92 results on '"Pantophlet R"'
Search Results
2. Residue 315 regulates V3 exposure and V3 antibody recognition on HIV subtype B and C viruses
- Author
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Manhas S, Clark B, Gorny MK, Zolla-Pazner S, and Pantophlet R
- Subjects
Immunologic diseases. Allergy ,RC581-607 - Published
- 2012
- Full Text
- View/download PDF
3. P04-03. Cross-clade neutralization analysis of plasmas from clade B, C and CRF01_AE HIV-infected donors
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Petropoulos C, Katinger H, Kunert R, Steigler G, Cavacini L, Taylor N, Lapedes A, Crooks ET, Phung P, Pantophlet R, Wrin T, Binley J, Richman D, Morris L, Sutthent R, and Burton DR
- Subjects
Immunologic diseases. Allergy ,RC581-607 - Published
- 2009
- Full Text
- View/download PDF
4. Improved design of an antigen with enhanced specificity for the broadly HIV-neutralizing antibody b12
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Pantophlet, R., Wilson, I.A., Burton, D.R., and Marks, James
- Published
- 2004
5. A novel form of carbohydrate recognition. The broadly neutralizing anti-HIV-1 antibody 2G12 recognizes a cluster of a1-2 mannose residues on the outer face of GP120
- Author
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Rudd, Pm, Scanlan, Cn, Pantophlet, R., Mark Wormald, Saphire, Eo, Stanfield, R., Wilson, Ia, Katinger, H., Dwek, Ra, and Burton, Dr
- Published
- 2016
6. Crystal structure of HIV neutralizing antibody 2G12 in complex with a bacterial oligosaccharide analog of mammalian oligomanose
- Author
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Stanfield, R.L., primary, Wilson, I.A., additional, De Castro, C., additional, Marzaioli, A.M., additional, and Pantophlet, R., additional
- Published
- 2014
- Full Text
- View/download PDF
7. Report on the AIDS Vaccine 2008 Conference
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Alter, G., Ananworanich, J., Pantophlet, R., Rybicki, E. P., Buonaguro, L., Alter, G., Ananworanich, J., Pantophlet, R., Rybicki, E. P., and Buonaguro, L.
- Abstract
The "AIDS Vaccine 2008" Conference was held in Cape Town, South Africa (October 13 to 16, 2008) and organized, under the aegis of the Global HIV Vaccine Enterprise, by Dr. Lynn Morris (Chair of the Conference) National Institute of Communicable Diseases; Dr. Koleka Mlisana from CAPRISA, University KwaZulu-Natal, Durban, Dr. Glenda Gray from Perinatal HIV Research Unit, University Witwatersrand, Johannesburg and Dr. Carolyn Williamson from Institute of Infectious Diseses. and Molecular Medicine, UCT, Cape Town (Co-Chairs of the Conference). Since the first AIDS Vaccine conference, organized in Paris in 2000, this was the first time it was held outside of the U.S. and Europe, and involved nearly 1,000 participants. Besides three Plenary Sessions with ten state-of-the-art plenary lectures and one Keynote Lecture given by Dr. A.S. Fauci (Director of NIAID, NIH, USA), the Conference was organized in nine oral sessions, four poster discussion groups covering a wide spectrum of scientific information relating to HIV vaccine research and development. Moreover three Symposia, two Special Sessions, one Roundtable as well as two Debates were held, the latter focusing on current controversial topics. The conference opening was memorable for a number of reasons: among these was the presence of South Africa's new Minister of Health, Barbara Hogan who, in her first speech in a major forum as a senior member of the SA Government, affirmed that HIV causes AIDS, and that the search for a vaccine is of paramount importance to SA and the rest of the world. A scientific summary of the Conference is reported in the present article, divided into four major topics: (1) vaccine concepts and design; (2) T-cell immunology and innate immunity; (3) B-cell immunology, neutralizing antibodies and mucosal immunology; and (4) clinical trials. © 2009 Landes Bioscience.
