Biology subjects

Lodha, R.

Publications and source records attributed to Lodha, R..

11 recordsLinked to original sources

bioRxiv2025

Immunogenicity and Structural Features of a Stabilized Clade-C HIV-1 Env Derived from a Pediatric Elite-neutralizer

The envelope (Env) glycoprotein derived from circulating viruses in elite-neutralizers (who naturally develop broadly neutralizing antibodies (bNAbs)), serves as potential template for HIV-1 vaccine design. Herein, we report the structure and immunogenicity of soluble clade-C HIV-1 Env trimer (330) derived from a pediatric elite-neutralizer (AIIMS_330). Using SOSIP, NFL and ferritin-nanoparticle (NP) platforms, we engineered immunogens that preserved native-like Env conformation, exhibited high thermostability and nanomolar affinity for diverse bNAbs, with minimal reactivity to non-neutralizing antibodies. Cryo-EM structure solved at 5 [A] resolution of 330-SOSIP trimer-autologous bNAb 44m complex revealed interactions at GDIR motif, N332 supersite along with additional contacts at E293, K337, K446 and glycans N326, N442, N448, as compared to our previously reported BG505-44m structure. Rabbit immunizations with soluble and NP-displayed formats elicited autologous, and heterologous neutralization of tier-1 clade-C viruses. Herein we define a structurally resolved HIV-1 clade C Env that supports multivalent vaccine strategies and provides mechanistic insights toward rational HIV-1 immunogen design.

immunology↗

bioRxiv2024

Path2Space: An AI Approach for Cancer Biomarker Discovery Via Histopathology Inferred Spatial Transcriptomics

Spatial transcriptomics (ST) is transforming our understanding of tumor heterogeneity by enabling high-resolution, location-specific mapping of gene expression across tumors and their microenvironment. However, the associated high cost of the assay has limited cohort size and hence large-scale biomarker discovery. Here we present Path2Space, a deep learning approach that predicts spatial gene expression directly from histopathology slides. Trained on substantial breast cancer ST data, it robustly predicts the spatial expression of over 4,300 genes in independent validations, markedly outperforming existing ST predictors. Path2Space additionally accurately infers cell-type abundances in the tumor microenvironment (TME) based on the inferred ST data. Applied to more than a thousand breast tumor histopathology slides from the TCGA, Path2Space characterizes their TME on an unprecedented scale and identifies three new spatially-grounded breast cancer subgroups with distinct survival rates. Path2Space-inferred TME landscapes enable more accurate predictions of patients response to chemotherapy and trastuzumab directly from H&E slides than those obtained by existing established sequencing-based biomarkers. Path2Space thus offers a transformative, fast and cost-effective approach to robustly delineate the TME directly from their histopathology slides, facilitating the development of spatially-grounded biomarkers to advance precision oncology.

cancer biology↗

bioRxiv2023

B cell repertoire sequencing of HIV-1 pediatric elite-neutralizers identifies multiple broadly neutralizing antibody clonotypes

A limited subset of HIV-1 infected adult individuals typically after at least 2-3 years of chronic infection, develop broadly neutralizing antibodies (bnAbs), suggesting that highly conserved neutralizing epitopes on the HIV-1 envelope glycoprotein are difficult for B cell receptors to effectively target, during natural infection. Recent studies have shown the evolution of bnAbs in HIV-1 infected infants. We used bulk BCR sequencing (BCR-seq) to profile the B cell receptors from longitudinal samples (3 time points) collected from a rare pair of antiretroviral-naive, HIV-1 infected pediatric monozygotic twins (AIIMS_329 and AIIMS_330) who displayed elite plasma neutralizing activity against HIV-1. BCR-seq of both twins revealed convergent antibody characteristics including V-gene use, CDRH3 lengths and somatic hypermutation (SHM). Further, antibody clonotypes with genetic features similar to highly potent bnAbs isolated from adults showed ongoing development in donor AIIMS_330 but not in AIIMS_329, corroborating our earlier findings based on plasma bnAbs responses. An increase in SHM was observed in sequences of the IgA isotype from AIIMS_330. This study suggests that children living with chronic HIV-1 can develop clonotypes of HIV-1 bnAbs against multiple envelope epitopes similar to those isolated from adults, highlighting that such B cells could be steered to elicit bnAbs responses through vaccines aimed to induce bnAbs against HIV-1 in a broad range of people including children.

