Biology subjects

Saito, T.

Publications and source records attributed to Saito, T..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Differences in components of reproductive behaviour between populations at the simultaneously hermaphroditic snail Lymnaea stagnalis

Differences in reproductive behaviour can contribute to speciation by establishing reproductive isolation and can thus be a significant driving force in ecology and evolution. However, studies investigating intraspecific variation in reproductive behaviour remain scarce. In this study, we focused on a simultaneously hermaphroditic freshwater snail, Lymnaea stagnalis, a model organism whose reproductive behaviour is well documented, to examine behavioural differences among populations. In addition to a laboratory population, ten wild populations were sampled and standardised under laboratory conditions. Mating behaviour and egg production were quantified through observation experiments. The observed traits were analysed using a hierarchical Bayesian model to estimate the effects of each population on reproductive traits. Moreover, genetic information of the populations was estimated using low-coverage whole genome sequencing data, and phylogenetic signals for each trait were assessed. Our results revealed that populations exhibited distinct behavioural traits, and most prominent were the differences in male behaviours and the motivation to mate in the male role (after short and long sexual isolation). Egg production also clearly differed between populations. However, no phylogenetic signals were detected for any of the traits, suggesting that the diversification of behavioural traits among populations may result from evolutionary processes such as divergent selection or founder effects. This study highlights that reproductive behaviour can be highly diversified within a single species, and that assuming homogeneity in behaviour should be done with care.

ecology↗

bioRxiv2025

Molecular basis behind the isoprene emission diversity in Fagaceae

Plants emit a large amount of volatile organic compounds (VOCs) into the atmosphere, reaching approximately 109 tons of carbon per year. These biogenic VOCs exhibit significant chemical diversity, with terpenoids being the dominant group, and isoprene accounting for nearly half of the total biogenic VOCs. Due to its high chemical reactivity, isoprene has a strong impact on atmospheric quality and climate. Quercus species (Fagaceae) are known to be the main isoprene emitters in the Northern Hemisphere. However, isoprene synthase is unknown in the entire Fagaceae family. Notably, even within a single genus such as Quercus, both isoprene-emitting and non-emitting species are present, yet the molecular basis of this dichotomy remains unclear. Here, we report the identification of the IspS gene from the isoprene-emitting species Quercus serrata (QsIspS1) through seasonal transcriptome analysis and its detailed biochemical characterization. We also identified two genes with high sequence similarity to QsIspS1 in the genomes of non-emitting species: Q. glauca (QgIspS1-like) and Lithocarpus edulis (LeIspS1-like). We discovered mutations in these sequences that likely impair their function. Biochemical analysis revealed that QgIspS1-like is a monoterpene synthase, whereas LeIspS1-like is a pseudogene incapable of isoprene synthesis, explaining these plants inability to emit isoprene. Furthermore, site-directed mutagenesis revealed an amino acid that plays a pivotal role in the substrate and product specificities of isoprene synthase. Our findings provide new insight into the molecular mechanisms of isoprene emission diversity in Fagaceae.

biochemistry↗

bioRxiv2025

Anti-amyloid beta therapy resolves stroke recovery impairment caused by Alzheimer's disease

Stroke and dementia are common comorbidities and a growing concern causing disability in aging societies worldwide. Although anti-amyloid beta (anti-A{beta}) antibodies have recently been anticipated to relieve preclinical Alzheimers disease pathology, we discovered that post-stroke administration of anti-A{beta} antibodies restored neural repair for stroke recovery impeded by cerebral A{beta} accumulation. Neuronal recovery-associated gene expression for stroke recovery was considerably impaired even by slight A{beta} accumulation in murine and human brain. Slight A{beta} accumulation had less impact on neurons without stroke but caused a unique myeloid immunity after an ischemic stroke that enhanced the inflammatory cascades impeding neural repair for stroke recovery. Aducanumab administration after ischemic stroke prevented formation of this malignant myeloid immunity, resolving the impairment of post-stroke neural repair caused by cerebral A{beta} accumulation. Thus, our study has revealed the ability of anti-A{beta} therapies to restore functional recovery after a stroke with cerebral A{beta} accumulation.

neuroscience↗

bioRxiv2025

Mechanisms of force transmission on cytokinesis Formin Cdc12 in fission yeast revealed by coiled-coil force sensors

