Postnatally-transmitted HIV-1 Envelope variants have similar neutralization-sensitivity and function to that of nontransmitted breast milk variants.
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2013-01-10
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BACKGROUND: Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n = 13 viruses), five clinically-matched nontransmitting mothers (n = 16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses). RESULTS: There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants. CONCLUSION: Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.
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Fouda, Genevieve G, Tatenda Mahlokozera, Jesus F Salazar-Gonzalez, Maria G Salazar, Gerald Learn, Surender B Kumar, S Moses Dennison, Elizabeth Russell, et al. (2013). Postnatally-transmitted HIV-1 Envelope variants have similar neutralization-sensitivity and function to that of nontransmitted breast milk variants. Retrovirology, 10. p. 3. 10.1186/1742-4690-10-3 Retrieved from https://hdl.handle.net/10161/10586.
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Scholars@Duke
Moses Sekaran
Feng Gao
Dr. Feng Gao is Professor of Medicine at Duke University. The Gao laboratory has a long-standing interest in elucidating the origins and evolution of human and simian inmmunodeficiency viruses (HIV and SIV), and in studying HIV/SIV gene function and pathogenic mechanisms from the evolutionary perspective. These studies have led to new strategies to better understand HIV origins, biology, pathogenesis and drug resistance, and to design new AIDS vaccines.
Barton Ford Haynes
Barton F. Haynes, M.D. is the Frederic M. Hanes Professor of Medicine and Immunology, and Director of the Duke Human Vaccine Institute. Prior to leading the DHVI, Dr. Haynes served as Chief of the Division of Rheumatology, Allergy and Clinical Immunology, and later as Chair of the Department of Medicine. As Director of the Duke Human Vaccine Institute, Bart Haynes is leading a team of investigators working on vaccines for emerging infections, including tuberculosis, pandemic influenza, emerging coronaviruses, and HIV/AIDS.
To work on the AIDS vaccine problem, his group has been awarded two large consortium grants from the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID) known as the Center for HIV/AIDS Vaccine Immunology (CHAVI) (2005-2012), and the Center for HIV/AIDS Vaccine Immunology-Immunogen Discovery (CHAVI-ID) (2012-2019) to conduct discovery science to speed HIV vaccine development. In July 2019, his team received the third of NIH “CHAVI” awards to complete the HIV vaccine development work - CHAV-D.
Since the beginning of the COVID-19 pandemic, Haynes and the DHVI Team has been working non-stop to develop vaccines, rapid and inexpensive tests and therapeutics to combat the pandemic. Since March 2020, he has served as a member of the NIH Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) committee to advise on COVID-19 vaccine development, and served as the co-chair of the ACTIV subcommittee on vaccine safety. Haynes is the winner of the Alexander Fleming Award from the Infectious Disease Society of America and the Ralph Steinman Award for Human Immunology Research from the American Association of Immunologists. He is a member of the National Academy of Medicine, National Academy of Inventors and the American Academy of Arts and Sciences.
About the Haynes LaboratoryThe Haynes lab is studying host innate and adaptive immune responses to the human immunodeficiency virus (HIV), tuberculosis (TB), and influenza in order to find the enabling technology to make preventive vaccines against these three major infectious diseases.
Mucosal Immune Responses in Acute HIV Infection
The Haynes lab is working to determine why broadly neutralizing antibodies are rarely made in acute HIV infection (AHI), currently a major obstacle in the development of an HIV vaccine. The lab has developed a novel approach to define the B cell repertories in AHI in order to find neutralizing antibodies against the virus. This approach uses linear Immunoglobulin (Ig) heavy and light chain gene expression cassettes to express Ig V(H) and V(L) genes isolated from sorted single B cells as IgG1 antibody without a cloning step. This strategy was used to characterize the Ig repertoire of plasma cells/plasmablasts in AHI and to produce recombinant influenza mAbs from sorted single human plasmablasts after influenza vaccination.
The lab is also studying the earliest effect HIV-1 has on B cells. Analyzing blood and gut-associated lymphoid tissues (GALT) during acute HIV infection, they have found that as early as 17 days after transmission HIV-1 induces B cell class switching and 47 days after transmission, HIV-1 causes considerable damage to GALT germinal centers. They found that in AHI, GALT memory B cells induce polyclonal B cell activation due to the presence of HIV-1-specific, influenza-specific, and autoreactive antibodies. The team concluded from this study that early induction of polyclonal B cell differentiation, along with follicular damage and germinal center loss, may explain why HIV-1 induced antibody responses decline rapidly during acute HIV infection and why plasma antibody responses are delayed.
