Biology subjects

Gulati, S.

Publications and source records attributed to Gulati, S..

14 recordsLinked to original sources

bioRxiv2026

Intranasal Delivery of Hypoxia Primed Whartons Jelly MSC Derived sEVs Reprograms Neuroimmune Signalling and Ameliorates Behavioural Deficits in a Valproic Acid Induced Mouse Model of Autism Spectrum Disorder

BackgroundBeyond disrupted neurodevelopment, autism spectrum disorder (ASD) encompasses progressive neurodegenerative alterations that remain refractory to standard of care behavioral therapies, highlighting the need for biologically targeted adjunctive interventions. Although, Mesenchymal stem cell (MSC) derived small extracellular vesicles (sEVs) have emerged as potent neuroprotective agents; however, the optimal MSC tissue source and strategies enhancing their efficacy for clinical translation remain undefined. Hypoxic preconditioning potentiates their therapeutic effects, however its specific impact on ASD-related impairments is yet to be established. This study conducts a head to head evaluation of sEVs from bone marrow (BM) and Whartons jelly (WJ) MSCs under normoxic and hypoxic conditions to delineate their comparative neuroregenerative efficacy in ASD. MethodsWe investigated the neuroprotective efficacy of sEVs derived from human tissue-specific mesenchymal stem cells (BM/WJ) cultured under normoxic (21% O2) and hypoxic (1% O2) conditions. In vitro assays evaluated sEV uptake, cell proliferation, neurodifferentiation, mitochondrial health, and immunomodulatory effects using neural stem cell (C17.2) and microglial (N9) cell lines. For in vivo studies, ASD-like phenotypes were induced in C57BL/6 mice via prenatal exposure to valproic acid (600 mg/kg), followed by the biodistribution of fluorescently labeled hypoxia-primed WJ MSCs sEVs (WJ-H-sEVs) following intranasal administration was assessed using IVIS imaging. Behavioural outcomes after intranasal treatment were evaluated. Additionally, post-mortem brain tissues were analyzed for neuroinflammation, oxidative stress, synaptic integrity, and downstream signalling pathways using immunofluorescence, Western blotting, and qRT-PCR, while systemic cytokine pro-inflammatory and anti-inflammatory levels were quantified by ELISA. Mechanistic involvement of Nrf2 and NF-{kappa}B signaling pathways was examined using pharmacological inhibitors. ResultsComparative analyses revealed that hypoxic priming significantly enhanced sEV yield and enriched neuroprotective miRNAs, with WJ-H-sEVs exhibiting elevated levels of miR-125b-5p, miR-21a-5p, and miR-145a-5p. Consistent with this enrichment, WJ-H-sEVs demonstrated superior cellular uptake as observed in neural stem cells and microglia, enhanced neurodifferentiation, robust antioxidant activity, effective immunomodulation, and improved mitochondrial health, thereby outperforming their normoxic and BM-derived counterparts. Intranasally administered WJ-H-sEVs efficiently localized to the brain within 12 h and significantly improved anxiety-like behavior, recognition memory, and spatial learning in ASD mice. These effects were accompanied by reduced neuroinflammation and oxidative damage, enhanced neuronal survival, decreased serum IL-6 levels, and increased IL-10 and TGF-{beta}. Mechanistically, therapeutic benefits were mediated through activation of the Nrf2 antioxidant pathway and suppression of NF-{kappa}B and JAK-STAT signaling. ConclusionIn this study, hypoxia emerges as a clinically exploitable priming strategy to enhance the neuroregenerative performance of tissue-specific MSC-derived sEVs, with potential applicability across MSC sources and other neurological disorders. Moreover, intranasal delivery of WJ-H-sEVs demonstrates translational feasibility, reinforcing their potential as an adjunctive, cell-free, pediatric-friendly neurotherapeutic modality for ASD management. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/721255v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@dd0f7forg.highwire.dtl.DTLVardef@1247d24org.highwire.dtl.DTLVardef@93e6deorg.highwire.dtl.DTLVardef@1a349d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2026

Pre-clinical efficacy of a C4BP hexameric IgG Fc fusion protein against Neisseria gonorrhoeae

