Biology subjects

Rahman, S. A.

Publications and source records attributed to Rahman, S. A..

6 recordsLinked to original sources

bioRxiv2022

Patterns of Volatility Across the Spike Protein Accurately Predict the Emergence of Mutations within SARS-CoV-2 Lineages

Mutations in the spike glycoprotein of SARS-CoV-2 allow the virus to probe the sequence space in search of higher-fitness states. New sublineages of SARS-CoV-2 variants-of-concern (VOCs) continuously emerge with such mutations. Interestingly, the sites of mutation in these sublineages vary between the VOCs. Whether such differences reflect the random nature of mutation appearance or distinct evolutionary spaces of spike in the VOCs is unclear. Here we show that each position of spike has a lineage-specific likelihood for mutations to appear and dominate descendent sublineages. This likelihood can be accurately estimated from the lineage-specific mutational profile of spike at a protein-wide level. The mutability environment of each position, including adjacent sites on the protein structure and neighboring sites on the network of comutability, accurately forecast changes in descendent sublineages. Mapping of imminent changes within the VOCs can contribute to the design of immunogens and therapeutics that address future forms of SARS-CoV-2.

bioinformatics↗

bioRxiv2022

Antibodies targeting conserved non-canonical antigens and endemic coronaviruses associate with favorable outcomes in severe COVID-19

While there have been extensive analyses characterizing cellular and humoral responses across the severity spectrum in COVID-19, predictors of outcomes within severe COVID-19 remain to be comprehensively elucidated. Recently, we identified divergent monocyte states as predictors of outcomes within severe COVID-19, but corresponding humoral profiles of risk have not been delineated. Furthermore, the nature of antibodies (Abs) directed against viral antigens beyond the spike protein or endemic coronavirus antigens and their associations with disease severity and outcomes remain poorly defined. We performed deep molecular profiling of Abs directed against a wide range of antigenic specificities in severe COVID-19 patients admitted to the ICU. The profiles consisted of canonical (S, RBD, N) and non-canonical (orf3a, orf8, nsp3, nps13 and M) antigenic specificities. Notably, multivariate machine learning (ML) models, generated using profiles of Abs directed against canonical or non-canonical antigens, were equally discriminative of recovery and mortality COVID-19 outcomes. In both ML models, survivors were associated with increased virus-specific IgA and IgG3 antibodies and with higher antigen-specific antibody galactosylation. Intriguingly, pre-pandemic healthy controls had cross-reactive Abs directed against nsp13 which is a conserved protein in other alpha and beta coronaviruses. Notably, higher levels of nsp13-specific IgA antibodies were associated with recovery in severe COVID-19. In keeping with these findings, a model built on Ab profiles for endemic coronavirus antigens was also predictive of COVID-19 outcome bifurcation, with higher levels of IgA and IgG3 antibodies against OC43 S and NL63 S being associated with survival. Our results suggest the importance of Abs targeting non-canonical SARS-CoV-2 antigens as well as those directed against endemic coronaviruses in favorable outcomes of severe COVID-19.

immunology↗

bioRxiv2021

Network-based integration of epigenetic landscapes unveils molecular programs underlying human T follicular helper cell differentiation

T follicular helper (Tfh) cells play a critical role in T-dependent humoral immune responses. While genetic programs controlling Tfh cell differentiation have been extensively studied using murine models, studies in humans have been hampered by the lack of a robust in vitro differentiation system for Tfh cells. We characterized epigenomic landscapes across stages of Tfh cell differentiation in a healthy human tonsil using ATAC-Seq and CUT&RUN for selected histone modifications. We combined these epigenomic datasets and integrated them with the reference human protein interactome using a novel network propagation approach. Our approach uncovered subnetworks integral to Tfh cell differentiation. These subnetworks captured known Tfh cell drivers to a greater extent than conventional gene-centric analyses would, and also revealed novel modules that may be required for Tfh cell differentiation. We find that human Tfh cell subnetworks are functionally associated with specific immune signaling cascades including cytokine receptor driven pathways. Analyses of transcriptomic data revealed that in addition to these immune pathways being significantly dysregulated in severe COVID-19, the corresponding Tfh cell subnetworks are also transcriptionally perturbed to a similar extent. This provides a molecular mechanistic basis for the previously observed impaired Tfh cell differentiation and loss of germinal centers in severe COVID-19.

