Biology subjects

Shirreff, L. M.

Publications and source records attributed to Shirreff, L. M..

3 recordsLinked to original sources

bioRxiv2026

Sustained Delivery of a SARS-CoV-2 Subunit Vaccine in An Adjuvanted Hydrogel Depot Enhances Vaccine Responses in Nonhuman Primates

While natural infections expose the immune system for days to weeks of inflammation and antigen presentation, immunizations with conventional bolus vaccines often lead to rapid clearance of antigens and adjuvants. Prolonged exposure to vaccines using controlled delivery devices or repeated dosing regimens has been shown to enhance germinal center reactions, leading to improved humoral responses, including increased magnitude of antibody titers and enhanced neutralizing activity. Herein, we report the use of injectable polymer-nanoparticle (PNP) hydrogels as a vaccine depot technology for sustained delivery of the clinically relevant SARS-CoV-2 Hexapro subunit antigen and a toll-like receptor agonist adjuvant. In mice, we demonstrated that PNP hydrogel vaccines enhanced germinal center responses and antibody responses relative to bolus vaccination. In nonhuman primates, hydrogel vaccines induced enhanced and durable antibody responses against wildtype and variants of concern such as Omicron BA.5 compared to bolus vaccination. We report the first use of a biomaterials-based approach for sustained delivery of vaccines in nonhuman primates, further advancing toward clinical translation.

bioengineering↗

bioRxiv2023

Extremely potent pan-sarbecovirus neutralizing antibodies generated by immunization of macaques with an AS03-adjuvanted monovalent subunit vaccine against SARS-CoV-2

The rapid emergence of SARS-CoV-2 variants that evade immunity to vaccination has placed a global health imperative on the development of therapeutic countermeasures that provide broad protection against SARS-CoV-2 and related sarbecoviruses. Here, we identified extremely potent pan-sarbecovirus antibodies from non-human primates vaccinated with an AS03 adjuvanted subunit vaccine against SARS-CoV-2 that recognize conserved epitopes in the receptor binding domain (RBD) with femtomolar affinities. Longitudinal analysis revealed progressive accumulation of somatic mutation in the immunoglobulin genes of antigen-specific memory B cells for at least one year following primary vaccination. 514 monoclonal antibodies (mAbs) were generated from antigen-specific memory B cells. Antibodies isolated at 5 to 12 months following vaccination displayed greater potency and breadth, relative to those identified at 1.4 months. Notably, 15 out of 338 ([~]4.4%) antibodies isolated at 1.4[~]6 months after the primary vaccination showed extraordinary neutralization potency against SARS-CoV-2 omicron BA.1, despite the absence of BA.1 neutralization in serum. Two of them, 25F9 and 20A7, neutralized authentic clade Ia sarbecoviruses (SARS-CoV, WIV-1, SHC014) and clade Ib sarbecoviruses (SARS-CoV-2 D614G, SARS-CoV-2 BA.1, Pangolin-GD) with half-maximal inhibition concentrations of (0.85 ng/ml, 3 ng/ml, 6 ng/ml, 6 ng/ml, 42 ng/ml, 6 ng/ml) and (13 ng/ml, 2 ng/ml, 18 ng/ml, 9 ng/ml, 6 ng/ml, 345 ng/ml), respectively. Furthermore, 20A7 and 27A12 showed potent neutralization against all SARS-CoV-2 variants of concern and multiple Omicron sublineages, including BA.1, BA.2, BA.3, BA.4/5, BQ.1, BQ.1.1 and XBB variants. X-ray crystallography studies revealed the molecular basis of broad and potent neutralization through targeting conserved RBD sites. In vivo prophylactic protection of 25F9, 20A7 and 27A12 was confirmed in aged Balb/c mice. Notably, administration of 25F9 provided complete protection against SARS-CoV-2, SARS-CoV-2 BA.1, SARS-CoV, and SHC014 challenge, underscoring that these mAbs are promising pan-sarbecovirus therapeutic antibodies. One Sentence SummaryExtremely potent pan-sarbecovirus neutralizing antibodies

immunology↗

bioRxiv2022

Blockade of TGF-β signaling reactivates HIV-1/SIV reservoirs and immune responses in vivo

Elevated levels of TGF-{beta}, a potent immunosuppressive factor, are present in HIV-1 infected individuals even after years of antiretroviral therapy (ART). TGF-{beta} plays a critical role in maintaining immune cells in a resting state by inhibiting cell activation and proliferation. Resting HIV-1 target cells represent one of the main cellular reservoirs after long term ART and the low inducibility of the latent provirus constitutes one of the major obstacles to "kick and kill" cure strategies. We hypothesized that releasing cells from TGF-{beta}-driven signaling would promote latency reversal. To test our hypothesis, we compared ex vivo models of HIV-1 latency reactivation with and without TGF-{beta} and a TGF-{beta} type 1 receptor (TGFBR1) inhibitor, galunisertib. We also tested the effect of galunisertib in SIV infected, ART treated macaques by monitoring SIV envelope (env) protein expression via PET/CT using the Cu64-anti gp120 Fab (7D3) probe, along with plasma and tissue viral loads (VL). Exogenous TGF-1{beta} reduced HIV-1 reactivation in U1 and ACH2 latency models. Galunisertib increased HIV-1 latency reversal both in ex vivo models and in PBMC from HIV-1 infected, cART treated aviremic donors. In vivo, oral galunisertib promoted increased SIV env protein total standardized uptake values (SUVtot) in PET/CT images of tissues (gut and lymph nodes) of 5 out of 7 aviremic, long-term ART-treated, SIV-infected, macaques. This increase correlated with an increase in SIV RNA in gut tissue. Two out of 7 animals also exhibited increases in plasma viral load. Higher anti-SIV T cell responses and anti-SIV env antibody titers were detected after galunisertib treatment in most animals. In summary, our data suggest that blocking TGF-{beta} signaling simultaneously increases retroviral reactivation events and enhances anti-SIV immune responses.

immunology↗