Prime-boost immunization of rabbits with HIV-1 gp120 elicits potent neutralization activity against a primary viral isolate

<div><p>Development of a vaccine for HIV-1 requires a detailed understanding of the neutralizing antibody responses that can be experimentally elicited to difficult-to-neutralize primary isolates. Rabbits were immunized with the gp120 subunit of HIV-1 JR-CSF envelope (Env) using a DNA-prime protein-boost regimen. We analyzed five sera that showed potent autologous neutralizing activity (IC50s at ∼10³ to 10⁴ serum dilution) against pseudoviruses containing Env from the primary isolate JR-CSF but not from the related isolate JR-FL. Pseudoviruses were created by exchanging each variable and constant domain of JR-CSF gp120 with that of JR-FL or with mutations in putative N-glycosylation sites. The sera contained different neutralizing activities dependent on C3 and V5, C3 and V4, or V4 regions located on the glycan-rich outer domain of gp120. All sera showed enhanced neutralizing activity toward an Env variant that lacked a glycosylation site in V4. The JR-CSF gp120 epitopes recognized by the sera are generally distinct from those of several well characterized mAbs (targeting conserved sites on Env) or other type-specific responses (targeting V1, V2, or V3 variable regions). The activity of one serum requires specific glycans that are also important for 2G12 neutralization and this serum blocked the binding of 2G12 to gp120. Our findings show that different fine specificities can achieve potent neutralization of HIV-1, yet this strong activity does not result in improved breadth.</p> </div

Exploring and exploiting the therapeutic potential of glycoconjugates.

Carbohydrates, either bound to proteins or in lipids, play essential roles as communication molecules in many intercellular and intracellular processes. In particular, carbohydrates are important mediators of cell-cell recognition events and have been implicated in related processes such as cell signaling regulation, cellular differentiation and immune response. This diverse utility has long suggested the power of carbohydrates in therapeutic approaches. This Concepts article highlights the recent potential uses of glycoconjugates as therapeutics, with particular reference to glycopeptides, glycoproteins, glycodendrimers, and glycoarrays

Direct deprotected glycosyl-asparagine ligation

A simple and efficient synthesis of N-linked glycoamino acids and glycopeptides from deprotected sugars using the Staudinger reactio

Envelope glycans of immunodeficiency virions are almost entirely oligomannose antigens

The envelope spike of HIV is one of the most highly N-glycosylated structures found in nature. However, despite extensive research revealing essential functional roles in infection and immune evasion, the chemical structures of the glycans on the native viral envelope glycoprotein gp120—as opposed to recombinantly generated gp120—have not been described. Here, we report on the identity of the N-linked glycans from primary isolates of HIV-1 (clades A, B, and C) and from the simian immunodeficiency virus. MS analysis reveals a remarkably simple and highly conserved virus-specific glycan profile almost entirely devoid of medial Golgi-mediated processing. In stark contrast to recombinant gp120, which shows extensive exposure to cellular glycosylation enzymes (>70% complex type glycans), the native envelope shows barely detectable processing beyond the biosynthetic intermediate Man(5)GlcNAc(2) (<2% complex type glycans). This oligomannose (Man(5–9)GlcNAc(2)) profile is conserved across primary isolates and geographically divergent clades but is not reflected in the current generation of gp120 antigens used for vaccine trials. In the context of vaccine design, we also note that Manα1→2Man-terminating glycans (Man(6–9)GlcNAc(2)) of the type recognized by the broadly neutralizing anti-HIV antibody 2G12 are 3-fold more abundant on the native envelope than on the recombinant monomer and are also found on isolates not neutralized by 2G12. The Manα1→2Man residues of gp120 therefore provide a vaccine target that is physically larger and antigenically more conserved than the 2G12 epitope itself. This study revises and extends our understanding of the glycan shield of HIV with implications for AIDS vaccine design

B cells from knock-in mice expressing broadly neutralizing HIV antibody b12 carry an innocuous B cell receptor responsive to HIV vaccine candidates

Broadly neutralizing antibodies (bNAbs) against HIV protect from infection, but their routine elicitation by vaccination has not been achieved. To generate small animal models to test vaccine candidates, we have generated targeted transgenic (“knock-in”) mice expressing, in the physiological immunoglobulin heavy (H) and light (L) chain loci, two well-studied bNAbs: 4E10, which interacts with the membrane proximal external region of gp41, and b12, which binds to the CD4 binding site on gp120. 4E10HL mice are described in the accompanying paper. Here, we describe b12 mice. B cells in b12HL mice, in contrast to the case in 4E10 mice, were abundant and essentially monoclonal, retaining the b12 specificity. In cell culture, b12HL B cells responded avidly to HIV Env gp140 trimers and to BCR ligands, but only weakly to HIV pseudovirions. Upon transfer to wild type recipients, b12HL B cells responded robustly to vaccination with gp140 trimers. Vaccinated b12H mice, while generating abundant precursors and antibodies with affinity for Env, were unable to rapidly generate neutralizing antibodies, highlighting the importance of developing antigen forms that better focus responses to neutralizing epitopes. b12HL and b12H mice should be useful in optimizing HIV vaccine candidates to elicit a neutralizing response while avoiding non-protective specificities

Anti-HIV B cell lines as candidate vaccine biosensors

Challenge studies following passive immunization with neutralizing Abs suggest that an HIV vaccine could be efficacious were it able to elicit broadly neutralizing Abs bNAbs).To betterunderstand the requirementsfor activation ofB cells producing bNAbs,we generated cell lines expressing bNAbs or their germline-revertedversions gl-bNAbs)as BCRs. We thentestedthe abilitiesof the bNAb-expressing cells to recognize HIV pseudovirions and vaccine candidate proteins by binding and activation assays. The results suggest that HIV envelope (Env) Ag-expressing, infection-competent virions are poorly recognized by high-affinity bNAb-expressing cells, as measured by the inability of Ags to induce rapid increases in intracellular calcium levels. Other Ag forms appear to be highly stimulatory, in particular, soluble gp140 trimers and a multimerized, scaffolded epitope protein. Virions failed to efficiently activate bNAb-expressing B cells owing to delayed or inefficient BCR recognition, most likely caused by the low density of Env spikes. Importantly, B cells carrying gl-bNAb BCRs were not stimulated by any of the tested vaccine candidates. These data provide insight into why many HIV immunogens, as well as natural HIV infections, fail to rapidly stimulate bNAb responses and suggest that bNAb-expressing cell lines might be useful tools in evaluation of vaccine Ags for infectious diseases. Because soluble Env trimers or multimerized scaffolded epitopes are best at activating B cell-expressing bNAbs, these antigenic forms should be considered as preferred vaccine components, although they should be modified to better target naive gl-bNAb B cells

Long COVID burden and risk factors in 10 UK longitudinal studies and electronic health records

The frequency of, and risk factors for, long COVID are unclear among community-based individuals with a history of COVID-19. To elucidate the burden and possible causes of long COVID in the community, we coordinated analyses of survey data from 6907 individuals with self-reported COVID-19 from 10 UK longitudinal study (LS) samples and 1.1 million individuals with COVID-19 diagnostic codes in electronic healthcare records (EHR) collected by spring 2021. Proportions of presumed COVID-19 cases in LS reporting any symptoms for 12+ weeks ranged from 7.8% and 17% (with 1.2 to 4.8% reporting debilitating symptoms). Increasing age, female sex, white ethnicity, poor pre-pandemic general and mental health, overweight / obesity, and asthma were associated with prolonged symptoms in both LS and EHR data, but findings for other factors, such as cardio-metabolic parameters, were inconclusive