Biology subjects

Tan, J.

Publications and source records attributed to Tan, J..

At least 73 records · Page 4Linked to original sources

bioRxiv2024

Characterization of tumor heterogeneity through segmentation-free representation learning

The interaction between tumors and their microenvironment is complex and heterogeneous. Recent developments in high-dimensional multiplexed imaging have revealed the spatial organization of tumor tissues at the molecular level. However, the discovery and thorough characterization of the tumor microenvironment (TME) remains challenging due to the scale and complexity of the images. Here, we propose a self-supervised representation learning framework, CANVAS, that enables discovery of novel types of TMEs. CANVAS is a vision transformer that directly takes high-dimensional multiplexed images and is trained using self-supervised masked image modeling. In contrast to traditional spatial analysis approaches which rely on cell segmentations, CANVAS is segmentation-free, utilizes pixel-level information, and retains local morphology and biomarker distribution information. This approach allows the model to distinguish subtle morphological differences, leading to precise separation and characterization of distinct TME signatures. We applied CANVAS to a lung tumor dataset and identified and validated a monocytic signature that is associated with poor prognosis.

cancer biology↗

bioRxiv2024

Deep contrastive learning enables genome-wide virtual screening

Numerous protein-coding genes are associated with human diseases, yet approximately 90% of them lack targeted therapeutic intervention. While conventional computational methods, such as molecular docking, have facilitated the discovery of potential hit compounds, the development of genome-wide virtual screening against the expansive chemical space remains a formidable challenge. Here we introduce DrugCLIP, a novel framework that combines contrastive learning and dense retrieval to achieve rapid and accurate virtual screening. Compared to traditional docking methods, DrugCLIP improves the speed of virtual screening by up to seven orders of magnitude. In terms of performance, DrugCLIP not only surpasses docking and other deep learning-based methods across two standard benchmark datasets, but also demonstrates high efficacy in wet-lab experiments. Specifically, DrugCLIP successfully identified agonists with < 100 nM affinities for 5HT2AR, a key target in psychiatric diseases. For another target NET, whose structure is newly solved and not included in the training set, our method achieved a hit rate of 15%, with 12 diverse molecules exhibiting affinities better than bupropion. Additionally, two chemically novel inhibitors were validated by structure determination with Cryo-EM. Finally, a novel potential drug target TRIP12, with no experimental structures and inhibitors for reference, was used to challenge DrugCLIP. DrugCLIP achieved a hit rate of 17.5% by screening a pocket identified on an AlphaFold2-predicted structure, verified with multi-cycle SPR assays. Molecules with the highest affinities also showed a dose-dependent inhibition to the enzymatic function of TRIP12. Building on this foundation, we present the results of a pioneering trillion-scale genome-wide virtual screening, encompassing approximately 10,000 AlphaFold2 predicted proteins within the human genome and 500 million molecules from the ZINC and Enamine REAL database. This work provides an innovative perspective on drug discovery in the post-AlphaFold era, where comprehensive targeting of all disease-related proteins is within reach.

bioinformatics↗

bioRxiv2024

Effect of fumarate and live yeast on methane emissions, rumen fermentation, blood metabolites, and lactation performance in dairy goats

The objective of this study was to evaluate the effects and combined effects of fumarate (32 g/d) and active dry yeast (ADY) (1.5 g/d) on methane emissions, rumen fermentation, microbial community and function, apparent total tract digestibility, blood metabolites, and lactation performance in 28 lactating goats using a randomized complete block design with a 2 x 2 factorial arrangement. Fumarate supplementation inhibited methane emission rates for 3 h post-feeding, while ADY increased the methane emission rates for 2 h pre-feeding, without combined effects between them. Fumarate increased the rumen pH and reduced total VFA concentration without changing the VFA profiles before feeding. Based on two custom dataset of 4,674 metagenome-assembled genomes and 7,758,615 nonredundant genes, neither fumarate nor live yeast influenced the rumen microbial community and function. The addition of fumarate reduced the concentrations of glucose, serum malondialdehyde (MDA), and ammonia in the serum, as well as the activity of insulin, while increasing the activity of serum malate dehydrogenase (MDH) and the levels of urea in both serum and milk. The addition of live yeast reduced serum glucose levels and increased serum MDA concentrations and MUN levels. There was a negative interaction between fumaric acid and live yeast on the levels of urea nitrogen in serum and milk. ConclusionsThe methane inhibition effect of fumaric acid persists for 3 h post-feeding, reflecting its retention or metabolism time in the rumen. Fumaric acid enhances the TCA cycle and the urea cycle in dairy goats, thereby improving energy utilization efficiency and reducing the risk of ammonia toxicity.

