Browsing by Subject "Neutralizing antibodies"

Now showing 1 - 5 of 5
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    Cell-to-cell transmission of HIV-1 from provirus-activated cells to resting naïve and memory human primary CD4 T cells is highly efficient and requires CD4 and F-actin but not chemokine receptors
    (Wiley, 2022) Lan, Jie; Li, Wei; Yu, Richard; Syed, Fahim; Yu, Qigui; Microbiology and Immunology, School of Medicine
    Latently infected cells harboring replication-competent proviruses represent a major barrier to HIV-1 cure. One major effort to purge these cells has focused on developing the "shock and kill" approach for forcing provirus reactivation to induce cell killing by viral cytopathic effects, host immune responses, or both. We conducted kinetic and mechanistic studies of HIV-1 protein expression, virion production, and cell-to-cell virus transmission during provirus reactivation. Provirus-activated ACH-2 cells stimulated with romidepsin (RMD) or PMA produced Nef early, and then Env and Gag in parallel with the appearance of virions. Env on the surface of provirus-activated cells and cellular F-actin were critical in the formation of virological synapses to mediate cell-to-cell transmission of HIV-1 from provirus-activated cells to uninfected cells. This HIV-1 cell-to-cell transmission was substantially more efficient than transmission seen via cell-free virus spread and required F-actin remodeling and CD4, but not chemokine receptors. Resting human primary CD4+ T cells including naïve and memory subpopulations and, especially the memory CD4+ T cells, were highly susceptible to HIV-1 infection via cell-to-cell transmission. Cell-to-cell transmission of HIV-1 from provirus-activated cells was profoundly decreased by protease inhibitors (PIs) and neutralizing antibodies (nAbs) that recognize the CD4-binding site (CD4bs) such as VRC01, but not by reverse transcriptase (RT) inhibitor Emtricitabine (FTC). Therefore, our results suggest that PIs with potent blocking abilities should be used in clinical application of the "shock and kill" approach, most likely in combination with CD4bs nAbs, to prevent new HIV-1 infections.
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    Development of Combination Vaccine Conferring Optimal Protection against Six Pore-Forming Toxins of Staphylococcus aureus
    (American Society for Microbiology, 2021) Zhang, QingFeng; Jiang, TingTing; Mao, Xinrui; Kim, Jae Deog; Ahn, Dong Ho; Jung, Yunjin; Bae, Taeok; Lee, Bok Luel; Microbiology and Immunology, School of Medicine
    In the Gram-positive pathogen Staphylococcus aureus, pore-forming toxins (PFTs), such as leukocidins and hemolysins, play prominent roles in staphylococcal pathogenesis by killing host immune cells and red blood cells (RBCs). However, it remains unknown which combination of toxin antigens would induce the broadest protective immune response against those toxins. In this study, by targeting six major staphylococcal PFTs (i.e., gamma-hemolysin AB [HlgAB], gamma-hemolysin CB [HlgCB], leukocidin AB [LukAB], leukocidin ED [LukED], Panton-Valentine leukocidin [LukSF-PV], and alpha-hemolysin [Hla]), we generated 10 recombinant toxins or toxin subunits, 3 toxoids, and their rabbit antibodies. Using the cytolytic assay for RBCs and polymorphonuclear cells (PMNs), we determined the best combination of toxin antibodies conferring the broadest protection against those staphylococcal PFTs. Although anti-HlgA IgG (HlgA-IgG) showed low cross-reactivity to other toxin components, it was essential to protect rabbit and human RBCs and human PMNs. For the protection of rabbit RBCs, HlaH35L toxoid-IgG was also required, whereas for human PMNs, LukS-IgG and LukAE323AB-IgG were essential too. When the toxin/toxoid antigens HlgA, LukS-PV, HlaH35L, and LukAE323AB were used to immunize rabbits, they increased rabbit survival; however, they did not block staphylococcal abscess formation in kidneys. Based on these results, we proposed that the combination of HlgA, LukS, HlaH35L, and LukAE323AB is the optimal vaccine component to protect human RBCs and PMNs from staphylococcal PFTs. We also concluded that a successful S. aureus vaccine requires not only those toxin antigens but also other antigens that can induce immune responses blocking staphylococcal colonization.
