scholarly journals Long-Term Persistence and Relevant Therapeutic Impact of High-Titer Viral-Neutralizing Antibody in a Convalescent COVID-19 Plasma Super-Donor: A Case Report

2021 ◽  
Vol 12 ◽  
Author(s):  
Mafalda De Rienzo ◽  
Maria Laura Foddai ◽  
Laura Conti ◽  
Chiara Mandoj ◽  
Stefano Iaboni ◽  
...  
Keyword(s):  
High Titer ◽  
Neutralizing Antibody ◽  
Plasma Source ◽  
Inhibition Test ◽  
National Study ◽  
Neutralizing Activity ◽  
Binding Inhibition ◽  
Voluntary Donor ◽  
Reported Data

A convalescent, non-severe, patient with COVID-19 was enrolled as a hyper-immune plasma voluntary donor by the Immuno-Hematology and Transfusion Unit of the Regina Elena National Cancer Institute in Rome, under the TSUNAMI national study criteria. During a nearly 6-month period (May–October 2020), the patient was closely monitored and underwent four hyperimmune plasma collections. Serum SARS-CoV-2 (anti-S + anti-N) IgG and IgM, anti-S1 IgA, and neutralizing titers (NTs) were measured. Anti-SARS-CoV-2 antibody levels steadily decreased. No correlation was found between anti-S/anti-N IgG and IgM levels and viral NT, measured by either a microneutralization test or the surrogate RBD/ACE2-binding inhibition test. Conversely, NTs directly correlated with anti-S1 IgA levels. Hyperimmune donor plasma, administered to five SARS-CoV-2 patients with persistent, severe COVID-19 symptoms, induced short-term clinical and pathological improvement. Reported data suggest that high NTs can persist longer than expected, thus widening hyperimmune plasma source, availability, and potential use. In vitro RBD/ACE2-binding inhibition test is confirmed as a convenient surrogate index for neutralizing activity and patients’ follow-up, suitable for clinical settings where biosafety level 3 facilities are not available. IgA levels may correlate with serum neutralizing activity and represent a further independent index for patient evaluation.

scholarly journals Epitope Determinants of a Chimpanzee Dengue Virus Type 4 (DENV-4)-Neutralizing Antibody and Protection against DENV-4 Challenge in Mice and Rhesus Monkeys by Passively Transferred Humanized Antibody

2007 ◽  
Vol 81 (23) ◽  
pp. 12766-12774 ◽  
Author(s):  
Ching-Juh Lai ◽  
Ana P. Goncalvez ◽  
Ruhe Men ◽  
Claire Wernly ◽  
Olivia Donau ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Virus Type ◽  
High Titer ◽  
Neutralizing Antibody ◽  
Denv Infection ◽  
Passive Transfer ◽  
Escape Mutant ◽  
Protective Capacity

ABSTRACT The chimpanzee monoclonal antibody (MAb) 5H2 is specific for dengue virus type 4 (DENV-4) and neutralizes the virus at a high titer in vitro. The epitope detected by the antibody was mapped by sequencing neutralization escape variants of the virus. One variant contained a Lys174-Glu substitution and another contained a Pro176-Leu substitution in domain I of the DENV-4 envelope protein (E). These mutations reduced binding affinity for the antibody 18- to >100-fold. Humanized immunoglobulin G (IgG) 5H2, originally produced from an expression vector, has been shown to be a variant containing a nine-amino-acid deletion in the Fc region which completely ablates antibody-dependent enhancement of DENV replication in vitro. The variant MAb, termed IgG 5H2 ΔD, is particularly attractive for exploring its protective capacity in vivo. Passive transfer of IgG 5H2 ΔD at 20 μg/mouse afforded 50% protection of suckling mice against challenge with 25 50% lethal doses of mouse neurovirulent DENV-4 strain H241. Passive transfer of antibody to monkeys was conducted to demonstrate proof of concept for protection against DENV challenge. Monkeys that received 2 mg/kg of body weight of IgG 5H2 ΔD were completely protected against 100 50% monkey infectious doses (MID50) of DENV-4, as indicated by the absence of viremia and seroconversion. A DENV-4 escape mutant that contained a Lys174-Glu substitution identical to that found in vitro was isolated from monkeys challenged with 106 MID50 of DENV-4. This substitution was also present in all naturally occurring isolates belonging to DENV-4 genotype III. These studies have important implications for possible antibody-mediated prevention of DENV infection.

scholarly journals Children with Invasive Staphylococcus aureus Disease Exhibit a Potently Neutralizing Antibody Response to the Cytotoxin LukAB