Gonorrhea is the second most common bacterial sexually transmitted infection and affects about 80 million people worldwide annually. The causative agent, Neisseria gonorrhoeae, has become resistant to almost every antibiotic used for its treatment. There is no licensed vaccine against gonorrhea. Therefore, there is an urgent need to develop novel prevention and treatment strategies to curb the spread of gonorrhea. The gonococcus has evolved several mechanisms to evade complement, a key arm of immune defenses against this pathogen, including binding of the human complement inhibitors Factor H (FH) and C4b-binding protein (C4BP). We previously showed that chimeric molecules fusing the gonococcal binding domains of FH and C4BP to IgG Fc and IgM Fc, respectively, mediate complement-dependent killing of gonococci in vitro and attenuate gonococcal colonization of mouse vaginas when administered topically. Here, we fused C4BP domains 1 and 2, which contain the gonococcal binding region, to IgG Fc bearing the IgM tail-piece to facilitate Fc hexamerization. This molecule, called C4BP-Hexa IgG Fc, showed [~]650-fold greater complement-dependent bactericidal activity on a molar basis than monomeric C4BP-IgG1 Fc. C4BP-Hexa IgG Fc enhanced association with and uptake by human neutrophils in a complement-independent manner. Despite off-target complement activation in solution, C4BP-Hexa IgG Fc reduced both the duration and the bacterial burden of gonococcal vaginal colonization in human FH and C4BP transgenic mice when administered intravaginally daily. In conclusion, we show proof-of-concept of the efficacy of a hexameric C4BP IgG Fc fusion molecule against N. gonorrhoeae, which could aid in the fight against this multidrug-resistant pathogen.

immunology↗

bioRxiv2026

Evaluating Limits of Machine Learning-Assisted Raman Spectroscopy in Classification of Biological Samples

Machine learning (ML)-assisted Raman spectroscopy has become a powerful analytical tool for the classification and identification of analytes; however, technical challenges impacting its detection accuracy have not been investigated. This study explores experimental factors affecting classification performance. Among the evaluated ML models, ML algorithms show minimal impacts on classification accuracy. Instead, experimental factors, including spectral similarity between tested samples and the data quality, dominate detection performance. Increases in spectral noises and spectral similarity significantly reduce classification accuracy. In well-controlled samples with low experimental noise, ML-assisted Raman spectroscopy can discriminate lipid mixtures with a composition difference of 1.85 mol%. To assess the effect of biological heterogeneity, we analyzed single-cell Raman spectra from Saccharomyces cerevisiae strains carrying single, double, or triple gene mutations. Intrinsic cell-to-cell variability introduced substantial spectral differences, severely reducing the accuracy of multiclass classification of these genetically similar strains at the single-cell level. Averaging Raman spectra across multiple cells improved classification accuracy by reducing this spectral variability. We also assess the effectiveness of transfer learning across different Raman spectrometers, specifically by applying a ML model trained on one instrument to another Raman spectrometer. Transfer learning can be improved with proper instrument calibration, highlighting the importance of instrument standardization. Overall, our results demonstrate that data quality and spectral similarity are the primary bottlenecks in ML-assisted Raman spectroscopy. Careful attention to sample preparation, data acquisition, measurement conditions, and instrument calibration is critical to achieving robust and reliable classification performance.

bioinformatics↗

bioRxiv2024

Cryogenic electron tomography and elemental analysis of mitochondrial granules in human retinal ganglion cells

Combining three-dimensional (3D) visualization with elemental analysis of vitrified cells can provide crucial insights into subcellular structures and elemental compositions in their native environments. We present a coordinated approach using cryogenic electron energy loss spectroscopy (cryoEELS) and cryogenic electron tomography (cryoET) to characterize the elemental distribution and ultrastructure of vitrified cells. We applied this method to examine calcium disposition in the mitochondria of cultured human retinal ganglion cells (RGCs) exposed to pro-calcifying conditions relevant to optic disc drusen pathology. Our cryoEELS analysis revealed mitochondrial granules with elevated calcium signals, offering direct evidence of mitochondrial calcification. Additionally, cryoET coupled with artificial intelligence-based analysis enabled quantification of the volume and spatial distribution of these calcium granules. This integrated workflow can be broadly applied to various cell types, facilitating the study of ultrastructure and elemental distribution in subcellular structures under diverse physiological and pathological conditions, as well as in response to therapeutic interventions.