Cytokinesis is a fundamental process in cell division, where an actomyosin contractile ring plays a central role in completing the cell division. Although some experimental and computational efforts have evaluated ring tension and the molecular organization of rings, the mechanisms of force transmission at the molecular level remain unclear. Here, we used our novel coiled-coil force sensors to measure the force distribution along the formin Cdc12, a key cytokinesis protein in fission yeast. Our force measurements revealed that individual formin Cdc12 molecules transmit up to [~]6 pN with distinct mechanisms between the regions upstream and downstream of the formin homology 2 (FH2) domain, which binds the barbed ends of actin filaments. The force transmitted on the N-terminal region before the FH2 domain requires anchoring to a cytokinetic node via the Cdc15 binding region, but is independent of the C-terminal region after FH2. In contrast, the region after the FH2 domain transmits forces independently of the Cdc12s N-terminal region. Force screening using the coiled-coil force sensors found that a region in Cdc12s disordered C-terminal tail can associate with the contractile ring. Altogether, the force measurements with our coiled-coil force sensors allowed us to uncover the mechanisms of force transmission along Cdc12 and characterize new motifs and binding partners.

cell biology↗

bioRxiv2025

Age-Dependent, Odorant-Specific Changes in Olfactory Sensitivity in an Alzheimer's Disease Mouse Model

BackgroundOlfactory impairment often precedes cognitive decline in Alzheimers disease (AD). Recent studies suggest odor specificity in olfactory deficits during early AD stages, making olfactory tests a promising tool for early diagnosis. However, the mechanisms underlying olfactory impairment remain unclear, complicating the identification of optimal odorants for diagnostic purposes. ObjectiveIn this study, we assessed olfactory sensitivity in a knock-in mouse model of Alzheimers disease (AppNL-G-F mice) that recapitulates key features of human AD pathology. MethodsTo evaluate odor detection thresholds, we employed an olfactory assay that leverages innate behavior without requiring associative learning. Six odorants representing distinct functional groups were tested in wild-type (WT) and AppNL-G-F mice at 2 and 4 months of age. ResultsAppNL-G-F mice exhibited odorant-specific hyposmia at 4 months of age, coinciding with amyloid deposition in cortical and subcortical regions but preceding measurable cognitive deficits. Unexpectedly, at an earlier stage (2 months), these mice showed odorant-specific hyperosmia to ester odorants, which transitioned to hyposmia by 4 months, indicating dynamic, age-dependent alterations in olfactory sensitivity as AD pathology progresses. ConclusionsOur findings demonstrate that odorant-specific olfactory testing could serve as a promising diagnostic tool for early-stage AD, providing insights into the mechanisms underlying olfactory dysfunction in neurodegenerative diseases.

pathology↗

bioRxiv2025

Common garden experiments suggest terpene-mediated interactions between phyllosphere microbes and Cryptomeria japonica

Plant-microbe interactions in the phyllosphere provide invaluable information on plant ecology, with implications for ecosystem functioning and plant-atmosphere feedbacks. The composition of phyllosphere microbial communities varies significantly depending on host lineages, geographic regions, and climatic conditions. However, the factors driving these variations in interactions with plants remain poorly understood. Biogenic volatile organic compounds (BVOCs) emitted by plants may be important in these interactions. Here, we quantified the composition of phyllosphere microbial communities and terpene emissions from leaves of Japanese cedar (Cryptomeria japonica) trees grown in two common gardens from cuttings collected from natural populations across Japan. Amplicon sequencing revealed that bacterial and fungal communities differed significantly between gardens and among host population origins. Analysis of BVOC profiles showed that the camphene emission rate was associated with bacterial community composition, whereas that of {beta}-farnesene was linked to fungal community composition. The relative abundances of certain putative plant pathogens and the emission rates of most monoterpenes were correlated with the climatic conditions at the origin sites of cedar trees. These findings highlight the intricate relationships between phyllosphere microbial communities and terpene emission from host trees and suggest the role of climatic factors in shaping these interactions.

plant biology↗

bioRxiv2025

MARK4 enhances stress granule formation and increases tau accumulation

Stress granules (SGs) are membrane-less organelles that are formed in response to cellular stress. SG formation protects cells against stress; however, their dysregulation and longer persistence may disrupt proteostasis. Abnormal activity of Microtubule-affinity regulating kinase 4 (MARK4) has been linked to cancer and Alzheimers disease. Here, we report that MARK4 is a component of SGs and enhances SG formation. MARK4 is found in SGs in mammalian cultured cells and primary neurons with T-cell intracellular antigen 1 (TIA1). MARK4 expression enhances SG formation induced by hydrogen peroxide. The spacer domain of MARK4 mediates its localization to SGs, and its kinase activity is required for the enhancement of SG formation. MARK4 suppresses TIA1 dimerization induced by hydrogen peroxide. Furthermore, we found that MARK4 and TIA1 synergistically promoted tau accumulation in cultured cells, and knockdown of a fly TIA1 homolog suppressed tau toxicity in a Drosophila model. These results indicate that MARK4 regulates TIA1 and SG formation and suggest that MARK4 and TIA1 synergistically contribute to tau toxicity.

