Biology subjects

Deshmukh, N.

Publications and source records attributed to Deshmukh, N..

4 recordsLinked to original sources

bioRxiv2026

High throughput chromatographic ultra-purification of virus-like particles for downstream viromics

Virus-like particles (VLPs) are an abundant component of microbiomes with critical ecological roles such as population control through viral predation and horizontal gene transfer. Studying the collection of viruses in microbiomes (the virome) through metagenomics has provided important insights into the composition and functions of VLPs in different environments. However, the current gold-standard method for VLP purification, CsCl density gradient ultracentrifugation (CsCl), is low throughput, time consuming and suffers from biases which limits the ability to study viromes in larger sample sets and can interfere with data interpretation. Here we present an anion exchange (AEX) chromatography-based approach for the purification of VLPs from microbiome samples that allows for significant increases in throughput and reproducibility while achieving VLP purity levels similar to or higher than CsCl. We used microbiome samples of known composition to first establish and evaluate the AEX approaches and compare them to CsCl. We implemented the AEX approach both for fast performance liquid chromatography (FPLC) and in multi-well plates. We compared the VLPs purified with CsCl and AEX using shotgun metagenomic sequencing and found that AEX performs similarly to or better than CsCl for purification of VLPs. AEX purified VLP-fractions captured significantly more viral DNA compared to CsCl. We also found that both AEX and CsCl were capable of capturing viruses present at extremely low relative abundances (<0.001%). Additionally, we found that DNase digestion and CsCl may bias against filamentous phage morphologies. Finally, we purified VLPs from conventional murine feces using AEX and CsCl. AEX purified murine fecal VLPs had a much higher viral DNA content (85%) than CsCl (41%). While there were some differences in viral contigs assembled from AEX and CsCl VLP metagenomes, these method unique viral contigs made up only small proportions (<8%) of the relative abundance in the VLP metagenomes. AEX, particularly in the multi-well format, enables the ultrapurification of VLPs from tens to hundreds of samples in a single day thus facilitating virome studies with the large sample numbers needed for translational and clinical research.

microbiology↗

bioRxiv2025

Gut microbial metabolites butyrate and acetate limit Zika virus replication and associated ocular manifestations via the G-protein coupled receptor 43/FFAR2.

Short-chain fatty acids (SCFAs) are gut microbial metabolites produced by gut microbiota from dietary fiber. SCFAs have shown both pro- and anti-viral roles among different viruses, and are known to regulate immune functions during infections. However, their role against the Zika virus (ZIKV) in general and ocular infection, in particular, has never been investigated. In the present study, we aimed to examine the role of three SCFA derivatives: phenylbutyrate (PBA), sodium butyrate (NaB), and sodium acetate (NaAC), on ZIKV replication and associated ocular complications using primary human trabecular meshwork cells (HTMCs) and an IFNAR1-deficient mouse model of ocular infection. Our findings reveal that PBA and NaAc treatment dramatically suppressed the ZIKV replication in HTMCs. NaB showed a slightly less effect than PBA and NaAc. PBA and NaAc treatment significantly attenuated the ZIKV-induced inflammatory cytokine, interferons, and interferon-stimulated genes response via antagonizing the RIG-I/NF{kappa}B/MAPKs/STAT1-3 signaling pathways. We discovered that ZIKV induces the expression of free fatty acid receptor 2 (FFAR2)/ GPR43 in HTMCs, which is further potentiated by PBA/NaAc. Pharmacological inhibition of FFAR2 abrogated the protective abilities of PBA/NaAc and significantly increased viral replication. Blocking FFAR2 receptors promoted ZIKV-induced cell death, which was suppressed by PBA and NaAc. Mechanistically, butyrate and acetate inhibited ZIKV binding and cellular entry and inactivated the virus before internalization. PBA and NaAc treatment in mice attenuated the ZIKV-induced ocular manifestations (intraocular pressure, RPE/retinal atrophy, and anterior segment inflammation), which was abrogated by FFAR2 inhibition. Collectively, our findings indicate that SCFA treatment is an effective approach to limit ZIKV replication and associated ocular damage and may be worth exploring as a means to treat or prevent ZIKV-induced ocular complications in humans. ImportanceZIKV is known to cause severe ocular manifestations in in-utero exposed infants; however, the molecular mechanisms of ZIKV-induced ocular complications remain unknown. SCFAs have demonstrated both pro- and anti-viral roles against different viruses; however, their role against ZIKV is unknown. We showed that SCFAs butyrate and acetate suppress ZIKV transmission and associated ocular complications. The anti-ZIKV activity of these SFACs is mediated via FFAR2, and pharmacological inhibition of FFAR2 promotes ZIKV-induced inflammatory and cell death responses, as well as ocular malformations.