biophysics↗

bioRxiv2024

Complete enzymatic depolymerization of polyethylene terephthalate (PET) plastic using a Saccharomyces cerevisiae-based whole-cell biocatalyst

Plastics like polyethylene terephthalate (PET) have become an integral part of everyday life, yet plastic waste management remains a significant challenge. Enzymatic biocatalysis is an eco- friendly approach for recycling and upcycling of plastic waste. PET-hydrolyzing enzymes (PHEs) such as IsPETase, along with its engineered variants like FAST-PETase, demonstrate promising PET depolymerization capabilities at ambient temperatures. Whole-cell biocatalysts, displaying PHEs on their cell surface, offer high efficiency, reusability, and stability for PET depolymerization. However, their efficacy in fully breaking down PET is hindered by the necessity of two enzymes - PETase and MHETase. Current whole-cell systems either display only one PHE or struggle with performance when displaying larger passenger proteins like the MHETase-PETase chimera. In this work, we developed a Saccharomyces cerevisiae-based whole-cell biocatalyst system for complete PET depolymerization. Leveraging a cellulosome-inspired trifunctional protein scaffoldin displayed on the yeast surface, we immobilized FAST-PETase and MHETase, forming a multi-enzyme cluster. Our whole cell biocatalyst achieved complete PET depolymerization at 30{degrees}C, yielding 4.9 mM TPA in seven days with no intermediate accumulation. Furthermore, we showed improved PET depolymerization ability by binding FAST-PETase at multiple sites on the trifunctional scaffoldin. This breakthrough in complete PET depolymerization marks an essential step towards a circular plastic economy.

bioengineering↗

bioRxiv2024

High-efficiency PET Degradation with a Duo-enzyme System Immobilized on Magnetic Nanoparticles

The widespread consumption of PET worldwide has necessitated the search for environment-friendly methods for PET degradation and recycling. Among these methods, biodegradation stands out as a promising approach for recycling PET. The discovery of duo enzyme system PETase and MHETase in 2016, along with their engineered variants, has demonstrated significant potential in breaking down PET. Previous studies have also demonstrated that the activity of the enzyme PETase increases when it is immobilized on nanoparticles. To achieve highly efficient and complete PET depolymerization, we immobilized both FAST PETase and MHETase at a specific ratio on magnetic nanoparticles. This immobilization resulted in a 2.5-fold increase in product release compared with free enzymes. Additionally, we achieved reusability and enhanced stability of the enzyme bioconjugates.

bioengineering↗

bioRxiv2024

Modulating Cas13a trans-cleavage by double strand RNA: Application to the development of an autocatalytic sensor

Cas13a-based diagnostic systems have been widely utilized for the detection of RNA targets. However, without preamplification such systems have sensitivity in the picomolar range only. Here, we found that double strand RNA (dsRNA) over 20nt is able to effectively activate the trans-cleavage activity of Cas13a RNP, while the cleavage rates of dsRNA by activated Cas13a RNP are very low. In addition, specially designed small circular RNA constructs (Cir-mediators comprising a 20nt dsRNA trigger with a 5nt ssRNA linker) have limited ability to activate Cas13a RNP, but this activation is restored once the circular structures are cleaved and become linear. Based on this new method to control trans-cleavage activity of Cas13 RNP, we developed a Cas13a autocatalytic biosensing system assisted by Cir-mediators, which allows one target RNA to activate numerous Cas13a RNPs. With this approach we show ultrasensitive detection of 1aM of synthetic RNA targets without preamplification within 15min. The sensor was successfully applied to monitor miRNA-21 concentration in clinical plasma samples in colorectal cancer. This investigation yields novel insights into the properties of Cas13a RNPs, and the Cir-mediator-based autosensor introduces a novel method for detecting RNA targets with exceptional sensitivity. HighlightsO_LIdsRNA is able to trigger activation of Cas13a RNP. C_LIO_LIActivated Cas13a RNP do not cleave dsRNA. C_LIO_LICir-mediator induces low levels of Cas13a RNP activation. C_LIO_LICir-mediator based Cas13a auto-catalysis biosensor can detect 1aM RNA targets. C_LI

molecular biology↗

bioRxiv2024

High-resolution single particle imaging at 100-200 keV with the Gatan Alpine direct electron detector.