- Published
- 2009
8. Hyperglycosylated gp120 mutants elicit improved CD4-binding site directed antibodies in a heterologous prime:boost regimen
- Author
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Ahmed, FK, primary, Clark, BE, additional, and Pantophlet, R, additional
- Published
- 2012
- Full Text
- View/download PDF
9. P04-03. Cross-clade neutralization analysis of plasmas from clade B, C and CRF01_AE HIV-infected donors
- Author
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Binley, J, primary, Wrin, T, additional, Pantophlet, R, additional, Phung, P, additional, Crooks, ET, additional, Lapedes, A, additional, Taylor, N, additional, Cavacini, L, additional, Steigler, G, additional, Kunert, R, additional, Katinger, H, additional, Petropoulos, C, additional, Richman, D, additional, Morris, L, additional, Sutthent, R, additional, and Burton, DR, additional
- Published
- 2009
- Full Text
- View/download PDF
10. Crystal Structure of the Broadly HIV-1 Neutralizing Fab X5 at 1.90 Angstrom Resolution
- Author
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Darbha, R., primary, Phogat, S., additional, Labrijn, A.F., additional, Shu, Y., additional, Gu, Y., additional, Andrykovitch, M., additional, Zhang, M.Y., additional, Pantophlet, R., additional, Martin, L., additional, Vita, C., additional, Burton, D.R., additional, Dimitrov, D.S., additional, and Ji, X., additional
- Published
- 2004
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- View/download PDF
11. Structural and serological characterisation of the O-antigenic polysaccharide of the lipopolysaccharide from Acinetobacter strain 96 (DNA group 11)
- Author
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Vinogradov, E.V., primary, Pantophlet, R., additional, Brade, H., additional, and Holst, O., additional
- Published
- 2001
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12. Detection of lipid A by monoclonal antibodies in S-form lipopolysaccharide after acidic treatment of immobilized LPS on Western blot
- Author
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Pantophlet, R., primary, Brade, L., additional, and Brade, H., additional
- Published
- 1997
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13. Differential roles of CD14 and toll-like receptors 4 and 2 in murine Acinetobacter pneumonia.
- Author
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Knapp S, Wieland CW, Florquin S, Pantophlet R, Dijkshoorn L, Tshimbalanga N, Akira S, and van der Poll T
- Abstract
RATIONALE: Acinetobacter baumannii is an opportunistic bacterial pathogen that is increasingly associated with gram-negative nosocomial pneumonia, but the molecular mechanisms that play a role in innate defenses during A. baumannii infection have not been elucidated. OBJECTIVE: To gain first insight into the role of CD14 and Toll-like receptors 4 and 2 in host response to A. baumannii pneumonia. METHODS: Respective gene-deficient mice were intranasally infected with A. baumannii, and bacterial outgrowth, lung inflammation, and pulmonary cytokine/chemokine responses were determined. To study the importance of LPS in the inflammatory response, mice were also challenged with A. baumannii LPS. MEASUREMENTS AND MAIN RESULTS: Bacterial counts were increased in CD14 and Toll-like receptor 4 gene-deficient mice, and only these animals developed bacteremia. The pulmonary cytokine/chemokine response was impaired in Toll-like receptor 4 knockout mice and the onset of lung inflammation was delayed. In contrast, Toll-like receptor 2-deficient animals displayed an earlier cell influx into lungs combined with increased macrophage inflammatory protein-2 and monocyte chemoattractant protein-1 concentrations, which was associated with accelerated elimination of bacteria from the pulmonary compartment. Neither CD14 nor Toll-like receptor 4 gene-deficient mice responded to intranasal administration of LPS, whereas Toll-like receptor 2 knockout mice were indistinguishable from wild-type animals. CONCLUSIONS: Our results suggest that CD14 and Toll-like receptor 4 play a key role in innate sensing of A. baumannii via the LPS moiety, resulting in effective elimination of the bacteria from the lung, whereas Toll-like receptor 2 signaling seems to counteract the robustness of innate responses during acute A. baumannii pneumonia. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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14. Detection of lipid A by monoclonal antibodies in S-form lipopolysaccharide after acidic treatment of immobilized LPS on Western blot.
- Author
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Pantophlet, R., Brade, L., and Brade, H.
