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ABSTRACT: Influenza remains one of the most important causes of respiratory infection despite the widespread availability of vaccines. As effective vaccines against influenza principally rely on the induction of strain-specific neutralizing antibodies for their protective efficacy, drifted escape mutants and genetically reassortant pandemic strains can rapidly overcome them. Several groups have recently described cross-reactive influenza antibodies in humans, some of which bind to the conserved hemagglutinin stem. If such antibodies could be consistently induced at high levels by vaccines, they might protect against both seasonal and pandemic influenza strains. Here we discuss the humoral responses to influenza infection and vaccination, with particular reference to the pandemic H1N1 2009 virus and induction of broadly cross-reactive stem-binding antibodies. Having shown that cross-reactive antibodies are preferentially induced by a pandemic hemagglutinin, the challenge is now to design a vaccine that applies these principles to the induction of heterosubtypic immunity.
Annals of the New York Academy of Sciences 02/2013; · 3.15 Impact Factor
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Gui-Mei Li,
Christopher Chiu,
Jens Wrammert, Megan McCausland,
Sarah F Andrews,
Nai-Ying Zheng,
Jane-Hwei Lee,
Min Huang,
Xinyan Qu,
Srilatha Edupuganti,
Mark Mulligan,
Suman R Das,
Jonathan W Yewdell,
Aneesh K Mehta,
Patrick C Wilson,
Rafi Ahmed
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ABSTRACT: We have previously shown that broadly neutralizing antibodies reactive to the conserved stem region of the influenza virus hemagglutinin (HA) were generated in people infected with the 2009 pandemic H1N1 strain. Such antibodies are rarely seen in humans following infection or vaccination with seasonal influenza virus strains. However, the important question remained whether the inactivated 2009 pandemic H1N1 vaccine, like the infection, could also induce these broadly neutralizing antibodies. To address this question, we analyzed B-cell responses in 24 healthy adults immunized with the pandemic vaccine in 2009. In all cases, we found a rapid, predominantly IgG-producing vaccine-specific plasmablast response. Strikingly, the majority (25 of 28) of HA-specific monoclonal antibodies generated from the vaccine-specific plasmablasts neutralized more than one influenza strain and exhibited high levels of somatic hypermutation, suggesting they were derived from recall of B-cell memory. Indeed, memory B cells that recognized the 2009 pandemic H1N1 HA were detectable before vaccination not only in this cohort but also in samples obtained before the emergence of the pandemic strain. Three antibodies demonstrated extremely broad cross-reactivity and were found to bind the HA stem. Furthermore, one stem-reactive antibody recognized not only H1 and H5, but also H3 influenza viruses. This exceptional cross-reactivity indicates that antibodies capable of neutralizing most influenza subtypes might indeed be elicited by vaccination. The challenge now is to improve upon this result and design influenza vaccines that can elicit these broadly cross-reactive antibodies at sufficiently high levels to provide heterosubtypic protection.
Proceedings of the National Academy of Sciences 05/2012; 109(23):9047-52. · 9.68 Impact Factor
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Christopher D O'Donnell,
Leatrice Vogel,
Amber Wright,
Suman R Das,
Jens Wrammert,
Gui-Mei Li, Megan McCausland,
Nai-Ying Zheng,
Jonathan W Yewdell,
Rafi Ahmed,
Patrick C Wilson,
Kanta Subbarao
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ABSTRACT: In 2009, a novel H1N1 influenza A virus (2009 pH1N1) emerged and caused a pandemic. A human monoclonal antibody (hMAb; EM4C04), highly specific for the 2009 pH1N1 virus hemagglutinin (HA), was isolated from a severely ill 2009 pH1N1 virus-infected patient. We postulated that under immune pressure with EM4C04, the 2009 pH1N1 virus would undergo antigenic drift and mutate at sites that would identify the antibody binding site. To do so, we infected MDCK cells in the presence of EM4C04 and generated 11 escape mutants, displaying 7 distinct amino acid substitutions in the HA. Six substitutions greatly reduced MAb binding (K123N, D131E, K133T, G134S, K157N, and G158E). Residues 131, 133, and 134 are contiguous with residues 157 and 158 in the globular domain structure and contribute to a novel pH1N1 antibody epitope. One mutation near the receptor binding site, S186P, increased the binding affinity of the HA to the receptor. 