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Alter, Galit

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Alter

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Galit

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Alter, Galit
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    IFN-γ-independent immune markers of Mycobacterium tuberculosis exposure
    (Springer Science and Business Media LLC, 2019-05-20) Lu, Lenette; Smith, Malisa; Yu, Krystle K. Q.; Luedemann, Corinne; Suscovich, Todd; Grace, Patricia; Cain, Adam; Yu, Wen-Han; McKitrick, Tanya; Lauffenburger, Douglas; Cummings, Richard; Mayanja-Kizza, Harriet; Hawn, Thomas R.; Boom, W. Henry; Stein, Catherine M.; Fortune, Sarah; Seshadri, Chetan; Alter, Galit
    Exposure to Mycobacterium tuberculosis (Mtb) results in heterogeneous clinical outcomes including primary progressive tuberculosis and latent Mtb infection (LTBI). Mtb infection is identified using the tuberculin skin test and interferon-γ (IFN-γ) release assay IGRA, and a positive result may prompt chemoprophylaxis to prevent progression to tuberculosis. In the present study, we report on a cohort of Ugandan individuals who were household contacts of patients with TB. These individuals were highly exposed to Mtb but tested negative by IFN-γ release assay and tuberculin skin test, ‘resisting’ development of classic LTBI. We show that ‘resisters’ possess IgM, class-switched IgG antibody responses and non-IFN-γ T cell responses to the Mtb-specific proteins ESAT6 and CFP10, immunologic evidence of exposure to Mtb. Compared to subjects with classic LTBI, ‘resisters’ display enhanced antibody avidity and distinct Mtb-specific IgG Fc profiles. These data reveal a distinctive adaptive immune profile among Mtb-exposed subjects, supporting an expanded definition of the host response to Mtb exposure, with implications for public health and the design of clinical trials.
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    Ultrasensitive high-resolution profiling of early seroconversion in patients with COVID-19
    (Springer Science and Business Media LLC, 2020-09-18) Norman, Maia; Gilboa Hitron, Tal; Ogata, Alana F.; Maley, Adam M.; Cohen, Limor; Cai, Yongfei; Zhang, Jun; Feldman, Jared E.; Hauser, Blake M.; Caradonna, Timothy M.; Chen, Bing; Schmidt, Aaron G.; Alter, Galit; Charles, Richelle C.; Ryan, Edward T.; Walt, David R.
    The COVID-19 pandemic continues to infect millions of people worldwide. In order to curb its spread and reduce morbidity and mortality, it is essential to develop sensitive and quantitative methods that identify infected individuals and enable accurate population-wide screening of both past and present infection. Here we show that Single Molecule Array assays detect seroconversion in COVID-19 patients as soon as one day after symptom onset using less than a microliter of blood. This multiplexed assay format allows us to quantitate IgG, IgM and IgA immunoglobulins against four SARS-CoV-2 targets, thereby interrogating 12 antibody isotype-viral protein interactions to give a high resolution profile of the immune response. Using a cohort of samples collected prior to the outbreak as well as samples collected during the pandemic, we demonstrate a sensitivity of 86% and a specificity of 100% during the first week of infection, and 100% sensitivity and specificity thereafter. This assay should become the gold standard for COVID19 serological profiling and will be a valuable tool for answering important questions about the heterogeneity of clinical presentation seen in the ongoing pandemic.
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    Modest Attenuation of HIV-1 Vpu Alleles Derived from Elite Controller Plasma
    (Public Library of Science, 2015) Chen, Jingyan; Tibroni, Nadine; Sauter, Daniel; Galaski, Johanna; Miura, Toshiyuki; Alter, Galit; Mueller, Birthe; Haller, Claudia; Walker, Bruce; Kirchhoff, Frank; Brumme, Zabrina L.; Ueno, Takamasa; Fackler, Oliver T.