- Abstract
Lipopolysaccharides (LPSs) were separated by SDS-PAGE, transferred onto polyvinylidene difluoride membranes, and hydrolyzed under acid conditions known to liberate lipid A from a broad variety of bacterial species. Independent of whether bis- or monophosphorylated lipid was set free, it remained bound to the membrane during subsequent immunostaining with monoclonal antibodies (MAbs) specific for the 1,4'-bis- or 4'-monophosphorylated lipid A backbone. Lipid A could be detected in the smooth (S)-form LPS from Enterobacteriaceae (Salmonella enterica, Citrobacter, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Yersinia enterocolitica), Pseudomonas aeruginosa, Chromobacterium violaceum, Acinetobacter, Vibrio cholerae and Legionella pneumophila, thus allowing LPS-phenotype determination. The procedure can be used for the majority of Gram-negative bacteria, since LPSs containing 2,3-diamino-2,3-dideoxy-glucose or glucosamine in the lipid A disaccharide backbone could be detected. It was shown to be sensitive (up to 20 ng of hydrolyzed LPS could be detected), and could be easily performed using isolated LPS or whole-cell lysates with or without prior digestion with proteinase K. In addition to opening several other application possibilities, the procedure may be particularly useful in cases where silver-staining of the O-chain in SDSpolyacrylamide gels fails and specific antibodies against the O-antigen are not available. [ABSTRACT FROM PUBLISHER]
- Published
- 1997
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15. Identification of Acinetobacter baumannii strains with monoclonal antibodies against the O antigens of their lipopolysaccharides.
- Author
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Pantophlet, R, Brade, L, and Brade, H
- Abstract
Despite the emergence of Acinetobacter baumannii strains as nosocomial pathogens, simple methods for their phenotypic identification are still unavailable. Murine monoclonal antibodies specific for the O-polysaccharide moiety of the lipopolysaccharide (LPS) of two A. baumannii strains were obtained after immunization with heat-killed bacteria. The monoclonal antibodies were characterized by enzyme immunoassay and by Western and dot blot analyses and were investigated for their potential use for the identification of A. baumannii strains. The antibodies reacted with 46 of the 80 A. baumannii clinical isolates that were investigated, and reactivity was observed with 11 of 14 strains which were isolated during outbreaks in different northwestern European cities; no reactivity was observed with Acinetobacter strains of other genomic species, including the closely related genomic species 1 (Acinetobacter calcoaceticus), 3, and 13 sensu Tjernberg and Ursing, or with other gram-negative bacterial strains. The results show that O-antigen-specific monoclonal antibodies such as the ones described are convenient reagents which can be used to identify Acinetobacter strains in clinical and research laboratories.
- Published
- 1999
16. Generation and serological characterization of murine monoclonal antibodies against O antigens from Acinetobacter reference strains.
- Author
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Pantophlet, R, Brade, L, and Brade, H
- Abstract
O-antigen-specific monoclonal antibodies were generated against Acinetobacter strains from international type culture collections and characterized by enzyme immunoassay and Western and colony blotting. The antibodies aid in the further completion of an O-serotyping scheme for Acinetobacter and, due to their high specificity, are especially useful to all working with these strains.
- Published
- 2001
- Full Text
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17. Antibody response to lipopolysaccharide in patients colonized or infected with an endemic strain of Acinetobacter genomic species 13 sensu Tjernberg and Ursing.
- Author
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Pantophlet, R, Seifert, H, Brade, L, and Brade, H
- Abstract
The levels of antilipopolysaccharide (anti-LPS) antibodies in patients colonized with an endemic Acinetobacter strain were compared to those in patients with bloodstream infections. Seropositivity and seronegativity correlated with positive and negative blood cultures, respectively, indicating that determination of the level of anti-LPS antibodies is useful for diagnosing Acinetobacter infections.
- Published
- 2000
18. Crystal structure of an intact human IgG: Antibody asymmetry, flexibility, and a guide for HIV-1 vaccine design
- Author
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Erica Ollmann Saphire, Stanfield, R. L., Crispin, M. D. M., Morris, G., Zwick, M. B., Pantophlet, R. A., Parren, P. W. H. I., Rudd, P. M., Dwek, R. A., Burton, D. R., and Wilson, I. A.
19. People With Human Immunodeficiency Virus Receiving Suppressive Antiretroviral Therapy Show Typical Antibody Durability After Dual Coronavirus Disease 2019 Vaccination and Strong Third Dose Responses.
