scholarly journals Identifying protein sites contributing to vaccine escape via statistical comparisons of short-term molecular dynamics simulations

2021 ◽  
Author(s):  
Madhusudan Rajendran ◽  
Maureen C. Ferran ◽  
Gregory A. Babbitt
Keyword(s):  
In Silico ◽  
Neutralizing Antibodies ◽  
Hot Spot ◽  
Comparative Method ◽  
Viral Evolution ◽  
Antibody Binding ◽  
Short Term ◽  
Desktop Computer ◽  
Leibler Divergence ◽  
Antigen Antibody

AbstractThe identification of viral mutations that confer escape from antibodies is crucial for understanding the interplay between immunity and viral evolution. We describe a molecular dynamic (MD) based approach that scales well to a desktop computer with a high-end modern graphics processor and enables the user to identify protein sites that are prone to vaccine escape in a viral antigen. We first implemented our MD pipeline to employ site-wise calculation of Kullback-Leibler divergence in atom fluctuation over replicate sets of short-term MD production runs to compare influenza hemagglutinin’s rapid motions in the presence and absence of three well-known neutralizing antibodies. Using this simple comparative method applied to motions of viral proteins, we successfully identified in silico all previously empirically confirmed sites of escape in hemagglutinin, predetermined via selection experiments and neutralization assays. After this validation of our computational approach, we identified potential hot spot residues in the receptor binding domain (RBD) of the SARS-CoV-2 virus in the presence of COVOX-222 and S2H97 antibodies. We identified sites in the antigen-antibody interface with strong dampening of fluctuation that may indicate potential antibody escape due to single mutations. Many of these sites were found to match known sites of mutations in SARS-CoV-2 variants of concern. The determination of single sites with large effect on antigen-antibody binding interfaces is crucial to discriminating neutral variants from potential escape variants. In summary, we provide a cheap, fast, and accurate in silico method to identify and quantify potential hot spots of functional evolution in antibody binding footprints.

scholarly journals In Silico Investigation of the New UK (B.1.1.7) and South African (501Y.V2) SARS-CoV-2 Variants with a Focus at the ACE2–Spike RBD Interface

2021 ◽  
Vol 22 (4) ◽  
pp. 1695
Author(s):  
Bruno O. Villoutreix ◽  
Vincent Calvez ◽  
Anne-Geneviève Marcelin ◽  
Abdel-Majid Khatib
Keyword(s):  
Amino Acid ◽  
South African ◽  
In Silico ◽  
Neutralizing Antibodies ◽  
Viral Escape ◽  
Spike Protein ◽  
Amino Acid Substitutions ◽  
The South ◽  
African Strain ◽  
The Uk

SARS-CoV-2 exploits angiotensin-converting enzyme 2 (ACE2) as a receptor to invade cells. It has been reported that the UK and South African strains may have higher transmission capabilities, eventually in part due to amino acid substitutions on the SARS-CoV-2 Spike protein. The pathogenicity seems modified but is still under investigation. Here we used the experimental structure of the Spike RBD domain co-crystallized with part of the ACE2 receptor, several in silico methods and numerous experimental data reported recently to analyze the possible impacts of three amino acid replacements (Spike K417N, E484K, N501Y) with regard to ACE2 binding. We found that the N501Y replacement in this region of the interface (present in both the UK and South African strains) should be favorable for the interaction with ACE2, while the K417N and E484K substitutions (South African strain) would seem neutral or even unfavorable. It is unclear if the N501Y substitution in the South African strain could counterbalance the K417N and E484K Spike replacements with regard to ACE2 binding. Our finding suggests that the UK strain should have higher affinity toward ACE2 and therefore likely increased transmissibility and possibly pathogenicity. If indeed the South African strain has a high transmission level, this could be due to the N501Y replacement and/or to substitutions in regions located outside the direct Spike–ACE2 interface but not so much to the K417N and E484K replacements. Yet, it should be noted that amino acid changes at Spike position 484 can lead to viral escape from neutralizing antibodies. Further, these amino acid substitutions do not seem to induce major structural changes in this region of the Spike protein. This structure–function study allows us to rationalize some observations made for the UK strain but raises questions for the South African strain.

