Explore the vast range of titles available.

A total of 33 participants who received both doses of the Moderna mRNA-1273 vaccine against SARS-CoV-2 had blood drawn over a period of 6 months after vaccination. SARS-CoV-2 neutralizing activity was maintained in all the patients through the entire period of follow-up. A half-life of 202 days was determined for the live-virus neutralization activity.

The present vaccine against influenza virus has the inevitable risk of antigenic discordance between the vaccine and the circulating strains, which diminishes vaccine efficacy. This necessitates new approaches that provide broader protection against influenza. Here we designed a vaccine using the hypervariable receptor-binding domain (RBD) of viral hemagglutinin displayed on a nanoparticle (np) able to elicit antibody responses that neutralize H1N1 influenza viruses spanning over 90 years. Co-display of RBDs from multiple strains across time, so that the adjacent RBDs are heterotypic, provides an avidity advantage to cross-reactive B cells. Immunization with the mosaic RBD–np elicited broader antibody responses than those induced by an admixture of nanoparticles encompassing the same set of RBDs as separate homotypic arrays. Furthermore, we identified a broadly neutralizing monoclonal antibody in a mouse immunized with mosaic RBD–np. The mosaic antigen array signifies a unique approach that subverts monotypic immunodominance and allows otherwise subdominant cross-reactive B cell responses to emerge. Antigenic variation of influenza A viruses necessitates the annual reformulation of vaccines. Kanekiyo et al. develop a mosaic nanoparticle vaccine against influenza virus that is able to elicit neutralizing antibodies that span nearly 100 years of variation of influenza A virus.

Ebola virus disease in humans is highly lethal, with case fatality rates ranging from 25 to 90%. There is no licensed treatment or vaccine against the virus, underscoring the need for efficacious countermeasures. We ascertained that a human survivor of the 1995 Kikwit Ebola virus disease outbreak maintained circulating antibodies against the Ebola virus surface glycoprotein for more than a decade after infection. From this survivor we isolated monoclonal antibodies (mAbs) that neutralize recent and previous outbreak variants of Ebola virus and mediate antibody-dependent cell-mediated cytotoxicity in vitro. Strikingly, monotherapy with mAb114 protected macaques when given as late as 5 days after challenge. Treatment with a single human mAb suggests that a simplified therapeutic strategy for human Ebola infection may be possible.

Broadly neutralizing antibodies (bnAbs) have been developed as potential countermeasures for seasonal and pandemic influenza. Deep characterization of these bnAbs and polyclonal sera provides pivotal understanding for influenza immunity and informs effective vaccine design. However, conventional virus neutralization assays require high-containment laboratories and are difficult to standardize and roboticize. Here, we build a panel of engineered influenza viruses carrying a reporter gene to replace an essential viral gene, and develop an assay using the panel for in-depth profiling of neutralizing antibodies. Replication of these viruses is restricted to cells expressing the missing viral gene, allowing it to be manipulated in a biosafety level 2 environment. We generate the neutralization profile of 24 bnAbs using a 55-virus panel encompassing the near-complete diversity of human H1N1 and H3N2, as well as pandemic subtype viruses. Our system offers in-depth profiling of influenza immunity, including the antibodies against the hemagglutinin stem, a major target of universal influenza vaccines. Understanding the human antibody response to influenza A virus strains is important for vaccine development. Here, Creanga et al. generate a panel of 55 replication-deficient reporter viruses representing diversity of human H1N1 and H3N2, and pandemic subtypes and characterize the neutralization profile of 24 antibodies and polyclonal sera.

Ebola virus causes hemorrhagic fever with a high case fatality rate for which there is no approved therapy. Two human monoclonal antibodies, mAb100 and mAb114, in combination, protect nonhuman primates against all signs of Ebola virus disease, including viremia. Here, we demonstrate that mAb100 recognizes the base of the Ebola virus glycoprotein (GP) trimer, occludes access to the cathepsin-cleavage loop, and prevents the proteolytic cleavage of GP that is required for virus entry. We show that mAb114 interacts with the glycan cap and inner chalice of GP, remains associated after proteolytic removal of the glycan cap, and inhibits binding of cleaved GP to its receptor. These results define the basis of neutralization for two protective antibodies and may facilitate development of therapies and vaccines.