- Author
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Lapointe HR, Mwimanzi F, Cheung PK, Sang Y, Yaseen F, Umviligihozo G, Kalikawe R, Speckmaier S, Moran-Garcia N, Datwani S, Duncan MC, Agafitei O, Ennis S, Young L, Ali H, Ganase B, Omondi FH, Dong W, Toy J, Sereda P, Burns L, Costiniuk CT, Cooper C, Anis AH, Leung V, Holmes DT, DeMarco ML, Simons J, Hedgcock M, Prystajecky N, Lowe CF, Pantophlet R, Romney MG, Barrios R, Guillemi S, Brumme CJ, Montaner JSG, Hull M, Harris M, Niikura M, Brockman MA, and Brumme ZL
- Subjects
- Humans, HIV, COVID-19 Vaccines, SARS-CoV-2, Antibodies, Vaccination, Antibodies, Viral, COVID-19 prevention & control, HIV Infections drug therapy
- Abstract
Background: Longer-term humoral responses to 2-dose coronavirus disease 2019 (COVID-19) vaccines remain incompletely characterized in people living with human immunodeficiency virus (HIV) (PLWH), as do initial responses to a third dose., Methods: We measured antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain, angiotensin-converting enzyme 2 (ACE2) displacement, and viral neutralization against wild-type and Omicron strains up to 6 months after 2-dose vaccination, and 1 month after the third dose, in 99 PLWH receiving suppressive antiretroviral therapy and 152 controls., Results: Although humoral responses naturally decline after 2-dose vaccination, we found no evidence of lower antibody concentrations or faster rates of antibody decline in PLWH compared with controls after accounting for sociodemographic, health, and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after 2 doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post-third-dose humoral responses substantially exceeded post-second-dose levels, though Omicron-specific responses were consistently weaker than responses against wild-type virus. Nevertheless, post-third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post-third-dose responses., Conclusion: PLWH receiving suppressive antiretroviral therapy mount strong antibody responses after 2- and 3-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron., Competing Interests: Potential conflicts of interest. All authors: no reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2023
- Full Text
- View/download PDF
20. Large-Scale Virtual Screening for the Discovery of SARS-CoV-2 Papain-like Protease (PLpro) Non-covalent Inhibitors.
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Garland O, Ton AT, Moradi S, Smith JR, Kovacic S, Ng K, Pandey M, Ban F, Lee J, Vuckovic M, Worrall LJ, Young RN, Pantophlet R, Strynadka NCJ, and Cherkasov A
- Subjects
- Humans, SARS-CoV-2, Antiviral Agents pharmacology, Antiviral Agents chemistry, Models, Molecular, Prospective Studies, Protease Inhibitors pharmacology, Protease Inhibitors chemistry, Viral Proteins chemistry, Peptide Hydrolases, COVID-19, Hepatitis C, Chronic
- Abstract
The rapid global spread of the SARS-CoV-2 virus facilitated the development of novel direct-acting antiviral agents (DAAs). The papain-like protease (PLpro) has been proposed as one of the major SARS-CoV-2 targets for DAAs due to its dual role in processing viral proteins and facilitating the host's immune suppression. This dual role makes identifying small molecules that can effectively neutralize SARS-CoV-2 PLpro activity a high-priority task. However, PLpro drug discovery faces a significant challenge due to the high mobility and induced-fit effects in the protease's active site. Herein, we virtually screened the ZINC20 database with Deep Docking (DD) to identify prospective noncovalent PLpro binders and combined ultra-large consensus docking with two pharmacophore (ph4)-filtering strategies. The analysis of active compounds revealed their somewhat-limited diversity, likely attributed to the induced-fit nature of PLpro's active site in the crystal structures, and therefore, the use of rigid docking protocols poses inherited limitations. The top hits were assessed against recombinant viral proteins and live viruses, demonstrating desirable inhibitory activities. The best compound VPC-300195 (IC
50 : 15 μM) ranks among the top noncovalent PLpro inhibitors discovered through in silico methodologies. In the search for novel SARS-CoV-2 PLpro-specific chemotypes, the identified inhibitors could serve as diverse templates for the development of effective noncovalent PLpro inhibitors.- Published
- 2023
- Full Text
- View/download PDF
21. Older Adults Mount Less Durable Humoral Responses to Two Doses of COVID-19 mRNA Vaccine but Strong Initial Responses to a Third Dose.