immunology↗

bioRxiv2023

Recognition determinants of broad and potent HIV-1 neutralization by an affinity matured antibody from a pediatric elite-neutralizer

The structural and characteristic features of HIV-1 broadly neutralizing antibodies (bnAbs) from chronically infected pediatric donors are currently unknown. Herein, we characterized a heavy chain matured HIV-1 bnAb 44m, identified from a pediatric elite-neutralizer. Interestingly, in comparison to its wild-type AIIMS-P01 bnAb, 44m exhibited moderately higher level of somatic hypermutations of 15.2%. The 44m neutralized 79% of HIV-1 heterologous viruses (n=58) tested, with a geometric mean IC50 titer of 0.36 {micro}g/ml. The cryo-EM structure of 44m Fab in complex with fully-cleaved glycosylated native-like BG505.SOSIP.664.T332N gp140 envelope trimer at 4.4[A] resolution revealed that 44m targets the V3-glycan N332-supersite and GDIR motif to neutralize HIV-1 with improved potency and breadth, plausibly attributed by a matured heavy chain as compared to that of wild-type AIIMS-P01. This study further improves our understanding on pediatric HIV-1 bnAbs and structural basis of broad HIV-1 neutralization by 44m may be useful blueprint for vaccine design in future.

immunology↗

bioRxiv2021

Immunophenotyping and transcriptional profiling of human plasmablasts in dengue.

Previous studies have shown that plasmablasts expand massively in dengue patients as compared to many other situations such as influenza infection or vaccination. However, a detailed understanding of the phenotypes and transcriptional features of these cells is lacking. Moreover, despite India having nearly a third of global dengue disease burden, there is virtually no information on plasmablasts responses in dengue patients from India. Here, we provide a detailed characterization of plasmablast responses from dengue confirmed febrile children in India. Immunophenotyping and RNA seq analysis showed that in addition to secreting dengue specific antibodies, these massively expanding cells expressed several adhesion molecules, chemokines and chemokine receptors that are involved in endothelial interactions, homing to skin or mucosal tissues including intestine. Surprisingly, we found that these cells also upregulated expression of several cytokine genes that are involved in angiogenesis, leukocyte extravasation and vascular permeability. These transcriptional features were qualitatively similar to plasmablasts from influenza vaccinees. Interestingly, the expansion of the plasmablasts in dengue patients was significantly lower in patients with primary dengue infection compared to those with secondary dengue. Moreover, within the primary dengue patients, their expansion was significantly lower in patients with mild dengue infection (DI) compared to patients with dengue with warning signs (DW) or severe dengue (SD). These results significantly improve our understanding of human plasmablast responses in dengue. Importance Dengue is a globally spreading with over 100 million clinical cases annually with symptoms ranging from mild self-limiting febrile illness to more severe and sometimes life-threatening dengue hemorrhagic fever or shock, especially among children. India contributes nearly a third of global dengue disease burden. The pathophysiology of dengue is complex and remains poorly understood despite many advances indicating a key role for antibody dependent enhancement of infection. While serum antibodies have been extensively studied, the characteristics of the cellular factories responsible for antibody production, i.e., plasmablasts, are only beginning to emerge. This study provides a comprehensive understanding of the magnitude, phenotype, functional and transcriptional profiles of human plasmablasts from dengue patients in India.

immunology↗

bioRxiv2021

Identification and characterization of novel infection associated transcripts in macrophages