microbiology↗

bioRxiv2024

High fat low carbohydrate diet is linked to protection against CNS autoimmunity

Multiple sclerosis (MS) is a common central nervous system (CNS) autoimmune disease, and diets and nutrients are emerging as critical contributing factors. However, a comprehensive understanding of their impacts and the underlying mechanisms involved is lacking. Harnessing state-of-the-art nutritional geometry analytical methods, we first revealed that globally, increased carbohydrate supply was associated with increased MS disease burden, while fat supply had an opposite effect. Furthermore, in a preclinical MS mouse model, experimental autoimmune encephalomyelitis (EAE), we found that an isocaloric diet high in carbohydrate aggravated EAE, while a diet enriched in fat was fully protective. This was reflected by reduced neuroinflammation and skewing towards anti-inflammatory phenotypes, which involved transcriptomic, epigenetic and immunometabolic changes. We showcased that manipulating diets is a potentially efficient and cost-effective approach to prevent and/or ameliorate EAE. This exhibits translational potentials for intervention/prevention of MS and possibly other autoimmune diseases.

immunology↗

bioRxiv2024

Two mechanisms of photoenergy regulation revealed by kinetic behaviors of chlorophyll fluorescence during light adaptation

Photochemical reactions were analyzed and modeled to observe photoenergy regulation mechanisms in PSII from measured chlorophyll fluorescence (ChlF) kinetics. Two pH-driven mechanisms were revealed: One is the PsbS-mediated non-photochemical quenching (NPQ) of activated antennae (A*), as commonly understood, and the other is a disruption of energy transfer from A* to P680. Representing the latter with a conformational change from complex formation of zeaxanthin and lutein with antennae closely described measured ChlF from initially dark-adapted state to light-adapted state and measured NPQ variations. Analysis based on the model indicates that zeaxanthin and lutein lead to slow protracted reductions in P680* and ChlF via the second mechanism without strong influence by pH or PsbS. Protonation of PsbS plays a major role via the first mechanism in responding to fast changes in illumination. The research provides insights into the mechanisms for photoenergy regulation in PSII and a kinetic model with broadened applicability.

bioengineering↗

bioRxiv2024

Spatiotemporally resolved transcriptome atlas of developing mouse placenta reveals mechanisms of embryonic lethality.

Proper placentation is fundamental to the growth and viability of the maturing embryo. However, a thorough grasp of the spatial organization of cell types, their interactions, and gene expression patterns along the maternal-fetal function during placental development remains incomplete. Here, we utilized Stereo-seq to construct the spatiotemporal transcriptomic atlas of the mouse placenta (STAMP) spanning embryonic (E) days 9.5 to 18.5 at single cell resolution (https://db.cngb.org/stomics/stamp/). This resource delineates spatially resolved cellular dynamics and gene expression patterns across placental and maternal compartments. We identified distinct glycogen trophoblast cell (GC) subclusters, mapped their developmental trajectories, and uncovered transcriptional transitions accompanying their migration from the junctional zone to the maternal decidua from E12.5 onward. In a defective placentation model with perinatal lethality, GCs abnormally persisted at E18.5 with excessive glycogen and reduced degradation metabolites in placenta and fetal liver, indicating impaired glycogen breakdown. Maternal glucose supplementation restored glucose levels and rescued fetal survival, underscoring GC-mediated metabolic support as critical for viability. Together, this study provides a comprehensive spatiotemporal placental atlas and demonstrates that GC-mediated glycogen metabolism is essential for sustaining fetal viability.

developmental biology↗

bioRxiv2024

Mitochondrial DNA is a sensitive surrogate and oxidative stress target in oral cancer cells

