the choice between regimens remains largely empirical. This narrative review summarizes biomarkers with potential to inform first-line selection in metastatic PDAC, emphasizing genomic and transcriptomic correlates of differential benefit. Recent head-to-head trials, particularly Pancreatic Adenocarcinoma Signature Stratification for Treatment (PASS-01) and GENERATE (Japan Clinical Oncology Group [JCOG] 1611), indicate that modified FOLFIRINOX (mFOLFIRINOX) is not uniformly superior to GnP, strengthening the rationale for biomarker-guided selection. The strongest evidence favoring platinum-based/FOLFIRINOX strategies involves homologous recombination repair deficiency (HRD), especially alterations in germline breast cancer gene 1/2 (BRCA1/2) or partner and localizer of BRCA2 (PALB2), as well as broader genomic scar signatures. Transcriptomic subtype and GATA-binding protein 6 (GATA6) expression are promising but remain unsettled because retrospective data favor classical/GATA6-high disease for FOLFIRINOX, whereas PASS-01 suggested better outcomes with GnP in classical tumors. Candidate biomarkers favoring GnP include high human equilibrative nucleoside transporter 1 (hENT1), low class III β-tubulin (TUBB3) expression, and exploratory phosphatidylinositol 3-kinase (PI3K)/KIT/NOTCH pathway mutation signals. Comprehensive molecular profiling also identifies actionable alterations that may redirect patients to targeted therapy or clinical trials rather than standard chemotherapy alone. Importantly, no biomarker has yet been prospectively validated in a biomarker-stratified randomized trial with regimen selection as the primary endpoint; all biomarker-regimen associations described in this review should therefore be considered hypothesis-generating rather than practice-defining. Nevertheless, the convergence of genomic, transcriptomic, and organoid-based approaches makes biologically informed first-line selection increasingly feasible in metastatic PDAC. Full article

To this day, the etiology of multiple sclerosis has yet to be fully comprehended by the scientific community. However, the knowledge on mechanisms leading to the development of this neurodegenerative autoimmune disorder increases daily, along with the development of new disease-modifying treatments. A correlation between Epstein–Barr Virus infection and the disease incidence has recently shed light on possible innovative antiviral therapies. Here, we review the literature on Human Endogenous Retroviral sequences as emerging actors for the impairment of remyelination as a major challenge in disease progression. Our primary focus is the HERV-W envelope protein, which has been found at elevated levels in individuals affected by this condition and is suggested here as a potential therapeutic target. We then continue analyzing the clinical cases where antiretroviral drugs have been tested to treat multiple sclerosis patients and, from successes and failures, we finally narrow down our therapeutic hypothesis to the administration of Nucleoside-analog Reverse Transcriptase Inhibitors to target the HERV-W envelope protein, possibly leading to remyelination and significantly improving the condition of those affected by the disease. The main purpose of this review is to present a rationale for the therapeutic potential of this drug class and offer a new perspective for therapeutic options against multiple sclerosis. Full article

Background/Objectives: It is challenging to develop efficient vaccines against intracellular pathogens such as viruses, and since viral infections are one of the main challenges for farmed salmon, a novel vaccine strategy is needed. mRNA vaccines are optimized and approved for humans, but for fish, the mRNA technology is new, and optimization is required to ensure efficient protein expression. We made an mRNA tailored to salmon and studied the effect of modified nucleosides and the length of the poly(A) tail on protein expression from in vitro-transcribed mRNA in CHSE-214 cells, using enhanced green fluorescent protein (EGFP) as a reporter. Methods: Different lengths of the poly(A) tail were tested, and various modified nucleotides were incorporated in the mRNA during in vitro transcription, including pseudouridine (Ψ), N1-methylpseudouridine (m1Ψ), N6-methyladenosine (m6A), 5-methyluridine (m5U), and 5-methylcytidine (m5C). Protein expression was observed in fluorescence microscopy and quantified using flow cytometry. Results: mRNA containing Ψ resulted in the strongest EGFP expression 1–3 days post-transfection (dpt), while EGFP expression from m5C mRNA was high throughout the experiment (<10 dpt). m5U-containing mRNA had low EGFP expression until 6 dpt, but reached the level of m5C mRNA at 10 dpt. The m5U mRNA, however, expressed EGFP at much higher intensity than all the other mRNAs at all time points. Poly(A) tails with lengths of 40, 100, and >100 were tested, and the one with >100 adenines showed the highest expression. The effects of phosphatase treatment and purification of the mRNA were also investigated. Furthermore, EGFP expression was observed in yolk-sac salmon larvae following micro-injection. Conclusions: Our study provides an important basis for the development of efficient mRNA-based vaccines in the future. Full article