Regulated expression of genes in response to internal and external stimuli is primarily responsible for the enormous plasticity and robustness of biological systems. Recent studies have elucidated complex regulatory non protein coding transcript (lncRNA) circuits in coordinated response of immune cells. By analysis of lncRNA expression profiles of macrophages in response to Mtb infection, we identified novel highly expressed transcripts, unique in encompassing one functional protein coding transcript- CMPK2 and a previously identified type I IFN responsive lncRNA- NRIR. While these RNA are induced by virulent Mtb early, the complete absence of expression in non-viable Mtb infected cells coupled to a more protracted expression profile in the case of BCG suggest an important role in macrophage response to mycobacteria. Moreover, enhanced expression was observed in macrophages from TB patients. The elevated expression by 1h in response to fast growing bacteria further emphasizes the importance of these RNAs in the macrophage infection response. These transcripts (TILT1, 2,3 - TLR4 and Infection induced Long Transcript) are triggered exclusively by TLR4 stimulation (LPS) with faster and stronger kinetics in comparison to the lncRNA - NRIR. Overall, we provide evidence for the presence of numerous transcripts that is a part of the early infection response program of macrophages.

immunology↗

bioRxiv2020

Plasma neutralizing antibodies in an infant with interclade HIV-1 superinfection preferentially neutralize superinfecting HIV-1 strains

HIV-1 superinfection is defined as infection by an unrelated second strain of HIV-1 after seroconversion due to primary infecting strain and has been associated with development of breadth in the neutralizing antibody (nAb) response, altered disease progression and efficacy of antiretrovirals; though conflicting observations have also been reported. Superinfection has been reported in HIV-1 infected adults. Recently we observed that multivariant infection in infants was associated with early induction of plasma broadly neutralizing antibodies (bnAbs) targeting diverse autologous viruses, however, there is paucity of information on infants with HIV-1 superinfection. Furthermore, the mechanisms by which superinfection in an infant, after priming by an initial infection, potentiate the evolution of a bnAb response have not been evaluated. Herein, we performed a longitudinal analysis and observed evolution of nAb responses in an antiretroviral naive perinatally HIV-1 infected infant, with interclade superinfection (clade C followed by a unique A1C recombinant). The nAb responses broadened rapidly after superinfection targeted an undefined glycan-dependent epitope on the superinfecting variant, while no enrichment of nAb response against the primary infecting strain occurred. Defining virological features in infants with sequential infection with highly divergent circulating viruses that improve nAb responses will contribute information that could be leveraged for optimization of multicomponent candidate vaccines. ImportanceHIV-1 infected infants develop bnAbs rapidly suggesting factors governing bnAb induction in infants are distinct from adults. HIV-1 superinfection is more common in adults whereas the stringent genetic bottleneck for transmission in infants often leads to infection by a single transmitted/founder HIV-1 strain. Longitudinal studies in infants with HIV-1 superinfection can provide key information on the viral factors that induce a bnAb response towards development of a polyvalent vaccine. Herein, we show that in infant who was sequentially infected with two HIV-1 strains from different clades, antibody responses were primarily generated against the superinfecting, second strain of HIV-1. These antibody responses were dependent on glycans, and targeted an undefined epitope in the C3V4 region of HIV-1 Env. A better understanding of how neutralizing antibody responses develop during natural HIV-1 superinfection in infants will provide information relevant to HIV Env vaccine development and evaluation.

immunology↗

bioRxiv2020

A rare mutation in an infant derived HIV-1 envelope glycoprotein alters interprotomer stability and susceptibility to broadly neutralizing antibodies targeting the trimer apex