Developments in direct electron detector technology have played a pivotal role in enabling high-resolution structural studies by cryo-EM at 200 and 300 keV. Yet, theory and recent experiments indicate advantages to imaging at 100 keV, energies for which the current detectors have not been optimized. In this study, we evaluated the Gatan Alpine detector, designed for operation at 100 and 200 keV. Compared to the Gatan K3, Alpine demonstrated a significant DQE improvement at these voltages, specifically a ~4-fold improvement at Nyquist at 100 keV. In single-particle cryo-EM experiments, Alpine datasets yielded better than 2 [A] resolution reconstructions of apoferritin at 120 and 200 keV on a ThermoFisher Scientific (TFS) Glacios microscope. We also achieved a ~3.2 [A] resolution reconstruction for a 115 kDa asymmetric protein complex, proving its effectiveness with complex biological samples. In-depth analysis revealed that Alpine reconstructions are comparable to K3 reconstructions at 200 keV, and remarkably, reconstruction from Alpine at 120 keV on a TFS Glacios surpassed all but the 300 keV data from a TFS Titan Krios with GIF/K3. Additionally, we show Alpines capability for high-resolution data acquisition and screening on lower-end systems by obtaining ~3 [A] resolution reconstructions of apoferritin and aldolase at 100 keV and detailed 2D averages of a 55 kDa sample using a side-entry cryo holder. Overall, we show that Gatan Alpine performs well with the standard 200 keV imaging systems and may potentially capture the benefits of lower accelerating voltages, possibly bringing smaller sized particles within the scope of cryo-EM.

biophysics↗

bioRxiv2024

Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma

Copper (Cu) is an essential trace element required for mitochondrial respiration. Late-stage clear cell renal cell carcinoma (ccRCC) accumulates Cu and allocates it to mitochondrial cytochrome c oxidase. We show that Cu drives coordinated metabolic remodeling of bioenergy, biosynthesis and redox homeostasis, promoting tumor growth and progression of ccRCC. Specifically, Cu induces TCA cycle-dependent oxidation of glucose and its utilization for glutathione biosynthesis to protect against H2O2 generated during mitochondrial respiration, therefore coordinating bioenergy production with redox protection. scRNA-seq determined that ccRCC progression involves increased expression of subunits of respiratory complexes, genes in glutathione and Cu metabolism, and NRF2 targets, alongside a decrease in HIF activity, a hallmark of ccRCC. Spatial transcriptomics identified that proliferating cancer cells are embedded in clusters of cells with oxidative metabolism supporting effects of metabolic states on ccRCC progression. Our work establishes novel vulnerabilities with potential for therapeutic interventions in ccRCC. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/575895v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@14e1b89org.highwire.dtl.DTLVardef@f1c83forg.highwire.dtl.DTLVardef@191aff8org.highwire.dtl.DTLVardef@1b7ccd1_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LIAccumulation of copper is associated with progression and relapse of ccRCC and drives tumor growth. C_LIO_LICu accumulation and allocation to cytochrome c oxidase (CuCOX) remodels metabolism coupling energy production and nucleotide biosynthesis with maintenance of redox homeostasis. C_LIO_LICu induces oxidative phosphorylation via alterations in the mitochondrial proteome and lipidome necessary for the formation of the respiratory supercomplexes. C_LIO_LICu stimulates glutathione biosynthesis and glutathione derived specifically from glucose is necessary for survival of CuHi cells. Biosynthesis of glucose-derived glutathione requires activity of glutamyl pyruvate transaminase 2, entry of glucose-derived pyruvate to mitochondria via alanine, and the glutamate exporter, SLC25A22. Glutathione derived from glucose maintains redox homeostasis in Cu-treated cells, reducing Cu-H2O2 Fenton-like reaction mediated cell death. C_LIO_LIProgression of human ccRCC is associated with gene expression signature characterized by induction of ETC/OxPhos/GSH/Cu-related genes and decrease in HIF/glycolytic genes in subpopulations of cancer cells. Enhanced, concordant expression of genes related to ETC/OxPhos, GSH, and Cu characterizes metabolically active subpopulations of ccRCC cells in regions adjacent to proliferative subpopulations of ccRCC cells, implicating oxidative metabolism in supporting tumor growth. C_LI

