Browsing by Author "Alter, Galit"

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    Determinants of protection among HIV‐exposed seronegative persons: an overview.
    (J Infect Dis, 2010-11-01) Lederman, Michael M; Alter, Galit; Daskalakis, Demetre C; Rodriguez, Benigno; Sieg, Scott F; Hardy, Gareth; Cho, Michael; Anthony, Donald; Harding, Clifford; Weinberg, Aaron; Silverman, Robert H; Douek, Daniel C; Margolis, Leonid; Goldstein, David B; Carrington, Mary; Goedert, James J
    Both clinical experience and a growing medical literature indicate that some persons who have been exposed to human immunodeficiency virus (HIV) infection remain uninfected. Although in some instances this may represent good fortune, cohorts of uninfected persons have been reported who are considered at high risk for infection. In these cohorts a variety of characteristics have been proposed as mediating protection, but to date only the 32–base pair deletion in the chemokine (C‐C motif) receptor 5 gene, which results in complete failure of cell surface expression of this coreceptor, has been associated with high‐level protection from HIV infection. With this in mind, there are probably many other factors that may individually or in combination provide some level of protection from acquisition of HIV infection. Because some of these factors are probably incompletely protective or inconsistently active, identifying them with confidence will be difficult. Nonetheless, clarifying the determinants of protection against HIV infection is a high priority that will require careful selection of high‐risk uninfected cohorts, who should undergo targeted studies of plausible mediators and broad screening for unexpected determinants of protection.
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    KIR polymorphisms modulate peptide-dependent binding to an MHC class I ligand with a Bw6 motif.
    (PLoS pathogens, 2011-03) Colantonio, Arnaud D; Bimber, Benjamin N; Neidermyer, William J; Reeves, R Keith; Alter, Galit; Altfeld, Marcus; Johnson, R Paul; Carrington, Mary; O'Connor, David H; Evans, David T
    Molecular interactions between killer immunoglobulin-like receptors (KIRs) and their MHC class I ligands play a central role in the regulation of natural killer (NK) cell responses to viral pathogens and tumors. Here we identify Mamu-A1*00201 (Mamu-A*02), a common MHC class I molecule in the rhesus macaque with a canonical Bw6 motif, as a ligand for Mamu-KIR3DL05. Mamu-A1*00201 tetramers folded with certain SIV peptides, but not others, directly stained primary NK cells and Jurkat cells expressing multiple allotypes of Mamu-KIR3DL05. Differences in binding avidity were associated with polymorphisms in the D0 and D1 domains of Mamu-KIR3DL05, whereas differences in peptide-selectivity mapped to the D1 domain. The reciprocal exchange of the third predicted MHC class I-contact loop of the D1 domain switched the specificity of two Mamu-KIR3DL05 allotypes for different Mamu-A1*00201-peptide complexes. Consistent with the function of an inhibitory KIR, incubation of lymphocytes from Mamu-KIR3DL05(+) macaques with target cells expressing Mamu-A1*00201 suppressed the degranulation of tetramer-positive NK cells. These observations reveal a previously unappreciated role for D1 polymorphisms in determining the selectivity of KIRs for MHC class I-bound peptides, and identify the first functional KIR-MHC class I interaction in the rhesus macaque. The modulation of KIR-MHC class I interactions by viral peptides has important implications to pathogenesis, since it suggests that the immunodeficiency viruses, and potentially other types of viruses and tumors, may acquire changes in epitopes that increase the affinity of certain MHC class I ligands for inhibitory KIRs to prevent the activation of specific NK cell subsets.
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    Maternal SARS-CoV-2 infection elicits sexually dimorphic placental immune responses.
    (Science translational medicine, 2021-10) Bordt, Evan A; Shook, Lydia L; Atyeo, Caroline; Pullen, Krista M; De Guzman, Rose M; Meinsohn, Marie-Charlotte; Chauvin, Maeva; Fischinger, Stephanie; Yockey, Laura J; James, Kaitlyn; Lima, Rosiane; Yonker, Lael M; Fasano, Alessio; Brigida, Sara; Bebell, Lisa M; Roberts, Drucilla J; Pépin, David; Huh, Jun R; Bilbo, Staci D; Li, Jonathan Z; Kaimal, Anjali; Schust, Danny J; Gray, Kathryn J; Lauffenburger, Douglas; Alter, Galit; Edlow, Andrea G
    There is a persistent bias toward higher prevalence and increased severity of coronavirus disease 2019 (COVID-19) in males. Underlying mechanisms accounting for this sex difference remain incompletely understood. Interferon responses have been implicated as a modulator of COVID-19 disease in adults and play a key role in the placental antiviral response. Moreover, the interferon response has been shown to alter Fc receptor expression and therefore may affect placental antibody transfer. Here, we examined the intersection of maternal-fetal antibody transfer, viral-induced placental interferon responses, and fetal sex in pregnant women infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Placental Fc receptor abundance, interferon-stimulated gene (ISG) expression, and SARS-CoV-2 antibody transfer were interrogated in 68 human pregnancies. Sexually dimorphic expression of placental Fc receptors, ISGs and proteins, and interleukin-10 was observed after maternal SARS-CoV-2 infection, with up-regulation of these features in placental tissue of pregnant individuals with male fetuses. Reduced maternal SARS-CoV-2–specific antibody titers and impaired placental antibody transfer were also observed in pregnancies with a male fetus. These results demonstrate fetal sex-specific maternal and placental adaptive and innate immune responses to SARS-CoV-2.
