Biology subjects

Kelleher, A.

Publications and source records attributed to Kelleher, A..

5 recordsLinked to original sources

bioRxiv2025

The tuberculosis-associated microenvironment promotes HIV-1 persistence by impairing CD8+ T cell-mediated viral control

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is the most common coinfection in people living with HIV-1 (PLWH). This coinfection is associated with accelerated HIV-1 disease progression and reduced survival. However, the immunological and virological mechanisms driving this progression are incompletely understood. To address this knowledge gap, using pleural effusion samples from PLWH and TB, we investigated the HIV-1 genetic landscape and the anti-HIV-1 immune response impacted by a TB-associated microenvironment. Our results revealed an enrichment of genetically intact HIV-1 and impaired CD8+ T cell-mediated antiviral response at the site of HIV-1/Mtb coinfection. These findings indicate that the TB-associated microenvironment promotes the persistence of cells infected with replication-competent HIV-1 by creating a niche of reduced antiviral immune pressure, potentially contributing to the worsened clinical outcomes observed in PLWH and TB.

immunology↗

bioRxiv2023

Long-term serial passaging of SARS-CoV-2 reveals signatures of convergent evolution

Understanding viral evolutionary dynamics is crucial to pandemic responses, prediction of virus adaptation over time, and virus surveillance for public health strategies. Whole-genome sequencing (WGS) of SARS-CoV-2 has enabled fine-grained studies of virus evolution in the human population. Serial passaging in vitro offers a complementary controlled environment to investigate the emergence and persistence of genetic variants that may confer selective advantage. In this study, nine virus lineages, including four "variants of concern" and three former "variants under investigation", were sampled over [≥]33 serial passages (range 33-100) in Vero E6 cells. WGS was used to examine virus evolutionary dynamics and identify key mutations with implications for fitness and/or transmissibility. Viruses accumulated mutations regularly during serial passaging. Many low-frequency variants were lost but others became fixed, suggesting either in vitro benefits, or at least a lack of deleterious effect. Mutations arose convergently both across passage lines, and when compared with contemporaneous SARS-CoV-2 clinical sequences. These mutations included some hypothesised to drive lineage success through host immune evasion (e.g. S:A67V, S:H655Y). The appearance of these mutations in vitro suggested key mutations can arise convergently even in the absence of a multicellular host immune response through mechanisms other than immune-driven mutation. Such mutations may provide other benefits to the viruses in vitro, or arise stochastically. Our quantitative investigation into SARS-CoV-2 evolutionary dynamics spans the greatest number of serial passages to date, and will inform measures to reduce the effects of SARS-CoV-2 infection on the human population. ImportanceThe ongoing evolution of SARS-CoV-2 remains a challenge for long term public health efforts to minimise the effects of COVID-19. Whole-genome sequencing of outbreak cases has enabled global contact tracing efforts and the identification of mutations of concern within the virus genome. However, complementary approaches are necessary to inform our understanding of virus evolution and clinical outcomes. Here we charted evolution of the virus within a controlled cell culture environment, focusing on nine different virus lineages. Our approach demonstrates how SARS-CoV-2 continues to evolve readily in vitro, with changes mirroring those seen in outbreak cases globally. Findings of the study are important for i) investigating the mechanisms of how mutations arise, ii) predicting the future evolutionary trajectory of SARS-CoV-2, and iii) informing treatment and prevention design.

evolutionary biology↗

bioRxiv2022

Broadly neutralizing SARS-CoV-2 antibodies through epitope-based selection from convalescent patients