VRC01 is an HIV-1 CD4 binding site broadly neutralizing antibody (bnAb) that is active against a broad range of HIV-1 primary isolates in vitro and protects against simian-human immunodeficiency virus (SHIV) when delivered parenterally to nonhuman primates. It has been shown to be safe and well tolerated after short-term administration in humans; however, its clinical and functional activity after longer-term administration has not been previously assessed. HIV Vaccine Trials Network (HVTN) 104 was designed to evaluate the safety and tolerability of multiple doses of VRC01 administered either subcutaneously or by intravenous (IV) infusion and to assess the pharmacokinetics and in vitro immunologic activity of the different dosing regimens. Additionally, this study aimed to assess the effect that the human body has on the functional activities of VRC01 as measured by several in vitro assays. Eighty-eight healthy, HIV-uninfected, low-risk participants were enrolled in 6 United States clinical research sites affiliated with the HVTN between September 9, 2014, and July 15, 2015. The median age of enrollees was 27 years (range, 18-50); 52% were White (non-Hispanic), 25% identified as Black (non-Hispanic), 11% were Hispanic, and 11% were non-Hispanic people of diverse origins. Participants were randomized to receive the following: a 40 mg/kg IV VRC01 loading dose followed by five 20 mg/kg IV VRC01 doses every 4 weeks (treatment group 1 [T1], n = 20); eleven 5 mg/kg subcutaneous (SC) VRC01 (treatment group 3 [T3], n = 20); placebo (placebo group 3 [P3], n = 4) doses every 2 weeks; or three 40 mg/kg IV VRC01 doses every 8 weeks (treatment group 2 [T2], n = 20). Treatment groups T4 and T5 (n = 12 each) received three 10 or 30 mg/kg IV VRC01 doses every 8 weeks, respectively. Participants were followed for 32 weeks after their first VRC01 administration and received a total of 249 IV infusions and 208 SC injections, with no serious adverse events, dose-limiting toxicities, nor evidence for anti-VRC01 antibodies observed. Serum VRC01 levels were detected through 12 weeks after final administration in all participants who received all scheduled doses. Mean peak serum VRC01 levels of 1,177 μg/ml (95% CI: 1,033, 1,340) and 420 μg/ml (95% CI: 356, 494) were achieved 1 hour after the IV infusion series of 30 mg/kg and 10 mg/kg doses, respectively. Mean trough levels at week 24 in the IV infusion series of 30 mg/kg and 10 mg/kg doses, respectively, were 16 μg/ml (95% CI: 10, 27) and 6 μg/ml (95% CI: 5, 9) levels, which neutralize a majority of circulating strains in vitro (50% inhibitory concentration [IC50] > 5 μg/ml). Post-infusion/injection serum VRC01 retained expected functional activity (virus neutralization, antibody-dependent cellular cytotoxicity, phagocytosis, and virion capture). The limitations of this study include the relatively small sample size of each VRC01 administration regimen and missing data from participants who were unable to complete all study visits. VRC01 administered as either an IV infusion (10-40 mg/kg) given monthly or bimonthly, or as an SC injection (5 mg/kg) every 2 weeks, was found to be safe and well tolerated. In addition to maintaining drug concentrations consistent with neutralization of the majority of tested HIV strains, VRC01 concentrations from participants' sera were found to avidly capture HIV virions and to mediate antibody-dependent cellular phagocytosis, suggesting a range of anti-HIV immunological activities, warranting further clinical trials. Clinical Trials Registration: NCT02165267.

The Antibody Mediated Prevention (AMP) trials (NCT02716675 and NCT02568215) demonstrated that passive administration of the broadly neutralizing monoclonal antibody VRC01 could prevent some HIV-1 acquisition events. Here, we use mathematical modeling in a post hoc analysis to demonstrate that VRC01 influenced viral loads in AMP participants who acquired HIV. Instantaneous inhibitory potential (IIP), which integrates VRC01 serum concentration and VRC01 sensitivity of acquired viruses in terms of both IC50 and IC80, follows a dose-response relationship with first positive viral load ( p  = 0.03), which is particularly strong above a threshold of IIP = 1.6 ( r  = -0.6, p  = 2e-4). Mathematical modeling reveals that VRC01 activity predicted from in vitro IC80s and serum VRC01 concentrations overestimates in vivo neutralization by 600-fold (95% CI: 300–1200). The trained model projects that even if future therapeutic HIV trials of combination monoclonal antibodies do not always prevent acquisition, reductions in viremia and reservoir size could be expected. Antibody Mediated Prevention (AMP) trials showed that the broadly neutralizing antibody VRC01 could prevent some HIV-1 acquisitions. Here the authors use VRC01 levels and the sensitivity of each acquired HIV virus to predict viral loads in the AMP studies and show that VRC01 influenced viral loads, though potency was lower in vivo than expected.

