Ancestral SARS-CoV-2-Driven Antibody Repertoire Diversity in an Unvaccinated Individual Correlates with Expanded Neutralization Breadth.

Understanding the quality of immune repertoire triggered during natural infection can provide vital clues that form the basis for development of a humoral immune response in some individuals capable of broadly neutralizing pan-SARS-CoV-2 variants. In the present study, we report variations in neutralization potential against Omicron variants of two novel neutralizing monoclonal antibodies (MAbs), THSC20.HVTR11 and THSC20.HVTR55, isolated from an unvaccinated convalescent individual that represent distinct B cell lineage origins and epitope specificity compared to five MAbs we previously reported that were isolated from the same individual. In addition, we observed neutralization of Omicron variants by plasma antibodies obtained from this particular individual postvaccination with increased magnitude. Interestingly, this observation was found to be comparable with six additional individuals who initially were also infected with ancestral SARS-CoV-2 and then received vaccines, indicating that hybrid immunity can provide robust humoral immunity likely by antibody affinity maturation. Development of a distinct antigen-specific B cell repertoire capable of producing polyclonal antibodies with distinct affinity and specificities offers the highest probability of protecting against evolving SARS-CoV-2 variants. IMPORTANCE Development of robust neutralizing antibodies in SARS-CoV-2 convalescent individuals is known; however, it varies at the population level. We isolated monoclonal antibodies from an individual infected with ancestral SARS-CoV-2 in early 2020 that not only varied in their B cell lineage origin but also varied in their capability and potency to neutralize all the known variants of concern (VOCs) and currently circulating Omicron variants. This indicated establishment of unique lineages that contributed in forming a B cell repertoire in this particular individual immediately following infection, giving rise to diverse antibody responses that could complement each other in providing a broadly neutralizing polyclonal antibody response. Individuals who were able to produce polyclonal antibody responses with higher magnitude have a higher chance of being protected from evolving SARS-CoV-2 variants.

A combination of potently neutralizing monoclonal antibodies isolated from an Indian convalescent donor protects against the SARS-CoV-2 Delta variant.

Although efficacious vaccines have significantly reduced the morbidity and mortality of COVID-19, there remains an unmet medical need for treatment options, which monoclonal antibodies (mAbs) can potentially fill. This unmet need is exacerbated by the emergence and spread of SARS-CoV-2 variants of concern (VOCs) that have shown some resistance to vaccine responses. Here we report the isolation of five neutralizing mAbs from an Indian convalescent donor, out of which two (THSC20.HVTR04 and THSC20.HVTR26) showed potent neutralization of SARS-CoV-2 VOCs at picomolar concentrations, including the Delta variant (B.1.617.2). One of these (THSC20.HVTR26) also retained activity against the Omicron variant. These two mAbs target non-overlapping epitopes on the receptor-binding domain (RBD) of the spike protein and prevent virus attachment to its host receptor, human angiotensin converting enzyme-2 (hACE2). Furthermore, the mAb cocktail demonstrated protection against the Delta variant at low antibody doses when passively administered in the K18 hACE2 transgenic mice model, highlighting their potential as a cocktail for prophylactic and therapeutic applications. Developing the capacity to rapidly discover and develop mAbs effective against highly transmissible pathogens like coronaviruses at a local level, especially in a low- and middle-income country (LMIC) such as India, will enable prompt responses to future pandemics as an important component of global pandemic preparedness.

Geospatial HIV-1 subtype C gp120 sequence diversity and its predicted impact on broadly neutralizing antibody sensitivity.

Evolving diversity in globally circulating HIV-1 subtypes presents a formidable challenge in defining and developing neutralizing antibodies for prevention and treatment. HIV-1 subtype C is responsible for majority of global HIV-1 infections. In the present study, we examined the diversity in genetic signatures and attributes that differentiate region-specific HIV-1 subtype C gp120 sequences associated with virus neutralization outcomes to key bnAbs having distinct epitope specificities. A total of 1814 full length HIV-1 subtype C gp120 sequence from 37 countries were retrieved from Los Alamos National Laboratory HIV database (www.hiv.lanl.gov). The amino acid sequences were assessed for their phylogenetic association, variable loop lengths and prevalence of potential N-linked glycosylation sites (pNLGS). Responses of these sequences to bnAbs were predicted with a machine learning algorithm 'bNAb-ReP' and compared with those reported in the CATNAP database. Subtype C sequences from Asian countries including India differed phylogenetically when compared with that from African countries. Variable loop lengths and charges within Indian and African clusters were also found to be distinct from each other, specifically for V1, V2 and V4 loops. Pairwise analyses at each of the 25 pNLG sites indicated distinct country specific profiles. Highly significant differences (p<0.001***) were observed in prevalence of four pNLGS (N130, N295, N392 and N448) between South Africa and India, having most disease burden associated with subtype C. Our findings highlight that distinctly evolving clusters within global intra-subtype C gp120 sequences are likely to influence the disparate region-specific sensitivity of circulating HIV-1 subtype C to bnAbs.

