scholarly journals Maintenance of neutralizing SARS-CoV-2 antibodies over five months in convalescent SARS-CoV-2 afflicted patients.

2020 ◽  
Author(s):  
Sissy Sonnleitner ◽  
Martina Prelog ◽  
Bainca Jansen ◽  
Chantal Rodgarkia-Dara ◽  
Sarah Gietl ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Primary Infection ◽  
Protective Immunity ◽  
Neutralization Assay ◽  
Immunofluorescence Assay ◽  
Crucial Importance ◽  
Wild Type ◽  
Specific Antibodies ◽  
Chemiluminescent Immunoassay ◽  
Type Infection

Level and duration of protective immunity against SARS-CoV-2 after primary infection is of crucial importance for preventive approaches. In order to provide evidence for the longevity of specific antibodies, we investigated the generation and maintenance of neutralizing antibodies of convalescent SARS-CoV-2-afflicted patients over a five month period post primary infection using an immunofluorescence assay, a commercial chemiluminescent immunoassay and an in-house enzyme-linked plaque-reduction neutralization assay. We present the successful application of an improved version of the plaque-reduction neutralization assay, which can be analyzed optometrically, significantly simplifying the interpretation of the results. Based on the results of the plaque-reduction neutralization assay, neutralizing antibodies were maintained in 85.3% of convalescent individuals without significant decay over five months. Furthermore, a positive correlation between severity of infection and neutralizing titer was shown. In conclusion, SARS-CoV-2-afflicted individuals have been proven to be able to establish and maintain neutralizing antibodies over a five months’ period after primary infection which allows to hope for long-lasting presumably protective humoral immunity after wild-type infection or even after vaccination.

scholarly journals Distinct Roles of CD28- and CD40 Ligand-Mediated Costimulation in the Development of Protective Immunity and Pathology during Chlamydia muridarum Urogenital Infection in Mice

2009 ◽  
Vol 77 (7) ◽  
pp. 3080-3089 ◽  
Author(s):  
Lili Chen ◽  
Wen Cheng ◽  
Pooja Shivshankar ◽  
Lei Lei ◽  
Xiaoyun Zhang ◽  
...  
Keyword(s):  
Primary Infection ◽  
Protective Immunity ◽  
Gene Knockout ◽  
Secondary Infection ◽  
Cd40 Ligand ◽  
Wild Type ◽  
Chlamydia Muridarum ◽  
Urogenital Infection ◽  
Costimulatory Signals ◽  
Deficient Mice

ABSTRACT Infection with Chlamydia muridarum in the mouse urogenital tract can induce both protective immunity and inflammatory pathologies, which has been used as a model for understanding the immune and pathogenic mechanisms of C. trachomatis infection. We compared the roles of CD28- and CD40 ligand (CD40L)-mediated costimulation in C. muridarum infection. Mice with CD28 or CD80/CD86 gene knockout (KO) displayed an infection course similar to that of wild-type mice during both primary and secondary infection, suggesting that CD28-mediated costimulation is not required for protection against C. muridarum infection. However, mice deficient in CD40L or CD40 displayed a prolonged infection course after primary or secondary infection, suggesting that CD40-CD40L costimulation plays an essential role in the development of anti-C. muridarum immunity. Interestingly, the CD28- or CD80/CD86-deficient mice displayed significantly lower levels of inflammatory pathologies in the upper genital tracts after primary infection, although the attenuation in inflammation was no longer significant during secondary infection. However, the CD40L or CD40 KO mice developed inflammatory pathologies as severe as those in wild-type mice following either primary or secondary infection despite the obvious deficits in adaptive immunity in these KO mice. The resistance of CD28 or CD80/CD86 KO mice to chlamydial infection correlated with production of gamma interferon, while the development of inflammatory pathologies in CD40L or CD40 KO mice correlated with the production of other proinflammatory cytokines in mouse urogenital tracts during the early stages of the infection. These observations together suggest that C. muridarum-induced protective immunity and inflammatory pathologies can be mediated by distinct costimulatory signals.

