Waves of SARS-CoV-2 infection have resulted from the emergence of viral variants with neutralizing antibody resistance mutations. Simultaneously, repeated antigen exposure has generated affinity ...matured B cells, producing broadly neutralizing receptor binding domain (RBD)-specific antibodies with activity against emergent variants. To determine how SARS-CoV-2 might escape these antibodies, we subjected chimeric viruses encoding spike proteins from ancestral, BA.1 or BA.2 variants to selection by 40 broadly neutralizing antibodies. We identify numerous examples of epistasis, whereby in vitro selected and naturally occurring substitutions in RBD epitopes that do not confer antibody resistance in the Wuhan-Hu-1 spike, do so in BA.1 or BA.2 spikes. As few as 2 or 3 of these substitutions in the BA.5 spike, confer resistance to nearly all of the 40 broadly neutralizing antibodies, and substantial resistance to plasma from most individuals. Thus, epistasis facilitates the acquisition of resistance to antibodies that remained effective against early omicron variants.
Hepatitis C virus (HCV) infection affects approximately 58 million people and causes ~300,000 deaths yearly. The only target for HCV neutralizing antibodies is the highly sequence diverse E1E2 ...glycoprotein. Eliciting broadly neutralizing antibodies that recognize conserved cross-neutralizing epitopes is important for an effective HCV vaccine. However, most recombinant HCV glycoprotein vaccines, which usually include only E2, induce only weak neutralizing antibody responses. Here, we describe recombinant soluble E1E2 immunogens that were generated by permutation of the E1 and E2 subunits. We displayed the E2E1 immunogens on two-component nanoparticles and these nanoparticles induce significantly more potent neutralizing antibody responses than E2. Next, we generated mosaic nanoparticles co-displaying six different E2E1 immunogens. These mosaic E2E1 nanoparticles elicit significantly improved neutralization compared to monovalent E2E1 nanoparticles. These results provide a roadmap for the generation of an HCV vaccine that induces potent and broad neutralization.
HIV-1 broadly neutralizing antibodies (bnAbs) are difficult to induce with vaccines but are generated in ∼50% of HIV-1-infected individuals. Understanding the molecular mechanisms of host control of ...bnAb induction is critical to vaccine design. Here, we performed a transcriptome analysis of blood mononuclear cells from 47 HIV-1-infected individuals who made bnAbs and 46 HIV-1-infected individuals who did not and identified in bnAb individuals upregulation of RAB11FIP5, encoding a Rab effector protein associated with recycling endosomes. Natural killer (NK) cells had the highest differential expression of RAB11FIP5, which was associated with greater dysregulation of NK cell subsets in bnAb subjects. NK cells from bnAb individuals had a more adaptive/dysfunctional phenotype and exhibited impaired degranulation and cytokine production that correlated with RAB11FIP5 transcript levels. Moreover, RAB11FIP5 overexpression modulated the function of NK cells. These data suggest that NK cells and Rab11 recycling endosomal transport are involved in regulation of HIV-1 bnAb development.
Display omitted
•Elevated RAB11FIP5 expression is associated with HIV-1 bnAb induction•NK cells show the highest differential RAB11FIP5 expression•NK cell subsets are more dysregulated in individuals developing bnAbs•Rab11Fip5 regulates NK cell function
Generation of broadly neutralizing antibodies against HIV-1 in humans is linked to the expression of a specific recycling endosome-associated effector in natural killer cells.
Bezlotoxumab was significantly associated with reduced odds of recurrent Clostridioides difficile infection and all-cause readmission at 90 days on both unadjusted and adjusted analysis. Bezlotoxumab ...was well tolerated with low frequency of adverse events observed.
Abstract
Background
Bezlotoxumab (BEZ) is a monoclonal antibody used to prevent recurrent Clostridioides difficile infection (rCDI). This study investigates BEZ effectiveness in relation to rCDI and patient-specific risk factors in a real-world setting.
Methods
A matched, retrospective cohort study was conducted from 2015 to 2019 to compare BEZ to historical standard of care (SoC) therapy with vancomycin or fidaxomicin. The primary outcome was incidence of 90-day rCDI. Secondary outcomes were incidence of all-cause hospital readmission and all-cause mortality at 90 days, infusion-related reactions, and incidence of heart failure exacerbation. Baseline confounding was addressed using inverse probability of treatment weighting (IPTW).