Neutralization diversity of HIV-1 Indian subtype C envelopes obtained from cross sectional and followed up individuals against broadly neutralizing monoclonal antibodies having distinct gp120 specificities.

BACKGROUND: The potential use of the broadly neutralizing monoclonal antibodies (bnAbs) towards prophylaxis and treatment to HIV-1 is currently being explored. While a number of promising bnAbs have been discovered and a few of them have progressed towards clinical development, their extent of neutralization coverage with respect to global HIV-1 variants given the existence of genetically distinct subtypes and recombinants circulating globally is not clearly known. In the present study, we examined the variation in the neutralization susceptibility of pseudoviruses expressing 71 full length primary HIV-1 subtype C envs obtained from limited cross-sectional individuals over different time points against four bnAbs that target gp120 with distinct specificities: VRC01, CAP256-VRC26.25, PGDM1400 and PGT121. RESULTS: We found significant variations in the susceptibility of Indian clade C to these four bnAbs. These variations were found to be distinct to that observed in African subtype C based on the existing datasets and concordant with their sequence diversity. Trend analysis indicated an increasing neutralization resistance observed over time with CAP25-VRC26.25, PGDM1400 and PGT121 when tested on pseudoviruses expressing envs obtained from 1999 to 2016. However, inconsistent trend in neutralization susceptibility was observed, when pseudoviruses expressing envs obtained from three followed up individuals were examined. Finally, through predictive analysis of the 98 Indian subtype C including those assessed in the present study by employing additive model implemented in CombiNAber ( http://www.hiv.lanl.gov ), we observed two possibilities where combinations of three bnAbs (VRC01/CAP56-VRC26.25/PGT121 and PGDM1400/CAP256-VRC26.25/PGT121) could achieve near 100% neutralization coverage. CONCLUSIONS: Our findings not only indicate disparate intra-clade C genetic vis-à-vis neutralization diversities but also warrant the need for more comprehensive study using additional isolates towards comparing inter and intra-clade neutralization diversities which will be necessary for selecting the bnAb combinations suitable for optimal coverage of the region-specific HIV-1 circulating subtypes. Expanding these efforts is imperative for designing efficacious bnAb based intervention strategies for India as well as subtype C in general.

Elicitation of potent serum neutralizing antibody responses in rabbits by immunization with an HIV-1 clade C trimeric Env derived from an Indian elite neutralizer.

Evaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The novel 1PGE-THIVC Env trimer displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM). This closed spike conformation of 1PGE-THIVC Env trimers was correlated with weak or undetectable binding of non-neutralizing monoclonal antibodies (mAbs) compared to neutralizing mAbs. Furthermore, 1PGE-THIVC SOSIP induced potent neutralizing antibodies in rabbits to autologous virus variants. The autologous neutralizing antibody specificity induced in rabbits by 1PGE-THIVC was mapped to the C3/V4 region (T362/P401) of viral Env. This observation agreed with electron microscopy polyclonal epitope mapping (EMPEM) of the Env trimer complexed with IgG Fab prepared from the immunized rabbit sera. Our study demonstrated neutralization of sequence matched and unmatched autologous viruses by serum antibodies induced in rabbits by 1PGE-THIVC and also highlighted a comparable specificity for the 1PGE-THIVC SOSIP trimer with that seen with polyclonal antibodies elicited in the elite neutralizer by negative-stain electron microscopy polyclonal epitope (ns-EMPEM) mapping.

HIV Skews a Balanced Mtb-Specific Th17 Response in Latent Tuberculosis Subjects to a Pro-inflammatory Profile Independent of Viral Load.