cell biology↗

bioRxiv2025

Mapping molecular diffusion across the whole cell with spatial statistics-based FRAP

Understanding molecular diffusion within cells is crucial for gaining insights into cellular biophysical mechanisms. Fluorescence recovery after photobleaching (FRAP) is a powerful technique for assessing molecular diffusion, yet its localized measurement approach hinders whole-cell analysis. To overcome this limitation, we developed Probabilistic FRAP (Pro-FRAP), a novel approach that integrates FRAP with sequential Gaussian simulation (SGS), an advanced spatial statistical method incorporating probabilistic modeling to estimate diffusion in unmeasured regions. Pro-FRAP applies SGS to standardize measured FRAP data, perform conditional simulations based on spatial correlations, and generate statistically robust estimates. In separate analyses, numerical simulations were conducted to optimize the spatial arrangement of measurement points, enhancing data accuracy and coverage. Unlike deterministic interpolation methods, Pro-FRAP captures spatial variability and quantifies uncertainty in intracellular diffusion, providing a more detailed representation of molecular transport. Thus, this framework extends FRAP beyond localized measurements, offering a refined approach for mapping intracellular diffusion with improved spatial coverage and statistical reliability. Significance statementUnderstanding molecular diffusion is essential for deciphering cellular functions and regulation. However, conventional fluorescence recovery after photobleaching (FRAP) techniques are constrained to localized measurements, limiting their ability to capture diffusion dynamics across entire cells. Here, we describe Probabilistic FRAP (Pro-FRAP), a novel framework that integrates FRAP with sequential Gaussian simulation (SGS), a spatial statistical method that enables the estimation of molecular diffusion in unmeasured regions. By incorporating probabilistic modeling, Pro-FRAP generates high-resolution diffusion maps with enhanced statistical reliability. This approach provides a more comprehensive perspective on intracellular transport, allowing for deeper insights into the spatial organization of cellular processes.

biophysics↗

bioRxiv2025

Decoupling diffusion, turnover, and advection in long-term FRAP

Intracellular molecular turnover is a dynamic process governed by diffusion, biochemical reactions, and intracellular transport dynamics. While fluorescence recovery after photobleaching (FRAP) has been widely used to quantify fluorescence recovery mechanisms, conventional models primarily focus on diffusion and reaction kinetics, often overlooking the influence of intracellular advection. However, in cytoskeletal structures such as stress fibers, myosin-driven actin retrograde flow generates a significant advective component, which complicates the interpretation of FRAP data, particularly in long-term observations where advective effects become sufficiently pronounced. Here, we develop an analytical framework that extends FRAP modeling to incorporate the coupled effects of diffusion, turnover, and intracellular advection within the photobleached region of interest. By deriving exact solutions to a reaction-diffusion-advection system, we identify three key dimensionless parameters that govern fluorescence recovery dynamics: the turnover-to-diffusion ratio, the monomer-to-filament ratio, and the advection magnitude. Our results demonstrate that, even in the absence of biochemical reactions, fluorescence recovery in a fixed region can occur due to advection, leading to potential misinterpretations of molecular exchange rates. The model provides a theoretical foundation for distinguishing these effects and offers a practical tool for long-term FRAP analysis, where the interplay of diffusion, turnover, and advection becomes increasingly relevant over extended timescales. By systematically characterizing the interplay between molecular diffusion, reaction kinetics, and intracellular transport, our framework provides deeper insight into protein turnover in complex biological environments.

biophysics↗

bioRxiv2025

Divergent Effects of APOE3 and APOE4 Human Astrocytes on Key Alzheimer's Disease Hallmarks in Chimeric Mice