microbiology↗

bioRxiv2019

Alpha herpesvirus egress and spread from neurons uses constitutive secretory mechanisms independent of neuronal firing activity

Alpha herpesviruses naturally infect the peripheral nervous system, and can spread to the central nervous system causing severe deadly or debilitating disease. Because alpha herpesviruses spread along synaptic circuits, and infected neurons exhibit altered electrophysiology and increased spontaneous firing, we hypothesized that alpha herpesviruses use activity-dependent synaptic vesicle-like regulated secretory mechanisms for egress and spread from neurons. To address this hypothesis, we used a compartmentalized primary neuron culture system to measure egress and spread of pseudorabies virus (PRV), pharmacological and optogenetics approaches to modulate neuronal firing activity, and a live-cell fluorescence microscopy assay to directly visualize the exocytosis of individual virus particles from infected neurons. Using tetrodotoxin to silence neuronal activity, we observed no inhibition of virus spread, and using potassium chloride or optogenetics to elevate neuronal activity, we also show no increase in virus spread. Using a live-cell fluorescence microscopy method to directly measure virus egress from infected neurons, we observed no association between virus particle exocytosis and intracellular Ca2+ signaling. Finally, we observed virus particle exocytosis occurs in association with constitutive secretory Rab GTPases, Rab6a and Rab8a, not Rab proteins that are associated with the Ca2+-regulated secretory pathway in neurons, Rab3a and Rab11a. Therefore, we conclude that alpha herpesvirus egress and spread is independent of neuronal activity and Ca2+ signaling because virus particle exocytosis uses constitutive secretory mechanisms in neurons.\n\nAuthor SummaryAlpha herpesviruses, including important human pathogens Herpes Simplex Virus 1 and 2, and Varicella-Zoster Virus, are among the very few viruses that naturally infect the nervous system. These viruses cause recurrent herpetic and zosteriform lesions, peripheral neuropathies, and deadly or debilitating central nervous system diseases. Many of the molecular and cellular mechanisms of viral egress and spread remain unknown, particularly in the context of specialized neuronal cell biology. Our results indicate that elevated firing activity of infected neurons is not functionally or mechanistically linked to virus egress and spread; therefore, therapies targeting peripheral neuropathic symptoms, elevated neuronal activity, and synaptic vesicle secretory mechanisms are unlikely to affect virus spread in the nervous system.

microbiology↗

bioRxiv2019

Nonlinear transfer and temporal gain control in ON bipolar cells

The separation of visual input into discrete channels begins at the photoreceptor to bipolar cell synapse. Current models of the ON pathway describe the time-varying membrane voltage of ON bipolar cells as a linear function of light fluctuations. While this linearity holds under some visual conditions, stimulating the retina with full-field, high contrast flashes reveals a number of nonlinearities already present in the input current of ON bipolar cells. First, we show that the synaptic input to ON bipolar cells is asymmetric in response to equal flashes of opposite polarity. Next, we show that this asymmetry emerges because the responses to dark flashes increase linearly with contrast, whereas responses to bright flashes are highly rectified. We also describe how the outward current saturates in response to dark flashes of increasing duration. Furthermore, varying the inter-flash interval between a pair of high contrast flashes reveals a rapid, transient form of gain control that modulates both the amplitude and time course of the flash response. We develop a phenomenological model that captures the primary features of the ON bipolar cell response at high contrast. Finally, we discuss the implications of these nonlinearities in our understanding of how retinal circuitry shapes the visual signal.

neuroscience↗