Emerging variants of concern (VOCs) are threatening to limit the effectiveness of SARS-CoV-2 monoclonal antibodies and vaccines currently used in clinical practice; broadly neutralizing antibodies and strategies for their identification are therefore urgently required. Here we demonstrate that broadly neutralizing antibodies can be isolated from peripheral blood mononuclear cells (PBMCs) of convalescent patients using SARS-CoV-2 receptor binding domains (RBDs) carrying epitope-specific mutations. This is exemplified by two human antibodies, GAR05, binding to epitope class 1, and GAR12, binding to a new epitope class 6 (located between class 3 and class 5). Both antibodies broadly neutralize VOCs, exceeding the potency of the clinical monoclonal sotrovimab (mAb S309) by orders of magnitude. They also provide potent prophylactic and therapeutic in vivo protection of hACE2 mice against viral challenge. Our results indicate that exposure to Wuhan SARS-CoV-2 induces antibodies that maintain potent and broad neutralization against emerging VOCs using two unique strategies: either by targeting the divergent class 1 epitope in a manner resistant to VOCs (ACE2 mimicry, as illustrated by GAR05 and mAbs P2C-1F11/S2K14); or alternatively, by targeting rare and highly conserved epitopes, such as the new class 6 epitope identified here (as illustrated by GAR12). Our results provide guidance for next generation monoclonal antibody development and vaccine design.

immunology↗

bioRxiv2020

Potent SARS-CoV-2 binding and neutralization through maturation of iconic SARS-CoV-1 antibodies

Antibodies against coronavirus spike protein potently protect against infection and disease, however it remains unclear if such protection can be extended to variant coronaviruses. This is exemplified by a set of iconic and well-characterized monoclonal antibodies developed after the 2003 SARS outbreak including mAbs m396, CR3022, CR3014 and 80R, which potently neutralize SARS-CoV-1, but not SARS-CoV-2. Here we explore antibody maturation strategies to change and broaden their specificity, enabling potent binding and neutralization of SARS-CoV-2. Using targeted mutagenesis as well as light chain shuffling on phage, we identified variants with considerably increased affinity and neutralization potential. The most potent antibody, derived from the NIH-developed mAb m396, neutralized live SARS-CoV-2 virus with a half-maximal inhibitory concentration (IC50) of 160 ng/ml. Intriguingly, while many of the matured clones maintained specificity of the parental antibody, new specificities were also observed, which was further confirmed by X-ray crystallography and cryo-electron microscopy, indicating that a limited set of antibodies can give rise to variants targeting diverse epitopes. Our findings open up over 15 years of antibody development efforts against SARS-CoV-1 to the SARS-CoV-2 field and outline general principles for the maturation of antibody specificity against emerging viruses.

immunology↗

bioRxiv2020

A single dose, BCG-adjuvanted SARS-CoV-2 vaccine induces Th1-polarized immunity and high-titre neutralizing antibodies in mice

Global control of COVID-19 requires broadly accessible vaccines that are effective against SARS-CoV-2 variants. In this report, we exploit the immunostimulatory properties of bacille Calmette-Guerin (BCG), the existing tuberculosis vaccine, to deliver a vaccination regimen with potent SARS-CoV-2-specific protective immunity. Combination of BCG with a stabilized, trimeric form of SARS-CoV-2 spike antigen promoted rapid development of virus-specific IgG antibodies in the blood of vaccinated mice, that was further augmented by the addition of alum. This vaccine formulation, BCG:CoVac, induced high-titre SARS-CoV-2 neutralizing antibodies (NAbs) and Th1-biased cytokine release by vaccine-specific T cells, which correlated with the early emergence of T follicular helper cells in local lymph nodes and heightened levels of antigen-specific plasma B cells after vaccination. Vaccination of K18-hACE2 mice with a single dose of BCG:CoVac almost completely abrogated disease after SARS-CoV-2 challenge, with minimal inflammation and no detectable virus in the lungs of infected animals. Boosting BCG:CoVac-primed mice with a heterologous vaccine further increased SARS-CoV-2-specific antibody responses, which effectively neutralized B.1.1.7 and B.1.351 SARS-CoV-2 variants of concern. These findings demonstrate the potential for BCG-based vaccination to protect against major SARS-CoV-2 variants circulating globally.

microbiology↗