Treatment-Emergent Influenza Variant Viruses With Reduced Baloxavir Susceptibility: Impact on Clinical and Virologic Outcomes in Uncomplicated Influenza

Abstract Background Single-dose baloxavir rapidly reduces influenza virus titers and symptoms in patients with uncomplicated influenza, but viruses with reduced in vitro susceptibility due to amino acid substitutions at position 38 of polymerase acidic protein (PA/I38X) sometimes emerge. Methods We evaluated the kinetics, risk factors, and effects on clinical and virologic outcomes of emergence of PA/I38X-substituted viruses. Results Viruses containing PA/I38X substitutions were identified 3–9 days after baloxavir treatment in 9.7% (36/370) of patients, of whom 85.3% had transient virus titer rises. Median time to sustained cessation of infectious virus detection was 192, 48, and 96 hours in the baloxavir recipients with PA/I38X-substituted viruses, without PA/I38X-substituted viruses, and placebo recipients, respectively. The corresponding median times to alleviation of symptoms were 63.1, 51.0, and 80.2 hours, respectively. After day 5, symptom increases occurred in 11.5%, 8.0%, and 13.0%, respectively, and in 8.9% of oseltamivir recipients. Variant virus emergence was associated with lower baseline neutralizing antibody titers. Conclusions The emergence of viruses with PA/I38X substitutions following baloxavir treatment was associated with transient rises in infectious virus titers, prolongation of virus detectability, initial delay in symptom alleviation, and uncommonly with symptom rebound. The potential transmissibility of PA/I38X-substituted viruses requires careful study. Clinical Trial Registration NCT02954354.

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Multivalent nanoparticle-based vaccines protect hamsters against SARS-CoV-2 after a single immunization

Communications Biology ◽

10.1038/s42003-021-02128-8 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Shiho Chiba ◽

Steven J. Frey ◽

Peter J. Halfmann ◽

Makoto Kuroda ◽

Tadashi Maemura ◽

...

Keyword(s):

Coat Protein ◽

Infectious Virus ◽

Neutralizing Antibody ◽

Vaccine Platform ◽

Death Rates ◽

Widespread Distribution ◽

Syrian Hamsters ◽

Vaccine Trials ◽

Multiple Copies ◽

Antibody Titers

AbstractThe COVID-19 pandemic continues to wreak havoc as worldwide SARS-CoV-2 infection, hospitalization, and death rates climb unabated. Effective vaccines remain the most promising approach to counter SARS-CoV-2. Yet, while promising results are emerging from COVID-19 vaccine trials, the need for multiple doses and the challenges associated with the widespread distribution and administration of vaccines remain concerns. Here, we engineered the coat protein of the MS2 bacteriophage and generated nanoparticles displaying multiple copies of the SARS-CoV-2 spike (S) protein. The use of these nanoparticles as vaccines generated high neutralizing antibody titers and protected Syrian hamsters from a challenge with SARS-CoV-2 after a single immunization with no infectious virus detected in the lungs. This nanoparticle-based vaccine platform thus provides protection after a single immunization and may be broadly applicable for protecting against SARS-CoV-2 and future pathogens with pandemic potential.

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STUDIES ON THE PSITTACOSIS-LYMPHOGRANULOMA GROUP

Journal of Experimental Medicine ◽

10.1084/jem.96.3.233 ◽

1952 ◽

Vol 96 (3) ◽

pp. 233-246 ◽

Cited By ~ 13

Author(s):

Anthony J. Girardi ◽

Emma G. Allen ◽

M. Michael Sigel

Keyword(s):

Tissue Culture ◽

Infectious Virus ◽

Virus Titer ◽

Subsequent Development ◽

Developmental Cycle ◽

In Ovo ◽

Virus Inoculation ◽

Virus Adsorption ◽

Infectious Form

The pattern of growth of meningopneumonitis virus in vitro seemed to be similar to that occurring in ovo and thus the initial stages of development, the adsorption and the latent periods, were investigated by the use of tissue culture procedures. The initial increment of infectivity in allantoic membrane suspensions following virus inoculation in ovo was due to prolonged adsorption of virus and not to immediate virus reproduction. The length of the adsorption period varied with the virus dilution employed. The reduction of virus titer in allantoic membrane suspensions subsequent to adsorption was due to a change of infectious virus to a non-infectious form and this seemed to be a part of the normal developmental cycle of the virus. The possible causes for both prolonged virus adsorption and for the subsequent development of a non-infectious form are discussed.