cancer biology↗

bioRxiv2021

Altered DNA methylation in ion transport and immune signalling genes is associated with severity in Pancreatic Ductal Adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the leading cancers worldwide and has a poor survival, with a relative five-year survival rate of only 8.5%. In this study we investigated epigenetic marksassociated with PDAC severity and prognosis, through studying alterations in DNA methylation patterns. MethodsDNA methylome for tumor and adjacent normal tissue samples from PDAC patients (n=7) were generated using Illumina 450K bead chips. Differentially methylated positions (DMPs) were identified with |delta beta| > 0.2 and p-value<0.01 by comparing tumors with the adjacent normal tissues. Validation of differential methylation and associated gene expression at selected genes was carried out in an independent cohort PDAC patient. ResultsWe identified 76 DMPs in PDAC patients that mapped to 43 genes. Among them, 44.7% (n=34) were hypo-methylated and 55.3% (n=42) were hyper-methylated DMPs in cancer samples. The trends of change in methylation at these 76 DMPs from well to moderate were like that from moderate to poorly differentiated cancer samples. The gradual trend in differential methylation was observed both in our cohort and the TCGA-PAAD cohort, suggesting methylation marks can serve as early indicators of disease pathology. Altered promoter methylation, which may affect gene expression, was observed for transcription regulators (BHLHE23, GSC2, FOXE1 and TWIST1), gated ion channels (KCNA6, and CACNB2), tumor suppressors (RASSF1, SPRED2, and NPY) and genes functioning in interferon signalling (SIGIRR, MX2, and OAS2). We also have compared the TCGA-PAAD dataset with normal pancreatic tissue data from GTEx V8 dataset leading to a confluent observation. ConclusionsWe reported the first study on methylome in PDAC tumors from patients in India. We identified altered DNA methylation associated with increasing severity in PDAC among some genes like SIGIRR, MX2 along with other previously reported loci. We also concluded a confluence in our observation when comparing the TCGA-PAAD dataset with GTEx V8 dataset.

cancer biology↗

bioRxiv2020

Ruling the Roost: Avian Species Reclaim Urban Habitat During India's COVID Lockdown

As we retreated to our dwellings in the "anthropause" of spring 2020, did other species return to our urban centres? We leverage an increase in balcony birdwatching, a million eBird entries, and difference-in-difference techniques to test if avian species richness rose during Indias COVID lockdown. We find that birdwatchers in Indias 20 most populous cities observed 8-17% more species during the lockdown. Most additional observations occurred after a two-week lag, signaling greater abundance instead of improved detection. More frequent appearances of at-risk, rare, and common species were recorded, implying that making our cities more wildlife friendly can protect threatened species in addition to urban specialists. Our contributions are: 1) to isolate and estimate a causal impact of reducing human activity on avian diversity, 2) to improve the external validity of this literature in rapidly urbanizing bio-diverse developing countries, and, 3) to illustrate a method separating abundance from detection in observational avian surveys.

ecology↗

bioRxiv2020

Melanopsin Carboxy-terminus Phosphorylation Plasticity and Bulk Negative Charge, not Strict Site Specificity, Achieves Phototransduction Deactivation

Melanopsin is a visual pigment expressed in a small subset of ganglion cells in the mammalian retina known as intrinsically photosensitive retinal ganglion cells (ipRGCs) and is implicated in regulating non-image forming functions such as circadian photoentrainment and pupil constriction and contrast sensitivity in image formation. Mouse melanopsins Carboxy-terminus (C-terminus) possesses 38 serine and threonine residues, which can potentially serve as phosphorylation sites for a G-protein Receptor Kinase (GRK) and be involved in the deactivation of signal transduction. Previous studies suggest that S388, T389, S391, S392, S394, S395 on the proximal region of the C-terminus of mouse melanopsin are necessary for melanopsin deactivation. We expressed a series of mouse melanopsin C-terminal mutants in HEK293 cells and using calcium imaging, and we found that the necessary cluster of six serine and threonine residues, while being critical, are insufficient for proper melanopsin deactivation. Interestingly, the additional six serine and threonine residues adjacent to the required six sites, in either proximal or distal direction, are capable of restoring wild-type deactivation of melanopsin. These findings suggest an element of plasticity in the molecular basis of melanopsin phosphorylation and deactivation. In addition, C-terminal chimeric mutants and molecular modeling studies support the idea that the initial steps of deactivation and {beta}-arrestin binding are centered around these critical phosphorylation sites (S388-S395). This degree of functional versatility could help explain the diverse ipRGC light responses as well as non-image and image forming behaviors, even though all six sub types of ipRGCs express the same melanopsin gene OPN4.