- Author
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Mwimanzi F, Lapointe HR, Cheung PK, Sang Y, Yaseen F, Umviligihozo G, Kalikawe R, Datwani S, Omondi FH, Burns L, Young L, Leung V, Agafitei O, Ennis S, Dong W, Basra S, Lim LY, Ng K, Pantophlet R, Brumme CJ, Montaner JSG, Prystajecky N, Lowe CF, DeMarco ML, Holmes DT, Simons J, Niikura M, Romney MG, Brumme ZL, and Brockman MA
- Subjects
- Aged, Angiotensin-Converting Enzyme 2, Antibodies, Neutralizing, Antibodies, Viral, Humans, RNA, Messenger, SARS-CoV-2, Spike Glycoprotein, Coronavirus, Vaccines, Synthetic, mRNA Vaccines, COVID-19 prevention & control, COVID-19 Vaccines
- Abstract
Background: Third coronavirus disease 2019 (COVID-19) vaccine doses are broadly recommended, but immunogenicity data remain limited, particularly in older adults., Methods: We measured circulating antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain, ACE2 displacement, and virus neutralization against ancestral and omicron (BA.1) strains from prevaccine up to 1 month following the third dose, in 151 adults aged 24-98 years who received COVID-19 mRNA vaccines., Results: Following 2 vaccine doses, humoral immunity was weaker, less functional, and less durable in older adults, where a higher number of chronic health conditions was a key correlate of weaker responses and poorer durability. One month after the third dose, antibody concentrations and function exceeded post-second-dose levels, and responses in older adults were comparable in magnitude to those in younger adults at this time. Humoral responses against omicron were universally weaker than against the ancestral strain after both the second and third doses. Nevertheless, after 3 doses, anti-omicron responses in older adults reached equivalence to those in younger adults. One month after 3 vaccine doses, the number of chronic health conditions, but not age, was the strongest consistent correlate of weaker humoral responses., Conclusions: Results underscore the immune benefits of third COVID-19 vaccine doses, particularly in older adults., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2022
- Full Text
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22. Synthetic Neoglycoconjugates of Hepta- and Nonamannoside Ligands for Eliciting Oligomannose-Specific HIV-1-Neutralizing Antibodies.
- Author
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Cattin M, Bruxelle JF, Ng K, Blaukopf M, Pantophlet R, and Kosma P
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- Antibodies, Neutralizing, Epitopes chemistry, HIV Antibodies chemistry, Humans, Ligands, Male, HIV-1
- Abstract
Oligomannose-type glycans on the spike protein of HIV-1 constitute relevant epitopes to elicit broadly neutralizing antibodies (bnAbs). Herein we describe an improved synthesis of α- and β-linked hepta- and nonamannosyl ligands that were subsequently converted into BSA and CRM
197 neoglycoconjugates. We assembled the ligands from anomeric 3-azidopropyl spacer glycosides from select 3-O-protected thiocresyl mannoside donors. Chain extensions were achieved using [4+3] or [4+5] block synthesis of thiocresyl and trichloroacetimidate glycosyl donors. Subsequent global deprotection generated the 3-aminopropyl oligosaccharide ligands. ELISA binding data obtained with the β-anomeric hepta- and nonamannosyl conjugates with a selection of HIV-1 bnAbs showed comparable binding of both mannosyl ligands by Fab fragments yet lesser binding of the nonasaccharide conjugate by the corresponding IgG antibodies. These results support previous observations that a complete Man9 structure might not be the preferred antigenic binding motif for some oligomannose-specific antibodies, and have implications for glycoside designs to elicit oligomannose-targeted HIV-1-neutralizing antibodies., (© 2022 The Authors. ChemBioChem published by Wiley-VCH GmbH.)- Published
- 2022
- Full Text
- View/download PDF
23. Reduced Magnitude and Durability of Humoral Immune Responses to COVID-19 mRNA Vaccines Among Older Adults.
- Author
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Brockman MA, Mwimanzi F, Lapointe HR, Sang Y, Agafitei O, Cheung PK, Ennis S, Ng K, Basra S, Lim LY, Yaseen F, Young L, Umviligihozo G, Omondi FH, Kalikawe R, Burns L, Brumme CJ, Leung V, Montaner JSG, Holmes D, DeMarco ML, Simons J, Pantophlet R, Niikura M, Romney MG, and Brumme ZL
- Subjects
- Aged, Antibodies, Neutralizing, Antibodies, Viral, Humans, Immunity, Humoral, Infant, RNA, Messenger, SARS-CoV-2, Vaccines, Synthetic, mRNA Vaccines, COVID-19 prevention & control, COVID-19 Vaccines
- Abstract
Background: The magnitude and durability of immune responses to coronavirus disease 2019 (COVID-19) mRNA vaccines remain incompletely characterized in the elderly., Methods: Anti-spike receptor-binding domain (RBD) antibodies, angiotensin-converting enzyme 2 (ACE2) competition, and virus neutralizing activities were assessed in plasma from 151 health care workers and older adults (range, 24-98 years of age) 1 month following the first vaccine dose, and 1 and 3 months following the second dose., Results: Older adults exhibited significantly weaker responses than younger health care workers for all humoral measures evaluated and at all time points tested, except for ACE2 competition activity after 1 vaccine dose. Moreover, older age remained independently associated with weaker responses even after correction for sociodemographic factors, chronic health condition burden, and vaccine-related variables. By 3 months after the second dose, all humoral responses had declined significantly in all participants, and remained significantly lower among older adults, who also displayed reduced binding antibodies and ACE2 competition activity towards the Delta variant., Conclusions: Humoral responses to COVID-19 mRNA vaccines are significantly weaker in older adults, and antibody-mediated activities in plasma decline universally over time. Older adults may thus remain at elevated risk of infection despite vaccination., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America.)
