scholarly journals Boosting subdominant neutralizing antibody responses with a computationally designed epitope-focused immunogen

2018 ◽  
Author(s):  
F Sesterhenn ◽  
M Galloux ◽  
SS Vollers ◽  
L Csepregi ◽  
C Yang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Viral Fusion ◽  
Viral Fusion Protein ◽  
Human B Cells ◽  
Syncytial Virus

AbstractThroughout the last decades, vaccination has been key to prevent and eradicate infectious diseases. However, many pathogens (e.g. respiratory syncytial virus (RSV), influenza, dengue and others) have resisted vaccine development efforts, largely due to the failure to induce potent antibody responses targeting conserved epitopes. Deep profiling of human B-cells often reveals potent neutralizing antibodies that emerge from natural infection, but these specificities are generally subdominant (i.e., are present in low titers). A major challenge for next-generation vaccines is to overcome established immunodominance hierarchies and focus antibody responses on crucial neutralization epitopes. Here, we show that a computationally designed epitope-focused immunogen presenting a single RSV neutralization epitope elicits superior epitope-specific responses compared to the viral fusion protein. In addition, the epitope-focused immunogen efficiently boosts antibodies targeting the Palivizumab epitope, resulting in enhanced neutralization. Overall, we show that epitope-focused immunogens can boost subdominant neutralizing antibody responses in vivo and reshape established antibody hierarchies.

scholarly journals Removal of the N-Glycosylation Sequon at Position N116 Located in p27 of the Respiratory Syncytial Virus Fusion Protein Elicits Enhanced Antibody Responses after DNA Immunization

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 426 ◽  
Author(s):  
Annelies Leemans ◽  
Marlies Boeren ◽  
Winke Van der Gucht ◽  
Isabel Pintelon ◽  
Kenny Roose ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Antibody Responses ◽  
F Protein ◽  
Glycosylation Sites ◽  
Potential Vaccine ◽  
Syncytial Virus ◽  
Tract Infections

Prevention of severe lower respiratory tract infections in infants caused by the human respiratory syncytial virus (hRSV) remains a major public health priority. Currently, the major focus of vaccine development relies on the RSV fusion (F) protein since it is the main target protein for neutralizing antibodies induced by natural infection. The protein conserves 5 N-glycosylation sites, two of which are located in the F2 subunit (N27 and N70), one in the F1 subunit (N500) and two in the p27 peptide (N116 and N126). To study the influence of the loss of one or more N-glycosylation sites on RSV F immunogenicity, BALB/c mice were immunized with plasmids encoding RSV F glycomutants. In comparison with F WT DNA immunized mice, higher neutralizing titres were observed following immunization with F N116Q. Moreover, RSV A2-K-line19F challenge of mice that had been immunized with mutant F N116Q DNA was associated with lower RSV RNA levels compared with those in challenged WT F DNA immunized animals. Since p27 is assumed to be post-translationally released after cleavage and thus not present on the mature RSV F protein, it remains to be elucidated how deletion of this glycan can contribute to enhanced antibody responses and protection upon challenge. These findings provide new insights to improve the immunogenicity of RSV F in potential vaccine candidates.

scholarly journals Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2270
Author(s):  
Gloria Griffante ◽  
Shikha Chandel ◽  
Daniela Ferrante ◽  
Valeria Caneparo ◽  
Daniela Capello ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Large Fraction ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Northern Italy ◽  
Serum Samples ◽  
Neutralization Titer ◽  
Igg Antibody

Longitudinal mapping of antibody-based SARS-CoV-2 immunity is critical for public health control of the pandemic and vaccine development. We performed a longitudinal analysis of the antibody-based immune response in a cohort of 100 COVID-19 individuals who were infected during the first wave of infection in northern Italy. The SARS-CoV-2 humoral response was tested using the COVID-SeroIndex, Kantaro Quantitative SARS-CoV-2 IgG Antibody RUO Kit (R&D Systems, Bio-Techne, Minneapolis, USA) and pseudotype-based neutralizing antibody assay. Using sequential serum samples collected from 100 COVID-19 recovered individuals from northern Italy—mostly with mild disease—at 2 and 10 months after their first positive PCR test, we show that 93% of them seroconverted at 2 months, with a geometric mean (GeoMean) half-maximal neutralization titer (NT50) of 387.9. Among the 35 unvaccinated subjects retested at 10 months, 7 resulted seronegative, with an 80% drop in seropositivity, while 28 showed decreased anti-receptor binding domain (RBD) and anti-spike (S) IgG titers, with a GeoMean NT50 neutralization titer dropping to 163.5. As an NT50 > 100 is known to confer protection from SARS-CoV-2 re-infection, our data show that the neutralizing activity elicited by the natural infection has lasted for at least 10 months in a large fraction of subjects.