The envelope glycoprotein (Env) of human immunodeficiency virus-1 (HIV-1) is the sole target of broadly neutralizing antibodies (bnAbs). Several mechanisms, such as acquisition of mutations due to the error prone reverse transcriptase, variability of loop length and alterations in glycan pattern are employed by the virus to shield neutralizing epitopes on the env, to sustain survival and infectivity within the host. Identification of mutations that can lead to viral evasion from host immune response is essential for optimization and engineering of Env based trimeric immunogens. Herein, we report a rare leucine to phenylalanine escape mutation (L184F) at the base of hypervariable loop 2 (population frequency of 0.0045%) in a nine-month-old perinatally HIV-1 infected infant broad neutralizer. The L184F mutation disrupted the intramolecular interaction, stabilizing the trimer apex thereby leading to viral escape from autologous plasma bnAbs and known bnAbs, targeting exclusively the N160 glycan at trimer apex and not any other known epitope. The L184F amino acid change led to acquisition of a relatively open trimeric configuration, often associated with tier 1 HIV-1 isolates and an increased susceptibility to neutralization by polyclonal plasma antibodies of weak neutralizers. While there was no impact of the L184F mutation on free virus transmission, a reduction in cell-to-cell transmission was observed. In conclusion, we report a viral escape mutation that plausibly destabilized the trimer apex and favoured evasion from broadly neutralizing antibodies. Such mutations, though rare, should be taken into consideration while designing an immunogen, based on a stable correctly-folded HIV-1 Env trimer. ImportanceDesign of HIV-1 envelope-based immunogens, capable of eliciting broadly neutralizing antibodies (bnAbs), are currently under active research. Some of the most potent bnAbs target the quaternary epitope at the V2 apex of HIV-1 Env trimer. By studying naturally circulating viruses from an HIV-1 perinatally infected infant, with plasma neutralizing antibodies targeted to the V2-apex, we identified a rare leucine to phenylalanine substitution in two out of six functional viral clones, that destabilized the trimer apex. This single amino acid alteration impaired the interprotomeric interactions that stabilize the trimer apex, resulting in an open trimer conformation, and escape from broadly neutralizing autologous plasma antibodies and known V2-apex directed bnAbs, thereby favouring viral evasion of the early bnAb response of the infected host. Defining the mechanisms by which viral mutations influence the sensitivity of HIV-1 to bnAbs is crucial for the development of effective vaccines against HIV-1 infection.

microbiology↗

bioRxiv2019

Multivariant HIV-1 infection in infants is associated with the induction of broadly neutralizing plasma antibodies.

Due to the extensive antigenic diversity of human immunodeficiency virus-1 (HIV-1), broadly neutralizing antibodies (bnAbs) develop in a subset of infected individuals over 2-3 years of infection. Interestingly, infected infants have been shown to develop plasma bnAbs frequently and as early as one-year post-infection, with features atypical than adult bnAbs, suggesting that the factors governing bnAb induction in infants are distinct from that in adults. Understanding the viral characteristics in infected infants with early bnAb responses will provide key information on the antigenic triggers driving B cell maturation pathways towards the induction of bnAbs. Herein, we evaluated the presence of plasma bnAbs in a cohort of 51 HIV-1 clade C perinatally infected infants of Indian origin and identified viral factors associated with early bnAb responses. Plasma bnAbs targeting V2-apex on the env were predominant in infant elite and broad neutralizers. Circulating viral variants in infant elite neutralizers were susceptible to known bnAbs against V2-apex while varied resistance profile to other bnAb classes was observed. In infant elite neutralizers, multivariant infection was associated with plasma bnAbs targeting diverse autologous viruses. Our data provides information supportive of polyvalent vaccination approaches capable of inducing V2-apex bnAbs against HIV-1.

immunology↗

bioRxiv2018

Viral characteristics associated with sustenance of elite neutralizing activity in chronically HIV-1C infected monozygotic pediatric twins