immunology↗

bioRxiv2021

Structure-function investigation of a new VUI-202012/01 SARS-CoV-2 variant

The SARS-CoV-2 (Severe Acute Respiratory Syndrome-Coronavirus) has accumulated multiple mutations during its global circulation. Recently, a new strain of SARS-CoV-2 (VUI 202012/01) had been identified leading to sudden spike in COVID-19 cases in South-East England. The strain has accumulated 23 mutations which have been linked to its immune evasion and higher transmission capabilities. Here, we have highlighted structural-function impact of crucial mutations occurring in spike (S), ORF8 and nucleocapsid (N) protein of SARS-CoV-2. Some of these mutations might confer higher fitness to SARS-CoV-2. SummarySince initial outbreak of COVID-19 in Wuhan city of central China, its causative agent; SARS-CoV-2 virus has claimed more than 1.7 million lives out of 77 million populations and still counting. As a result of global research efforts involving public-private-partnerships, more than 0.2 million complete genome sequences have been made available through Global Initiative on Sharing All Influenza Data (GISAID). Similar to previously characterized coronaviruses (CoVs), the positive-sense single-stranded RNA SARS-CoV-2 genome codes for ORF1ab non-structural proteins (nsp(s)) followed by ten or more structural/nsps [1, 2]. The structural proteins include crucial spike (S), nucleocapsid (N), membrane (M), and envelope (E) proteins. The S protein mediates initial contacts with human hosts while the E and M proteins function in viral assembly and budding. In recent reports on evolution of SARS-CoV-2, three lineage defining non-synonymous mutations; namely D614G in S protein (Clade G), G251V in ORF3a (Clade V) and L84S in ORF 8 (Clade S) were observed [2-4]. The latest pioneering works by Plante et al and Hou et al have shown that compared to ancestral strain, the ubiquitous D614G variant (clade G) of SARS-CoV-2 exhibits efficient replication in upper respiratory tract epithelial cells and transmission, thereby conferring higher fitness [5, 6]. As per latest WHO reports on COVID-19, a new strain referred as SARS-CoV-2 VUI 202012/01 (Variant Under Investigation, year 2020, month 12, variant 01) had been identified as a part of virological and epidemiological analysis, due to sudden rise in COVID-19 detected cases in South-East England [7]. Preliminary reports from UK suggested higher transmissibility (increase by 40-70%) of this strain, escalating Ro (basic reproduction number) of virus to 1.5-1.7 [7, 8]. This apparent fast spreading variant inculcates 23 mutations; 13 non-synonymous, 6 synonymous and 4 amino acid deletions [7]. In the current scenario, where immunization programs have already commenced in nations highly affected by COVID-19, advent of this new strain variant has raised concerns worldwide on its possible role in disease severity and antibody responses. The mutations also could also have significant impact on diagnostic assays owing to S gene target failures.

bioinformatics↗

bioRxiv2020

Mutational signatures in countries affected by SARS-CoV-2: Implications in host-pathogen interactome

We are in the midst of the third severe coronavirus outbreak caused by SARS-CoV-2 with unprecedented health and socio-economic consequences due to the COVID-19. Globally, the major thrust of scientific efforts has shifted to the design of potent vaccine and anti-viral candidates. Earlier genome analyses have shown global dominance of some mutations purportedly indicative of similar infectivity and transmissibility of SARS-CoV-2 worldwide. Using high-quality large dataset of 25k whole-genome sequences, we show emergence of new cluster of mutations as result of geographic evolution of SARS-CoV-2 in local population ([≥]10%) of different nations. Using statistical analysis, we observe that these mutations have either significantly co-occurred in globally dominant strains or have shown mutual exclusivity in other cases. These mutations potentially modulate structural stability of proteins, some of which forms part of SARS-CoV-2-human interactome. The high confidence druggable host proteins are also up-regulated during SARS-CoV-2 infection. Mutations occurring in potential hot-spot regions within likely T-cell and B-cell epitopes or in proteins as part of host-viral interactome, could hamper vaccine or drug efficacy in local population. Overall, our study provides comprehensive view of emerging geo-clonal mutations which would aid researchers to understand and develop effective countermeasures in the current crisis. SignificanceOur comparative analysis of globally dominant mutations and region-specific mutations in 25k SARS-CoV-2 genomes elucidates its geo-clonal evolution. We observe locally dominant mutations (co-occurring or mutually exclusive) in nations with contrasting COVID-19 mortalities per million of population) besides globally dominant ones namely, P314L (ORF1b) and D164G (S) type. We also see exclusive dominant mutations such as in Brazil (I33T in ORF6 and I292T in N protein), England (G251V in ORF3a), India (T2016K and L3606F in ORF1a) and in Spain (L84S in ORF8). The emergence of these local mutations in ORFs within SARS-CoV-2 genome could have interventional implications and also points towards their potential in modulating infectivity of SARS-CoV-2 in regional population.

bioinformatics↗

bioRxiv2020

Modified Vaccinia Ankara Based SARS-CoV-2 Vaccine Expressing Full-Length Spike Induces Strong Neutralizing Antibody Response

There is a great need for the development of vaccines for preventing SARS-CoV-2 infection and mitigating the COVID-19 pandemic. Here, we developed two modified vaccinia Ankara (MVA) based vaccines which express either a membrane anchored full-length spike protein (MVA/S) stabilized in a prefusion state or the S1 region of the spike (MVA/S1) which forms trimers and is secreted. Both immunogens contained the receptor-binding domain (RBD) which is a known target of antibody-mediated neutralization. Following immunizations with MVA/S or MVA/S1, both spike protein recombinants induced strong IgG antibodies to purified full-length SARS-CoV-2 spike protein. The MVA/S induced a robust antibody response to purified RBD, S1 and S2 whereas MVA/S1 induced an antibody response to the S1 region outside of the RBD region. Both vaccines induced an antibody response in the lung and that was associated with induction of bronchus-associated lymphoid tissue. MVA/S but not MVA/S1 vaccinated mice generated robust neutralizing antibody responses against SARS-CoV-2 that strongly correlated with RBD antibody binding titers. Mechanistically, S1 binding to ACE-2 was strong but reduced following prolonged pre-incubation at room temperature suggesting confirmation changes in RBD with time. These results demonstrate MVA/S is a potential vaccine candidate against SARS-CoV-2 infection.Competing Interest StatementThe authors have declared no competing interest.View Full Text

immunology↗