Biology subjects

Daar, E. S.

Publications and source records attributed to Daar, E. S..

4 recordsLinked to original sources

bioRxiv2023

SARS-CoV-2 monoclonal antibody treatment followed by vaccination shifts human memory B cell epitope recognition suggesting antibody feedback

Therapeutic anti-SARS-CoV-2 monoclonal antibodies (mAbs) have been extensively studied in humans, but the impact on immune memory of mAb treatment during an ongoing immune response has remained unclear. Here, we evaluated the effect of infusion of the anti-SARS-CoV-2 spike receptor binding domain (RBD) mAb bamlanivimab on memory B cells (MBCs) in SARS-CoV-2-infected individuals. Bamlanivimab treatment skewed the repertoire of memory B cells targeting Spike towards non-RBD epitopes. Furthermore, the relative affinity of RBD memory B cells was weaker in mAb-treated individuals compared to placebo-treated individuals over time. Subsequently, after mRNA COVID-19 vaccination, memory B cell differences persisted and mapped to a specific defect in recognition of the class II RBD site, the same RBD epitope recognized by bamlanivimab. These findings indicate a substantial role of antibody feedback in regulating human memory B cell responses, both to infection and vaccination. These data indicate that mAb administration can promote alterations in the epitopes recognized by the B cell repertoire, and the single administration of mAb can continue to determine the fate of B cells in response to additional antigen exposures months later. SIGNIFICANCE STATEMENTEvaluating the therapeutic use of monoclonal antibodies during SARS-CoV-2 infection requires a comprehensive understanding of their impact on B cell responses at the cellular level and how these responses are shaped after vaccination. We report for the first time the effect of bamlanivimab on SARS-CoV-2 specific human memory B cells of COVID-19 infected humans receiving, or not, mRNA immunization.

immunology↗

bioRxiv2023

Early antiviral CD4 and CD8 T cell responses are associated with upper respiratory tract clearance of SARS-CoV-2

T cells are involved in protective immunity against numerous viral infections. Data regarding functional roles of human T cells in SARS-CoV-2 (SARS2) viral clearance in primary COVID-19 are limited. To address this knowledge gap, samples were assessed for associations between SARS2 upper respiratory tract viral RNA levels and early virus-specific adaptive immune responses for 95 unvaccinated clinical trial participants with acute primary COVID-19 aged 18-86 years old, approximately half of whom were considered high risk for progression to severe COVID-19. Functionality and magnitude of acute SARS2-specific CD4 and CD8 T cell responses were evaluated, in addition to antibody responses. Most individuals with acute COVID-19 developed SARS2-specific T cell responses within 6 days of COVID-19 symptom onset. Early CD4 T cell and CD8 T cell responses were polyfunctional, and both strongly associated with reduced upper respiratory tract SARS2 viral RNA, independent of neutralizing antibody titers. Overall, these findings provide evidence for protective roles for circulating SARS2-specific CD4 and CD8 T cells during acute COVID-19.

immunology↗

bioRxiv2023

Modeling the emergence of viral resistance for SARS-CoV-2 during treatment with an anti-spike monoclonal antibody

The COVID-19 pandemic has led to over 760 million cases and 6.9 million deaths worldwide. To mitigate the loss of lives, emergency use authorization was given to several anti-SARS-CoV-2 monoclonal antibody (mAb) therapies for the treatment of mild-to-moderate COVID-19 in patients with a high risk of progressing to severe disease. Monoclonal antibodies used to treat SARS-CoV-2 target the spike protein of the virus and block its ability to enter and infect target cells. Monoclonal antibody therapy can thus accelerate the decline in viral load and lower hospitalization rates among high-risk patients with susceptible variants. However, viral resistance has been observed, in some cases leading to a transient viral rebound that can be as large as 3-4 orders of magnitude. As mAbs represent a proven treatment choice for SARS-CoV-2 and other viral infections, evaluation of treatment-emergent mAb resistance can help uncover underlying pathobiology of SARS-CoV-2 infection and may also help in the development of the next generation of mAb therapies. Although resistance can be expected, the large rebounds observed are much more difficult to explain. We hypothesize replenishment of target cells is necessary to generate the high transient viral rebound. Thus, we formulated two models with different mechanisms for target cell replenishment (homeostatic proliferation and return from an innate immune response anti-viral state) and fit them to data from persons with SARS-CoV-2 treated with a mAb. We showed that both models can explain the emergence of resistant virus associated with high transient viral rebounds. We found that variations in the target cell supply rate and adaptive immunity parameters have a strong impact on the magnitude or observability of the viral rebound associated with the emergence of resistant virus. Both variations in target cell supply rate and adaptive immunity parameters may explain why only some individuals develop observable transient resistant viral rebound. Our study highlights the conditions that can lead to resistance and subsequent viral rebound in mAb treatments during acute infection. Author summaryMonoclonal antibodies have been used as a treatment for SARS-CoV-2. However, viral evolution and development of variants has compromised the use of all currently authorized monoclonal antibodies for SARS-CoV-2. In some individuals treated with one such monoclonal antibody, bamlanivimab, transient nasal viral rebounds of 3-4 logs associated with resistant viral strains occur. To better understand the mechanisms underlying resistance emergence with high viral load rebounds, we developed two different models that incorporate drug sensitive and drug resistant virus as well as target cell replenishment and fit them to data. The models accurately capture the observed viral dynamics as well as the proportion of resistant virus for each studied individual with little variation in model parameters. In the models with best-fit parameters, bamlanivimab selects for resistance mutants that can expand to high levels due to target cell replenishment. The ultimate clearance of virus however depends on the development of adaptive immunity.

immunology↗

bioRxiv2020

Tissue specificity-aware TWAS (TSA-TWAS) framework identifies novel associations with metabolic, immunologic, and virologic traits in HIV-positive adults

As a type of relatively new methodology, the transcriptome-wide association study (TWAS) has gained interest due to capacity for gene-level association testing. However, the development of TWAS has outpaced statistical evaluation of TWAS gene prioritization performance. Current TWAS methods vary in underlying biological assumptions about tissue specificity of transcriptional regulatory mechanisms. In a previous study from our group, this may have affected whether TWAS methods better identified associations in single tissues versus multiple tissues. We therefore designed simulation analyses to examine how the interplay between particular TWAS methods and tissue specificity of gene expression affects power and type I error rates for gene prioritization. We found that cross-tissue identification of expression quantitative trait loci (eQTLs) improved TWAS power. Single-tissue TWAS (i.e., PrediXcan) had robust power to identify genes expressed in single tissues, but, had high false positive rates for genes that are expressed in multiple tissues. Cross-tissue TWAS (i.e., UTMOST) had overall equal or greater power and controlled type I error rates for genes expressed in multiple tissues. Based on these simulation results, we applied a tissue specificity-aware TWAS (TSA-TWAS) analytic framework to look for gene-based associations with pre-treatment laboratory values from AIDS Clinical Trial Group (ACTG) studies. We replicated several proof-of-concept transcriptionally regulated gene-trait associations, including UGT1A1 (encoding bilirubin uridine diphosphate glucuronosyl transferase enzyme) and total bilirubin levels (p = 3.59x10-12), and CETP (cholesteryl ester transfer protein) with high-density lipoprotein cholesterol (p = 4.49x10-12). We also identified several novel genes associated with metabolic and virologic traits, as well as pleiotropic genes that linked plasma viral load, absolute basophil count, and/or triglyceride levels. By highlighting the advantages of different TWAS methods, our simulation study promotes a tissue specificity-aware TWAS analytic framework that revealed novel aspects of HIV-related traits. publicly available.

bioinformatics↗