2013 ◽  
Vol 82 (3) ◽  
pp. 1234-1242 ◽  
Author(s):  
Isaac P. Thomsen ◽  
Ashley L. DuMont ◽  
David B. A James ◽  
Pauline Yoong ◽  
Benjamin R. Saville ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibody Response ◽  
High Titer ◽  
Humoral Response ◽  
Neutralizing Antibody ◽  
Human Neutrophils ◽  
Serum Samples ◽  
Marked Rise ◽  
Content Type

ABSTRACTDespite the importance ofStaphylococcus aureusas a common invasive bacterial pathogen, the humoral response to infection remains inadequately defined, particularly in children. The purpose of this study was to assess the humoral response to extracellular staphylococcal virulence factors, including the bicomponent leukotoxins, which are critical for the cytotoxicity ofS. aureustoward human neutrophils. Children with culture-provenS. aureusinfection were prospectively enrolled and stratified by disease type. Fifty-three children were enrolled in the study, of which 90% had invasive disease. Serum samples were obtained during the acute (within 48 h) and convalescent (4 to 6 weeks postinfection) phases, at which point both IgG titers againstS. aureusexotoxins were determined, and the functionality of the generated antibodies was evaluated. Molecular characterization of clinical isolates was also performed. We observed a marked rise in antibody titer from acute-phase to convalescent-phase sera for LukAB, the most recently describedS. aureusbicomponent leukotoxin. LukAB production by the isolates was strongly correlated with cytotoxicityin vitro, and sera containing anti-LukAB antibodies potently neutralized cytotoxicity. Antibodies toS. aureusantigens were detectable in healthy pediatric controls but at much lower titers than in sera from infected subjects. The discovery of a high-titer, neutralizing antibody response to LukAB during invasive infections suggests that this toxin is producedin vivoand that it elicits a functional humoral response.

scholarly journals Weak Cross-Lineage Neutralization by Anti SARS-CoV-2 Spike Antibodies after Natural Infection or Vaccination Is Rescued by Repeated Immunological Stimulation

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1124
Author(s):  
Sara Caucci ◽  
Benedetta Corvaro ◽  
Sofia Maria Luigia Tiano ◽  
Anna Valenza ◽  
Roberta Longo ◽  
...  
Keyword(s):  
Single Dose ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Natural Immunity ◽  
Anamnestic Response ◽  
Neutralizing Activity ◽  
Immunological Markers ◽  
The Cross ◽  
One Year

After over one year of evolution, through billions of infections in humans, SARS-CoV-2 has evolved into a score of slightly divergent lineages. A few different amino acids in the spike proteins of these lineages can hamper both natural immunity against reinfection, and vaccine efficacy. In this study, the in vitro neutralizing potency of sera from convalescent COVID-19 patients and vaccinated subjects was analyzed against six different SARS-CoV-2 lineages, including the latest B.1.617.2 (or Delta variant), in order to assess the cross-neutralization by anti-spike antibodies. After both single dose vaccination, or natural infection, the neutralizing activity was low and fully effective only against the original lineage, while a double dose or a single dose of vaccine, even one year after natural infection, boosted the cross-neutralizing activity against different lineages. Neither binding, nor the neutralizing activity of sera after vaccination, could predict vaccine failure, underlining the need for additional immunological markers. This study points at the importance of the anamnestic response and repeated vaccine stimulations to elicit a reasonable cross-lineage neutralizing antibody response.

scholarly journals A Recombinant Protein SARS-CoV-2 Candidate Vaccine Elicits High-titer Neutralizing Antibodies in Macaques.

2021 ◽  
Author(s):  
Gary Baisa ◽  
David Rancour ◽  
Keith Mansfield ◽  
Monika Burns ◽  
Lori Martin ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
High Titer ◽  
Binding Domain ◽  
Pseudotyped Virus ◽  
Receptor Binding Domain ◽  
Binding Assays ◽  
Neutralizing Activity ◽  
Terminal Domain

Abstract BackgroundVaccines that generate robust and long-lived protective immunity against SARS-CoV-2 infection are urgently required. MethodsWe assessed the potential of vaccine candidates based on the SARS-CoV-2 spike in cynomolgus macaques (M. fascicularis) by examining their ability to generate spike binding antibodies with neutralizing activity. Antigens were derived from two distinct regions of the spike S1 subunit, either the N-terminal domain or an extended C-terminal domain containing the receptor-binding domain and were fused to the human IgG1 Fc domain. Three groups of 2 animals each were immunized with either antigen, alone or in combination. The development of antibody responses was evaluated through 20 weeks post-immunization. ResultsA robust IgG response to the spike protein was detected as early as 2 weeks after immunization with either protein and maintained for over 20 weeks. Sera from animals immunized with antigens derived from the RBD were able to prevent binding of soluble spike proteins to the ACE2 receptor, shown by in vitro binding assays, while sera from animals immunized with the N-terminal domain alone lacked this activity. Crucially, sera from animals immunized with the extended receptor binding domain but not the N-terminal domain had potent neutralizing activity against SARS-CoV-2 pseudotyped virus, with titers in excess of 10,000, greatly exceeding that typically found in convalescent humans. Neutralizing activity persisted for more than 20 weeks. ConclusionsThese data support the utility of spike subunit-based antigens as a vaccine for use in humans.

scholarly journals A recombinant protein SARS-CoV-2 candidate vaccine elicits high-titer neutralizing antibodies in macaques.