186P and 131E are present in the highly virulent 1918 virus HA and were recently identified as virulence determinants in a mouse-passaged pH1N1 virus. We found that pH1N1 escape variants expressing these substitutions enhanced replication and lethality in mice compared to wild-type 2009 pH1N1 virus. The increased virulence of these viruses was associated with an increased affinity for α2,3 sialic acid receptors. Our study demonstrates that antibody pressure by an hMAb targeting a novel epitope in the Sa region of 2009 pH1N1 HA is able to inadvertently drive the development of a more virulent virus with altered receptor binding properties. This broadens our understanding of antigenic drift. IMPORTANCE: Influenza viruses accumulate amino acid substitutions to evade the antibody response in a process known as antigenic drift, making it necessary to vaccinate against influenza annually. Mapping human monoclonal antibody (hMAb) epitopes is a necessary step towards understanding antigenic drift in humans. We defined the specificity of an hMAb that specifically targeted the 2009 pH1N1 virus and describe a novel epitope. In addition, we identified a previously unappreciated potential for antibody escape to enhance the pathogenicity of a virus. The escape mutation that we identified with in vitro immune pressure was independently reported by other investigators using in vivo selection in nonimmune mice. Although in vitro generation of escape mutants is unlikely to recapitulate antigenic drift in its entirety, the data demonstrate that pressure by a human monoclonal antibody targeting a novel epitope in the hemagglutinin of the 2009 pandemic H1N1 virus can inadvertently drive the development of escape mutants, of which a subset have increased virulence and altered receptor binding properties.
mBio 01/2012; 3(3). · 5.31 Impact Factor
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Jens Wrammert,
Dimitrios Koutsonanos,
Gui-Mei Li,
Srilatha Edupuganti,
Jianhua Sui,
Michael Morrissey, Megan McCausland,
Ioanna Skountzou,
Mady Hornig,
W Ian Lipkin, [......],
Youliang Wang,
Suman Ranjan Das,
Christopher David O'Donnell,
Jon W Yewdell,
Kanta Subbarao,
Wayne A Marasco,
Mark J Mulligan,
Richard Compans,
Rafi Ahmed,
Patrick C Wilson
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ABSTRACT: The 2009 pandemic H1N1 influenza pandemic demonstrated the global health threat of reassortant influenza strains. Herein, we report a detailed analysis of plasmablast and monoclonal antibody responses induced by pandemic H1N1 infection in humans. Unlike antibodies elicited by annual influenza vaccinations, most neutralizing antibodies induced by pandemic H1N1 infection were broadly cross-reactive against epitopes in the hemagglutinin (HA) stalk and head domain of multiple influenza strains. The antibodies were from cells that had undergone extensive affinity maturation. Based on these observations, we postulate that the plasmablasts producing these broadly neutralizing antibodies were predominantly derived from activated memory B cells specific for epitopes conserved in several influenza strains. Consequently, most neutralizing antibodies were broadly reactive against divergent H1N1 and H5N1 influenza strains. This suggests that a pan-influenza vaccine may be possible, given the right immunogen. Antibodies generated potently protected and rescued mice from lethal challenge with pandemic H1N1 or antigenically distinct influenza strains, making them excellent therapeutic candidates.
Journal of Experimental Medicine 01/2011; 208(1):181-93. · 13.85 Impact Factor
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Helder I Nakaya,
Jens Wrammert,
Eva K Lee,
Luigi Racioppi,
Stephanie Marie-Kunze,
W Nicholas Haining,
Anthony R Means,
Sudhir P Kasturi,
Nooruddin Khan,
Gui-Mei Li, Megan McCausland,
Vibhu Kanchan,
Kenneth E Kokko,
Shuzhao Li,
Rivka Elbein,
Aneesh K Mehta,
Alan Aderem,
Kanta Subbarao,
Rafi Ahmed,
Bali Pulendran
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ABSTRACT: Here we have used a systems biology approach to study innate and adaptive responses to vaccination against influenza in humans during three consecutive influenza seasons. We studied healthy adults vaccinated with trivalent inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). TIV induced higher antibody titers and more plasmablasts than LAIV did. In subjects vaccinated with TIV, early molecular signatures correlated with and could be used to accurately predict later antibody titers in two independent trials. Notably, expression of the kinase CaMKIV at day 3 was inversely correlated with later antibody titers. Vaccination of CaMKIV-deficient mice with TIV induced enhanced antigen-specific antibody titers, which demonstrated an unappreciated role for CaMKIV in the regulation of antibody responses. Thus, systems approaches can be used to predict immunogenicity and provide new mechanistic insights about vaccines.