scholarly journals A Universal Dengue Vaccine Elicits Neutralizing Antibodies Against Strains from All Four Dengue Serotypes

2020 ◽  
Author(s):  
Naoko Uno ◽  
Ted M. Ross
Keyword(s):  
Dengue Virus ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Rhesus Macaques ◽  
Effective Vaccine ◽  
Wild Type ◽  
Monovalent Vaccine ◽  
Viral Particles ◽  
Tropical Areas

Any potential dengue virus (DENV) vaccine needs to elicit protective immunity against strains from all four serotypes to avoid potential antibody dependent enhancement (ADE). In this study, four independent DENV envelope (E) glycoproteins were generated using wild-type E sequences from viruses isolated between 1943 to 2006 using computationally-optimized broadly reactive antigen (COBRA) methodology. COBRA and wild-type E antigens were expressed on the surface of subvirion viral particles (SVPs). Four separate wild-type E antigens were used for each serotype. Mice vaccinated with wild-type DENV SVPs had anti-E IgG antibodies that neutralized serotype specific viruses. COBRA DENV SVPs elicited a broader breadth of antibodies that neutralized strains across all four serotypes. Two COBRA DENV vaccine candidates that elicited the broadest breadth of neutralizing antibodies in mice were used to vaccinate rhesus macaques (Macca mulata) that were either immunologically naïve to any DENV serotype or were had pre-existing antibodies to DENV. Antibodies elicited by COBRA DENV E immunogens neutralized all 12 strains of DENV in vitro, which was comparable to antibodies elicited by a tetravalent wild-type E SVP vaccination mixture. Therefore, using a single DENV COBRA E protein can elicit neutralizing antibodies against strains representing all four serotypes of DENV in both naïve and dengue pre-immune populations. Importance Dengue virus infects millions of people living in the tropical areas of the world. Dengue induced diseases can range from mild to severe with death. An effective vaccine will need to neutralize viruses from all four serotypes of dengue without induced enhanced disease. A dengue E vaccine candidate generated by computationally optimized broadly reactive antigen algorithms elicits broadly neutralizing protection for current circulating strains from all four serotypes regardless of immune status. Most Dengue vaccines in development formulate four separate components based on prM-E from a wild type strain representing each serotype. Designing a monovalent vaccine that elicits protective immunity against all four serotypes is an effective and economical strategy

scholarly journals α-Hemolysin-Aided Oligomerization of the Spike Protein RBD Resulted in Improved Immunogenicity and Neutralization Against SARS-CoV-2 Variants

2021 ◽  
Vol 12 ◽  
Author(s):  
Jintao Zou ◽  
Haiming Jing ◽  
Xiaoli Zhang ◽  
Yiheng Liu ◽  
Zhuo Zhao ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralization Assay ◽  
Spike Protein ◽  
Wild Type Virus ◽  
Carrier Protein ◽  
Specific Antibodies ◽  
Linear Epitopes ◽  
Cellular Immune ◽  
Candidate Antigen

The increase in confirmed COVID-19 cases and SARS-CoV-2 variants calls for the development of safe and broad cross-protective vaccines. The RBD of the spike protein was considered to be a safe and effective candidate antigen. However, the low immunogenicity limited its application in vaccine development. Herein, we designed and obtained an RBD heptamer (mHla-RBD) based on a carrier protein-aided assembly strategy. The molecular weight of mHla-RBD is up to 450 kDa, approximately 10 times higher than that of the RBD monomer. When formulated with alum adjuvant, mHla-RBD immunization significantly increased the immunogenicity of RBD, as indicated by increased titers of RBD-specific antibodies, neutralizing antibodies, Th2 cellular immune response, and pseudovirus neutralization activity, when compared to RBD monomer. Furthermore, we confirmed that RBD-specific antibodies predominantly target conformational epitopes, which was approximately 200 times that targeting linear epitopes. Finally, a pseudovirus neutralization assay revealed that neutralizing antibodies induced by mHla-RBD against different SARS-CoV-2 variants were comparable to those against the wild-type virus and showed broad-spectrum neutralizing activity toward different SARS-CoV-2 variants. Our results demonstrated that mHla-RBD is a promising candidate antigen for development of SARS-CoV-2 vaccines and the mHla could serve as a universal carrier protein for antigen design.