The lab is also looking at ways of generating long-lived memory B cell responses to HIV infection, another major hurdle in the development of a successful HIV-1 vaccine. The lab has found that in HIV-1 gp120 envelope vaccination and chronic HIV-1 infection, HIV-1 envelope induces predominantly short-lived memory B cell-dependent plasma antibodies.
Immunogen Design
To overcome the high level of genetic diversity in HIV-1 envelope genes, the Haynes lab is developing strategies to induce antibodies that cross-react with multiple strains of HIV. The lab has designed immunogens based on transmitted founder Envs and mosaic consensus Envs in collaboration with Dr. Bette Korber at Los Alamos National Laboratory. These immunogens are designed to induce antibodies that cross-react with a multiple subtype Env glycoproteins. The goal is to determine if cross-reactive mAbs to highly conserved epitopes in HIV-1 envelope glycoproteins can be induced. The team recently characterized a panel of ten mAbs that reacted with varying breadth to subtypes A, B, C, D, F, G, CRF01_AE, and a highly divergent SIVcpzUS Env protein. Two of the mAbs cross-reacted with all tested Env proteins, including SIVcpzUS Env and bound Env proteins with high affinity.
Mucosal Immune Responses in TB and Influenza
The Haynes lab is helping to develop novel approaches to TB vaccine development. The current therapeutic vaccine for TB, called BCG, may prevent complications from TB in children, but offers little protection against infection and disease in adults. The lab is focused on using live attenuated Mycobacterium tuberculosis mutants as vaccine candidates and is currently evaluating this approach in non-human primate studies. As part of the DHVI Influenza program, they are studying the B cell response to influenza in order to generate a “universal” flu vaccine. They are currently trying to express more highly conserved influenza antigens in recombinant vesicular stomatitis virus (rVSV) vectors in order to elicit robust T cell and antibody responses to those antigens.
S. Munir Alam
Research Interests.
The Alam laboratory’s primary research is focused on understanding the biophysical properties of antigen-antibody binding and the molecular events of early B cell activation using the HIV-1 broadly neutralizing antibody (bnAb) lineage models. We are studying how HIV-1 Envelope proteins of varying affinities are sensed by B cells expressing HIV-1 bnAbs or their germline antigen receptors and initiate early signaling events for their activation. In the long-term these studies will facilitate design and pre-selection of immunogens for testing in animal models and accelerate HIV-1 vaccine development.
Current research include the following NIAID-funded projects
Antigen recognition and activation of B cell antigen receptors with the specificity of HIV-1 broadly neutralizing antibodies. This project involves elucidating the early events on the B cell surface following antigen (Ag) engagement of the B cell antigen receptor (BCR) and to provide an assessment of the in vivo potential of an Ag to drive B cell activation. We are performing biophysical interactions analyses and using high-resolution microscopy to define the physico-chemical properties of BCR-Ag interactions that govern signaling and activation thresholds for BCR triggering and the BCR endocytic function in antigen internalization. The overall objective of these studies is to bridge the quantitative biophysical and membrane dynamics measurements of Ag-BCR interactions to ex-vivo and in-vivo B cell activation. This NIAID-funded research is a collaboration with co-investigators Professor Michael Reth (University of Freiburg, Germany) and Dr. Laurent Verkoczy (San Diego Biomedical Research Institute, CA).
Immunogen Design for Induction of HIV gp41 Broadly Neutralizing Antibodies. This research project addresses the critical problem of vaccine induction of disfavored HIV-1 antibody lineages, like those that target the membrane proximal external region (MPER) of HIV Env gp41. This program combines structure and lineage-based vaccine development strategies to design immunogens that will induce bnAb lineages that are not polyreactive and therefore easier to induce. The overall objective of this program grant is to develop and test sequential immunogens that will initiate and induce HIV-1 bnAb lineages like the potent MPER bnAb DH511. Using a germline-targeting (GT) epitope scaffold design and a prime/boost strategy, we are testing induction of DH511-like bnAbs in knock-in (KI) mice models expressing the DH511 germline receptors. This P01 research program is in collaboration with Dr. William Schief (The Scripps Research Institute, CA), who leads the team that are designing germline targeting (GT)-scaffold prime and boost immunogens and Dr. Ming Tian at Harvard University who developed relevant knock-mice models for the study.
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