Despite strong evidence supporting that both astrocytes and apolipoprotein E (APOE) play crucial roles in the pathogenesis and progression of Alzheimers disease (AD), the impact of astrocytes carrying different APOE variants on key AD pathological hallmarks remains largely unknown. To explore such effects in a human relevant context, we generated a chimeric model of AD. We transplanted isogenic APOE3 or APOE4 human induced pluripotent stem cell (hiPSC)-derived astrocyte progenitors into neonatal brains of AD model mice. We show that at five to six months after transplantation, transplanted cells have differentiated into mature astrocytes (h-astrocytes) that often integrate in upper layers of one cortical hemisphere. APOE3 and APOE4 h-astrocytes differentially express and secrete the APOE protein, which binds to A{beta} plaques with an isoform-dependent affinity. Remarkably, APOE3 h-astrocytes ameliorate A{beta} pathology, Tau pathology and neuritic dystrophy. In contrast, APOE4 h-astrocytes aggravate these AD processes. Moreover, APOE3 and APOE4 h-astrocytes modulate microglia responses to A{beta} pathology in opposite ways. APOE4 h-astrocytes enhance microglia clustering around A{beta} plaques and exacerbate DAM state whereas APOE3 h-astrocytes reduce microglia clustering and induce a more homeostatic state on plaque-associated microglia. These findings highlight a critical contribution of h-astrocytes not only to A{beta} pathology but also to other key AD hallmarks in chimeric mice. In addition, our findings reveal that h-astrocytes with different APOE variants and the different forms of APOE they secrete have a crucial role in AD progression.

neuroscience↗

bioRxiv2025

Involvement of orexin nerves in early stage of Alzheimer's disease model mice and preventive effect of orexin receptor antagonists

BackgroundMild cognitive impairment (MCI) is a condition between healthy cognition and dementia with a high probability of progression to Alzheimers disease (AD). Elevated levels of orexin (OX) have been reported in the cerebrospinal fluid of patients with MCI and AD. ObjectiveTo investigate the efficacy of dual OX receptor antagonists (suvorexant and lemborexant) in an early-stage AD mouse model (App-KI). MethodsThe expression of the OX receptor gene, the levels of suvorexant and lemborexant in the brain after a single oral dose, and their effects on locomotor activity were investigated in wild-type mice. In addition, the cognitive function of wild-type and App-KI mice was assessed using the Y-maze test after oral administration of suvorexant or lemborexant once a day for 60 d. After the behavioral test, amyloid-beta levels were quantified in the hippocampal CA1 region of App-KI mice. ResultsThe expression of the OX receptor gene was highest in the lateral hypothalamus and was also observed in other brain regions. Drug levels peaked at 20-40 min for suvorexant and 15 min for lemborexant and declined, still detectable 24 h later. Locomotor activity was reduced after suvorexant or lemborexant administration; however, 24 h after administration, locomotor activity did not differ from the control group. In particular, the Y-maze test showed that suvorexant and lemborexant prevented cognitive impairment in App-KI mice. Furthermore, suvorexant and lemborexant suppressed amyloid-beta accumulation in the hippocampal CA1 region of App-KI mice. ConclusionThe results suggest that suvorexant and lemborexant effectively suppress the early stages of AD.

animal behavior and cognition↗

bioRxiv2025

Misclassification in memory modification in AppNL-G-F knock-in mouse model of Alzheimers disease

Alzheimers disease (AD), the leading cause of dementia, could potentially be mitigated through early detection and interventions. However, it remains challenging to assess subtle cognitive changes in the early AD continuum. Computational modeling is a promising approach to explain a generative process underlying subtle behavioral changes with a number of putative variables. Nonetheless, internal models of the patient remain underexplored in AD. Determining the states of an internal model between measurable pathological states and behavioral phenotypes would advance explanations about the generative process in earlier disease stages beyond assessing behavior alone. In this study, we assumed the latent cause model as an internal model and estimated internal states defined by the model parameters being in conjunction with measurable behavioral phenotypes. The 6- and 12-month-old AppNL-G-F knock-in AD model mice and the age-matched control mice underwent memory modification learning, which consisted of classical fear conditioning, extinction, and reinstatement. The results showed that AppNL-G-F mice exhibited a lower extent of reinstatement of fear memory. Computational modeling revealed that the deficit in the AppNL-G-F mice would be due to their internal states being biased toward overgeneralization or overdifferentiation of their observations, and consequently the competing memories were not retained. This deficit was replicated in another type of memory modification learning in the reversal Barnes maze task. Following reversal learning, AppNL- G-F mice, given spatial cues, failed to infer coexisting memories for two goal locations during the trial. We concluded that the altered internal states of AppNL-G-F mice illustrated their misclassification in the memory modification process. This novel approach highlights the potential of investigating internal states to precisely assess cognitive changes in early AD and multidimensionally evaluate how early interventions may work.