neuroscience↗

bioRxiv2019

Protein features for assembly of the RNA editing helicase 2 subcomplex (REH2C) in Trypanosome holo-editosomes

Uridylate insertion/deletion RNA editing in Trypanosoma brucei is a complex system that is not found in humans, so there is interest in targeting this system for drug development. This systeme uses hundreds of small non-coding guide RNAs (gRNAs) to modify the mitochondrial mRNA transcriptome. This process occurs in holo-editosomes that assemble several macromolecular trans factors around mRNA: the RNA-free RNA editing core complex (RECC) and auxiliary RNPs. Yet, the regulatory mechanisms of editing remain obscure. The enzymatic accessory RNP complex, termed the REH2C, includes mRNA substrates and products, the multi-domain 240 kDa RNA Editing Helicase 2 (REH2) and an intriguing 8-zinc finger protein termed REH2-Associated Factor 1 (H2F1). Both proteins are essential in editing. REH2 is a member of the DExH/RHA subfamily of RNA helicases with a conserved C-terminus that includes a regulatory OB-fold domain. In trypanosomes, H2F1 recruits REH2 to the editing apparatus, and H2F1 downregulation causes REH2 fragmentation. Our systematic mutagenesis dissected determinants in REH2 and H2F1 for the assembly of REH2C, the stability of REH2, and the RNA-mediated association of REH2C with other editing trans factors. We identified functional OB-fold amino acids in eukaryotic DExH/RHA helicases that are conserved in REH2 and impact the assembly and interactions of REH2C. H2F1 upregulation stabilized the large REH2 polypeptide in vivo. Mutation of the core cysteines or basic amino acids in individual zinc fingers affected the stabilizing property of H2F1 but not its interactions with other examined editing components. Thus, most if not all fingers may contribute to REH2 stabilization. Finally, a recombinant REH2 (240 kDa) established that the full-length protein is a bona fide RNA helicase with ATP-dependent unwinding activity. REH2 is the only DExH/RHA-type helicase in kinetoplastid holo-editosomes.

molecular biology↗

bioRxiv2018

A novel sialylation site on Neisseria gonorrhoeae lipooligosaccharide links heptose II lactose expression with pathogenicity

Sialylation of lacto-W-neotetraose (LNnT) extending from heptose I (HepI) of gonococcal lipooligosaccharide (LOS) contributes to pathogenesis. Previously, gonococcal LOS sialyltransterase (Lst) was shown to sialylate LOS in Triton X-100 extracts of strain 15253, which expresses lactose from both HepI and HepII, the minimal structure required for mAb 2C7 binding. Ongoing work has shown that growth of 15253 in cytidine monophospho-W-acetylneuraminic acid (CMP-Neu5Ac)-containing media enables binding to CD33/Siglec-3, a cell surface receptor that binds sialic acid, suggesting that lactose termini on LOS of intact gonococci can be sialylated. Neu5Ac was detected on LOSs of strains 15253 and a MS11 mutant with only lactose from HepI and HepII by mass spectrometry; deleting HepII lactose rendered Neu5Ac undetectable. Resistance of HepII lactose Neu5Ac to desialylation by 2-3-specific neuraminidase suggested an 2-6-linkage. Although not associated with increased factor H binding, HepII lactose sialylation inhibited complement C3 deposition on gonococci. 15253 mutants that lacked Lst or HepII lactose were significantly attenuated in mice, confirming the importance of HepII Neu5Ac in virulence. All 75 minimally passaged clinical isolates from Nanjing, China, expressed HepII lactose, evidenced by reactivity with mAb 2C7; mAb 2C7 was bactericidal against the first 62 (of 75) isolates that had been collected sequentially and were sialylated before testing. mAb 2C7 effectively attenuated 15253 vaginal colonization in mice. In conclusion, this novel sialylation site could explain the ubiquity of gonococcal HepII lactose in vivo. Our findings reiterate the candidacy of the 2C7 epitope as a vaccine antigen and mAb 2C7 as an immunotherapeutic antibody.

microbiology↗