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    MHC class I chain-related protein A shedding in chronic HIV-1 infection is associated with profound NK cell dysfunction.
    (Virology, 2010-10) Nolting, Anne; Dugast, Anne-Sophie; Rihn, Suzannah; Luteijn, Rutger; Carrington, Mary F; Kane, Katherine; Jost, Stephanie; Toth, Ildiko; Nagami, Ellen; Faetkenheuer, Gerd; Hartmann, Pia; Altfeld, Marcus; Alter, Galit
    Natural killer (NK) cells play a critical role in host defense against viral infections. However chronic HIV-1 infection is associated with an accumulation of dysfunctional NK cells, that poorly control viral replication. The underlying mechanisms for this NK cell mediated dysfunction are not understood. Certain tumors evade NK cell mediated detection by dampening NK cell activity through the downregulation of NKG2D, via the release of soluble NKG2D-ligands, resulting in a potent suppression of NK cell function. Here we show that chronic HIV-1 infection is associated with a specific defect in NKG2D-mediated NK cell activation, due to reduced expression and transcription of NKG2D. Reduced NKG2D expression was associated with elevated levels of the soluble form of the NKG2D-ligand, MICA, in patient sera, likely released by HIV+CD4+ T cells. Thus, like tumors, HIV-1 may indirectly suppress NK cell recognition of HIV-1-infected CD4+ T cells by enhancing NKG2D-ligand secretion into the serum resulting in a profound impairment of NK cell function.
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    Single-shot Ad26 vaccine protects against SARS-CoV-2 in rhesus macaques.
    (Nature, 2020-10) Mercado, Noe B; Zahn, Roland; Wegmann, Frank; Loos, Carolin; Chandrashekar, Abishek; Yu, Jingyou; Liu, Jinyan; Peter, Lauren; McMahan, Katherine; Tostanoski, Lisa H; He, Xuan; Martinez, David R; Rutten, Lucy; Bos, Rinke; van Manen, Danielle; Vellinga, Jort; Custers, Jerome; Langedijk, Johannes P; Kwaks, Ted; Bakkers, Mark JG; Zuijdgeest, David; Rosendahl Huber, Sietske K; Atyeo, Caroline; Fischinger, Stephanie; Burke, John S; Feldman, Jared; Hauser, Blake M; Caradonna, Timothy M; Bondzie, Esther A; Dagotto, Gabriel; Gebre, Makda S; Hoffman, Emily; Jacob-Dolan, Catherine; Kirilova, Marinela; Li, Zhenfeng; Lin, Zijin; Mahrokhian, Shant H; Maxfield, Lori F; Nampanya, Felix; Nityanandam, Ramya; Nkolola, Joseph P; Patel, Shivani; Ventura, John D; Verrington, Kaylee; Wan, Huahua; Pessaint, Laurent; Van Ry, Alex; Blade, Kelvin; Strasbaugh, Amanda; Cabus, Mehtap; Brown, Renita; Cook, Anthony; Zouantchangadou, Serge; Teow, Elyse; Andersen, Hanne; Lewis, Mark G; Cai, Yongfei; Chen, Bing; Schmidt, Aaron G; Reeves, R Keith; Baric, Ralph S; Lauffenburger, Douglas A; Alter, Galit; Stoffels, Paul; Mammen, Mathai; Van Hoof, Johan; Schuitemaker, Hanneke; Barouch, Dan H
    A safe and effective vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be required to end the coronavirus disease 2019 (COVID-19) pandemic1-8. For global deployment and pandemic control, a vaccine that requires only a single immunization would be optimal. Here we show the immunogenicity and protective efficacy of a single dose of adenovirus serotype 26 (Ad26) vector-based vaccines expressing the SARS-CoV-2 spike (S) protein in non-human primates. Fifty-two rhesus macaques (Macaca mulatta) were immunized with Ad26 vectors that encoded S variants or sham control, and then challenged with SARS-CoV-2 by the intranasal and intratracheal routes9,10. The optimal Ad26 vaccine induced robust neutralizing antibody responses and provided complete or near-complete protection in bronchoalveolar lavage and nasal swabs after SARS-CoV-2 challenge. Titres of vaccine-elicited neutralizing antibodies correlated with protective efficacy, suggesting an immune correlate of protection. These data demonstrate robust single-shot vaccine protection against SARS-CoV-2 in non-human primates. The optimal Ad26 vector-based vaccine for SARS-CoV-2, termed Ad26.COV2.S, is currently being evaluated in clinical trials.
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    The humoral response to HIV-1: new insights, renewed focus.
    (J Infect Dis, 2010-10-15) Alter, Galit; Moody, M Anthony
    During the past 2 decades, significant advances in our understanding of the humoral immune response to human immunodeficiency virus type 1 (HIV-1) infection have been made, yet a tremendous amount of work lies ahead. Despite these advances, strategies to reliably induce antibodies that can control HIV-1 infection are still critically needed. However, recent advances in our understanding of the kinetics, specificity, and function of early humoral responses offer alternative new approaches to attain this goal. These results, along with the new broadly neutralizing antibody specificities, the role for other antibody functions, the increased understanding of HIV-1-induced changes to B cell biology, and results from the RV144 "Thai" trial showing potential modest sterilizing protection by nonneutralizing antibody responses, have renewed focus on the humoral system. In this review, recent advances in our understanding of the earliest humoral responses are discussed, highlighting presentations from the meeting on the Biology of Acute HIV Infection.