While current influenza vaccines often lack broad protection against antigenically drifted strains, some modified hemagglutinin (HA) protein antigens have shown promise in eliciting broadly neutralizing antibodies against conserved epitopes. During infection, the mildly acidic environment of the late endosome triggers irreversible HA conformational changes resulting in a post-fusion structure with altered antigenicity. While enhancing the stability of other structural class I viral fusion protein antigens has been instrumental in improving the effectiveness of COVID-19 and RSV vaccines, the role of HA stability in influenza vaccine immunogenicity is relatively unclear. Here, we used the nucleoside-modified mRNA-LNP platform to test engineered HA antigens with specific acid-stabilizing mutations (E47K, K58I, R106K, and K153E) in the HA stalk. All mutations increased HA acid stability, but E47K and R106K did not increase immunogenicity. K153E and K58I, but not E47K and R106K, enhanced the cell-surface expression of the HA protein in vitro. In mice, K153E- and K58I-containing mRNA-LNP vaccines elicited increased neutralizing antibody titers against homologous virus. K153E conferred greater protection than wild-type vaccine against lethal heterologous A/PR/8/34 challenge at low doses (0.5–1.0 µg), despite the absence of neutralizing antibodies against the challenge strain. K153E also elicited greater expansion of antigen-specific antibody-secreting cells (ASCs) in the bone marrow, as well as cross-reactive T follicular helper (Tfh) cells in the spleen. For the vaccines studied, increased HA expression was a stronger correlate of mRNA-LNP enhancement than increased HA stability. Full article

Background/Objectives: Pathogenic mammarenaviruses cause severe hemorrhagic and neurologic disease in humans. Machupo virus (MACV), a New World (NW) mammarenavirus, causes Bolivian hemorrhagic fever in humans, and there are no approved vaccines. Methods: Here, we describe and compare the immunogenicity of three vaccines expressing the MACV glycoprotein complex (GPC) in C57BL/6 mice: a recombinant vesicular stomatitis virus (rVSV) and two different lipid nanoparticle (LNP)-encapsulated nucleoside-modified mRNA (mRNA-LNP) vaccines. The first mRNA-LNP vaccine, designated MACV mRNA, expresses the full-length MACV GPC. The second mRNA-LNP vaccine, called MACV VLP mRNA, encodes MACV GPC with appended sequences that induce the budding of virus-like particles (VLPs) with MACV GPC on the surface. This is the first description of any mRNA-LNP vaccine for MACV and the first comparison of mRNA and rVSVs as vaccine candidates for MACV. Results: We find that two doses of either MACV mRNA or MACV VLP mRNA are required for the induction of robust humoral and cellular immune responses including total MACV GPC IgG, neutralizing antibodies, cross-reactive antibodies that bind the related Junín virus GPC, and MACV-specific T-cell responses. To further investigate vaccination strategies for MACV, we also evaluated a heterologous prime-boost regimen involving the MACV mRNA vaccine coupled with the rVSV-based MACV vaccine. We find that the highest levels of MACV GPC-specific IgG and neutralizing titers were achieved when heterologous mRNA and rVSV prime-boost regimens were employed. Conclusions: These results elucidate differences in the immune response to different vaccine platforms for MACV and can inform future vaccine development for NW arenaviruses. Full article

Background/Objectives: Eye infection with herpes simplex virus type 1 (HSV-1) can result in keratitis, a leading cause of corneal blindness. We evaluated whether an experimental vaccine containing HSV-2 immunogens to prevent genital herpes also protects against HSV-1 eye infection and neuroinvasion. Methods: Mice were immunized twice, one month apart, with PBS or a nucleoside-modified lipid nanoparticle vaccine containing mRNA encoding for gC2, gD2, and gE2. One month later, 10⁶ plaque forming units (PFU) (10 lethal dose 50, LD₅₀) of the HSV-1 McKrae strain were added to the intact cornea of each eye. Results: The vaccine prevented death and markedly reduced eyelid and attached conjunctival inflammation (blepharoconjunctivitis) and weight loss compared with the PBS group. Tissues from the ocular conjunctiva and eye bulb, olfactory bulb/peduncle, trigeminal ganglia, and brain (brainstem, cerebrum, and cerebellum) were harvested 5 days post-infection from 5 mice each in the PBS and vaccine groups, and from another 10 mice in the vaccine group 7 weeks post-infection. At 5 days, HSV-1 was not detected in any tissue in the vaccine group, while viral titers were positive in 16 of 25 (64%), and HSV-1 DNA was detected in 22 of 25 (88%) individual tissues in the PBS group. Histopathological and immunohistochemical analysis at 5 days post-infection confirmed that the vaccine protected against inflammation; however, some animals experienced breakthrough blepharoconjunctivitis. At 7 weeks, 3 of 10 (30%) mice in the vaccine group had HSV-1 DNA detected in the eyes or trigeminal ganglia tissues, but no animal had HSV-1 DNA detected in brain tissues. The vaccine produced cross-reactive HSV-1 neutralizing antibodies and gD1 IgG binding antibodies, but low or undetectable cross-reactive binding antibodies to gC1 and gE1. Conclusions: Despite occasional mild, localized breakthrough infections, the vaccine provided disease-modifying immunity and was neuroprotective. The results suggest that a single herpes vaccine effective against genital HSV-2 may be neuroprotective against HSV-1 following eye infection. Full article