Protein-Protein Interactions (PPIs) as an Alternative to Targeting the ATP Binding Site of Kinase

2016 ◽  
pp. 249-277
Author(s):  
Sailu Sarvagalla ◽  
Mohane Selvaraj Coumar
Keyword(s):  
Protein Interactions ◽  
In Silico ◽  
Rational Design ◽  
Kinase Activity ◽  
Hot Spot ◽  
Binding Pocket ◽  
Atp Binding ◽  
Protein Protein Interactions ◽  
Structure Based Drug Design ◽  
Atp Binding Site

Most of the developed kinase inhibitor drugs are ATP competitive and suffer from drawbacks such as off-target kinase activity, development of resistance due to mutation in the ATP binding pocket and unfavorable intellectual property situations. Besides the ATP binding pocket, protein kinases have binding sites that are involved in Protein-Protein Interactions (PPIs); these PPIs directly or indirectly regulate the protein kinase activity. Of recent, small molecule inhibitors of PPIs are emerging as an alternative to ATP competitive agents. Rational design of inhibitors for kinase PPIs could be carried out using molecular modeling techniques. In silico tools available for the prediction of hot spot residues and cavities at the PPI sites and the means to utilize this information for the identification of inhibitors are discussed. Moreover, in silico studies to target the Aurora B-INCENP PPI sites are discussed in context. Overall, this chapter provides detailed in silico strategies that are available to the researchers for carrying out structure-based drug design of PPI inhibitors.

scholarly journals A Highly Conserved Epitope (RNNQIPQDF) of Porcine teschovirus Induced a Group-Specific Antiserum: A Bioinformatics-Predicted Model with Pan-PTV Potential

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1225
Author(s):  
Tung-Hsuan Tsai ◽  
Chia-Yi Chang ◽  
Fun-In Wang
Keyword(s):  
In Silico ◽  
Neutralizing Antibodies ◽  
Age Groups ◽  
Epitope Prediction ◽  
Toxin B ◽  
Swine Pathogen ◽  
Porcine Teschovirus ◽  
A Subunit ◽  
Predicted Model ◽  
Conserved Epitope

Porcine teschovirus (PTV) is an OIE-listed pathogen with 13 known PTV serotypes. Heterologous PTV serotypes frequently co-circulate and co-infect with another swine pathogen, causing various symptoms in all age groups, thus highlighting the need for a pan-PTV diagnostic tool. Here, a recombinant protein composed of a highly conserved “RNNQIPQDF” epitope on the GH loop of VP1, predicted in silico, and a tandem repeat of this epitope carrying the pan DR (PADRE) and Toxin B epitopes was constructed to serve as a PTV detection tool. This recombinant GST-PADRE-(RNNQIPQDF)n-Toxin B protein was used as an immunogen, which effectively raised non-neutralizing or undetectable neutralizing antibodies against PTV in mice. The raised antiserum was reactive against all the PTV serotypes (PTV–1–7) tested, but not against members of the closely related genera Sapelovirus and Cardiovirus, and the unrelated virus controls. This potential pan-PTV diagnostic reagent may be used to differentiate naturally infected animals from vaccinated animals that have antibodies against a subunit vaccine that does not contain this epitope or to screen for PTV before further subtyping. To our knowledge, this is the first report that utilized in silico PTV epitope prediction to find a reagent broadly reactive to various PTV serotypes.

scholarly journals Autologous IgG antibodies block outgrowth of a substantial but variable fraction of viruses in the latent reservoir for HIV-1

2020 ◽  
Vol 117 (50) ◽  
pp. 32066-32077
Author(s):  
Lynn N. Bertagnolli ◽  
Joseph Varriale ◽  
Sarah Sweet ◽  
Jacqueline Brockhurst ◽  
Francesco R. Simonetti ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Neutralizing Antibodies ◽  
Cell Activation ◽  
Viral Evolution ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Env Protein ◽  
Autologous Antibodies ◽  
Hiv 1

In untreated HIV-1 infection, rapid viral evolution allows escape from immune responses. Viral replication can be blocked by antiretroviral therapy. However, HIV-1 persists in a latent reservoir in resting CD4+ T cells, and rebound viremia occurs following treatment interruption. The reservoir, which is maintained in part by clonal expansion, can be measured using quantitative viral outgrowth assays (QVOAs) in which latency is reversed with T cell activation to allow viral outgrowth. Recent studies have shown that viruses detected in QVOAs prior to treatment interruption often differ from rebound viruses. We hypothesized that autologous neutralizing antibodies directed at the HIV-1 envelope (Env) protein might block outgrowth of some reservoir viruses. We modified the QVOA to reflect pressure from low concentrations of autologous antibodies and showed that outgrowth of a substantial but variable fraction of reservoir viruses is blocked by autologous contemporaneous immunoglobulin G (IgG). A reduction in outgrowth of >80% was seen in 6 of 15 individuals. This effect was due to direct neutralization. We established a phylogenetic relationship between rebound viruses and viruses growing out in vitro in the presence of autologous antibodies. Some large infected cell clones detected by QVOA carried neutralization-sensitive viruses, providing a cogent explanation for differences between rebound virus and viruses detected in standard QVOAs. Measurement of the frequency of reservoir viruses capable of outgrowth in the presence of autologous IgG might allow more accurate prediction of time to viral rebound. Ultimately, therapeutic immunization targeting the subset of variants resistant to autologous IgG might contribute to a functional cure.

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