    In the absence of antiretroviral therapy, infection with human immunodeficiency virus type 1 (HIV-1) can typically not be controlled by the infected host and results in the development of acquired immunodeficiency. In rare cases, however, patients spontaneously control HIV-1 replication. Mechanisms by which such elite controllers (ECs) achieve control of HIV-1 replication include particularly efficient immune responses as well as reduced fitness of the specific virus strains. To address whether polymorphisms in the accessory HIV-1 protein Vpu are associated with EC status we functionally analyzed a panel of plasma-derived vpu alleles from 15 EC and 16 chronic progressor (CP) patients. Antagonism of the HIV particle release restriction by the intrinsic immunity factor CD317/tetherin was well conserved among EC and CP Vpu alleles, underscoring the selective advantage of this Vpu function in HIV-1 infected individuals. In contrast, interference with CD317/tetherin induced NF-κB activation was little conserved in both groups. EC Vpus more frequently displayed reduced ability to downregulate cell surface levels of CD4 and MHC class I (MHC-I) molecules as well as of the NK cell ligand NTB-A. Polymorphisms potentially associated with high affinity interactions of the inhibitory killer immunoglobulin-like receptor (KIR) KIR2DL2 were significantly enriched among EC Vpus but did not account for these functional differences. Together these results suggest that in a subgroup of EC patients, some Vpu functions are modestly reduced, possibly as a result of host selection.
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    CD39 Expression Identifies Terminally Exhausted CD8+ T Cells
    (Public Library of Science, 2015) Gupta, Prakash K.; Godec, Jernej; Wolski, David; Adland, Emily; Yates, Kathleen; Pauken, Kristen E.; Cosgrove, Cormac; Ledderose, Carola; Junger, Wolfgang; Robson, Simon; Wherry, E. John; Alter, Galit; Goulder, Philip J. R.; Klenerman, Paul; Sharpe, Arlene; Lauer, Georg; Haining, W. Nicholas
    Exhausted T cells express multiple co-inhibitory molecules that impair their function and limit immunity to chronic viral infection. Defining novel markers of exhaustion is important both for identifying and potentially reversing T cell exhaustion. Herein, we show that the ectonucleotidse CD39 is a marker of exhausted CD8+ T cells. CD8+ T cells specific for HCV or HIV express high levels of CD39, but those specific for EBV and CMV do not. CD39 expressed by CD8+ T cells in chronic infection is enzymatically active, co-expressed with PD-1, marks cells with a transcriptional signature of T cell exhaustion and correlates with viral load in HIV and HCV. In the mouse model of chronic Lymphocytic Choriomeningitis Virus infection, virus-specific CD8+ T cells contain a population of CD39high CD8+ T cells that is absent in functional memory cells elicited by acute infection. This CD39high CD8+ T cell population is enriched for cells with the phenotypic and functional profile of terminal exhaustion. These findings provide a new marker of T cell exhaustion, and implicate the purinergic pathway in the regulation of T cell exhaustion.
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    Plasma CXCL13 but Not B Cell Frequencies in Acute HIV Infection Predicts Emergence of Cross-Neutralizing Antibodies
    (Frontiers Media S.A., 2017) Mabuka, Jenniffer M.; Dugast, Anne-Sophie; Muema, Daniel M.; Reddy, Tarylee; Ramlakhan, Yathisha; Euler, Zelda; Ismail, Nasreen; Moodley, Amber; Dong, Krista L.; Morris, Lynn; Walker, Bruce; Alter, Galit; Ndung’u, Thumbi
    Immunological events in acute HIV-1 infection before peak viremia (hyperacute phase) may contribute to the development of broadly cross-neutralizing antibodies. Here, we used pre-infection and acute-infection peripheral blood mononuclear cells and plasma samples from 22 women, including 10 who initiated antiretroviral treatment in Fiebig stages I–V of acute infection to study B cell subsets and B-cell associated cytokines (BAFF and CXCL13) kinetics for up to ~90 days post detection of plasma viremia. Frequencies of B cell subsets were defined by flow cytometry while plasma cytokine levels were measured by ELISA. We observed a rapid but transient increase in exhausted tissue-like memory, activated memory, and plasmablast B cells accompanied by decline in resting memory cells in untreated, but not treated women. B cell subset frequencies in untreated women positively correlated with viral loads but did not predict emergence of cross-neutralizing antibodies measured 12 months post detection of plasma viremia. Plasma BAFF and CXCL13 levels increased only in untreated women, but their levels did not correlate with viral loads. Importantly, early CXCL13 but not BAFF levels predicted the later emergence of detectable cross-neutralizing antibodies at 12 months post detection of plasma viremia. Thus, hyperacute HIV-1 infection is associated with B cell subset changes, which do not predict emergence of cross-neutralizing antibodies. However, plasma CXCL13 levels during hyperacute infection predicted the subsequent emergence of cross-neutralizing antibodies, providing a potential biomarker for the evaluation of vaccines designed to elicit cross-neutralizing activity or for natural infection studies to explore mechanisms underlying development of neutralizing antibodies.