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Antibody Protects Macaques against Vaginal Challenge with a Pathogenic R5 Simian/Human Immunodeficiency Virus at Serum Levels Giving Complete Neutralization In Vitro

Journal of Virology ◽

10.1128/jvi.75.17.8340-8347.2001 ◽

2001 ◽

Vol 75 (17) ◽

pp. 8340-8347 ◽

Cited By ~ 521

Author(s):

Paul W. H. I. Parren ◽

Preston A. Marx ◽

Ann J. Hessell ◽

Amara Luckay ◽

Janet Harouse ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Neutralizing Antibody ◽

Serum Levels ◽

Mucosal Transmission ◽

Infected People ◽

Virus Challenge ◽

Immunodeficiency Virus ◽

Antibody Titers ◽

Hiv 1

ABSTRACT A major unknown in human immunodeficiency virus (HIV-1) vaccine design is the efficacy of antibodies in preventing mucosal transmission of R5 viruses. These viruses, which use CCR5 as a coreceptor, appear to have a selective advantage in transmission of HIV-1 in humans. Hence R5 viruses predominate during primary infection and persist throughout the course of disease in most infected people. Vaginal challenge of macaques with chimeric simian/human immunodeficiency viruses (SHIV) is perhaps one of the best available animal models for human HIV-1 infection. Passive transfer studies are widely used to establish the conditions for antibody protection against viral challenge. Here we show that passive intravenous transfer of the human neutralizing monoclonal antibody b12 provides dose-dependent protection to macaques vaginally challenged with the R5 virus SHIV162P4. Four of four monkeys given 25 mg of b12 per kg of body weight 6 h prior to challenge showed no evidence of viral infection (sterile protection). Two of four monkeys given 5 mg of b12/kg were similarly protected, whereas the other two showed significantly reduced and delayed plasma viremia compared to control animals. In contrast, all four monkeys treated with a dose of 1 mg/kg became infected with viremia levels close to those for control animals. Antibody b12 serum concentrations at the time of virus challenge corresponded to approximately 400 (25 mg/kg), 80 (5 mg/kg), and 16 (1 mg/kg) times the in vitro (90%) neutralization titers. Therefore, complete protection against mucosal challenge with an R5 SHIV required essentially complete neutralization of the infecting virus. This suggests that a vaccine based on antibody alone would need to sustain serum neutralizing antibody titers (90%) of the order of 1:400 to achieve sterile protection but that lower titers, around 1:100, could provide a significant benefit. The significance of such substerilizing neutralizing antibody titers in the context of a potent cellular immune response is an important area for further study.

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Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

10.1101/2021.06.11.448032 ◽

2021 ◽

Author(s):

Margherita Rosati ◽

Mahesh Agarwal ◽

Xintao Hu ◽

Santhi Devasundaram ◽

Dimitris Stellas ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Protective Efficacy ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Anatomical Site ◽

Cell Responses ◽

Cellular Immune Responses ◽

Antibody Titers ◽

Cellular Immune

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

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SARS-CoV-2 seroprevalence and neutralizing activity in donor and patient blood from the San Francisco Bay Area

10.1101/2020.05.19.20107482 ◽

2020 ◽

Cited By ~ 18

Author(s):

Dianna L. Ng ◽

Gregory M. Goldgof ◽

Brian R. Shy ◽

Andrew G. Levine ◽

Joanna Balcerek ◽

...

Keyword(s):

San Francisco ◽

Immunoglobulin G ◽

Neutralizing Antibodies ◽

San Francisco Bay ◽

San Francisco Bay Area ◽

Neutralizing Antibody ◽

Immunoglobulin M ◽

Bay Area ◽

Antibody Titers

ABSTRACTWe report very low SARS-CoV-2 seroprevalence in two San Francisco Bay Area populations. Seropositivity was 0.26% in 387 hospitalized patients admitted for non-respiratory indications and 0.1% in 1,000 blood donors. We additionally describe the longitudinal dynamics of immunoglobulin-G, immunoglobulin-M, and in vitro neutralizing antibody titers in COVID-19 patients. Neutralizing antibodies rise in tandem with immunoglobulin levels following symptom onset, exhibiting median time to seroconversion within one day of each other, and there is >93% positive percent agreement between detection of immunoglobulin-G and neutralizing titers.

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Memory B Cells Encode Neutralizing Antibody Specific for Toxin B from the Clostridium difficile Strains VPI 10463 and NAP1/BI/027 but with Superior Neutralization of VPI 10463 Toxin B

Infection and Immunity ◽

10.1128/iai.00011-15 ◽

2015 ◽

Vol 84 (1) ◽

pp. 194-204 ◽

Cited By ~ 6

Author(s):

T. Scott Devera ◽

Gillian A. Lang ◽

Jordi M. Lanis ◽

Pragya Rampuria ◽

Casey L. Gilmore ◽

...

