Biology subjects

Kale, D.

Publications and source records attributed to Kale, D..

5 recordsLinked to original sources

bioRxiv2025

Distinct region-specific neutralization profiles of contemporary HIV-1 clade C against best-in-class broadly neutralizing antibodies

Broadly neutralizing antibodies (bnAb) have been clinically proven to be an excellent choice for HIV-1 prevention. However, the relative effectiveness of best-in-class bnAbs against regionally relevant circulating HIV-1 forms is not clear. In the present study, we compared the degree of neutralization sensitivity of contemporary HIV-1 Indian clade C with that of South African origin. Phylogenetic analysis revealed that these clade C viruses continue to evolve distinctly from one another. Env-pseudotyped viruses prepared using contemporary HIV-1 clade C env genes (N=115) obtained from nine geographically distinct sites in India (between 2020-2023) were found to be most sensitive to V3-directed bnAbs 10-1074 and BG18, and second generation CD4 binding site (CD4bs) directed bnAbs (VRC07, N6 and 1-18), however they were found to be significantly resistant to V1/V2 apex directed bnAbs. Moreover, we observed that the degree of sensitivity varied between contemporary Indian and South African clade C viruses. Differences in degree of neutralization susceptibility were associated with differences observed in key residues that form bnAb contact sites, gp120 loop lengths and the number of N-linked glycans in the V4 hypervariable region. Interestingly, the second generation CD4bs bnAbs (VRC07, N6, 1-18) showed neutralization of VRC01 and 3BNC117 resistant viruses but with 2-7-fold reduced potency compared to the VRC01 sensitive counterparts, likely due to the enrichment of resistance associated residues observed in loop D. Predictive analysis indicated that combination of BG18, N6 and PGDM1400 can provide over 95% neutralization coverage at 1g/mL of contemporary India clade C, an observation found to be distinct to that reported for the Africa clade C viruses. Taken together, we found distinct neutralization patterns and env signatures associated with resistance to key bnAbs. Our study highlights that towards achieving clinical effectiveness, both the complementarity of bnAb classes and the regionally relevant HIV forms need to be considered. Author summaryWhile the development of vaccines to prevent HIV infection remains a global priority, their potential effectiveness is limited by the extraordinarily diversified circulating forms of HIV-1. The prospect of best-in-class bnAbs as potential prevention option has been demonstrated in several studies including the Phase II Antibody Mediated Prevention (AMP) trial; however, to be broadly applicable, bnAbs will need to overcome the substantial variability of HIV env. The present study highlights that the contemporary HIV-1 clade C viruses are evolving to be less sensitive to the best-in-class bnAbs and HIV-1 clade C that predominates in India and South Africa vary in their degree of susceptibility to best-in-class clinically relevant bnAbs. This indicates differences in the antigenic properties between globally circulating HIV-1 clade C at a population level. Overall, the outcome of this study highlights the need for periodic assessment of sequence and neutralization profiles of the circulating regionally relevant HIV-1 forms towards prioritizing the bnAb combination suitable for effective intervention.

immunology↗

bioRxiv2023

Rv0687 a Putative Short-Chain Dehydrogenase is indispensable for pathogenesis of Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb), a successful human pathogen, resides in host sentinel cells and combats the stressful intracellular environment induced by reactive oxygen and nitrogen species during infection. Mtb employs several evasion mechanisms in the face of the host as a survival strategy, including detoxifying enzymes as short-chain dehydrogenases/ reductases (SDRs) to withstand host-generated insults. In this study, using specialized transduction we have generated a Rv0687 deletion mutant and its complemented strain and investigated the functional role of Rv0687, a member of SDRs family genes in Mtb pathogenesis. Wildtype (WT) and mutant Mtb strain lacking Rv0687 (Rv{Delta}0687) were tested for in-vitro stress response and in-vivo survival in macrophages and mice models of infection. The study demonstrates that Rv0687 is crucial for sustaining bacterial growth in nutrition-limited conditions. The deletion of Rv0687 elevated the sensitivity of Mtb to oxidative and nitrosative stress-inducing agents. Furthermore, the lack of Rv0687 compromised the survival of Mtb in primary bone marrow macrophages and led to an increase in the levels of the secreted proinflammatory cytokines TNF-, and MIP-1. Interestingly, the growth of WT and Rv{Delta}0687 was similar in the lungs of infected immunocompromised mice however, a significant reduction in Rv{Delta}0687 growth was observed in the spleen of immunocompromised Rag-/- mice at 4 weeks post-infection. Moreover Rag-/- mice infected with Rv{Delta}0687 survived longer compared to WT Mtb strain. Additionally, we observed significant reduction in bacterial burden in spleens and lungs of immunocompetent C57BL/6 mice infected with Rv{Delta}0687 compared to complemented and WT Mtb strains. Collectively, this study reveals that Rv0687 plays a role in Mtb pathogenesis.