2020 ◽  
Author(s):  
Gary Baisa ◽  
David Rancour ◽  
Keith Mansfield ◽  
Monika Burns ◽  
Lori Martin ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
High Titer ◽  
Pseudotyped Virus ◽  
Binding Assays ◽  
Neutralizing Activity ◽  
Terminal Domain ◽  
Vitro Binding ◽  
Cynomolgus Macaques ◽  
Human Igg1

Vaccines that generate robust and long-lived protective immunity against SARS-CoV-2 infection are urgently required. We assessed the potential of vaccine candidates based on the SARS-CoV-2 spike in cynomolgus macaques (M. fascicularis) by examining their ability to generate spike binding antibodies with neutralizing activity. Antigens were derived from two distinct regions of the spike S1 subunit, either the N-terminal domain (NTD) or an extended C-terminal domain containing the receptor-binding domain (RBD) and were fused to the human IgG1 Fc domain. Three groups of 2 animals each were immunized with either each antigen, alone or in combination. The development of antibody responses was evaluated through 20 weeks post-immunization. A robust IgG response to the spike protein was detected as early as 2 weeks after immunization with either protein and was maintained for over 20 weeks. Sera from animals immunized with antigens derived from the RBD were able to prevent binding of soluble spike proteins to the ACE2 receptor, shown by in vitro binding assays, while sera from animals immunized with the NTD alone lacked this activity. Crucially, sera from animals immunized with the RBD but not the NTD had potent neutralizing activity against SARS-CoV-2 pseudotyped virus, with titers in excess of 10,000, greatly exceeding that typically found in convalescent humans. Neutralizing activity persisted for more than 20 weeks. These data support the utility of spike subunit-based antigens as a vaccine for use in humans.

scholarly journals Enveloped Virus-Like Particle Expression of Human Cytomegalovirus Glycoprotein B Antigen Induces Antibodies with Potent and Broad Neutralizing Activity

2013 ◽  
Vol 21 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Marc Kirchmeier ◽  
Anne-Catherine Fluckiger ◽  
Catalina Soare ◽  
Jasminka Bozic ◽  
Barthelemy Ontsouka ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Matrix Protein ◽  
High Titer ◽  
Neutralizing Antibody ◽  
Glycoprotein B ◽  
Solid Organ ◽  
Neutralizing Activity ◽  
Enveloped Virus

ABSTRACTA prophylactic vaccine to prevent the congenital transmission of human cytomegalovirus (HCMV) in newborns and to reduce life-threatening disease in immunosuppressed recipients of HCMV-infected solid organ transplants is highly desirable. Neutralizing antibodies against HCMV confer significant protection against infection, and glycoprotein B (gB) is a major target of such neutralizing antibodies. However, one shortcoming of past HCMV vaccines may have been their failure to induce high-titer persistent neutralizing antibody responses that prevent the infection of epithelial cells. We used enveloped virus-like particles (eVLPs), in which particles were produced in cells after the expression of murine leukemia virus (MLV) viral matrix protein Gag, to express either full-length CMV gB (gB eVLPs) or the full extracellular domain of CMV gB fused with the transmembrane and cytoplasmic domains from vesicular stomatitis virus (VSV)-G protein (gB-G eVLPs). gB-G-expressing eVLPs induced potent neutralizing antibodies in mice with a much greater propensity toward epithelial cell-neutralizing activity than that induced with soluble recombinant gB protein. An analysis of gB antibody binding titers and T-helper cell responses demonstrated that high neutralizing antibody titers were not simply due to enhanced immunogenicity of the gB-G eVLPs. The cells transiently transfected with gB-G but not gB plasmid formed syncytia, consistent with a prefusion gB conformation like those of infected cells and viral particles. Two of the five gB-G eVLP-induced monoclonal antibodies we examined in detail had neutralizing activities, one of which possessed particularly potent epithelial cell-neutralizing activity. These data differentiate gB-G eVLPs from gB antigens used in the past and support their use in a CMV vaccine candidate with improved neutralizing activity against epithelial cell infection.

scholarly journals Studies of the Neutralizing Activity and Avidity of Anti-Human Immunodeficiency Virus Type 1 Env Antibody Elicited by DNA Priming and Protein Boosting