KRAS is one of the most frequently mutated genes in all human cancers, and its oncogenic mutation hotspots are glycine 12 (G12), glycine 13 (G13), glutamine 61 (Q61) and alanine 146 (A146). Among these hotspot mutations, A146 substitution mutations (A146X) occur relatively infrequently, except for haematopoietic and lymphoid cancers, suggesting that A146X causes intrinsically distinct KRAS signalling compared to other KRAS oncogenic alleles. However, due to the absence of model A146X cell lines derived from haematopoietic sources, the cellular mechanisms that cause the differences between KRAS.A146X and other common KRAS mutants, such as KRAS.G12X, remain largely unexplored. In this study, we developed a set of isogenic model haematopoietic cell lines expressing KRAS.A146T, KRAS.G12V and KRAS.G12G (non-mutated) from the endogenous locus by genetically modifying the human lymphoblastoid TK6 cell line. We found that TK6 cells carrying KRAS^A146T/+ or KRAS^G12V/+ exhibited increased replication stress compared to KRAS wild-type cells. Strikingly, KRAS^A146T/+ cells strongly rely on PrimPol for maintaining cellular survival upon replication stress. In contrast, KRAS^G12V/+ cells exhibited hypersensitivity to inhibitors for the ATR-Chk1 checkpoint signalling axis and to nucleoside analogues commonly used to treat cancers and viral infections. Our findings demonstrate that the endogenously expressed oncogenic KRAS mutations exacerbate the replication stress and reveal KRAS allele-specific replication phenotypes, facilitating the development of effective chemotherapies tailored to specific oncogenic KRAS mutation alleles and types of cancer. Moreover, our study offers valuable model cell lines for investigating mechanisms underlying replication vulnerability in cancers harbouring oncogenic KRAS mutations. Full article

Background/Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the global COVID-19 pandemic, which led to hundreds of millions of human infections and more than seven million deaths worldwide. Major variants of concern, particularly the Omicron variant and its associated subvariants, can escape the vaccines developed so far to target previous strains/subvariants. Therefore, effective vaccines that broadly neutralize different Omicron subvariants and show good protective efficacy are needed to prevent further spread of Omicron. The spike (S) protein, including its receptor-binding domain (RBD), is a key vaccine target. Methods: Here, we designed a unique mRNA vaccine encoding Omicron-KP.3 RBD based on RBD-truncated S protein backbone of an earlier Omicron subvariant EG.5 (KP3 mRNA), and evaluated its stability, immunogenicity, neutralizing activity, and protective efficacy in a mouse model. Results: Our data showed that the nucleoside-modified, lipid nanoparticle-encapsulated mRNA vaccine was stable at various temperatures during the period of detection. In addition, the vaccine elicited potent antibody responses with broadly neutralizing activity against multiple Omicron subvariants, including KP.2, KP.3, XEC, and NB.1.8.1. This mRNA vaccine protected immunized transgenic mice from challenge with SARS-CoV-2 Omicron-KP.3. Immune serum also protected against subsequent virus challenge, with the level of protection associating positively with the serum neutralizing antibody titer. Conclusions: Taken together, the data presented herein suggest that this newly designed mRNA vaccine has potential against current and future Omicron subvariants. Full article