scholarly journals Elicitation of potent serum neutralizing antibody responses in rabbits by immunization with an HIV-1 clade C trimeric Env derived from an Indian elite neutralizer

2020 ◽  
Author(s):  
Rajesh Kumar ◽  
Suprit Deshpande ◽  
Leigh M. Sewall ◽  
Gabriel Ozorowski ◽  
Christopher A. Cottrell ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Clade C ◽  
Immunogen Design ◽  
Env Protein ◽  
Immunogenic Properties ◽  
Hiv 1

AbstractEvaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The thermostable 1PGE-THIVC Env displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM). This closed spike conformation of 1PGE-THIVC Env trimers was correlated with weak or undetectable binding of non-neutralizing monoclonal antibodies (mAbs) compared to neutralizing mAbs. Furthermore, 1PGE-THIVC SOSIP induced potent neutralizing antibodies in rabbits to autologous virus variants. The autologous neutralizing antibody specificity induced in rabbits by 1PGE-THIVC was mapped to the C3/V4 region (T362/P401) of viral Env. This observation agreed with electron microscopy polyclonal epitope mapping (EMPEM) of the Env trimer complexed with IgG Fab prepared from the immunized rabbit sera. While the specificity of antibodies elicited in rabbits associated with neutralizing autologous viruses were distinct to those developed in the elite neutralizer, EMPEM analysis demonstrated significant changes to Env conformations when incubated with polyclonal antibody sera from the elite neutralizer, suggesting these antibodies lead to the destabilization of Env trimers. Our study not only shows distinct mechanisms associated with potent neutralization of sequence matched and unmatched autologous viruses by antibodies induced in rabbits and in the elite neutralizer, but also highlights how neutralizing antibodies developed during the course of natural infection can impact viral Env conformations.Author SummaryThe interplay between circulating virus variants and broadly cross neutralizing polyclonal antibodies developed in a subset of elite neutralizers is widely believed to provide strategies for rational immunogen design. In the present study, we studied the structural, antigenic and immunogenic properties of a thermostable soluble trimeric protein with near native pre-fusion conformation prepared using the primary sequence of an HIV-1 clade C env isolated from the broadly cross neutralizing plasma of an elite neutralizer. This novel SOSIP Env trimer demonstrated comparable antigenic, structural and immunogenic properties that favoured several ongoing subunit vaccine design efforts. The novel clade C SOSIP induced polyclonal neutralizing antibody response developed in rabbits not only differed in its epitope specificity compared to that elicited in natural infection in presence of pool of viral quasispecies but also showed how they differ in their ability to influence Env structure and conformation. A better understanding of how vaccine-induced polyclonal neutralizing antibody responses compares to responses that developed in natural infection will improve our knowledge in designing better vaccine design strategies.

scholarly journals Antibody responses induced by SHIV infection are more focused than those induced by soluble native HIV-1 envelope trimers in non-human primates

2021 ◽  
Vol 17 (8) ◽  
pp. e1009736
Author(s):  
Jelle van Schooten ◽  
Marlies M. van Haaren ◽  
Hui Li ◽  
Laura E. McCoy ◽  
Colin Havenar-Daughton ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Broadly Neutralizing Antibodies ◽  
Antibody Diversity ◽  
Infected Infant ◽  
Immunodeficiency Virus ◽  
Shiv Infection ◽  
Hiv 1