Epstein-Barr virus (EBV), the causative agent of mononucleosis, is linked to over 140,000 annual cancer-related deaths globally and increases the risk of multiple sclerosis by up to 32-fold. As a herpesvirus, EBV establishes lifelong infection, and over 90% of U.S. adults are EBV-seropositive. Despite its significant disease burden, no approved EBV vaccines or therapeutics exist. Among EBV envelope glycoproteins, the fusion protein (gB) is strictly required for epithelial and B cell infection. Here, using a combination of AlphaFold-guided modeling, rational design, and ThermoMPNN-informed optimization, we engineer a stabilized prefusion gB variant, C3-GT. This construct incorporates two inter-protomeric disulfide bonds and three cavity-filling substitutions, resulting in a melting temperature of 54 °C. Cryo-EM analysis of this construct reveals the prefusion structure of EBV gB, providing insights into the structural transitions required to adopt the postfusion conformation. Murine immunizations and depletion studies with human sera suggest a trend toward improved functional immunogenicity of C3-GT compared to postfusion gB. Collectively, these studies define engineering principles to stabilize class III fusion proteins, provide reagents to interrogate the human antibody response to EBV gB, and lay a foundation for further studies to develop EBV gB-based vaccine candidates. Epstein–Barr virus (EBV) is a widespread herpesvirus linked to cancer and autoimmune disease. The authors in this work design and characterize a stabilized prefusion form of gB, an essential viral fusion protein, advancing EBV vaccine and therapeutic development.

Chikungunya virus (CHIKV) is an alphavirus that has emerged as a global health burden. There are 3 CHIKV genotypes: Asian, West African, and Eastern/Central/South African. No licensed CHIKV vaccine is available, and whether the antibody response elicited by one genotype can neutralize heterologous genotypes is unclear. We assessed neutralizing antibody (NAb) responses of volunteers in a phase 1 study of a CHIKV vaccine against 9 viral strains representing all 3 genotypes. Minimal differences in vaccine-elicited NAb responses were observed among genotypes, suggesting that vaccination with a single CHIKV strain can elicit cross-protective NAbs against all 3 genotypes.

Ebola virus and Marburg virus cause serious disease outbreaks with high case fatality rates. We aimed to assess the safety and immunogenicity of two investigational DNA vaccines, one (EBO vaccine) encoding Ebola virus Zaire and Sudan glycoproteins and one (MAR) encoding Marburg virus glycoprotein. RV 247 was a phase 1b, double-blinded, randomised, placebo-controlled clinical trial in Kampala, Uganda to examine the safety and immunogenicity of the EBO and MAR vaccines given individually and concomitantly. Healthy adult volunteers aged 18–50 years were randomly assigned (5:1) to receive three injections of vaccine or placebo at weeks 0, 4, and 8, with vaccine allocations divided equally between three active vaccine groups: EBO vaccine only, MAR vaccine only, and both vaccines. The primary study objective was to investigate the safety and tolerability of the vaccines, as assessed by local and systemic reactogenicity and adverse events. We also assessed immunogenicity on the basis of antibody responses (ELISA) and T-cell responses (ELISpot and intracellular cytokine staining assays) 4 weeks after the third injection. Participants and investigators were masked to group assignment. Analysis was based on the intention-to-treat principle. This trial is registered at ClinicalTrials.gov, number NCT00997607. 108 participants were enrolled into the study between Nov 2, 2009, and April 15, 2010. All 108 participants received at least one study injection (including 100 who completed the injection schedule) and were included in safety and tolerability analyses; 107 for whom data were available were included in the immunogenicity analyses. Study injections were well tolerated, with no significant differences in local or systemic reactions between groups. The vaccines elicited antibody and T-cell responses specific to the glycoproteins received and we detected no differences between the separate and concomitant use of the two vaccines. 17 of 30 (57%, 95% CI 37–75) participants in the EBO vaccine group had an antibody response to the Ebola Zaire glycoprotein, as did 14 of 30 (47%, 28–66) in the group that received both vaccines. 15 of 30 (50%, 31–69) participants in the EBO vaccine group had an antibody response to the Ebola Sudan glycoprotein, as did 15 of 30 (50%, 31–69) in the group that received both vaccines. Nine of 29 (31%, 15–51) participants in the MAR vaccine groups had an antibody response to the Marburg glycoprotein, as did seven of 30 (23%, 10–42) in the group that received both vaccines. 19 of 30 (63%, 44–80) participants in the EBO vaccine group had a T-cell response to the Ebola Zaire glycoprotein, as did 10 of 30 (33%, 17–53) in the group that received both vaccines. 13 of 30 (43%, 25–63) participants in the EBO vaccine group had a T-cell response to the Ebola Sudan glycoprotein, as did 10 of 30 (33%, 17–53) in the group that received both vaccines. 15 of 29 (52%, 33–71) participants in the MAR vaccine group had a T-cell response to the Marburg glycoprotein, as did 13 of 30 (43%, 25–63) in the group that received both vaccines. This study is the first Ebola or Marburg vaccine trial done in Africa, and the results show that, given separately or together, both vaccines were well tolerated and elicited antigen-specific humoral and cellular immune responses. These findings have contributed to the accelerated development of more potent Ebola virus vaccines that encode the same wild-type glycoprotein antigens as the EBO vaccine, which are being assessed during the 2014 Ebola virus disease outbreak in west Africa. US Department of Defense Infectious Disease Clinical Research Program and US National Institutes of Health Intramural Research Program.