Background/Objectives: Tyrosinemia type 1 (HT-1) is a treatable inherited disorder characterized by disrupted tyrosine metabolism, leading to severe liver, renal, and occasionally neurological dysfunction. Early diagnosis by newborn screening markedly reduces the risk of hepatocellular carcinoma (HCC), the most serious complication. A deeper understanding of HT-1 pathophysiology is necessary to prevent disease complications and improve diagnostic and therapeutic strategies. This study explored the untargeted serum metabolomic profiles of HT-1 patients. Methods: High-resolution untargeted metabolomics coupled with liquid chromatography was applied for serum analysis of 16 late-diagnosed Chilean HT-1 patients on nitisinone (NTBC) therapy and 16 age- and sex-matched controls. The statistically significant up- and down-regulated features were used for annotation and association with different metabolic pathways. Results: Untargeted metabolomics revealed 1066 features significantly changed in HT-1 patients. Increased metabolites included aromatic compounds, medium- and long-chain acyl-carnitines, bile acids (prevalently taurine-conjugated), indole-based compounds, modified nucleosides and nucleobases. Decreased metabolites were mainly related to lipid class, including lysophosphatidylcholines, lysophosphatidic acids, long-chain fatty acids, and acylglycerols. Conclusions: Untargeted metabolomics showed perturbation of tyrosine- and tryptophan-related pathways and described a novel HT-1 metabolomic pattern demonstrating net dysregulation of lipid and bile acid metabolism in NTBC-treated patients with delay diagnoses. Increased acylcarnitines, taurine-conjugated bile acids, modified nucleobases, and reduced lysophosphatidylcholines overlap with the metabolomic pattern previously reported in Wnt/β-catenin-associated HCC. Although direct mechanistic link cannot be established in this study, these alterations may reflect persistent disease-related metabolic adaptations and warrant further investigation to clarify their potential relevance with long-term complications. Full article

Many polar compounds of biochemical and pharmaceutical relevance exhibit low retention in reversed-phase liquid chromatography (RPLC), making their separation challenging. While hydrophilic interaction liquid chromatography (HILIC) columns are commonly used for such analyses, they require mobile phases with high organic solvent content. This work explores an alternative approach using RPLC with conventional C18 columns and mobile phases containing low percentages of acetonitrile, along with small amounts of the surfactant sodium dodecyl sulfate (SDS). This combination significantly enhances the retention of highly polar compounds. When the SDS concentration is sufficiently low, below the critical micellar concentration in water (8 mM), the retention increase follows a linear pattern. The retention behavior of polar compounds with different properties (nucleosides, methylxanthines, sulfonamides, and the diuretic hydrochlorothiazide) is examined using mobile phases in the submicellar region, with SDS concentrations ranging from 0 to 0.3 mM, acetonitrile contents between 10 and 20% (v/v), and temperatures varying from 25 to 55 °C. Changes in peak half-widths are also analyzed. Since SDS adsorbs onto the stationary phase, modifying its surface, the equilibration time has been investigated as a critical factor affecting retention reproducibility, influenced by the SDS concentration, acetonitrile content, and temperature. The results emphasize the need for complete equilibration to ensure reliable and consistent results. Full article

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate molecules, such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) in the active sites of HGPRT and similar proteins. We report the crystal structure of HGPRT from Escherichia coli (EcoHGPRT) in a complex with HEPES. In the obtained X-ray structure, a HEPES molecule binds to the active site in a position that mimics one of the HGPRT substrates, namely phosphoribosylpyrophosphate (PRPP). Enzymological study has shown that HEPES is an inhibitor of EcoHGPRT, along with two structurally similar molecules, namely MES and PIPES. Comparison of the observed EcoHGPRT/HEPES complex to other reported structures in the context of inhibition study results provides an opportunity to explore the variety of binding modes of HEPES and similar molecules and to discuss the structure–function relationship in this enzyme and similar proteins. Full article