Cellular oxidative stress mediated by intrinsic and/or extrinsic reactive oxygen species (ROS) is associated with disease pathogenesis. Oxidative DNA damage can naturally be substituted by mitochondrial DNA (mtDNA), leading to base lesion/strand break formation, copy number changes, and mutations. In this study, we devised a single test for the sensitive quantification of acute mtDNA damage, repair, and copy number changes using supercoiling-sensitive quantitative PCR (ss-qPCR) and examined how oxidative stress-related mtDNA damage responses occur in oral cancer cells. We observed that exogenous hydrogen peroxide (H2O2) induced dynamic mtDNA damage responses, as reflected by early structural DNA damage, followed by DNA repair if damage did not exceed a particular threshold. However, high oxidative stress levels induced persistent mtDNA damage and caused a 5-30-fold depletion in mtDNA copy numbers over late responses. This dramatic depletion was associated with significant growth arrest and apoptosis, suggesting persistent functional consequences. Moreover, oral cancer cells responded differentially to oxidative injury when compared with normal cells, and different ROS species triggered different biological consequences under stress conditions. In conclusion, we developed a new method for the sensitive detection of mtDNA damage and copy number changes, with exogenous H2O2 inducing dynamic mtDNA damage responses associated with functional changes in stressed cancer cells. Finally, our method can help characterize oxidative DNA damage in cancer and other human diseases.

cancer biology↗

bioRxiv2024

Structural basis of the bacterial flagellar motor rotational switching

The bacterial flagellar motor is a huge bidirectional rotary nanomachine that drives rotation of the flagellum for bacterial motility1-5. The cytoplasmic C ring of the flagellar motor functions as the switch complex for the rotational direction switching from counterclockwise to clockwise2,3,6-9. However, the structural basis of the rotational switching and how the C ring is assembled have long remained elusive. Here, we present two high-resolution cryo-electron microscopy structures of the C ring-containing flagellar motor-hook complex from Salmonella Typhimurium, which are in the default counterclockwise state and in a constitutively active CheY mutant-induced clockwise state, respectively. In both complexes, the C ring consists of four subrings, but is in two different conformations. The CheY proteins are bound into an open groove between two adjacent protomers on the surface of the middle subring of the C ring and interact with the FliG and FliM subunits. The binding of the CheY protein induces a significant upward shift of the C ring towards the MS ring and inward movements of its protomers towards the motor center, which eventually remodels the structures of the FliG subunits and reverses the orientations and surface electrostatic potential of the torque helices to trigger the counterclockwise-to-clockwise rotational switching. The conformational changes of the FliG subunits reveal that the stator units on the flagellar motors require a relocation process in the bacterial inner membrane during the rotational switching. This study provides unprecedented molecular insights into the rotational switching mechanism and a detailed overall structural view of the bacterial flagellar motors.

microbiology↗

bioRxiv2024

DNA virus infections shape transposable elements activity in vitro and in vivo

Transposable elements (TEs) are implicated in a variety of processes including placental and preimplantation development and a variety of human diseases. TEs are known to be activated in the context of some viral infections, but the mechanisms and consequences are not understood. We show strong activation of TEs upon DNA virus infection, in particular the MLT- and THE1-class of LTR-containing retrotransposons as well as a subset of LINE-1-, Alu-elements and HERVs. Mechanistically, two key pathways induce TEs upregulation: inhibition of the KAP1/TRIM28 repressive complex by phosphorylation, and expression of the pioneer transcription factor double-homeobox 4 (DUX4), which is known to be involved in TE-induction during zygotic genome activation in embryonic development. DUX4 is induced by DNA viruses, it binds to TEs upon infection and analysis of genes adjacent to TEs shows pathways that are important for DNA virus infections. Analysis of knockdown, knockout and overexpression data reveal that almost all TEs expressed upon herpesviral infection are regulated by KAP1/TRIM28 and DUX4. Interestingly, analysis of single cell sequencing data from patients with DNA virus-associated cancers showed that in vivo TEs expression strongly correlates with virus infection, indicating a possible role in viral oncogenesis.

genomics↗

bioRxiv2024

A 6-minute Limb Function Assessment for Therapeutic Testing in Experimental Peripheral Artery Disease Models