The development of an effective human immunodeficiency virus (HIV-1) vaccine is a high global health priority. Soluble native-like HIV-1 envelope glycoprotein trimers (Env), including those based on the SOSIP design, have shown promise as vaccine candidates by inducing neutralizing antibody responses against the autologous virus in animal models. However, to overcome HIV-1’s extreme diversity a vaccine needs to induce broadly neutralizing antibodies (bNAbs). Such bNAbs can protect non-human primates (NHPs) and humans from infection. The prototypic BG505 SOSIP.664 immunogen is based on the BG505 env sequence isolated from an HIV-1-infected infant from Kenya who developed a bNAb response. Studying bNAb development during natural HIV-1 infection can inform vaccine design, however, it is unclear to what extent vaccine-induced antibody responses to Env are comparable to those induced by natural infection. Here, we compared Env antibody responses in BG505 SOSIP-immunized NHPs with those in BG505 SHIV-infected NHPs, by analyzing monoclonal antibodies (mAbs). We observed three major differences between BG505 SOSIP immunization and BG505 SHIV infection. First, SHIV infection resulted in more clonal expansion and less antibody diversity compared to SOSIP immunization, likely because of higher and/or prolonged antigenic stimulation and increased antigen diversity during infection. Second, while we retrieved comparatively fewer neutralizing mAbs (NAbs) from SOSIP-immunized animals, these NAbs targeted more diverse epitopes compared to NAbs from SHIV-infected animals. However, none of the NAbs, either elicited by vaccination or infection, showed any breadth. Finally, SOSIP immunization elicited antibodies against the base of the trimer, while infection did not, consistent with the base being placed onto the virus membrane in the latter setting. Together these data provide new insights into the antibody response against BG505 Env during infection and immunization and limitations that need to be overcome to induce better responses after vaccination.

scholarly journals The receptor binding domain of SARS-CoV-2 spike is the key target of neutralizing antibody in human polyclonal sera

2020 ◽  
Author(s):  
Tara L. Steffen ◽  
E. Taylor Stone ◽  
Mariah Hassert ◽  
Elizabeth Geerling ◽  
Brian T. Grimberg ◽  
...  
Keyword(s):  
Antibody Response ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Binding Domain ◽  
Antigenic Determinants ◽  
Receptor Binding Domain ◽  
Neutralization Capacity

AbstractNatural infection of SARS-CoV-2 in humans leads to the development of a strong neutralizing antibody response, however the immunodominant targets of the polyclonal neutralizing antibody response are still unknown. Here, we functionally define the role SARS-CoV-2 spike plays as a target of the human neutralizing antibody response. In this study, we identify the spike protein subunits that contain antigenic determinants and examine the neutralization capacity of polyclonal sera from a cohort of patients that tested qRT-PCR-positive for SARS-CoV-2. Using an ELISA format, we assessed binding of human sera to spike subunit 1 (S1), spike subunit 2 (S2) and the receptor binding domain (RBD) of spike. To functionally identify the key target of neutralizing antibody, we depleted sera of subunit-specific antibodies to determine the contribution of these individual subunits to the antigen-specific neutralizing antibody response. We show that epitopes within RBD are the target of a majority of the neutralizing antibodies in the human polyclonal antibody response. These data provide critical information for vaccine development and development of sensitive and specific serological testing.

Development of a Norovirus P Particle Platform for Eliciting Neutralizing Antibody Responses to the Membrane Proximal External Region of Human Immunodeficiency Virus Type 1 Envelope

2014 ◽  
Vol 21 (12) ◽  
pp. 1230-1239
Author(s):  
Yang Zang ◽  
Jinpeng Bi ◽  
Dongchuan Du ◽  
Xintao Liu ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Broadly Neutralizing Antibodies ◽  
External Region ◽  
Membrane Proximal External Region ◽  
Immunodeficiency Virus ◽  
Hiv 1

Eliciting efficient broadly neutralizing antibodies (BnAbs) is an important goal that has yet to be achieved for human immunodeficiency type 1 (HIV-1) vaccine development, although they are rarely produced in virus-infected individuals. In particular, inducing specific neutralizing antibodies to the gp41 membrane proximal external region (MPER) has proven a difficult task. In this study, we introduce Norovirus P particles as a new platform to display the MPER epitope of HIV-1 as a vaccine with the aim of enhancing immune responses. The results showed that HIV-1 chimeric P particles were capable of inducing MPER-specific antibody responses in immunized guinea pigs, although only weakly neutralizing activity could be detected. These findings are consistent with other previous studies which have also focused on the well-studied 2F5 and 4E10 BnAbs. Our findings provide an alternate strategy for design of vaccines against HIV-1. However, great challenges remain in the effort to develop vaccines that can induce efficient HIV-1 neutralizing antibodies.

scholarly journals SARS-CoV-2 antibodies remain detectable 12 months after infection and antibody magnitude is associated with age and COVID-19 severity