HIV infection predisposes latent tuberculosis-infected (LTBI) subjects to active TB. This study is designed to determine whether HIV infection of LTBI subjects compromises the balanced Mycobacterium tuberculosis (Mtb)-specific T helper 17 (Th17) response of recognized importance in anti-TB immunity. Comparative analysis of Mtb- and cytomegalovirus (CMV)-specific CD4+ T cell responses demonstrates a marked dampening of the Mtb-specific CD4+ T cell effectors and polyfunctional cells while preserving CMV-specific response. Additionally, HIV skews the Mtb-specific Th17 response in chronic HIV-infected LTBI progressors, but not long-term non-progressors (LTNPs), with preservation of pro-inflammatory interferon (IFN)-γ+/interleukin-17+ (IL-17+) and significant loss of anti-inflammatory IL-10+/IL-17+ effectors that is restored by anti-retroviral therapy (ART). HIV-driven impairment of Mtb-specific response cannot be attributed to preferential infection as cell-associated HIV DNA and HIV RNA reveal equivalent viral burden in CD4+ T cells from different antigen specificities. We therefore propose that beyond HIV-induced loss of Mtb-specific CD4+ T cells, the associated dysregulation of Mtb-specific T cell homeostasis can potentially enhance the onset of TB in LTBI subjects.

Effect of diversity in gp41 membrane proximal external region of primary HIV-1 Indian subtype C sequences on interaction with broadly neutralizing antibodies 4E10 and 10E8.

Human Immunodeficiency Virus-1 Clade C (HIV-1C) dominates the AIDS epidemic in India, afflicting 2.1 million individuals within the country and more than 15 million people worldwide. Membrane proximal external region (MPER) is an attractive target for broadly neutralizing antibody (bNAb) based therapies. However, information on MPER sequence diversity from India is meagre due to limited sampling of primary viral sequences. In the present study, we examined the variation in MPER of HIV-1C from 24 individuals in Mumbai, India by high throughput sequencing of uncultured viral sequences. Deep sequencing of MPER (662-683; HXB2 envelope amino acid numbering) allowed quantification of intra-individual variation up to 65% at positions 662, 665, 668, 674 and 677 within this region. These variable positions included contact sites targeted by bNAbs 2F5, Z13e1, 4E10 as well as 10E8. Both major and minor epitope variants i.e. 'haplotypes' were generated for each sample dataset. A total of 23, 34 and 25 unique epitope haplotypes could be identified for bNAbs 2F5, Z13e1 and 4E10/10E8 respectively. Further analysis of 4E10 and 10E8 epitopes from our dataset and meta-analysis of previously reported HIV-1 sequences from India revealed 26 epitopes (7 India-specific), heretofore untested for neutralization sensitivity. Peptide-Ab docking predicted 13 of these to be non-binding to 10E8. ELISA, Surface Plasmon Resonance and peptide inhibition of HIV-1 neutralization assays were then performed which validated predicted weak/non-binding interactions for peptides corresponding to six of these epitopes. These results highlight the under-representation of 10E8 non-binding HIV-1C MPER sequences from India. Our study thus underscores the need for increased surveillance of primary circulating envelope sequences for development of efficacious bNAb-based interventions in India.

Emergence of drug resistance in human immunodeficiency virus type 1 infected patients from pune, India, at the end of 12 months of first line antiretroviral therapy initiation.

Introduction. In India, 4,86,173 HIV infected patients are on first line antiretroviral therapy (ART) as of January 2012. HIV drug resistance (HIVDR) is drug and regimen-specific and should be balanced against the benefits of providing a given ART regimen. Material & Methods. The emergence of HIVDR mutations in a cohort of 100 consecutive HIV-1 infected individuals attending ART centre, on first line ART for 12 months, was studied. CD4(+) T-cell counts and plasma HIV-1 RNA level were determined. Result. Out of the 100 HIV-1 infected individuals, 81 showed HIVDR prevention (HIV-1 RNA level < 1000/mL), while the remaining 19 had HIV-1 viral RNA level > 1000/mL. HIVDR genotyping was carried out for individuals with evidence of virologic failure (HIV-1 RNA level > 1000/mL). The most frequent NRTI-associated mutation observed was M184V, while K103N/S was the commonest mutation at NNRTI resistance position. Conclusion. Our study has revealed the emergence of HIVDR in HIV-1 infected patients at the end of 12 months of first line ART initiation. For NRTIs, the prevalence of HIVDR mutations was 9% and 10% for NNRTIs. Our findings will contribute information in evidence-based decision making with reference to first and second line ART delivery and prevention of HIVDR emergence.