BackgroundThe translation of promising therapies from pre-clinical models of hindlimb ischemia (HLI) to patients with peripheral artery disease (PAD) has been inadequate. While this failure is multifactorial, primary outcome measures in preclinical HLI models and clinical trials involving patients with PAD are not aligned well. For example, laser Doppler perfusion recovery measured under resting conditions is the most used outcome in HLI studies, whereas clinical trials involving patients with PAD primarily assess walking performance. Here, we sought to develop a 6-min limb function test for preclinical HLI models that assess muscular performance and hemodynamics congruently. MethodsWe developed an in situ 6-min limb function test that involves repeated isotonic (shortening) contractions performed against a submaximal load. Continuous measurement of muscle blood flow was performed using laser Doppler flowmetry. Quantification of muscle power, work, and perfusion are obtained across the test. To assess the efficacy of this test, we performed HLI via femoral artery ligation on several mouse strains: C57BL6J, BALBc/J, and MCK-PGC1 (muscle-specific overexpression of PGC1). Additional experiments were performed using an exercise intervention (voluntary wheel running) following HLI. ResultsThe 6-min limb function test was successful at detecting differences in limb function of C57BL6/J and BALBc/J mice subjected to HLI with effect sizes superior to laser Doppler perfusion recovery. C57BL6/J mice randomized to exercise therapy following HLI had smaller decline in muscle power, greater hyperemia, and performed more work across the 6-min limb function test compared to non-exercise controls with HLI. Mice with muscle-specific overexpression of PGC1 had no differences in perfusion recovery in resting conditions, but exhibited greater capillary density, increased muscle mass and absolute force levels, and performed more work across the 6-min limb function test compared to their wildtype littermates without the transgene. ConclusionThese results demonstrate the efficacy of the 6-min limb function test to detect differences in the response to HLI across several interventions including where traditional perfusion recovery, capillary density, and muscle strength measures were unable to detect therapeutic differences.

physiology↗

bioRxiv2024

Nanoparticles alter the nature and strength of intraploidy and interploidy interactions in plants

Engineered nanoparticles have profound impacts on organisms, yet there is limited understanding of how nanoparticle exposure shapes species interactions that are key for natural community dynamics. By growing plants of the same (intraploidy) and different ploidy levels (interploidy) of Fragaria in axenic microcosms, we examined the influence of nanoparticles on species interactions in polyploid and diploid plants. We found that, under copper oxide (CuO) nanoparticle exposure, polyploids experienced reduced competition when growing with polyploids (the effect of polyploids on polyploids, RII8x,8x), and a shift towards facilitation when growing with diploids (the effect of diploids on polyploids, RII8x,2x). This reduction in competitive interactions in polyploids, in line with the stress gradient hypothesis, was primarily caused by nanoscale effects, because the strength of competitive interactions (RII8x,8x and RII8x,2x) remained relatively unchanged under CuO bulk particles compared to control conditions. In contrast, diploids experienced a shift from facilitation (RII2x,2x and RII2x,8x) under control conditions to neutrality under CuO nanoparticles, with a similar reduction in facilitation observed with both nanoparticles and bulk particles. These findings underscore ploidy specific interaction dynamics and the need of considering species interactions when predicting organismal responses to nanoparticle pollution in ecological communities.

ecology↗

bioRxiv2024

Gut microbes of the cecum versus the colon drive more severe lethality and multi-organ damage

An intestinal perforation or puncture leads to a high risk of sepsis-associated morbidity. A perforation initiates the transfer of the intestinal contents (ICs) to the peritoneal cavity, leading to abdominal infections and varying with different prognoses. However, the mechanisms associated with different perforations in the cecum and colon remain unknown. We sought to examine how different gut flora contribute to prognoses in different intestinal perforation sites. We compared the microbiome of the ICs in the cecum and colon in a fecal-induced peritonitis mouse model. The results showed that cecum ICs developed more severe sepsis than colon ICs, including a shorter median survival time, increased biochemical indicators, more pathological changes in multiple organs and overwhelmed systematic inflammation. Moreover, our results demonstrated that cecum ICs hold more bacterial burden in unit weight than colon ICs, and the microbial communities differed between the ICs from the cecum and colon. A more detailed comparison of the two microbiome groups showed that the abundance of potentially pathogenic bacteria increased in the cecum ICs. Our data suggest that the sepsis severity developed by perforation was associated with bacterial burden and increased abundance of potentially pathogenic bacteria in the cecum. Our findings first compared the differences in the lethality associated with the ICs of the cecum and colon, which pointed out that the site of perforation could help providers predict the severity of sepsis.