scholarly journals Non-structural proteins of dengue 2 virus offer limited protection to interferon-deficient mice after dengue 2 virus challenge

2006 ◽  
Vol 87 (2) ◽  
pp. 339-346 ◽  
Author(s):  
Amanda E. Calvert ◽  
Claire Y.-H. Huang ◽  
Richard M. Kinney ◽  
John T. Roehrig
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Structural Proteins ◽  
Wild Type ◽  
Survival Times ◽  
E Proteins ◽  
Virus Challenge ◽  
E Protein ◽  
Low Levels ◽  
Deficient Mice

Chimeric (D2/WN) viruses containing the pre-membrane (prM) and envelope (E) proteins of West Nile virus (WN virus) and the capsid (C) and non-structural proteins of dengue 2 (DEN2) virus were used to evaluate the protective immunity elicited by either the flaviviral E protein or non-structural proteins. AG129 interferon-deficient mice, previously shown to be protected against lethal DEN1 or DEN2 viral infection after vaccination with a wild-type or candidate vaccine strain of DEN1 or DEN2 virus, respectively, were immunized with chimeric D2/WN virus and then challenged with DEN2 virus. D2/WN chimeric viruses were non-pathogenic in AG129 mice. These viruses elicited little anti-DEN E antibody, high levels of anti-DEN NS1 antibody and no or very low levels of DEN2 virus-neutralizing antibodies. Only 15 % of D2/WN-immunized mice survived challenge with DEN2 virus. However, their mean survival time increased by 11–14 days over non-immunized controls. These results suggest that, whilst the non-structural proteins were able to enhance mean survival times of AG129 mice, this protection was not as effective as protection mediated by the E protein.

scholarly journals Early Antibodies Specific for the Neutralizing Epitope on the Receptor Binding Subunit of the Lymphocytic Choriomeningitis Virus Glycoprotein Fail To Neutralize the Virus

2007 ◽  
Vol 81 (21) ◽  
pp. 11650-11657 ◽  
Author(s):  
Bruno Eschli ◽  
Raphaël M. Zellweger ◽  
Alexander Wepf ◽  
Karl S. Lang ◽  
Katharina Quirin ◽  
...  
Keyword(s):  
B Cells ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
Wild Type ◽  
Neutralizing Epitope ◽  
Specific Antibodies ◽  
Deficient Mice ◽  
Binding Subunit

ABSTRACT Lymphocytic choriomeningitis virus (LCMV) is a murine arenavirus whose glycoprotein consists of a transmembrane subunit (GP-2) and a receptor-binding subunit (GP-1). LCMV-neutralizing antibodies (nAbs) are directed against a single site on GP-1 and occur 1 month after the infection of cytotoxic-T-lymphocyte (CTL) deficient mice. In wild-type mice, however, CTLs control early infection, and weak nAb titers emerge very late (after 70 to 150 days) if at all. Production of recombinant GP-1 in native conformation enabled us to study the emergence of GP-1-binding antibodies directed against the neutralizing epitope. By combining binding and neutralization assays, we correlated the development of binding antibodies versus nAbs in wild-type and CTL-deficient mice after infection with different LCMV doses. We found that wild-type mice developed GP-1-specific antibodies already by day 8 after exposure to high but not low doses, demonstrating that naive GP-1-specific B cells were infrequent. Furthermore, the induced antibodies bound to the neutralizing GP-1 epitope but failed to neutralize the virus and therefore were of low affinity. In CTL-deficient mice, where massive viremia quickly levels initial differences in viral load, low and high doses induced low-affinity non-neutralizing GP-1-binding antibodies with kinetics similar to high-dose-infected wild-type mice. Only in CTL-deficient mice, however, the GP-1-specific antibodies developed into nAbs within 1 month. We conclude that LCMV uses a dual strategy to evade nAb responses in wild-type mice. First, LCMV exploits a “hole” in the murine B-cell repertoire, which provides only a small and narrow initial pool of low-affinity GP-1-specific B cells. Second, affinity maturation of the available low-affinity non-neutralizing antibodies is impaired.