2021 ◽  
Author(s):  
Eric D. Laing ◽  
Nusrat J. Epsi ◽  
Stephanie A. Richard ◽  
Emily C. Samuels ◽  
Wei Wang ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Serum Samples ◽  
Military Hospitals ◽  
Igg Binding ◽  
One Year

ABSTRACTImportanceThe persistence of SARS-CoV-2 antibodies may be a predictive correlate of protection for both natural infections and vaccinations. Identifying predictors of robust antibody responses is important to evaluate the risk of re-infection / vaccine failure and may be translatable to vaccine effectiveness.ObjectiveTo 1) determine the durability of anti-SARS-CoV-2 IgG and neutralizing antibodies in subjects who experienced mild and moderate to severe COVID-19, and 2) to evaluate the correlation of age and IgG responses to both endemic human seasonal coronaviruses (HCoVs) and SARS-CoV-2 according to infection outcome.DesignLongitudinal serum samples were collected from PCR-confirmed SARS-CoV-2 positive participants (U.S. active duty service members, dependents and military retirees, including a range of ages and demographics) who sought medical treatment at seven U.S. military hospitals from March 2020 to March 2021 and enrolled in a prospective observational cohort study.ResultsWe observed SARS-CoV-2 seropositivity in 100% of inpatients followed for six months (58/58) to one year (8/8), while we observed seroreversion in 5% (9/192) of outpatients six to ten months after symptom onset, and 18% (2/11) of outpatients followed for one year. Both outpatient and inpatient anti-SARS-CoV-2 binding-IgG responses had a half-life (T1/2) of >1000 days post-symptom onset. The magnitude of neutralizing antibodies (geometric mean titer, inpatients: 378 [246-580, 95% CI] versus outpatients: 83 [59-116, 95% CI]) and durability (inpatients: 65 [43-98, 95% CI] versus outpatients: 33 [26-40, 95% CI]) were associated with COVID-19 severity. Older age was a positive correlate with both higher IgG binding and neutralizing antibody levels when controlling for COVID-19 hospitalization status. We found no significant relationships between HCoV antibody responses and COVID-19 clinical outcomes, or the development of SARS-CoV-2 neutralizing antibodies.Conclusions and RelevanceThis study demonstrates that humoral responses to SARS-CoV-2 infection are robust on longer time-scales, including those arising from milder infections.However, the magnitude and durability of the antibody response after natural infection was lower and more variable in younger participants who did not require hospitalization for COVID-19. These findings support vaccination against SARS-CoV-2 in all suitable populations including those individuals that have recovered from natural infection.

scholarly journals A high-throughput cell- and virus-free assay shows reduced neutralization of SARS-CoV-2 variants by COVID-19 convalescent plasma

2021 ◽  
pp. eabi8452
Author(s):  
Craig Fenwick ◽  
Priscilla Turelli ◽  
Céline Pellaton ◽  
Alex Farina ◽  
Jérémy Campos ◽  
...  
Keyword(s):  
High Throughput ◽  
Neutralizing Antibodies ◽  
Competitive Inhibition ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Spike Protein ◽  
Serum Samples ◽  
Live Virus ◽  
Protein Variants

The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies in the serum of an individual indicates prior infection or vaccination. However, it provides limited insight into the protective nature of this immune response. Neutralizing antibodies recognizing the viral spike protein are more revealing, yet their measurement traditionally requires virus- and cell-based systems that are costly, time-consuming, inflexible, and potentially biohazardous. Here, we present a cell-free quantitative neutralization assay based on the competitive inhibition of trimeric SARS-CoV-2 spike protein binding to the angiotensin converting enzyme 2 (ACE2) receptor. This high-throughput method matches the performance of the gold standard live virus infection assay, as verified with a panel of 206 seropositive donors with varying degrees of infection severity and virus-specific IgG titers, achieving 96.7% sensitivity and 100% specificity. Furthermore, it allows for the parallel assessment of neutralizing activities against multiple SARS-CoV-2 spike protein variants of concern. We used our assay to profile serum samples from 59 patients hospitalized with coronavirus disease 2019 (COVID-19). We found that, although most sera had high activity against the 2019-nCoV parental spike protein and, to a lesser extent, the α (B.1.1.7) variant, only 58% of serum samples could efficiently neutralize a spike protein derivative containing mutations present in the β (B.1.351) variant. Thus, we have developed an assay that can evaluate effective neutralizing antibody responses to SARS-CoV-2 spike protein variants of concern after natural infection and that can be applied to characterize vaccine-induced antibody responses or to assess the potency of monoclonal antibodies.