immunology↗

bioRxiv2024

Thyroid Hormone Suppresses Medulloblastoma Progression Through Promoting Terminal Differentiation of Tumor Cells

Hypothyroidism is commonly detected in patients with medulloblastoma (MB). A possible link between thyroid hormone (TH) signaling and MB pathogenicity has not been reported. Here, we find that TH plays a critical role in promoting tumor cell differentiation. Reduction in TH levels frees the TH receptor, TR1, to bind to EZH2 and repress expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH reverses EZH2-mediated repression of NeuroD1 by abrogating the binding of EZH2 and TR1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, TH-induced differentiation of tumor cells is not restricted by the molecular subgroup of MB. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising modality for MB treatment.

cancer biology↗

bioRxiv2024

Functional characterization of CCHamides and deorphanization of their receptors in the yellow fever mosquito, Aedes aegypti

As a widely distributed anthropophilic mosquito species and vector of various arboviruses, Aedes aegypti poses a significant threat to human health on a global scale. Investigating mosquito neuropeptides allows us to better understand their physiology. The neuropeptides CCHamide1 (CCHa-1) and CCHamide-2 (CCHa-2) and their associated G protein-coupled receptors (CCHa-1R and CCHa-2R) were recently identified and studied across insects. However, expression profiles and physiological roles of CCHamides and their receptors in many other insects, including A. aegypti, remain unclear. This research aimed to quantify and localize the expression of CCHamides along with their receptors and to elucidate their physiological function in the yellow fever mosquito. RT-qPCR analysis revealed transcript abundance of CCHamides and receptors changes over development. Differential expression was also observed in tissues/organs of adult mosquitoes indicating CCHa-1 and CCHa-2 transcripts are most highly enriched in the midgut, while receptors are expressed across various tissues. Further, CCHamides were immunolocalized in neurons in the brain and ventral nerve cord along with enteroendocrine cells in the posterior midgut adjacent to the midgut-hindgut junction, corroborating their transcript expression profiles. Using different mass spectrometrical approaches, presence of CCHamides were confirmed in the brain of both sexes, including the pars intercerebralis of female mosquitoes, as well as in the gut of adult mosquitoes. For chemical identification of predicted CCHamides, we analyzed brain and gut extracts by ESI-Q Exactive Orbitrap MS and resulting fragmentations confirmed CCHa1 and CCHa2 in brain and midgut samples of both male and female mosquitoes. A heterologous functional assay was used to confirm the specificity and sensitivity of the two CCHamide receptors by assessing their activation in response to diverse mosquito peptides, which confirmed CCHa-1 and CCHa-2 as the natural ligands. Finally, using a capillary feeder (CAFE) bioassay, our results suggest that CCHa-2 modulates feeding behaviour in female mosquitoes.

zoology↗

bioRxiv2024

Self-inspired learning to denoise for live-cell super-resolution microscopy

Every collected photon is precious in live-cell super-resolution (SR) fluorescence microscopy for contributing to breaking the diffraction limit with the preservation of temporal resolvability. Here, to maximize the utilization of accumulated photons, we propose SN2N, a Self-inspired Noise2Noise engine with self-supervised data generation and self-constrained learning process, which is an effective and data-efficient learning-based denoising solution for high-quality SR imaging in general. Through simulations and experiments, we show that the SN2Ns performance is fully competitive to the supervised learning methods but circumventing the need for large training-set and clean ground-truth, in which a single noisy frame is feasible for training. By one-to-two orders of magnitude increased photon efficiency, the direct applications on various confocal-based SR systems highlight the versatility of SN2N for allowing fast and gentle 5D SR imaging. We also integrated SN2N into the prevailing SR reconstructions for artifacts removal, enabling efficient reconstructions from limited photons. Together, we anticipate our SN2N and its integrations could inspire further advances in the rapidly developing field of fluorescence imaging and benefit subsequent precise structure segmentation irrespective of noise conditions.

