Selection and T-cell antigenicity of synthetic long peptides derived from SARS-CoV-2.

The pandemic caused by SARS-CoV-2 has led to the successful development of effective vaccines however the prospect of variants of SARS-CoV-2 and future coronavirus outbreaks necessitates the investigation of other vaccine strategies capable of broadening vaccine mediated T-cell responses and potentially providing cross-immunity. In this study the SARS-CoV-2 proteome was assessed for clusters of immunogenic epitopes restricted to diverse human leucocyte antigen. These regions were then assessed for their conservation amongst other coronaviruses representative of different alpha and beta coronavirus genera. Sixteen highly conserved peptides containing numerous HLA class I and II restricted epitopes were synthesized from these regions and assessed in vitro for their antigenicity against T-cells from individuals with previous SARS-CoV-2 infection. Monocyte derived dendritic cells were generated from these peripheral blood mononuclear cells (PBMC), loaded with SARS-CoV-2 peptides, and used to induce autologous CD4+ and CD8+ T cell activation. The SARS-CoV-2 peptides demonstrated antigenicity against the T-cells from individuals with previous SARS-CoV-2 infection indicating that this approach holds promise as a method to activate anti-SAR-CoV-2 T-cell responses from conserved regions of the virus which are not included in vaccines utilising the Spike protein.

Directing T-Cell Immune Responses for Cancer Vaccination and Immunotherapy.

Cancer vaccination and immunotherapy revolutionised the treatment of cancer, a result of decades of research into the immune system in health and disease. However, despite recent breakthroughs in treating otherwise terminal cancer, only a minority of patients respond to cancer immunotherapy and some cancers are largely refractive to immunotherapy treatment. This is due to numerous issues intrinsic to the tumour, its microenvironment, or the immune system. CD4+ and CD8+ αß T-cells emerged as the primary effector cells of the anti-tumour immune response but their function in cancer patients is often compromised. This review details the mechanisms by which T-cell responses are hindered in the setting of cancer and refractive to immunotherapy, and details many of the approaches under investigation to direct T-cell function and improve the efficacy of cancer vaccination and immunotherapy.

Correlation of Antibody Responses to a Peptide Antigen gp120-C5501-512/gp41732-744 with HIV Disease Progression.

Antibodies to the carboxy-terminal constant (C5) region 5 of the HIV-1 envelope glycoprotein gp120 have previously been associated with slow disease progression. This is one of the regions on gp120 that interact with the transmembrane glycoprotein, gp41, anchoring it to the viral and infected cell membrane. This study analyzed humoral responses to a novel heterodimeric peptide construct comprising the C5501-512 region and a compatible region on gp41732-744. Antibody levels to C5501-512/gp41732-744 were associated with slow disease progression in a treatment naive historical longitudinal cohort from Norway (n = 32; p = .00001). Elevated anti-C5501-512/gp41732-744 antibody levels correlated with moderate viral load (VL) (50-10,000 copies/ml) in a cohort, including natural viral suppressors (NVS) in the Unites States (n = 58; p = .002). Analysis of HIV-positive sera from treatment naive patients in Estonia (n = 300) showed an inverse correlation between anti-C5501-512/gp41732-744 antibodies and VL when comparing VL 2,000-10,000 copies/ml with VL >10,000 (p = .050). Further mapping using peptide inhibition of antibody binding revealed that responses to the C5501-506 subdomain correlated with preserved CD4 counts (n = 55; p = .0012) irrespective of VL in this cohort. The C5 region encompassing C5501-506 shows sequence similarity to the shared epitope (SE) of certain HLA-DR associated with immune dysfunction. Partial antigenic cross-reactivity between SE and C5 is indicated by partial inhibition of NVS antibody binding using SE 15-mer peptide (median 65% inhibition), the C5501-506 6-mer peptide (79% inhibition), and binding of rheumatoid arthritis patient sera to both SE and C5 peptide sequences. The potential influence of these observations on HIV-1 pathogenesis remains to be determined.

TLR2-mediated leukocyte trafficking to the developing brain.

Inflammation is a significant risk factor for brain injury in the perinatal period. In this study, we tested the hypothesis that activation of peripheral TLR induces inflammation in the brain, including leukocyte trafficking. Postnatal day 8 mice were injected intraperitoneally with a TLR1/2 (Pam3CSK4, P3C), TLR2/6 (FSL-1) or TLR4 (LPS) agonist, and the peripheral and central cytokine and chemokine response was determined. Infiltration of immune cells to the CSF and brain was examined by flow cytometry, and brain permeability was investigated by radioactively labeled sucrose. We report that peripheral administration of P3C to neonatal mice induces significant influx of leukocytes, mainly neutrophils and monocytes, to the CSF and brain. Infiltration of leukocytes was TLR2 and MyD88 dependent, but largely absent after administration of LPS or FSL-1. PC3-mediated accumulation of immune cells in the brain was observed in classic CNS-leukocyte gateways, the subarachnoid space and choroid plexus, as well as in the median eminence. Although P3C and LPS induced a similar degree of peripheral inflammatory responses, P3C provoked a distinct brain chemokine response and increased permeability, in particular, of the blood-CSF barrier. Collectively, our results do not support the hypothesis that TLR activation, in general, induces immune cell infiltration to the brain. Instead, we have discovered a specific TLR2-mediated mechanism of CNS inflammation and leukocyte invasion into the neonatal brain. This interaction between peripheral and central immune responses is to a large extent via the blood-CSF barrier.

Developments in HIV-1 immunotherapy and therapeutic vaccination.

Since the human immunodeficiency virus (HIV-1) pandemic began, few prophylactic vaccines have reached phase III trials. Only one has shown partial efficacy in preventing HIV-1 infection. The introduction of antiretroviral therapy (ART) has had considerable success in controlling infection and reducing transmission but in so doing has changed the nature of HIV-1 infection for those with access to ART. Access, compliance, and toxicity alongside the emergence of serious non-AIDS morbidity and the sometimes poor immune reconstitution in ART-treated patients have emphasized the need for additional therapies. Such therapy is intended to contribute to control of HIV-1 infection, permit structured treatment interruptions, or even establish a functional cure of permanently suppressed and controlled infection. Both immunotherapy and therapeutic vaccination have the potential to reach these goals. In this review, the latest developments in immunotherapy and therapeutic vaccination are discussed.