scholarly journals Persistence of robust humoral immune response in COVID-19 convalescent individuals over 12 months after infection

2021 ◽  
Author(s):  
Kei Miyakawa ◽  
Sousuke Kubo ◽  
Sundararaj Stanleyraj Jeremiah ◽  
Hirofumi Go ◽  
Yutaro Yamaoka ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Receptor Binding Domain ◽  
Wild Type ◽  
Virus Antibody ◽  
Neutralization Activity ◽  
Humoral Immune ◽  
Antibody Titers ◽  
Viral Nucleocapsid

SARS-CoV-2 infection elicits varying degrees of protective immunity conferred by neutralizing antibodies (nAbs). Here we report the persistence of nAb responses over 12 months after infection despite its decreasing trend noticed from 6 months. The study included sera from 358 individuals who had been infected with SARS-CoV-2 between January and May 2020. Samples were collected at 6 and 12 months after onset. The titers of IgG to the viral nucleocapsid protein (NP) and receptor-binding domain of the spike protein (RBD) were measured by CLEIA. The nAb titer was determined using lentivirus-based pseudovirus or authentic virus. Antibody titers of NP-IgG, RBD-IgG, and nAbs were higher in severe and moderate cases than in mild cases at 12 months after onset. While the nAb levels were likely to confer adequate protection against wild-type viral infection, the neutralization activity to recently circulating variants in some of the mild cases (~30%) was undermined, implying the susceptibility of reinfection to the variants of concerns (VOCs). COVID-19 convalescent individuals have robust humoral immunity even at 12 months after infection albeit that the medical history and background of patients could affect the function and dynamics of antibody response to the VOCs.

scholarly journals 163. Enhancing the Immunogenicity of a Novel, Low-cost Ebola Vaccine

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S211-S211
Author(s):  
Samuel D Stampfer ◽  
Rui Jin ◽  
Chinglai Yang
Keyword(s):  
Dna Vaccine ◽  
Disulfide Bonds ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Cost Effective ◽  
Hemorrhagic Fever ◽  
Wild Type ◽  
Mammalian Expression ◽  
Antibody Titers

Abstract Background Ebolaviruses cause viral hemorrhagic fever with high mortality rates. Nearly all Ebola vaccines in development use Ebola glycoprotein (GP) as the immunizing antigen. GP is present on the viral membrane and functions in cell entry by binding the cellular receptor and mediating membrane fusion; antibodies to GP induce protective immunity. Ebola also produces sGP: a smaller, secreted form of GP containing the receptor-binding domain; it is also able to induce protective immunity. sGP naturally refolds after thermal denaturation and thus may be more stable than GP, and may also be more cost effective as it is produced easily in high quantities. sGP is a homodimer that is covalently linked by a cysteine near its C-terminus. In this work, we explored how modifications to sGP that affect its ability to dimerize also alter its immunogenicity. Methods sGP mutants were generated in the pCAGGS mammalian expression plasmid, and injected into mice as a DNA vaccine. Mouse sera was tested by ELISA against sGP and GP proteins, and in a neutralization assay against GP-typed pseudovirions. Results We generated 4 different mutants of sGP that had altered abilities to form inter-protomer disulfide bonds. All had a mutated or deleted cysteine at position 306; two had disulfide-bonding restored by introduction of an engineered inter-protomer disulfide bond. Mice were immunized with a DNA vaccine encoding either an sGP mutant or wild-type sGP, and sera were collected. We found that sera from sGP mutants with reduced interprotomer disulfide bonds had significantly higher antibody titers to sGP and GP than sera from our wild-type sGP and engineered-disulfide sGP immunized mice. Antibody titers were similar between sGP and GP; these titers correlated with neutralization ability. Relative binding to sGP & GP (by ELISA OD) & relative % neutralization of pseudovirions at 1:10 dilution Conclusion Immunogenicity of Ebola sGP was enhanced significantly when mutations were introduced to reduce its ability to covalently dimerize. Immunogenicity correlated with induction of neutralizing antibodies, implying that our mutants may outperform wild-type sGP when used as a vaccine in vivo. This work helps paves the way for an alternative Ebola vaccine that has the potential to be more cost-effective and heat-stable than the currently-licensed vaccine. Disclosures Samuel D. Stampfer, MD/PhD, Gilead (Shareholder)