bioengineering↗

bioRxiv2024

Targeting transcription factors through an IMiD independent zinc finger domain

Immunomodulatory imide drugs (IMiDs) degrade specific C2H2 zinc finger degrons in transcription factors, making them effective against certain cancers. SALL4, a cancer driver, contains seven C2H2 zinc fingers in four clusters, including an IMiD degron in zinc finger cluster two (ZFC2). Surprisingly, IMiDs do not inhibit growth of SALL4 expressing cancer cells. To overcome this limit, we focused on a non-IMiD degron, SALL4 zinc finger cluster four (ZFC4). By combining AlphaFold and the ZFC4-DNA crystal structure, we identified a potential ZFC4 drug pocket. Utilizing an in silico docking algorithm and cell viability assays, we screened chemical libraries and discovered SH6, which selectively targets SALL4-expressing cancer cells. Mechanistic studies revealed that SH6 degrades SALL4 protein through the CUL4A/CRBN pathway, while deletion of ZFC4 abolished this activity. Moreover, SH6 led to significant 62% tumor growth inhibition of SALL4+ xenografts in vivo and demonstrated good bioavailability in pharmacokinetic studies. In summary, these studies represent a new approach for IMiD independent drug discovery targeting C2H2 transcription factors in cancer. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/574032v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@b8e4e8org.highwire.dtl.DTLVardef@bc6f01org.highwire.dtl.DTLVardef@11bbe85org.highwire.dtl.DTLVardef@791cb1_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Oblique Line Scan Illumination Enables Expansive, Accurate and Sensitive Single Protein Measurements in Solution and in Living Cells

Single-molecule localization microscopy (SMLM) techniques, such as single-molecule tracking (SMT), enable in situ measurements in cells from which data-rich metrics can be extracted. SMT has been successfully applied to a variety of biological questions and model systems, aiming to unravel the spatiotemporal regulation of molecular mechanisms that govern protein function, downstream pathway effects, and cellular function. While powerful, SMLM often suffers from low throughput and illumination inhomogeneity, along with microscope and user-induced technical biases. Due to technical limitations in scaling SMLM techniques, a tradeoff between spatiotemporal resolution and throughput has been made historically, restricting broad application of these technologies. Here we address these limitations using Oblique Line Scan (OLS), a robust single-objective light-sheet based illumination and detection modality that achieves nanoscale spatial resolution and sub-millisecond temporal resolution across a 250 x 190 m field of view. We demonstrate OLS-enabled SMT on Halo-Tagged proteins in living cells capturing protein motion up to 14 m2 /s. By exploiting the adaptability of the acquisition frame rate and the improved rejection of out of focus light, we extend the utility of OLS beyond cellular compartments with in-solution SMT (isSMT) for single-molecule measurement of ligand-protein interactions and disruption of protein-protein interactions (PPI). We illustrate the versatility of OLS by showcasing two-color SMT, STORM, and single molecule fluorescence recovery after photobleaching (FRAP). OLS expands the range of SMLM applications and paves the way for robust, high-throughput single-molecule investigations of protein dynamics required for drug screening and systems biology studies, both in cells and in solution.

biophysics↗

bioRxiv2023

Assessing Immune Factors in Maternal Milk and Paired Infant Plasma Antibody Binding to Human Rhinoviruses

Before they can produce their own antibodies, newborns are protected from infections by transplacental transfer of maternal IgG antibodies and after birth through breast milk IgA antibodies. Rhinovirus (RV) infections are extremely common in early childhood, and while RV infections often result in only mild upper respiratory illnesses, they can also cause severe lower respiratory illnesses such as bronchiolitis and pneumonia. We used high-density peptide arrays to profile infant and maternal antibody reactivity to capsid and full proteome sequences of three human RVs - A16, B52, and C11. Numerous plasma IgG and breast milk IgA RV epitopes were identified that localized to regions of the RV capsid surface and interior, and also to several non-structural proteins. While most epitopes were bound by both IgG and IgA, there were several instances where isotype-specific and RV-specific binding were observed. We also profiled 62 unique RV-C dominant protein loop sequences characteristic of this species capsid VP1 protein. Many of these RV-C sites were highly bound by IgG from one-year-old infants, indicating recent or ongoing active infections, or alternatively, a level of cross-reactivity among homologous RV-C sites.

immunology↗