microbiology↗

bioRxiv2022

Simple, rapid, and sensitive quantification of dolichyl phosphates using phosphate methylation and reverse-phase liquid chromatography-high resolution mass spectrometry

Dolichyl monophosphates (DolPs) are essential lipids in glycosylation pathways that are highly conserved across almost all domains of life. The availability of DolP is crucial for all glycosylation processes, as these lipids serve as membrane-anchored building blocks that various types of glycosyltransferases use to generate complex post-translational modifications of proteins and lipids. Analysis of DolP species by reverse-phase liquid chromatography-mass spectrometry (RPLC-MS) has remained challenging due to their very low abundance and wide range of lipophilicities. Until now, a method for the simultaneous qualitative and quantitative assessment of DolP species from biological membranes has been lacking. Here we describe a novel approach based on simple sample preparation, rapid and efficient trimethylsilyl diazomethane (TMSD)-dependent phosphate methylation and RPLC-MS analysis for quantification of DolP species with different isoprene chain lengths. We used this workflow to selectively quantify DolP species from lipid extracts derived of Saccharomyces cerevisiae, HeLa and human skin fibroblasts from steroid 5--reductase 3-congenital disorders of glycosylation (SRD5A3-CDG) patients and healthy controls. Integration of this workflow with global lipidomics analyses will be a powerful tool to further our understanding of the role of DolPs in pathophysiological alterations of metabolic pathways downstream of HMG-CoA reductase, associated with CDGs, hypercholesterolemia, neurodegeneration, and cancer.

biochemistry↗

bioRxiv2021

Intramembrane protease SPP defines a cholesterol-regulated switch of the mevalonate pathway

Intramembrane proteolysis regulates important processes such as signaling and transcriptional and posttranslational abundance control of proteins with key functions in metabolic pathways. This includes transcriptional control of mevalonate pathway genes, thereby ensuring balanced biosynthesis of cholesterol and other isoprenoids. Our work shows that, at high cholesterol levels, signal peptide peptidase (SPP) cleaves squalene synthase (SQS), an enzyme that defines the branching point for allocation of isoprenoids to the sterol and non-sterol arms of the mevalonate pathway. This intramembrane cleavage releases SQS from the membrane and targets it for proteasomal degradation. Regulation of this mechanism is achieved by the E3 ubiquitin ligase TRC8 that, in addition to ubiquitinating SQS in response to cholesterol levels, acts as an allosteric activator of SPP-catalyzed intramembrane cleavage of SQS. Cellular cholesterol levels increase in the absence of SPP activity. Hence, SPP-TRC8 mediated abundance control of SQS acts as a regulation step within the mevalonate pathway.

cell biology↗

bioRxiv2020

Public LC-Orbitrap-MS/MS Spectral Library for Metabolite Identification

Liquid chromatography-mass spectrometry(LC-MS)-based untargeted metabolomics studies require high-quality spectral libraries for reliable metabolite identification. We have constructed EMBL-MCF, an open LC-MS/MS spectral library that currently contains over 1600 fragmentation spectra from 435 authentic standards of endogenous metabolites and lipids. The unique features of the library are presence of chromatographic profiles acquired with different LC-MS methods and coverage of different adduct ions. The library covers many biologically important metabolites with some unique metabolites and lipids as compared to other public libraries. The EMBL-MCF spectral library is created and shared using an in-house developed web-application at https://curatr.mcf.embl.de/. The library is freely available online and also integrated with other mass spectral repositories.

biochemistry↗