scholarly journals Vaccination with SARS-CoV-2 variants of concern protects mice from challenge with wild-type virus

PLoS Biology ◽  
2021 ◽  
Vol 19 (12) ◽  
pp. e3001384
Author(s):  
Fatima Amanat ◽  
Shirin Strohmeier ◽  
Philip Meade ◽  
Nicholas Dambrauskas ◽  
Barbara Mühlemann ◽  
...  
Keyword(s):  
Mouse Model ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Fold Reduction ◽  
Reactive Antibody

Vaccines against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) have been highly efficient in protecting against Coronavirus Disease 2019 (COVID-19). However, the emergence of viral variants that are more transmissible and, in some cases, escape from neutralizing antibody responses has raised concerns. Here, we evaluated recombinant protein spike antigens derived from wild-type SARS-CoV-2 and from variants B.1.1.7, B.1.351, and P.1 for their immunogenicity and protective effect in vivo against challenge with wild-type SARS-CoV-2 in the mouse model. All proteins induced high neutralizing antibodies against the respective viruses but also induced high cross-neutralizing antibody responses. The decline in neutralizing titers between variants was moderate, with B.1.1.7-vaccinated animals having a maximum fold reduction of 4.8 against B.1.351 virus. P.1 induced the most cross-reactive antibody responses but was also the least immunogenic in terms of homologous neutralization titers. However, all antigens protected from challenge with wild-type SARS-CoV-2 in a mouse model.

scholarly journals Live-Attenuated Respiratory Syncytial Virus Vaccine With M2-2 Deletion and With Small Hydrophobic Noncoding Region Is Highly Immunogenic in Children

2020 ◽  
Vol 221 (12) ◽  
pp. 2050-2059 ◽  
Author(s):  
Elizabeth J McFarland ◽  
Ruth A Karron ◽  
Petronella Muresan ◽  
Coleen K Cunningham ◽  
Charlotte Perlowski ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Neutralizing Antibodies ◽  
Phase 1 ◽  
Regulatory Protein ◽  
Neutralizing Antibody ◽  
Respiratory Illness ◽  
Antibody Responses ◽  
Upper Respiratory Tract ◽  
Syncytial Virus ◽  
Placebo Recipients

Abstract Background Respiratory syncytial virus (RSV) is the leading viral cause of severe pediatric respiratory illness, and vaccines are needed. Live RSV vaccine D46/NS2/N/ΔM2-2-HindIII, attenuated by deletion of the RSV RNA regulatory protein M2-2, is based on previous candidate LID/ΔM2-2 but incorporates prominent differences from MEDI/ΔM2-2, which was more restricted in replication in phase 1. Methods RSV-seronegative children aged 6–24 months received 1 intranasal dose (105 plaque-forming units [PFUs] of D46/NS2/N/ΔM2-2-HindIII [n = 21] or placebo [n = 11]) and were monitored for vaccine shedding, reactogenicity, RSV-antibody responses and RSV-associated medically attended acute respiratory illness (RSV-MAARI) and antibody responses during the following RSV season. Results All 21 vaccinees were infected with vaccine; 20 (95%) shed vaccine (median peak titer, 3.5 log10 PFUs/mL with immunoplaque assay and 6.1 log10 copies/mL with polymerase chain reaction). Serum RSV-neutralizing antibodies and anti-RSV fusion immunoglobulin G increased ≥4-fold in 95% and 100% of vaccines, respectively. Mild upper respiratory tract symptoms and/or fever occurred in vaccinees (76%) and placebo recipients (18%). Over the RSV season, RSV-MAARI occurred in 2 vaccinees and 4 placebo recipients. Three vaccinees had ≥4-fold increases in serum RSV-neutralizing antibody titers after the RSV season without RSV-MAARI. Conclusions D46/NS2/N/ΔM2-2-HindIII had excellent infectivity and immunogenicity and primed vaccine recipients for anamnestic responses, encouraging further evaluation of this attenuation strategy. Clinical Trials Registration NCT03102034 and NCT03099291.

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