Nature Immunology 01/2011; 12(8):786-95. · 26.01 Impact Factor
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ABSTRACT: CD137 (4-1BB), is an inducible T-cell costimulatory receptor and a member of the tumor necrosis factor receptor (TNFR) superfamily. It is expressed on activated T cells and activated natural killer (NK) cells, but is constitutively expressed on a population of splenic dendritic cells (DCs). The natural counter receptor for CD137 is 4-1BB ligand, a member of the TNF superfamily that is weakly expressed on naïve or resting B cells, macrophages, and DCs. Upon activation, the level of 4-1BBL expression increases on these cells. In T cells CD137-induced signals lead to the recruitment of TRAF family members and activation of several kinases, including ASK-1, MKK, MAPK3/ MAPK4, p38, and JNK/SAPK. Kinase activation is then followed by the activation and nuclear translocation of several transcription factors, including ATF-2, Jun, and NF-kappaB. CD137-mediated T-cell costimulation as measured by enhanced proliferation and cytokine production can be induced by anti-CD137 monoclonal antibodies (MAbs) or by employing immobilized 4-1BB ligand. In addition to augmenting suboptimal TCR-induced proliferation, CD137-mediated signaling protects T cells, and in particular, CD8+ T cells from activation-induced cell death (AICD). Although studies with CD137-deficient or 4-1BBL-deficient mice failed to demonstrate any loss of essential immunological function, or other noteworthy deficits, we have found that 4-1BBL-deficient mice failed to generate a strong antiviral immune response following lymphocytic choriomeningitis virus (LCMV) peptide vaccination. We further found that although compromised, the immune response to LCMV vaccination in these mice could be fully restored by injecting them with anti-CD137 MAbs at the time of vaccination. Finally, we have found that injecting normal mice with anti-CD137 MAbs had profound effects on their ability to develop immune responses to allo- and autoantigens. The results of these studies discussed in this article provide a rationale for assessing the potential use of anti-CD137 MAbs for therapeutic purposes.
Immunologic Research 02/2004; 29(1-3):197-208. · 3.03 Impact Factor
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ABSTRACT: T cell receptor recognition of antigen and major histocompatibility complex (signal 1) and T cell co-stimulation (signal 2) are essential for full T cell activation, differentiation, and survival of naïve and activated T cells. The proto-typical T cell co-stimulatory receptor, CD28, is a constitutively expressed type I integral transmembrane protein and member of the Ig superfamily. Since its discovery, additional T cell co-stimulatory receptors have been identified, a number of which belong to the tumor necrosis factor receptor superfamily. Included within this group is CD137 (4-1BB), an activation-inducible, type I transmembrane protein. Co-stimulation of T cells through CD137 effectively up-regulates CD8 T cell activation and survival. Although CD4(+) T cells are efficiently activated through the T cell receptor and CD137 receptor, it provokes CD4(+) T cell anergy and blockade of T-dependent humoral immune responses. Therefore, we tested whether agonistic anti-CD137 monoclonal antibodies (mAbs) would be effective in blocking the induction or progression of B cell dependent autoimmune disease. Herein, we demonstrate the protective effect of agonistic anti-CD137 mAbs in blocking systemic lupus erythematosus (SLE) disease progression in NZB/W F1 mice. Protection from SLE following anti-CD137 mAb treatment is not confined to rescuing mice from disease progression; rather, it fully protects young mice from developing any symptoms of disease. We further found that treatment of proteinuric mice with anti-CD137 blocks ongoing anti-dsDNA autoantibody production.
Annals of the New York Academy of Sciences 05/2003; 987:230-5. · 3.15 Impact Factor