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    Immune Response Mechanisms against AAV Vectors in Animal Models
    (Elsevier, 2020-06) Martino, Ashley T.; Markusic, David M.; Pediatrics, School of Medicine
    Early preclinical studies in rodents and other species did not reveal that vector or transgene immunity would present a significant hurdle for sustained gene expression. While there was early evidence of mild immune responses to adeno-associated virus (AAV) in preclinical studies, it was generally believed that these responses were too weak and transient to negatively impact sustained transduction. However, translation of the cumulative success in treating hemophilia B in rodents and dogs with an AAV2-F9 vector to human studies was not as successful. Despite significant progress in recent clinical trials for hemophilia, new immunotoxicities to AAV and transgene are emerging in humans that require better animal models to assess and overcome these responses. The animal models designed to address these immune complications have provided critical information to assess how vector dose, vector capsid processing, vector genome, difference in serotypes, and variations in vector delivery route can impact immunity and to develop approaches for overcoming pre-existing immunity. Additionally, a comprehensive dissection of innate, adaptive, and regulatory responses to AAV vectors in preclinical studies has provided a framework that can be utilized for development of immunomodulatory therapies to overcome or bypass immune responses and for developing strategic approaches toward engineering stealth AAV vectors that can circumvent immunity.
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    Neutralizing the Neutralizers in AAV Gene Therapy
    (Elsevier, 2020-08-05) Herzog, Roland W.; Biswas, Moanaro; Pediatrics, School of Medicine
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    Severe Acute Respiratory Syndrome Coronavirus 2 Convalescent Plasma Versus Standard Plasma in Coronavirus Disease 2019 Infected Hospitalized Patients in New York: A Double-Blind Randomized Trial
    (Wolters Kluwer, 2021) Bennett-Guerrero, Elliott; Romeiser, Jamie L.; Talbot, Lillian R.; Ahmed, Tahmeena; Mamone, Linda J.; Singh, Sunitha M.; Hearing, Janet C.; Salman, Huda; Holiprosad, Dishaw D.; Freedenberg, Alex T.; Carter, Jason A.; Browne, Nicholas J.; Cosgrove, Megan E.; Shevik, Margaret E.; Generale, Laura M.; Andrew, Margaret A.; Nachman, Sharon; Fries, Bettina C.; Stony Brook Medicine COVID Plasma Trial Group; Medicine, School of Medicine
    Objectives: Four peer-reviewed publications have reported results from randomized controlled trials of convalescent plasma for coronavirus disease 2019 infection; none were conducted in the United States nor used standard plasma as a comparator. To determine if administration of convalescent plasma to patients with coronavirus disease 2019 increases antibodies to severe acute respiratory syndrome coronavirus 2 and improves outcome. Design: Double-blind randomized controlled trial. Setting: Hospital in New York. Patients: Patients with polymerase chain reaction documented coronavirus disease 2019 infection. Interventions: Patients were randomized (4:1) to receive 2 U of convalescent plasma versus standard plasma. Antibodies to severe acute respiratory syndrome coronavirus 2 were measured in plasma units and in trial recipients. Measurements and main results: Enrollment was terminated after emergency use authorization was granted for convalescent plasma. Seventy-four patients were randomized. At baseline, mean (sd) Acute Physiology and Chronic Health Evaluation II score (23.4 [5.6] and 22.5 [6.6]), percent of patients intubated (19% and 20%), and median (interquartile range) days from symptom onset to randomization of 9 (6-18) and 9 (6-15), were similar in the convalescent plasma versus standard plasma arms, respectively. Convalescent plasma had high neutralizing activity (median [interquartile range] titer 1:526 [1:359-1:786]) and its administration increased antibodies to severe acute respiratory syndrome coronavirus 2 by 14.4%, whereas standard plasma administration led to an 8.6% decrease (p = 0.005). No difference was observed for ventilator-free days through 28 days (primary study endpoint): median (interquartile range) of 28 (2-28) versus 28 (0-28; p = 0.86) for the convalescent plasma and standard plasma groups, respectively. A greater than or equal to 2 point improvement in the World Health Organization scale was achieved by 20% of subjects in both arms (p = 0.99). All-cause mortality through 90 days was numerically lower in the convalescent plasma versus standard plasma groups (27% vs 33%; p = 0.63) but did not achieve statistical significance. A key prespecified subgroup analysis of time to death in patients who were intubated at baseline was statistically significant; however, sample size numbers were small. Conclusions: Administration of convalescent plasma to hospitalized patients with coronavirus disease 2019 infection increased antibodies to severe acute respiratory syndrome coronavirus disease 2 but was not associated with improved outcome.