scholarly journals Protective Immunity in Macaques Vaccinated with a Modified Vaccinia Virus Ankara-Based Measles Virus Vaccine in the Presence of Passively Acquired Antibodies

2000 ◽  
Vol 74 (9) ◽  
pp. 4236-4243 ◽  
Author(s):  
Koert J. Stittelaar ◽  
Linda S. Wyatt ◽  
Rik L. de Swart ◽  
Helma W. Vos ◽  
Jan Groen ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Measles Virus ◽  
Wild Type ◽  
Live Attenuated Vaccine ◽  
Cell Responses ◽  
Modified Vaccinia Virus Ankara ◽  
Current Vaccine ◽  
Induced Immunity

ABSTRACT Recombinant modified vaccinia virus Ankara (MVA), encoding the measles virus (MV) fusion (F) and hemagglutinin (H) (MVA-FH) glycoproteins, was evaluated in an MV vaccination-challenge model with macaques. Animals were vaccinated twice in the absence or presence of passively transferred MV-neutralizing macaque antibodies and challenged 1 year later intratracheally with wild-type MV. After the second vaccination with MVA-FH, all the animals developed MV-neutralizing antibodies and MV-specific T-cell responses. Although MVA-FH was slightly less effective in inducing MV-neutralizing antibodies in the absence of passively transferred antibodies than the currently used live attenuated vaccine, it proved to be more effective in the presence of such antibodies. All vaccinated animals were effectively protected from the challenge infection. These data suggest that MVA-FH should be further tested as an alternative to the current vaccine for infants with maternally acquired MV-neutralizing antibodies and for adults with waning vaccine-induced immunity.

scholarly journals A Novel Mechanism Underlying Antiviral Activity of an Influenza Virus M2-Specific Antibody

2020 ◽  
Vol 95 (1) ◽  
Author(s):  
Rashid Manzoor ◽  
Nao Eguchi ◽  
Reiko Yoshida ◽  
Hiroichi Ozaki ◽  
Tatsunari Kondoh ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Influenza A ◽  
Binding Capacity ◽  
Vaccine Antigen ◽  
Progeny Virus ◽  
M2 Protein ◽  
Specific Antibodies ◽  
Infected Cells