Results
Overall, 107 participants were included (54 BEZ and 53 SoC). Mean number of prior CDI episodes was 2, median number of risk factors for rCDI was 4, and 28% of participants had severe CDI. Incidence of 90-day rCDI was 11% BEZ vs 43% SoC (P = < .001) and 90-day all-cause readmission was 40% BEZ vs 64% SoC (P = .011). In IPTW-adjusted analyses, BEZ was associated with significantly reduced odds of rCDI (odds ratio OR, 0.14 95% confidence interval {CI}: .05–.41) and all-cause readmission (OR, 0.36 95% CI: .16–.81). No safety signals were detected with BEZ use.
Conclusions
BEZ is effective for the prevention of rCDI and reduction in all-cause hospital readmission for patients at high risk for recurrence, supporting current guideline recommendations.
Background : The adeno-associated virus (AAV) vector is a promising vector for ocular gene therapy. Surgical internal limiting membrane peeling before AAV vector administration is useful for ...efficient retinal transduction. However, no report has investigated localization of AAV vectors after administration into a post-vitrectomy eye. This study investigated the effects of vitrectomy surgery on intravitreal-injected AAV vector-mediated gene expression in the anterior segment and examined the presence of neutralizing antibodies (NAbs) in serum before and after AAV vector administration. Methods : Of six eyes from three female cynomolgus monkeys, four were vitrectomized (Group VIT) and two were non-vitrectomized (Group IV). All eyes were injected with 50 μL of triple-mutated self-complementary AAV2 vector (1.9 x 1013 v.g./mL) encoding green fluorescent protein (GFP). NAbs in the serum were examined before administration and at 2 and 6 weeks after administration. GFP expression was analyzed at 19 weeks after administration. Results : Immunohistological analysis showed no GFP expression in the trabecular meshwork in any eye. The GFP genome copy in two slices of the anterior segment was 2.417 (vector genome copies/diploid genome) in Group VIT and 4.316 (vector genome copies/diploid genome) in group IV. The NAb titer was 1:15.9 (geometric mean) before administration, 1:310.7 at 2 weeks after administration, and 1:669.4 at 6 weeks after administration. Conclusion : Previous vitrectomy surgery did not affect gene expression in the anterior segment after intravitreal injection of AAV vectors.
The recently emerged Omicron subvariants XBB and BQ.1.1 have presented striking immune evasion against most monoclonal neutralizing antibodies and convalescent plasma. Therefore, it is essential to ...develop broad-spectrum COVID-19 vaccines to combat current and future emerging variants. Here, we found that the human IgG Fc-conjugated RBD of the original SARS-CoV-2 strain (WA1) plus a novel STING agonist-based adjuvant CF501 (CF501/RBD-Fc) could induce highly potent and durable broad-neutralizing antibody (bnAb) responses against Omicron subvariants, including BQ.1.1 and XBB in rhesus macaques with NT50s ranging from 2,118 to 61,742 after three doses. A decline of 0.9- to 4.7-fold was observed in the neutralization activity of sera in the CF501/RBD-Fc group against BA.2.2, BA.2.9, BA.5, BA.2.75, and BF.7 relative to D614G after three doses, while a significant decline of NT50 against BQ.1.1 (26.9-fold) and XBB (22.5-fold) relative to D614G. However, the bnAbs were still effective in neutralizing BQ.1.1 and XBB infection. These results suggest that the conservative but nondominant epitopes in RBD could be stimulated by CF501 to generate bnAbs, providing a proof-of-concept for using "nonchangeable against changeables" strategy to develop pan-sarbecovirus vaccines against sarbecoviruses, including SARS-CoV-2 and its variants.
•Pre-existing cross-reactive antibodies do not correlate with COVID-19 severity.•Pre-existing cross-reactive antibodies are related to lower COVID-19 mortality.•Cross-reactive non-neutralizing ...antibodies do not drive ADE in SARS-CoV2 infection.
Antibody-dependent enhancement (ADE) is a complex phenomenon mediated by antibodies, frequently pre-existing non-neutralizing or sub-neutralizing antibodies. In the course of infectious diseases, ADE may be responsible for worsening the clinical course of the disease by increasing the virulence of pathogens (ADE of infection) or enhancing disease severity (ADE of disease). Here we reviewed the mechanisms thought to be behind the ADE phenomenon and its potential relationship with COVID-19 severity. Since the early COVID-19 epidemics, ADE has been mentioned as a possible mechanism involved in severe COVID-19 disease and, later, as a potential risk in the case of infection after vaccination. However, current data do not support its role in disease severity, both after infection and reinfection.