Background: HIV drug resistance (DR) mutations can compromise antiretroviral therapy (ART) success among children living with HIV (CLHIV). We conducted a secondary analysis using data from a randomized control trial for ART monitoring among CLHIV in Kisumu County, Kenya from 2019 to 2023, to assess clinical, psychosocial, and structural factors associated with HIV DR. Methods: 704 CLHIV were followed for 12+ months, with characteristics captured at enrollment and follow-up visits in the “parent” randomized-controlled-trial (of point-of-care plasma viral load testing and for viremias ≥ 1000 copies/mL HIV genotyping for DR vs. standard-of-care) and an observational “extension” substudy (of participants on a dolutegravir-containing ART with genotyping performed on viremic specimens ≥ 200 copies/mL). A multivariate modified Poisson regression model was used to analyze factors associated with sequences yielding a Stanford HIVDR database DR penalty score (DR-PS) ≥ 30 to a nucleos(t)ides and/or non-nucleoside reverse transcriptase inhibitor, protease inhibitor (PI), and/or integrase inhibitor (INSTI). Results: Among 113 (16.1%) participants who underwent genotyping, 93 (82.3%) had a DR-PS ≥ 30. DR-PS ≥ 30 were associated with age 1–5 years (adjusted risk ratio (ARR) = 1.84; 95% confidence interval (CI): 1.07, 3.14), history of viremia ≥ 1000 copies/mL (ARR = 4.18; 95% CI: 2.77, 6.31), prescription of a PI- (ARR = 6.05; 95% CI: 3.43, 10.68) or INSTI-containing regimen (ARR = 1.83; 95% CI: 1.08, 3.11), poor adherence to ART (ARR = 1.91; 95% CI: 1.32, 2.76), lack of caregiver confidence in ART administration (ARR = 1.89; 95% CI: 1.11, 3.22), and mid-sized clinic populations (ARR = 0.55; 95% CI: 0.33, 0.92). Conclusion: Addressing social factors associated with DR-PS ≥ 30 may improve ART success among CLHIV. Full article

Cytidine deaminase (CDA) and deoxycytidine monophosphate deaminase (DCTD) play crucial roles in pyrimidine metabolism, affecting DNA synthesis, cell cycle progression, and the efficacy of numerous nucleoside analog-based chemotherapeutics. Given their significance, accurate and sensitive measurement of their enzymatic activity is paramount for both fundamental biochemical research and clinical applications. This review provides a comprehensive overview of the methodologies used to assess CDA and DCTD activity, both established and emerging. We systematically categorize and discuss various approaches, including spectrophotometric, fluorimetric, liquid chromatography-based (Ultraviolet-Visible, fluorescence, and mass spectrometry), radiometric, and cell-based assays. For each method, we present its underlying principles, advantages, and limitations. Furthermore, we draw comparisons across the techniques to highlight their suitability for specific research questions. Full article

Background: Severe fever with thrombocytopenia syndrome virus (SFTSV) is a highly pathogenic bunyavirus with a high case-fatality ratio for which there is no approved vaccine. Studies have assessed different vaccine technologies. However, few studies have yet assessed the immunogenicity of heterologous prime-boost regimens. Methods: Here, we compare a lipid nanoparticle (LNP)-encapsulated nucleoside-modified mRNA-based vaccine encoding the SFTSV glycoproteins, Gn and Gc, to our recently described recombinant VSV SFTSV (rVSV-SFTSV) vaccine in single dose, homologous, and heterologous prime-boost regimens in mice. Results: We show that all regimens protect from pathogenic SFTSV challenge and elicit strong long-lasting antibody responses. Furthermore, strong cellular immunity is elicited by mRNA-LNP immunizations and by heterologous immunization with an rVSV-SFTSV prime and mRNA-LNP boost. Cellular responses robustly polarized towards a type 1 response, characterized by high levels of IFNγ, TNFα, and IL-2. Immunization with mRNA led to a mixed type 1/type 2 immune response, as determined by antibody isotypes IgG1 and IgG2c. We found that homologous immunization leads to stronger antibody responses while heterologous immunization drives a slightly stronger cellular response. Conclusions: Taken together, the vaccine platforms described here represent strong vaccine candidates for further development. Full article

In this study, we investigated the effects of air packaging, vacuum packaging and modified atmosphere packaging (CO₂/N₂: 80/20) on the purine metabolism and enzyme activities of refrigerated large yellow croakers. The results showed that modified atmosphere packaging significantly inhibited microbial growth, delayed adenosine triphosphate degradation and maintained higher IMP content (1.93 μmol/g on day 21) compared to the air packaging group (2.82 μmol/g on day 12). The total purine content increased with storage time, with hypoxanthine content increasing significantly and occupying most of the total content, which was the key factor for the elevation of purine, followed by adenine content showing a significant decreasing trend. Hypoxanthine accumulation was significantly suppressed in the modified atmosphere packaging group (2.31 μmol/g on day 18), which was much lower than that in the air packaging group (5.64 μmol/g), whereas xanthine and guanine did not show significant differences among the groups. The key enzymes xanthine oxidase and purine nucleoside phosphorylase were much less active in modified atmosphere packaging, effectively delaying the cascade reaction of inosine monophosphate → hypoxanthine → xanthine. The study confirmed that modified atmosphere packaging intervenes in purine metabolism through enzyme activity regulation, providing a theoretical basis for the preservation of low purine aquatic products. Full article