Keyword(s):

B Cells ◽

Clostridium Difficile ◽

Mononuclear Cells ◽

Neutralizing Antibody ◽

Memory B Cells ◽

Lethal Challenge ◽

Toxin B ◽

Content Type ◽

Antibody Titers

Secreted toxin B (TcdB) substantially contributes to the pathology observed duringClostridium difficileinfection. To be successfully incorporated into a vaccine, TcdB-based immunogens must stimulate the production of neutralizing antibody (Ab)-encoding memory B cells (Bmem cells). Despite numerous investigations, a clear analysis of Bmem cellular responses following vaccination against TcdB is lacking. B6 mice were therefore used to test the ability of a nontoxigenic C-terminal domain (CTD) fragment of TcdB to induce Bmem cells that encode TcdB-neutralizing antibody. CTD was produced from the historical VPI 10463 strain (CTD1) and from the hypervirulent strain NAP1/BI/027 (CTD2). It was then demonstrated that CTD1 induced strong recall IgG antibody titers, and this led to the development of functional Bmem cells that could be adoptively transferred to naive recipients. Bmem cell-driven neutralizing Ab responses conferred protection against lethal challenge with TcdB1. Further experiments revealed that an experimental adjuvant (Imject) and a clinical adjuvant (Alhydrogel) were compatible with Bmem cell induction. Reactivity of human Bmem cells to CTD1 was also evident in human peripheral blood mononuclear cells (PBMCs), suggesting that CTD1 could be a good vaccine immunogen. However, CTD2 induced strong Bmem cell-driven antibody titers, and the CTD2 antibody was neutralizingin vitro, but its protection against lethal challenge with TcdB2 was limited to delaying time to death. Therefore, CTD from differentC. difficilestrains may be a good immunogen for stimulating B cell memory that encodesin vitroneutralizing Ab but may be limited by variable protection against intoxicationin vivo.

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INFECTIOUS VIRUS-ANTIBODY COMPLEX IN THE BLOOD OF CHRONICALLY INFECTED MICE

Journal of Experimental Medicine ◽

10.1084/jem.124.1.81 ◽

1966 ◽

Vol 124 (1) ◽

pp. 81-97 ◽

Cited By ~ 104

Author(s):

Abner Louis Notkins ◽

Suellen Mahar ◽

Christina Scheele ◽

Joel Goffman

Keyword(s):

Infectious Virus ◽

Neutralizing Antibody ◽

Lactic Dehydrogenase ◽

Resistant Virus ◽

Virus Antibody ◽

In Vitro Exposure ◽

Antiviral Antibody ◽

Antibody Complex

If viremic sera from mice chronically infected with lactic dehydrogenase virus (LDV) were first treated with ether or ultraviolet light to inactivate the infectious virus, neutralizing antibody could be demonstrated. Significant amounts of antibody, however, were not detected until the mice had been infected for about 2½ months and its presence did not result in the elimination of the chronic viremia. Virus isolated from sera containing neutralizing antibody was found to be relatively resistant to neutralization by anti-LDV. Further studies revealed that the resistant virus existed in the form of an infectious virus-antibody complex (sensitized virus). The presence of such a complex was demonstrated by the fact that the virus fraction which persisted after in vivo or in vitro exposure to mouse anti-LDV was readily neutralized by goat anti-mouse sera or goat anti-mouse γ-globulin, whereas virus that had not been previously exposed to mouse anti-LDV was completely resistant to neutralization by goat anti-mouse sera. These findings suggest that (a) sensitization may play an important role in the resistance and susceptibility of a virus to neutralization by antiviral antibody, and (b) an anti-γ-globulin may prove useful in neutralizing the resistant fraction and in demonstrating otherwise undetectable antiviral antibody.

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SARS-CoV-2 seroprevalence and neutralizing activity in donor and patient blood

Nature Communications ◽

10.1038/s41467-020-18468-8 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 8

Author(s):

Dianna L. Ng ◽

Gregory M. Goldgof ◽

Brian R. Shy ◽

Andrew G. Levine ◽

Joanna Balcerek ◽

...

Keyword(s):

San Francisco ◽

Neutralizing Antibodies ◽

Neutralizing Antibody ◽

Immunoglobulin M ◽

Bay Area ◽

Neutralizing Capacity ◽

Antibody Titers ◽

Different Populations ◽

Low Prevalence

Abstract Given the limited availability of serological testing to date, the seroprevalence of SARS-CoV-2-specific antibodies in different populations has remained unclear. Here, we report very low SARS-CoV-2 seroprevalence in two San Francisco Bay Area populations. Seroreactivity was 0.26% in 387 hospitalized patients admitted for non-respiratory indications and 0.1% in 1,000 blood donors in early April 2020. We additionally describe the longitudinal dynamics of immunoglobulin-G (IgG), immunoglobulin-M (IgM), and in vitro neutralizing antibody titers in COVID-19 patients. The median time to seroconversion ranged from 10.3–11.0 days for these 3 assays. Neutralizing antibodies rose in tandem with immunoglobulin titers following symptom onset, and positive percent agreement between detection of IgG and neutralizing titers was >93%. These findings emphasize the importance of using highly accurate tests for surveillance studies in low-prevalence populations, and provide evidence that seroreactivity using SARS-CoV-2 anti-nucleocapsid protein IgG and anti-spike IgM assays are generally predictive of in vitro neutralizing capacity.