- Published
- 2022
- Full Text
- View/download PDF
24. People with HIV receiving suppressive antiretroviral therapy show typical antibody durability after dual COVID-19 vaccination, and strong third dose responses.
- Author
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Lapointe HR, Mwimanzi F, Cheung PK, Sang Y, Yaseen F, Umviligihozo G, Kalikawe R, Speckmaier S, Moran-Garcia N, Datwani S, Duncan MC, Agafitei O, Ennis S, Young L, Ali H, Ganase B, Omondi FH, Dong W, Toy J, Sereda P, Burns L, Costiniuk CT, Cooper C, Anis AH, Leung V, Holmes D, DeMarco ML, Simons J, Hedgcock M, Prystajecky N, Lowe CF, Pantophlet R, Romney MG, Barrios R, Guillemi S, Brumme CJ, Montaner JSG, Hull M, Harris M, Niikura M, Brockman MA, and Brumme ZL
- Abstract
Background: Longer-term humoral responses to two-dose COVID-19 vaccines remain incompletely characterized in people living with HIV (PLWH), as do initial responses to a third dose., Methods: We measured antibodies against the SARS-CoV-2 spike protein receptor-binding domain, ACE2 displacement and viral neutralization against wild-type and Omicron strains up to six months following two-dose vaccination, and one month following the third dose, in 99 PLWH receiving suppressive antiretroviral therapy, and 152 controls., Results: Though humoral responses naturally decline following two-dose vaccination, we found no evidence of lower antibody concentrations nor faster rates of antibody decline in PLWH compared to controls after accounting for sociodemographic, health and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after two doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post-third-dose humoral responses substantially exceeded post-second-dose levels, though anti-Omicron responses were consistently weaker than against wild-type.Nevertheless, post-third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post-third-dose responses., Conclusion: PLWH receiving suppressive antiretroviral therapy mount strong antibody responses after two- and three-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron.
- Published
- 2022
- Full Text
- View/download PDF
25. Humoral immune responses to COVID-19 vaccination in people living with HIV receiving suppressive antiretroviral therapy.
- Author
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Brumme ZL, Mwimanzi F, Lapointe HR, Cheung PK, Sang Y, Duncan MC, Yaseen F, Agafitei O, Ennis S, Ng K, Basra S, Lim LY, Kalikawe R, Speckmaier S, Moran-Garcia N, Young L, Ali H, Ganase B, Umviligihozo G, Omondi FH, Atkinson K, Sudderuddin H, Toy J, Sereda P, Burns L, Costiniuk CT, Cooper C, Anis AH, Leung V, Holmes D, DeMarco ML, Simons J, Hedgcock M, Romney MG, Barrios R, Guillemi S, Brumme CJ, Pantophlet R, Montaner JSG, Niikura M, Harris M, Hull M, and Brockman MA
- Abstract
Humoral responses to COVID-19 vaccines in people living with HIV (PLWH) remain incompletely characterized. We measured circulating antibodies against the SARS-CoV-2 spike protein receptor-binding domain (RBD), ACE2 displacement and viral neutralization activities one month following the first and second COVID-19 vaccine doses, and again 3 months following the second dose, in 100 adult PLWH and 152 controls. All PLWH were receiving suppressive antiretroviral therapy, with median CD4+ T-cell counts of 710 (IQR 525-935) cells/mm
3 , though nadir CD4+ T-cell counts ranged as low as <10 cells/mm3 . After adjustment for sociodemographic, health and vaccine-related variables, HIV infection was associated with lower anti-RBD antibody concentrations and ACE2 displacement activity after one vaccine dose. Following two doses however, HIV was not significantly associated with the magnitude of any humoral response after multivariable adjustment. Rather, older age, a higher burden of chronic health conditions, and dual ChAdOx1 vaccination were associated with lower responses after two vaccine doses. No significant correlation was observed between recent or nadir CD4+ T-cell counts and responses to two vaccine doses in PLWH. These results indicate that PLWH with well-controlled viral loads and CD4+ T-cell counts in a healthy range generally mount strong initial humoral responses to dual COVID-19 vaccination. Factors including age, co-morbidities, vaccine brand, response durability and the rise of new SARS-CoV-2 variants will influence when PLWH will benefit from additional doses. Further studies of PLWH who are not receiving antiretroviral treatment or who have low CD4+ T-cell counts are needed, as are longer-term assessments of response durability., (© 2022. The Author(s).)- Published
- 2022
- Full Text
- View/download PDF
26. Older Adults Mount Less Durable Humoral Responses to a Two-dose COVID-19 mRNA Vaccine Regimen, but Strong Initial Responses to a Third Dose.