A goal of HIV vaccine development is to elicit antibodies with neutralizing breadth. Broadly neutralizing antibodies (bNAbs) to HIV often have unusual sequences with long heavy-chain ...complementarity-determining region loops, high somatic mutation rates and polyreactivity. A subset of HIV-infected individuals develops such antibodies, but it is unclear whether this reflects systematic differences in their antibody repertoires or is a consequence of rare stochastic events involving individual clones. We sequenced antibody heavy-chain repertoires in a large cohort of HIV-infected individuals with bNAb responses or no neutralization breadth and uninfected controls, identifying consistent features of bNAb repertoires, encompassing thousands of B cell clones per individual, with correlated T cell phenotypes. These repertoire features were not observed during chronic cytomegalovirus infection in an independent cohort. Our data indicate that the development of numerous B cell lineages with antibody features associated with autoreactivity may be a key aspect in the development of HIV neutralizing antibody breadth.
Passively administered broadly neutralizing antibodies (bNAbs) targeting the HIV-1 envelope glycoprotein (Env) have been shown to protect non-human primates (NHPs) against chimeric simian-human ...immunodeficiency virus (SHIV) infection. With data from multiple non-human primate SHIV challenge studies that used single bNAbs, we conducted a meta-analysis to examine the relationship between predicted serum 50% neutralization titer (ID50) against the challenge virus and infection outcome. In a logistic model that adjusts for bNAb epitopes and challenge viruses, serum ID50 had a highly significant effect on infection risk (p < 0.001). The estimated ID50 to achieve 50%, 75%, and 95% protection was 91 (95% confidence interval CI: 55, 153), 219 (117, 410), and 685 (319, 1471), respectively. This analysis indicates that serum neutralizing titer against the relevant virus is a key parameter of protection and that protection from acquisition by a single bNAb might require substantial levels of neutralization at the time of exposure.
Display omitted
•Meta-analysis of NHP studies administering a single bNAb before SHIV challenge•Serum neutralizing titers correlate strongly with protection against SHIV infection•ID50, ID80, and IIP all predict protection, with ID50 and ID80 stronger predictors•Substantial levels of neutralization might be needed for protection by a single bNAb
Pegu et al. present a meta-analysis of nonhuman primate studies that administered a single broadly neutralizing antibody (bNAb) before SHIV challenge. Serum neutralizing titer against the challenge virus strongly correlates with protection. Further, protection mediated by a single bNAb might require substantial levels of neutralization at the time of exposure.
Immunotherapy using broadly neutralizing antibodies (bNAbs) endowed with Fc-mediated effector functions has been shown to be critical for protecting or controlling viral replication in animal models. ...In human, the RV144 Thai trial was the first trial to demonstrate a significant protection against HIV infection following vaccination. Analysis of the correlates of immune protection in this trial identified an association between the presence of antibody-dependent cellular cytotoxicity (ADCC) mediated by immunoglobulin G (IgG) antibodies (Abs) to HIV envelope (Env) V1/V2 loop structures and protection from infection, provided IgA Abs with competing specificity were not present. Systems serology analyses implicated a broader range of Ab-dependent functions in protection from HIV infection, including but not limited to ADCC and Ab-dependent NK cell activation (ADNKA) for secretion of IFN-γ and CCL4 and expression of the degranulation marker CD107a. The existence of such correlations in the absence of bNAbs in the RV144 trial suggest that NK cells could be instrumental in protecting against HIV infection by limiting viral spread through Fc-mediated functions such as ADCC and the production of antiviral cytokines/chemokines. Beside the engagement of FcγRIIIa or CD16 by the Fc portion of anti-Env IgG1 and IgG3 Abs, natural killer (NK) cells are also able to directly kill infected cells and produce cytokines/chemokines in an Ab-independent manner. Responsiveness of NK cells depends on the integration of activating and inhibitory signals through NK receptors, which is determined by a process during their development known as education. NK cell education requires the engagement of inhibitory NK receptors by their human leukocyte antigen ligands to establish tolerance to self while allowing NK cells to respond to self cells altered by virus infection, transformation, stress, and to allogeneic cells. Here, we review recent findings regarding the impact of inter-individual differences in NK cell education on Ab-dependent functions such as ADCC and ADNKA, including what is known about the HIV Env epitope specificity of ADCC competent Abs and the conformation of HIV Env on target cells used for ADCC assays.
PDF