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Shedding of infectious SARS-CoV-2 by hospitalized COVID-19 patients in relation to serum antibody responses

BMC Infectious Diseases ◽

10.1186/s12879-021-06202-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Hedvig Glans ◽

Sara Gredmark-Russ ◽

Mikaela Olausson ◽

Sara Falck-Jones ◽

Renata Varnaite ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Serum Antibody ◽

Neutralizing Antibody ◽

University Hospital ◽

Pcr Analysis ◽

Symptom Duration ◽

Cross Sectional ◽

Antibody Titers ◽

Specific Igg

Abstract Background Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global pandemic. The understanding of the transmission and the duration of viral shedding in SARS-CoV-2 infection is still limited. Objectives To assess the timeframe and potential risk of SARS-CoV-2 transmission from hospitalized COVID-19 patients in relation to antibody response. Method We performed a cross-sectional study of 36 COVID-19 patients hospitalized at Karolinska University Hospital. Patients with more than 8 days of symptom duration were sampled from airways, for PCR analysis of SARS-CoV-2 RNA and in vitro culture of replicating virus. Serum SARS-CoV-2-specific immunoglobulin G (IgG) and neutralizing antibodies titers were assessed by immunofluorescence assay (IFA) and microneutralization assay. Results SARS-CoV-2 RNA was detected in airway samples in 23 patients (symptom duration median 15 days, range 9–53 days), whereas 13 patients were SARS-CoV-2 RNA negative (symptom duration median 21 days, range 10–37 days). Replicating virus was detected in samples from 4 patients at 9–16 days. All but two patients had detectable levels of SARS-CoV-2-specific IgG in serum, and SARS-CoV-2 neutralizing antibodies were detected in 33 out of 36 patients. Total SARS-CoV-2-specific IgG titers and neutralizing antibody titers were positively correlated. High levels of both total IgG and neutralizing antibody titers were observed in patients sampled later after symptom onset and in patients where replicating virus could not be detected. Conclusions Our data suggest that the presence of SARS-Cov-2 specific antibodies in serum may indicate a lower risk of shedding infectious SARS-CoV-2 by hospitalized COVID-19 patients.

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Rapid Immune Responses to a Botulinum Neurotoxin Hc Subunit Vaccine throughIn VivoTargeting to Antigen-Presenting Cells

Infection and Immunity ◽

10.1128/iai.00166-11 ◽

2011 ◽

Vol 79 (8) ◽

pp. 3388-3396 ◽

Cited By ~ 13

Author(s):

David M. White ◽

Sabine Pellett ◽

Mark A. Jensen ◽

William H. Tepp ◽

Eric A. Johnson ◽

...

Keyword(s):

Immune Responses ◽

Neutralizing Antibody ◽

Antigen Presenting Cells ◽

Binding Assays ◽

Content Type ◽

Botulinum Neurotoxins ◽

Protein Toxins ◽

Antibody Titers ◽

Antigen Presenting

ABSTRACTThe clostridial botulinum neurotoxins (BoNTs) are the most potent protein toxins known. The carboxyl-terminal fragment of the toxin heavy chain (Hc) has been intensively investigated as a BoNT vaccine immunogen. We sought to determine whether targeting Hc to antigen-presenting cells (APCs) could accelerate the immune responses to vaccination with BoNT serotype A (BoNT/A) Hc. To test this hypothesis, we targeted Hc to the Fc receptors for IgG (FcγRs) expressed by dendritic cells (DCs) and other APCs. Hc was expressed as a fusion protein with a recombinant ligand for human FcγRs (R4) to produce HcR4 or a similar ligand for murine FcγRs to produce HcmR4. HcR4, HcmR4, and Hc were produced as secreted proteins using baculovirus-mediated expression in SF9 insect cells.In vitroreceptor binding assays showed that HcR4 effectively targets Hc to all classes of FcγRs. APCs loaded with HcR4 or HcmR4 are substantially more effective at stimulating Hc-reactive T cells than APCs loaded with nontargeted Hc. Mice immunized with a single dose of HcmR4 or HcR4 had earlier and markedly higher Hc-reactive antibody titers than mice immunized with nontargeted Hc. These results extend to BoNT neutralizing antibody titers, which are substantially higher in mice immunized with HcmR4 than in mice immunized with Hc. Our results demonstrate that targeting Hc to FcγRs augments the pace and magnitude of immune responses to Hc.

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