- Author
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Mwimanzi F, Lapointe HR, Cheung PK, Sang Y, Yaseen F, Umviligihozo G, Kalikawe R, Datwani S, Omondi FH, Burns L, Young L, Leung V, Agafitei O, Ennis S, Dong W, Basra S, Lim LY, Ng K, Pantophlet R, Brumme CJ, Montaner JSG, Prystajecky N, Lowe CF, DeMarco ML, Holmes DT, Simons J, Niikura M, Romney MG, Brumme ZL, and Brockman MA
- Abstract
Background: Third COVID-19 vaccine doses are broadly recommended, but immunogenicity data remain limited, particularly in older adults., Methods: We measured circulating antibodies against the SARS-CoV-2 spike protein receptor-binding domain, ACE2 displacement, and virus neutralization against ancestral and Omicron (BA.1) strains from pre-vaccine up to one month following the third dose, in 151 adults aged 24-98 years who received COVID-19 mRNA vaccines., Results: Following two vaccine doses, humoral immunity was weaker, less functional and less durable in older adults, where a higher number of chronic health conditions was a key correlate of weaker responses and poorer durability. Third doses boosted antibody binding and function to higher levels than second-doses, and induced responses in older adults that were comparable in magnitude to those in younger adults. Humoral responses against Omicron were universally weaker than against the ancestral strain after both second and third doses; nevertheless, after three doses, anti-Omicron responses in older adults reached equivalence to those in younger adults. After three vaccine doses, the number of chronic health conditions, but not age per se, was the strongest consistent correlate of weaker humoral responses., Conclusion: Results underscore the immune benefits of third COVID-19 vaccine doses, particularly in older adults.
- Published
- 2022
- Full Text
- View/download PDF
27. Humoral immune responses to COVID-19 vaccination in people living with HIV receiving suppressive antiretroviral therapy.
- Author
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Brumme ZL, Mwimanzi F, Lapointe HR, Cheung P, Sang Y, Duncan MC, Yaseen F, Agafitei O, Ennis S, Ng K, Basra S, Lim LY, Kalikawe R, Speckmaier S, Moran-Garcia N, Young L, Ali H, Ganase B, Umviligihozo G, Omondi FH, Atkinson K, Sudderuddin H, Toy J, Sereda P, Burns L, Costiniuk CT, Cooper C, Anis AH, Leung V, Holmes D, DeMarco ML, Simons J, Hedgcock M, Romney MG, Barrios R, Guillemi S, Brumme CJ, Pantophlet R, Montaner JSG, Niikura M, Harris M, Hull M, and Brockman MA
- Abstract
Humoral responses to COVID-19 vaccines in people living with HIV (PLWH) remain incompletely understood. We measured circulating antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, ACE2 displacement and live viral neutralization activities one month following the first and second COVID-19 vaccine doses in 100 adult PLWH and 152 controls. All PLWH were receiving suppressive antiretroviral therapy, with median CD4+ T-cell counts of 710 (IQR 525-935) cells/mm
3 . Nadir CD4+ T-cell counts ranged as low as <10 (median 280; IQR 120-490) cells/mm3 . After adjustment for sociodemographic, health and vaccine-related variables, HIV infection was significantly associated with 0.2 log10 lower anti-RBD antibody concentrations (p=0.03) and ∼11% lower ACE2 displacement activity (p=0.02), but not lower viral neutralization (p=0.1) after one vaccine dose. Following two doses however, HIV was no longer significantly associated with the magnitude of any response measured. Rather, older age, a higher burden of chronic health conditions, and having received two ChAdOx1 doses (versus a heterologous or dual mRNA vaccine regimen) were independently associated with lower responses. After two vaccine doses, no significant correlation was observed between the most recent or nadir CD4+ T-cell counts and vaccine responses in PLWH. These results suggest that PLWH with well-controlled viral loads on antiretroviral therapy and CD4+ T-cell counts in a healthy range will generally not require a third COVID-19 vaccine dose as part of their initial immunization series, though other factors such as older age, co-morbidities, vaccine regimen type, and durability of vaccine responses will influence when this group may benefit from additional doses. Further studies of PLWH who are not receiving antiretroviral treatment and/or who have low CD4+ T-cell counts are needed.- Published
- 2021
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28. Weak humoral immune reactivity among residents of long-term care facilities following one dose of the BNT162b2 mRNA COVID-19 vaccine.