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    Exploiting glycan topography for computational design of Env glycoprotein antigenicity
    (Public Library of Science, 2018) Yu, Wen-Han; Zhao, Peng; Draghi, Monia; Arevalo, Claudia; Karsten, Christina; Suscovich, Todd J.; Gunn, Bronwyn; Streeck, Hendrik; Brass, Abraham L.; Tiemeyer, Michael; Seaman, Michael; Mascola, John R.; Wells, Lance; Lauffenburger, Douglas A.; Alter, Galit
    Mounting evidence suggests that glycans, rather than merely serving as a “shield”, contribute critically to antigenicity of the HIV envelope (Env) glycoprotein, representing critical antigenic determinants for many broadly neutralizing antibodies (bNAbs). While many studies have focused on defining the role of individual glycans or groups of proximal glycans in bNAb binding, little is known about the effects of changes in the overall glycan landscape in modulating antibody access and Env antigenicity. Here we developed a systems glycobiology approach to reverse engineer the complexity of HIV glycan heterogeneity to guide antigenicity-based de novo glycoprotein design. bNAb binding was assessed against a panel of 94 recombinant gp120 monomers exhibiting defined glycan site occupancies. Using a Bayesian machine learning algorithm, bNAb-specific glycan footprints were identified and used to design antigens that selectively alter bNAb antigenicity as a proof-of concept. Our approach provides a new design strategy to predictively modulate antigenicity via the alteration of glycan topography, thereby focusing the humoral immune response on sites of viral vulnerability for HIV.
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    Lack of Protection following Passive Transfer of Polyclonal Highly Functional Low-Dose Non-Neutralizing Antibodies
    (Public Library of Science, 2014) Dugast, Anne-Sophie; Chan, Ying; Hoffner, Michelle; Licht, Anna; Nkolola, Joseph; Li, Hualin; Streeck, Hendrik; Suscovich, Todd J.; Ghebremichael, Musie; Ackerman, Margaret E.; Barouch, Dan; Alter, Galit
    Recent immune correlates analysis from the RV144 vaccine trial has renewed interest in the role of non-neutralizing antibodies in mediating protection from infection. While neutralizing antibodies have proven difficult to induce through vaccination, extra-neutralizing antibodies, such as those that mediate antibody-dependent cellular cytotoxicity (ADCC), are associated with long-term control of infection. However, while several non-neutralizing monoclonal antibodies have been tested for their protective efficacy in vivo, no studies to date have tested the protective activity of naturally produced polyclonal antibodies from individuals harboring potent ADCC activity. Because ADCC-inducing antibodies are highly enriched in elite controllers (EC), we passively transferred highly functional non-neutralizing polyclonal antibodies, purified from an EC, to assess the potential impact of polyclonal non-neutralizing antibodies on a stringent SHIV-SF162P3 challenge in rhesus monkeys. Passive transfer of a low-dose of ADCC inducing antibodies did not protect from infection following SHIV-SF162P3 challenge. Passively administered antibody titers and gp120-specific, but not gp41-specific, ADCC and antibody induced phagocytosis (ADCP) were detected in the majority of the monkeys, but did not correlate with post infection viral control. Thus these data raise the possibility that gp120-specific ADCC activity alone may not be sufficient to control viremia post infection but that other specificities or Fc-effector profiles, alone or in combination, may have an impact on viral control and should be tested in future passive transfer experiments.