1998 ◽  
Vol 72 (11) ◽  
pp. 9092-9100 ◽  
Author(s):  
J. F. L. Richmond ◽  
S. Lu ◽  
J. C. Santoro ◽  
J. Weng ◽  
Shiu-Lok Hu ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
High Titer ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Neutralizing Activity ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT DNA vaccination is an effective means of eliciting strong antibody responses to a number of viral antigens. However, DNA immunization alone has not generated persistent, high-titer antibody and neutralizing antibody responses to human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env). We have previously reported that DNA-primed anti-Env antibody responses can be augmented by boosting with Env-expressing recombinant vaccinia viruses. We report here that recombinant Env protein provides a more effective boost of DNA-initiated antibody responses. In rabbits primed with Env-expressing plasmids, protein boosting increased titer, persistence, neutralizing activity, and avidity of anti-Env responses. While titers increased rapidly after boosting, avidity and neutralizing activity matured more slowly over a 6-month period following protein boosting. DNA priming and protein immunization with HIV-1 HXB-2 Env elicited neutralizing antibody for T cell line-adapted, but not primary isolate, viruses. The most effective neutralizing antibody responses were observed after priming with plasmids which expressed noninfectious virus-like particles. In contrast to immunizations with HIV-1 Env, DNA immunizations with the influenza virus hemagglutinin glycoprotein did not require a protein boost to achieve high-titer antibody with good avidity and persistence.

scholarly journals In vitro neutralizing activity of BNT162b2 mRNA-induced antibodies against full B.1.351 SARS-CoV-2 variant

2021 ◽  
Author(s):  
Federico García ◽  
Esther Serrano-Conde ◽  
Alba Leyva ◽  
Ana Fuentes-Lopez ◽  
Adolfo de Salazar ◽  
...  
Keyword(s):  
Single Dose ◽  
Antibody Response ◽  
Neutralizing Antibodies ◽  
Healthcare Workers ◽  
Neutralizing Antibody ◽  
Neutralization Activity ◽  
Neutralizing Activity ◽  
Study Participants ◽  
Prior Infection

Background: SARS-CoV-2 variation represents a serious challenge to current COVID-19 vaccines. Recent reports suggest that B.1.351 and other variants may escape the neutralization activity of the antibodies generated by current vaccines. Methods: Ninety-nine healthcare workers undertaking BNT162b2 mRNA vaccination were sampled at baseline, on the day of the second dose, and 14 days after the latter. Neutralization activity against SARS-CoV-2 B.1, B.1.1.7 and B.1.351 was investigated using a Vero-E6 model. Results: Eleven of the study participants had prior infection with SARS-CoV-2. Neutralization titers against the B.1 and the B.1.1.7 variants were not statistically different and were significantly higher than titers against the B.1.351 variant across pre-exposed and non-pre-exposed vaccinated individuals ( p<0.01). While all vaccinated individuals presented neutralizing antibodies against B.1 and B 1.1.7 after the second dose, 14% were negative against B.1.351, and 76% had low titers (1/20-1/80). Pre-exposed vaccinated individuals showed higher titers than non-pre-exposed after the first (median titers of 1/387 versus 1/28, respectively) and the second doses (1/995 versus 1/703, respectively). As high as 72% of the pre-exposed vaccinees presented titers >1/80 after a single dose, while only 11% of non-exposed vaccinated individuals had titers >1/80. Conclusions: BNT162b2 mRNA-induced antibodies show a lower in vitro neutralizing activity against B.1.351 variant compared to neutralization against B.1.1.7 or B.1 variants. Interestingly, for individuals pre-exposed to SARS-CoV-2, one dose of BNT162b2 mRNA may be adequate to produce neutralizing antibodies against B.1.1.7 and B.1, while two doses of BNT162b2 mRNA provide optimal neutralizing antibody response against B.1.351 too.

Hypercoagulability Syndrome Due to Heparin Co-Factor Deficiency

1964 ◽  
Vol 11 (02) ◽  
pp. 485-496 ◽  
Author(s):  
B. J Koszewski ◽  
H Vahabzadeh
Keyword(s):  
Dynamic Process ◽  
Blood Clotting ◽  
Complete Recovery ◽  
Inhibition Test ◽  
Factor Deficiency ◽  
Heparin Resistance ◽  
Fever Therapy ◽  
Intensive Course ◽  
Plasma Infusions

SummaryA case of hypercoagulability syndrome in a 35 years old male is reported. An abnormal heparin resistance was found which could be defined by means of a heparin clot-inhibition test as a deficiency in heparin co-factor. The required anticoagulant doses of heparin were forty times as high as in cases with intact heparin co-factor. The factor seemed to be used up in the process of coagulation, as plasma, but not serum, was able to correct the deficiency in vitro. Plasma infusions were helpful for four days, but a complete recovery was achieved only after an intensive course of fever therapy.The phenomenon of blood clotting should be regarded as a dynamic process which is facilitated by an array of clot promoting factors and opposed by a system of natural anticoagulants.

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