Evaluations of an in-house drug resistance method for HIV-1 drug resistance using ViroSeq™ 2.0 genotyping system as a gold standard.

An in-house method was evaluated for its efficiency to detect the HIV-1 drug resistance mutations. This method was compared with the ViroSeq™ Genotyping System 2.0 (Celera Diagnostics, US) a gold standard. Sixty-five stored plasma samples, previously tested for HIV-1 drug resistance using the ViroSeq™ method were used to evaluate the in-house method. Out of the sixty five plasma samples, sixty were HIV-1 positive clinical samples; four samples from the Virology Quality Assessment (VQA) program and one positive control from the ViroSeq™ kit were used in this study. The sequences generated by the ViroSeq™ and an in-house method showed 99.5±0.5% and 99.7±0.4% (mean±SD) nucleotide and amino acid identity, respectively. Out of 214 Stanford HIVdb listed HIV-1 drug resistance mutations in the protease and reverse transcriptase regions, concordance was observed in 203 (94.9%), partial discordance in 11 (5.1%) and complete discordance was absent. The in-house primers are broadly sensitive in genotyping multiple HIV-1 group M subtypes. The amplification sensitivity of the in-house method was 1000 copies/ml. The evaluation of the in-house method provides results comparable with that of ViroSeq™ method thus, making the in-house method suitable for HIV-1 drug resistance testing in the developing countries.

Initial virologic response and HIV drug resistance among HIV-infected individuals initiating first-line antiretroviral therapy at 2 clinics in Chennai and Mumbai, India.

Human immunodeficiency virus drug resistance (HIVDR) in cohorts of patients initiating antiretroviral therapy (ART) at clinics in Chennai and Mumbai, India, was assessed following World Health Organization (WHO) guidelines. Twelve months after ART initiation, 75% and 64.6% of participants at the Chennai and Mumbai clinics, respectively, achieved viral load suppression of <1000 copies/mL (HIVDR prevention). HIVDR at initiation of ART (P <.05) and 12-month CD4 cell counts <200 cells/µL (P <.05) were associated with HIVDR at 12 months. HIVDR prevention exceeded WHO guidelines (≥ 70%) at the Chennai clinic but was below the target in Mumbai due to high rates of loss to follow-up. Findings highlight the need for defaulter tracing and scale-up of routine viral load testing to identify patients failing first-line ART.

Surveillance of transmitted HIV type 1 drug resistance among HIV type 1-positive women attending an antenatal clinic in Kakinada, India.

The World Health Organizations HIV Drug Resistance (WHO HIVDR) Threshold survey method was used to assess transmitted HIVDR in newly diagnosed HIV-1-infected primigravida women attending the Prevention of Parent to Child Transmission (PPTCT) centers in Kakinada, in whom it is likely that the infection had recently occurred. Out of the 56 consecutively collected eligible specimens, 51 were tested using the ViroSeq RT-PCR method (Abbott Germany) to obtain 47 consecutive sequences for the HIV-1 protease (PR) and reverse transcriptase (RT) region. As per the 2009 WHO list of mutations for surveillance of transmitted HIVDR, only one nonnucleoside reverse transcriptase inhibitor (NNRTI) mutation was detected at K101E from all specimens tested, suggesting a low prevalence (<5%) of resistance to NNRTIs and no mutations were detected at other sites, suggesting a low prevalence (<5%) of resistance to nucleoside reverse transcriptase inhibitors (NRTI) and protease inhibitors (PI) drug classes as well. Phylogenetic analysis showed all sequences belonged to HIV-1 subtype C. In the wake of antiretroviral treatment (ART) scale-up, future evaluation of transmitted HIVDR is essential in Kakinada as well as in other regions of India.

Transmitted HIV drug resistance among HIV-infected voluntary counseling and testing centers (VCTC) clients in Mumbai, India.