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    The Effects of Somatic Hypermutation on Neutralization and Binding in the PGT121 Family of Broadly Neutralizing HIV Antibodies
    (Public Library of Science, 2013) Sok, Devin; Laserson, U; Laserson, Jonathan; Liu, Yi; Vigneault, F; Julien, Jean-Philippe; Briney, Bryan; Ramos, Alejandra; Saye, Karen F.; Le, Khoa; Mahan, A; Wang, Shenshen; Kardar, Mehran; Yaari, Gur; Walker, Laura M.; Simen, Birgitte B.; St. John, Elizabeth P.; Chan-Hui, Po-Ying; Swiderek, Kristine; Kleinstein, Stephen H.; Alter, Galit; Seaman, Michael; Chakraborty, Arup K.; Koller, Daphne; Wilson, Ian A.; Church, George; Burton, Dennis R.; Poignard, Pascal
    Broadly neutralizing HIV antibodies (bnAbs) are typically highly somatically mutated, raising doubts as to whether they can be elicited by vaccination. We used 454 sequencing and designed a novel phylogenetic method to model lineage evolution of the bnAbs PGT121–134 and found a positive correlation between the level of somatic hypermutation (SHM) and the development of neutralization breadth and potency. Strikingly, putative intermediates were characterized that show approximately half the mutation level of PGT121–134 but were still capable of neutralizing roughly 40–80% of PGT121–134 sensitive viruses in a 74-virus panel at median titers between 15- and 3-fold higher than PGT121–134. Such antibodies with lower levels of SHM may be more amenable to elicitation through vaccination while still providing noteworthy coverage. Binding characterization indicated a preference of inferred intermediates for native Env binding over monomeric gp120, suggesting that the PGT121–134 lineage may have been selected for binding to native Env at some point during maturation. Analysis of glycan-dependent neutralization for inferred intermediates identified additional adjacent glycans that comprise the epitope and suggests changes in glycan dependency or recognition over the course of affinity maturation for this lineage. Finally, patterns of neutralization of inferred bnAb intermediates suggest hypotheses as to how SHM may lead to potent and broad HIV neutralization and provide important clues for immunogen design.
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    Altered distribution of mucosal NK cells during HIV infection
    (2013) Sips, Magdalena; Sciaranghella, Gaia; Diefenbach, Thomas; Dugast, Anne-Sophie; Berger, Christoph T.; Liu, Qingquan; Kwon, Douglas; Ghebremichael, Musie; Estes, Jacob D.; Carrington, Mary; Martin, Jeffrey N.; Deeks, Steven G.; Hunt, Peter W.; Alter, Galit
    The human gut mucosa is a major site of HIV infection and infection-associated pathogenesis. Increasing evidence shows that natural killer (NK) cells play an important role in control of HIV infection but the mechanism(s) by which they mediate antiviral activity in the gut is unclear. Here we show two distinct subsets of NK cells exist in the gut, one localized to intraepithelial spaces (IEL) and the other to the lamina propria (LP). The frequency of both subsets of NK cells was reduced in chronic infection, whereas IEL NK cells remained stable in spontaneous controllers with protective KIR/HLA genotypes. Both IEL and LP NK cells were significantly expanded in immunologic non-responsive (INR) patients, who incompletely recovered CD4+ T cells on HAART. These data suggest that both IEL and LP NK cells may expand in the gut in an effort to compensate for compromised CD4+ T cell recovery, but that only IEL NK cells may be involved in providing durable control of HIV in the gut,
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    Association of HLA-DRB1-restricted CD4+ T cell responses with HIV immune control
    (2013) Ranasinghe, Srinika; Cutler, Sam; Davis, Isaiah; Lu, Richard; Soghoian, Damien; Qi, Ying; Sidney, John; Kranias, Gregory; Flanders, Michael; Lindqvist, Madelene; Kuhl, Bjorn; Alter, Galit; Deeks, Steven G.; Walker, Bruce; Gao, Xiaojiang; Sette, Alessandro; Carrington, Mary; Streeck, Hendrik
    The contribution of HLA class II-restricted CD4+ T cell responses to HIV immune control is poorly defined. Here, we delineated novel peptide-DRB1 restrictions in functional assays and analyzed the host genetic effects of HLA-DRB1 alleles on HIV viremia in a large cohort of HIV controllers and progressors (n=1085). We found distinct stratifications in the effect of HLA-DRB1 alleles on HIV viremia, with DRB1*15:02 significantly associated with low viremia (P=0.003, q=0.04) and DRB1*03:01 significantly associated with high viremia (P=0.004, q=0.04). Interestingly, a sub-group of HLA-DRB1 alleles linked with low viremia showed the ability to promiscuously present a larger breadth of peptides with lower functional avidity when compared to HLA-DRB1 alleles linked with high viremia (p=0.018). Our data provide systematic evidence that HLA-DRB1 allele expression significantly impacts the durable control of HIV replication, an effect that appears to be mediated primarily by the protein-specificity of HIV-specific CD4+ T cell responses to Gag and Nef.