Preexisting compensatory amino acids compromise fitness costs of a HIV-1 T cell escape mutation.
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2014-11-19
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BACKGROUND: Fitness costs and slower disease progression are associated with a cytolytic T lymphocyte (CTL) escape mutation T242N in Gag in HIV-1-infected individuals carrying HLA-B*57/5801 alleles. However, the impact of different context in diverse HIV-1 strains on the fitness costs due to the T242N mutation has not been well characterized. To better understand the extent of fitness costs of the T242N mutation and the repair of fitness loss through compensatory amino acids, we investigated its fitness impact in different transmitted/founder (T/F) viruses. RESULTS: The T242N mutation resulted in various levels of fitness loss in four different T/F viruses. However, the fitness costs were significantly compromised by preexisting compensatory amino acids in (Isoleucine at position 247) or outside (glutamine at position 219) the CTL epitope. Moreover, the transmitted T242N escape mutant in subject CH131 was as fit as the revertant N242T mutant and the elimination of the compensatory amino acid I247 in the T/F viral genome resulted in significant fitness cost, suggesting the fitness loss caused by the T242N mutation had been fully repaired in the donor at transmission. Analysis of the global circulating HIV-1 sequences in the Los Alamos HIV Sequence Database showed a high prevalence of compensatory amino acids for the T242N mutation and other T cell escape mutations. CONCLUSIONS: Our results show that the preexisting compensatory amino acids in the majority of circulating HIV-1 strains could significantly compromise the fitness loss due to CTL escape mutations and thus increase challenges for T cell based vaccines.
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Liu, Donglai, Tao Zuo, Bhavna Hora, Hongshuo Song, Wei Kong, Xianghui Yu, Nilu Goonetilleke, Tanmoy Bhattacharya, et al. (2014). Preexisting compensatory amino acids compromise fitness costs of a HIV-1 T cell escape mutation. Retrovirology, 11. p. 101. 10.1186/s12977-014-0101-0 Retrieved from https://hdl.handle.net/10161/10437.
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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.
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.
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