neuroscience↗

bioRxiv2025

Genetically encoded mechano-sensors with versatile readouts and compact size

Mechanical forces are critical for virtually all fundamental biological processes, yet quantification of mechanical forces at the molecular scale in vivo remains challenging. Here, we present a new strategy using calibrated coiled coils as genetically encoded, compact, tunable, and modular mechano-sensors to substantially simplify force measurement in vivo, via diverse readouts (luminescence, fluorescence and analytical biochemistry) and instrumentation readily available in biology labs. We demonstrate the broad applicability and ease-of-use of these coiled coil mechano-sensors by measuring forces during cytokinesis (formin Cdc12) and endocytosis (epsin Ent1) in yeast, force distributions in nematode axons ({beta}-spectrin UNC-70), and forces transmitted to the nucleus (mini-nesprin-2G) and within focal adhesions (vinculin) in mammalian cells. We report discoveries in intracellular force transmission that have been elusive to existing tools.

cell biology↗

bioRxiv2025

Mitochondria as Indispensable Yet Replaceable Components of Germ Plasm: Insights into Primordial Germ Cell Specification in Non-Teleost Sturgeons

While it is widely recognized that mitochondria are components of germ plasm, their specific role in the formation and specification of primordial germ cells (PGCs) remains poorly understood. Furthermore, it has not been established whether mitochondria in germ plasm possess unique characteristics essential for their function. In this study, we demonstrate that mitochondria are indispensable for PGCs development in non-teleost fishes and that their role is not dependent on their origin from germ plasm. Using sturgeon embryos, we showed that UV radiation applied to the vegetal pole effectively eliminates germ plasm, including mitochondria, and prevents PGCs formation. Remarkably, we restored germ plasm function and PGCs development by injecting mitochondria derived from donor eggs, even when these mitochondria were not originally part of the germ plasm. Transplanted mitochondria were successfully identified in larval PGCs using a fluorescent PKH26 tracer, and in interspecies transplantation experiments, their presence was confirmed using species-specific mtDNA and mtRNA primers in larvae and individual PGCs. Our findings reveal that mitochondria are critical but not germ plasm-specific determinants of PGCs formation. This study provides novel insights into the developmental pathways of germ cells and establishes a previously unrecognized flexibility in mitochondrial functionality within the germline. These findings also offer a potential method for conserving matrilineal genetics in critically endangered species like sturgeons, while simultaneously opening new avenues for studying germlines with high interspecies mitochondrial heteroplasmy and contributing to broader evolutionary and conservation biology.

developmental biology↗

bioRxiv2024

Involvement of Hepatitis B Core-Related Antigen in Viral Genome Integration in Patients With Prior Hepatitis B Virus Infection

BackgroundThe incidence of non-B non-C hepatocellular carcinoma (NBNC-HCC), which is negative for hepatitis B surface antigen and hepatitis C virus antibodies, is on the rise. Relatively high numbers of NBNC-HCC patients are hepatitis B core antibody (HBcAb) positive, suggesting that previous HBV infection may play a role in NBNC-HCC development, though the exact mechanisms are unclear. This study aimed to investigate whether HBV genomes are integrated into the host genome of HBcAb-positive NBNC-HCC cases and how these integrations may contribute to cancer development and progression. MethodsHBV detection PCR using HBV-specific primers on DNA extracted from HBcAb-positive NBNC-HCC tissue samples was performed. Positive samples were further examined for HBV integration sites using viral DNA-capture sequencing. Additionally, hepatitis B core-related antigen (HBcrAg) serum levels were measured to assess whether they could be predictive for HBV detection PCR results. ResultsAmong 90 HBcAb-positive NBNC-HCC samples, HBV genome amplification was detected in 18 samples, and elevated HBcrAg levels were associated with the HBV detection PCR results. Seventeen of these samples exhibited HBV integration. The HBV genome was integrated near the TERT gene in 7 samples, resulting in significantly increased TERT mRNA levels; in the KMT2B gene (2 samples); and downstream of LOC441666 (2 samples). ConclusionThe integration sites we identified in our samples have been previously reported in HBV-related HCC, suggesting that HBV integration may also contribute to hepatocarcinogenesis in HBcAb-positive NBNC-HCC. Furthermore, HBcrAg could serve as a potential, noninvasive marker for detecting HBV integration in these cases.

microbiology↗

bioRxiv2024

Age and amyloidβ-dependent initiation of neurofibrillary tau tangles: an improved mouse model of Alzheimers disease without mutations in MAPT.