ABSTRACT Protective immunity against influenza A viruses (IAVs) generally depends on antibodies to the major envelope glycoprotein, hemagglutinin (HA), whose antigenicity is distinctive among IAV subtypes. On the other hand, the matrix 2 (M2) protein is antigenically highly conserved and has been studied as an attractive vaccine antigen to confer cross-protective immunity against multiple subtypes of IAVs. However, antiviral mechanisms of M2-specific antibodies are not fully understood. Here, we report the molecular basis of antiviral activity of an M2-specific monoclonal antibody (MAb), rM2ss23. We first found that rM2ss23 inhibited A/Aichi/2/1968 (H3N2) (Aichi) but not A/PR/8/1934 (H1N1) (PR8) replication. rM2ss23 altered the cell surface distribution of M2, likely by cross-linking the molecules, and interfered with the colocalization of HA and M2, resulting in reduced budding of progeny viruses. However, these effects were not observed for another strain, PR8, despite the binding capacity of rM2ss23 to PR8 M2. Interestingly, HA was also involved in the resistance of PR8 to rM2ss23. We also found that two amino acid residues at positions 54 and 57 in the M2 cytoplasmic tail were critical for the insensitivity of PR8 to rM2ss2. These findings suggest that the disruption of the M2-HA colocalization on infected cells and subsequent reduction of virus budding is one of the principal mechanisms of antiviral activity of M2-specific antibodies and that anti-M2 antibody-sensitive and -resistant IAVs have different properties in the interaction between M2 and HA. IMPORTANCE Although the IAV HA is the major target of neutralizing antibodies, most of the antibodies are HA subtype specific, restricting the potential of HA-based vaccines. On the contrary, the IAV M2 protein has been studied as a vaccine antigen to confer cross-protective immunity against IAVs with multiple HA subtypes, since M2 is antigenically conserved. Although a number of studies highlight the protective role of anti-HA neutralizing and nonneutralizing antibodies, precise information on the molecular mechanism of action of M2-specific antibodies is still obscure. In this study, we found that an anti-M2 antibody interfered with the HA-M2 association, which is important for efficient budding of progeny virus particles from infected cells. The antiviral activity was IAV strain dependent despite the similar binding capacity of the antibody to M2, and, interestingly, HA was involved in susceptibility to the antibody. Our data provide a novel mechanism underlying antiviral activity of M2-specific antibodies.

scholarly journals Depletion of measles virus glycoprotein-specific antibodies from human sera reveals genotype-specific neutralizing antibodies

2009 ◽  
Vol 90 (12) ◽  
pp. 2982-2989 ◽  
Author(s):  
Rik L. de Swart ◽  
Selma Yüksel ◽  
Carianne N. Langerijs ◽  
Claude P. Muller ◽  
Albert D. M. E. Osterhaus
Keyword(s):  
Neutralizing Antibodies ◽  
Measles Virus ◽  
Complete Elimination ◽  
Wild Type ◽  
Specific Antibodies ◽  
F Protein ◽  
Virus Glycoprotein ◽  
Measles Outbreak ◽  
Human Sera ◽  
H Protein

Measles virus (MV)-neutralizing antibodies in sera from vaccinated subjects are mainly directed against the haemagglutinin (H) protein. It has been shown previously that depletion of vaccination-induced H-specific antibodies by co-culture of sera with cells expressing the MV Edmonston strain H glycoprotein resulted in almost complete elimination of neutralizing activity. In the present study, MV H and/or fusion (F) protein-specific antibodies were depleted from sera of naturally immune subjects. Early convalescent samples were collected 1.5 years after a well-characterized measles outbreak in Luxembourg caused by a genotype C2 virus, whilst late convalescent samples were collected from healthy Dutch subjects born between 1960 and 1970. Depletion of both H- and F-specific antibodies completely eliminated virus-neutralizing (VN) activity against MV Edmonston. However, in the early convalescent samples, residual VN antibody against wild-type MV genotype C2 was detected. This demonstrated that, although the majority of MV-specific VN antibodies recognized epitopes conserved between different genotypes, genotype-specific VN epitopes were also induced. In sera depleted of H-specific antibodies only, VN activity against MV Edmonston was not completely eliminated, demonstrating the presence of F-specific VN antibodies. In conclusion, this study demonstrated that a fraction of VN antibodies induced by wild-type MV genotype C2 does not neutralize MV strain Edmonston. In addition, it was shown that, in sera from naturally immune donors, the majority of VN antibodies are specific for MV H protein, but up to 10 % of neutralizing antibodies are specific for MV F protein.

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