Broad and potent neutralizing antibodies (bnAbs) with multiple epitope specificities evolve in HIV-1 infected children. Herein we studied two antiretroviral naive chronically HIV-1C in-fected monozygotic pediatric twins AIIMS_329 and AIIMS_330 with potent plasma bnAbs. Elite plasma neutralizing activity was observed since initial sampling at 78 months in AIIMS_330 and persisted throughout, while in AIIMS_329 it was seen at 90-months of age after which potency decreased overtime. We evaluated potential viral characteristics associated with the varied immune profile by generating single genome amplified pseudoviruses. The AIIMS_329 viruses generated from 90-month time point sampling were neutralization sensitive to second generation bnAbs and contemporaneous autologous plasma antibodies, while viruses from 112-months and 117-month timepoints were resistant to most bnAbs and autologous contemporaneous plasma. AIIMS_329 viruses developed resistance to plasma nAbs plausibly by N160-glycan loss, V1- and V4-loop lengthening. The viruses generated from AIIMS_330 at 90-month and 117-month timepoint showed varied susceptibility to bnAbs and autologous contemporaneous plasma antibodies while the viruses of 112-month timepoint, at which plasma nAb specificities mapped to the V2-glycan, V3-glycan and CD4bs, were resistant to autologous contemporaneous plasma antibodies as well as most bnAbs. We observed evolution of a viral pool in AIIMS_330 donor, comprising of plasma antibody neutralization sensitive or resistant diverse autologous viruses that in turn may have contributed to development and maintenance of elite neutralizing activity. The findings of this study provide information towards understanding factors involved in generation and maintenance of potent plasma nAbs.\n\nImportanceChronically HIV-1 infected children that develop elite neutralizing activity are suitable candidates to understand the mechanisms that lead to the co-evolution of virus and antibody response. Here, we evaluated the alterations in virus and antibody responses over time in chronically HIV-1C infected monozygotic pediatric twins, AIIMS_329 and AIIMS_330, who had acquired the infection by vertical transmission. AIIMS_330 retained the elite plasma neutralizing activity throughout, while in AIIMS_329, the potency decreased post 90 months of age. The corresponding viral pool from post 90-month samples in AIIMS_330 showed varied susceptibility, while that in AIIMS_329, developed resistance to bnAbs and autologous plasma antibodies. The findings of this study, conducted in twin children of same genetic make-up and infected at birth with a single source of HIV-1C, suggest that a viral pool with varied susceptibility to antibodies could have been one of the factors responsible for sustained elite neutralizing activity in AIIMS_330.

immunology↗

bioRxiv2018

An HIV-1 broadly neutralizing antibody from a clade C infected pediatric elite neutralizer potently neutralizes the contemporaneous and autologous evolving viruses

Broadly neutralizing antibodies (bNAbs) have demonstrated protective effects against HIV-1 in primate studies and recent human clinical trials. Elite-neutralizers are potential candidates for isolation of HIV-1 bNAbs and coexistence of bNAbs such as BG18 with neutralization susceptible autologous viruses in an HIV-1 infected adult elite controller has been suggested to control viremia. Disease progression is faster in HIV-1 infected children than adults. Plasma bNAbs with multiple epitope specificities are developed in HIV-1 chronically infected children with more potency and breadth than in adults. Therefore, we evaluated the specificity of plasma neutralizing antibodies of an antiretroviral naive HIV-1 clade C chronically infected pediatric elite neutralizer AIIMS_330. The plasma antibodies showed broad and potent HIV-1 neutralizing activity with >87% (29/33) breadth, median inhibitory dilution (ID50) value of 1246 and presence of N160 and N332-supersite dependent HIV-1 bNAbs. The sorting of BG505.SOSIP.664.C2 T332N gp140 HIV-1 antigen-specific single B cells of AIIMS_330 resulted in the isolation of an HIV-1 N332-supersite dependent bNAb AIIMS-P01. The AIIMS-P01 neutralized 67% of HIV-1 cross-clade viruses; exhibited substantial indels despite limited somatic hypermutations; interacted with native-like HIV-1 trimer as observed in negative stain electron microscopy and demonstrated high binding affinity. In addition, AIIMS-P01 potently neutralized the coexisting and evolving autologous viruses suggesting the coexistence of vulnerable autologous viruses and HIV-1 bNAbs in AIIMS_330 pediatric elite neutralizer. Further studies on such pediatric elite-neutralizers and isolation of novel HIV-1 pediatric bNAbs may provide newer insights to guide vaccine design.\n\nImportanceMore than 50% of the HIV-1 infections globally are caused by clade C viruses. Till date, there is no effective vaccine to prevent HIV-1 infection. Based on the structural information of the currently available HIV-1 bNAbs, attempts are underway to design immunogens that can elicit correlates of protection upon vaccination. Here we report the isolation and characterization of an HIV-1 N332-supersite dependent bNAb AIIMS-P01 from a clade C chronically infected pediatric elite neutralizer. The N332-supersite is an important epitope and is one of the current HIV-1 vaccine targets. AIIMS-P01 potently neutralized the contemporaneous and autologous evolving viruses and exhibits substantial indels despite low somatic hypermutations. Taken together with the information on infant bNAbs, further isolation of bNAbs contributing to the plasma breadth in HIV-1 infected children may help to better understand their development and characteristics, which in turn may guide vaccine design.

immunology↗