A survey for transmitted HIV drug resistance (HIVDR) was conducted according to WHO guidelines among clients newly diagnosed with HIV-1 infection at two voluntary counseling and testing centers (VCTC) in Mumbai. HIVDR testing was performed using the ViroSeq RT-PCR method (Abbott). Out of 50 successfully amplified and sequenced specimens, analysis of the first 34 consecutively collected specimens revealed no nucleoside reverse transcriptase inhibitor, nonnucleoside reverse transcriptase inhibitor, or protease inhibitor mutations from the 2007 WHO list of mutations for surveillance of transmitted HIVDR, indicating that the prevalence of transmitted HIVDR to all three drug classes was <5% among recently infected VCTC clients in Mumbai. The phylogenetic analysis revealed that all samples belonged to HIV-1 subtype C. Continued ART program monitoring and further evaluation of transmitted HIV drug resistance in coming years are essential in Mumbai as well as in other regions of the country in which ART is being scaled up rapidly.

One-, two-, and three-class resistance among HIV-infected patients on antiretroviral therapy in private care clinics: Mumbai, India.

HIV-infected patients receiving antiretroviral (ARV) therapy (ART) in India are not all adequately virally suppressed. We analyzed ARV drug resistance in adults receiving ART in three private clinics in Mumbai, India. HIV viral load was measured in 200 patients with the Roche AMPLICOR HIV-1 Monitor Test, v1.5. HIV genotyping was performed with the ViroSeq HIV-1 Genotyping System for 61 participants who had HIV-1 RNA >1000 copies/ml. Genotyping results were obtained for 51 samples. The participants with resistance results were on ART for a median of 24 months and were on their current regimen for a median of 12 months (median CD4 cell count: 217 cells/mm(3); median HIV viral load: 28,200 copies/ml). ARV regimens included nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens (n = 27), dual nucleoside reverse transcriptase inhibitors (NRTIs, n = 19), protease inhibitor (PI)-based regimens (n = 3), and other regimens (n = 2). Twenty-six participants (51.0%) were on their first ARV regimen and 24 (47%) reported >95% adherence. Forty-nine participants (96.1%) had resistance to at least one ARV drug; 47 (92.2%) had NRTI resistance, 32 (62.7%) had NNRTI resistance, and four (7.8%) had PI resistance. Thirty (58.8%) had two-class resistance and three (5.9%) had three-class resistance. Four (8%) had three or more resistance mutations associated with etravirine resistance and two (4%) had two mutations associated with reduced darunavir susceptibility. Almost all patients with HIV-1 RNA >1000 copies/ml had NRTI resistance and nearly two-thirds had NNRTI resistance; PI resistance was uncommon. Nearly 60% and 6% had two- and three-class resistance, respectively. This emphasizes the need for greater viral load and resistance monitoring, use of optimal ART combinations, and increased availability of second- and third-line agents for patients with ARV resistance.

Analysis of mitochondrial DNA sequences in childhood encephalomyopathies reveals new disease-associated variants.

BACKGROUND: Mitochondrial encephalomyopathies are a heterogeneous group of clinical disorders generally caused due to mutations in either mitochondrial DNA (mtDNA) or nuclear genes encoding oxidative phosphorylation (OXPHOS). We analyzed the mtDNA sequences from a group of 23 pediatric patients with clinical and morphological features of mitochondrial encephalopathies and tried to establish a relationship of identified variants with the disease. METHODOLOGY/PRINCIPLE FINDINGS: Complete mitochondrial genomes were amplified by PCR and sequenced by automated DNA sequencing. Sequencing data was analyzed by SeqScape software and also confirmed by BLASTn program. Nucleotide sequences were compared with the revised Cambridge reference sequence (CRS) and sequences present in mitochondrial databases. The data obtained shows that a number of known and novel mtDNA variants were associated with the disease. Most of the non-synonymous variants were heteroplasmic (A4136G, A9194G and T11916A) suggesting their possibility of being pathogenic in nature. Some of the missense variants although homoplasmic were showing changes in highly conserved amino acids (T3394C, T3866C, and G9804A) and were previously identified with diseased conditions. Similarly, two other variants found in tRNA genes (G5783A and C8309T) could alter the secondary structure of Cys-tRNA and Lys-tRNA. Most of the variants occurred in single cases; however, a few occurred in more than one case (e.g. G5783A and A10149T). CONCLUSIONS AND SIGNIFICANCE: The mtDNA variants identified in this study could be the possible cause of mitochondrial encephalomyopathies with childhood onset in the patient group. Our study further strengthens the pathogenic score of known variants previously reported as provisionally pathogenic in mitochondrial diseases. The novel variants found in the present study can be potential candidates for further investigations to establish the relationship between their incidence and role in expressing the disease phenotype. This study will be useful in genetic diagnosis and counseling of mitochondrial diseases in India as well as worldwide.