The lack of models in which ageing and amyloid-{beta} (A{beta}) initiate neurofibrillary tau tangles, independent of MAPT mutations, limits mechanistic insights into Alzheimers disease. Here, we characterise NLFTaum/h, a novel mouse model that recapitulates the gradual transition from A{beta} accumulation to tau pathology by 24 months. We show that combined effects of ageing, A{beta}, and human tau expression promote tau pathology. However, either A{beta} plaques or human tau alone can initiate tau pathology, but only in even older mice. This may be exacerbated by increased neuronal vulnerability across all genotypes with age. Moreover, multi-omic analyses reveal that human tau can induce early alterations in mitochondrial and synaptic pathways, priming this latent vulnerability preceding tau pathology. Together, this suggests that ageing and other interacting triggers accelerate the onset of tau pathology. This opens possibilities for translatable testing of improved therapies for Alzheimers disease, breaking the link between A{beta} and tau pathologies.

neuroscience↗

bioRxiv2024

Long term rescue of Alzheimer deficits in vivo by one-time gene-editing of App C-terminus.

Gene-editing technologies promise to create a new class of therapeutics that can achieve permanent correction with a single intervention. Besides eliminating mutant alleles in familial disease, gene-editing can manipulate upstream pathophysiologic events and alter disease-course in wider patient populations. Here we use CRISPR-Cas9 to edit the last exon of amyloid precursor protein (App), relevant for Alzheimers disease (AD). Our strategy effectively eliminates an endocytic (YENPTY) motif at APP C-terminus in mouse and human neurons, while preserving N-terminus and compensatory APP-homologues. This manipulation favorably alters events along the amyloid-pathway; inhibiting toxic APP-beta-cleavage fragments (including Abeta) and upregulating neuroprotective APP-alpha-cleavage. AAV-editing ameliorates neuropathologic, electrophysiologic, and behavioral deficits in an AD knockin mouse model. Effects persist for many months with no detectable abnormalities in germline-edited WT mice, and pathologic alterations in glial-transcriptomes are also normalized. Our strategy takes advantage of innate transcriptional rules that render terminal exons insensitive to nonsense-decay, and this upstream manipulation is expected to be effective for all forms of AD.

neuroscience↗

bioRxiv2024

Unraveling factors responsible for pathogenic differences in Lassa virus strains

Lassa virus (LASV) is the etiological agent of Lassa fever (LF), a severe hemorrhagic disease with potential for lethal outcomes. Apart from acute symptoms, LF survivors often endure long-term complications, notably hearing loss, which significantly impacts their quality of life and socioeconomic status in endemic regions of West Africa. Classified as a Risk Group 4 agent, LASV poses a substantial public health threat in affected areas. Our laboratory previously developed a novel lethal guinea pig model of LF utilizing the clinical isolate LASV strain LF2384. However, the specific pathogenic factors underlying LF2384 infection in guinea pigs remained elusive. In this study, we aimed to elucidate the differences in the immunological response induced by LF2384 and LF2350, another LASV isolate from a non-lethal LF case within the same outbreak. Through comprehensive immunological gene profiling, we compared the expression kinetics of key genes in guinea pigs infected with LASV LF2384 and LF2350. Our analysis revealed differential expression patterns for several immunological genes, including CD94, CD19-2, CD23, IL-7, and CIITA, during LF2384 and LF2350 infection. Moreover, through the generation of recombinant LASVs, we sought to identify the specific viral genes responsible for the observed pathogenic differences between LF2384 and LF2350. Our investigations pinpointed the L protein as a crucial determinant of pathogenicity in guinea pigs infected with LASV LF2384. Author summaryLassa virus (LASV) is known to cause lethal hemorrhagic fever, Lassa fever, and is classified as a Risk Group-4 agent, which need to be handled in the highest biocontainment laboratories, biosafety level-4 (BSL-4), due to its high pathogenicity and the lack of preventive or treatment methods. LASV infection has a huge impact on public health and socioeconomics in endemic areas, however, its pathogenic mechanism is still largely unknown. In order to unveil the mechanisms of LASV pathogenesis, we compared the pathogenicity of two LASV isolates, which have opposite phenotypes in guinea pigs. Additionally, we determined the viral factor responsible for pathogenic differences between LASV isolates using reverse genetics. In summary, our study provides valuable insights into the immunological and virological factors underlying the pathogenic differences between LASV strains associated with lethal and non-lethal LF cases. Understanding these distinctions is essential for informing strategies for the diagnosis, treatment, and prevention of LF.

microbiology↗