- Author
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Brockman MA, Mwimanzi F, Sang Y, Ng K, Agafitei O, Ennis S, Lapointe H, Young L, Umviligihozo G, Burns L, Brumme C, Leung V, Montaner JSG, Holmes D, DeMarco M, Simons J, Niikura M, Pantophlet R, Romney MG, and Brumme ZL
- Abstract
Background: Several Canadian provinces are extending the interval between COVID-19 vaccine doses to increase population vaccine coverage more rapidly. However, immunogenicity of these vaccines after one dose is incompletely characterized, particularly among the elderly, who are at greatest risk of severe COVID-19., Methods: We assessed SARS-CoV-2 humoral responses pre-vaccine and one month following the first dose of BNT162b2 mRNA vaccine, in 12 COVID-19 seronegative residents of long-term care facilities (median age, 82 years), 18 seronegative healthcare workers (HCW; median age, 36 years) and 4 convalescent HCW. Total antibody responses to SARS-CoV-2 nucleocapsid (N) and spike protein receptor binding domain (S/RBD) were assessed using commercial immunoassays. We quantified IgG and IgM responses to S/RBD and determined the ability of antibodies to block S/RBD binding to ACE2 receptor using ELISA. Neutralizing antibody activity was also assessed using pseudovirus and live SARS-CoV-2., Results: After one vaccine dose, binding antibodies against S/RBD were ~4-fold lower in residents compared to HCW (p<0.001). Inhibition of ACE2 binding was 3-fold lower in residents compared to HCW (p=0.01) and pseudovirus neutralizing activity was 2-fold lower (p=0.003). While six (33%) seronegative HCW neutralized live SARS-CoV-2, only one (8%) resident did (p=0.19). In contrast, convalescent HCW displayed 7- to 20-fold higher levels of binding antibodies and substantial ability to neutralize live virus after one dose., Interpretation: Extending the interval between COVID-19 vaccine doses may pose a risk to the elderly due to lower vaccine immunogenicity in this group. We recommend that second doses not be delayed in elderly individuals.
- Published
- 2021
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29. A glycoside analog of mammalian oligomannose formulated with a TLR4-stimulating adjuvant elicits HIV-1 cross-reactive antibodies.
- Author
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Bruxelle JF, Kirilenko T, Trattnig N, Yang Y, Cattin M, Kosma P, and Pantophlet R
- Subjects
- Animals, Mice, Mice, Transgenic, Cross Reactions, HIV Antibodies immunology, HIV-1 immunology, Mannose chemistry, Toll-Like Receptor 4 immunology
- Abstract
The occurrence of oligomannose-specific broadly neutralizing antibodies (bnAbs) has spurred efforts to develop immunogens that can elicit similar antibodies. Here, we report on the antigenicity and immunogenicity of a CRM
197 -conjugate of a previously reported oligomannose mimetic. Oligomannose-specific bnAbs that are less dependent on interactions with the HIV envelope protein sequence showed strong binding to the glycoconjugates, with affinities approximating those reported for their cognate epitope. The glycoconjugate is also recognized by inferred germline precursors of oligomannose-specific bnAbs, albeit with the expected low avidity, supporting its potential as an immunogen. Immunization of human-antibody transgenic mice revealed that only a TLR4-stimulating adjuvant formulation resulted in antibodies able to bind a panel of recombinant HIV trimers. These antibodies bound at relatively modest levels, possibly explaining their inability to neutralize HIV infectivity. Nevertheless, these findings contribute further to understanding conditions for eliciting HIV-cross-reactive oligomannose-specific antibodies and inform on next steps for improving on the elicited response.- Published
- 2021
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30. HIV-1 Entry and Prospects for Protecting against Infection.
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Bruxelle JF, Trattnig N, Mureithi MW, Landais E, and Pantophlet R
- Abstract
Human Immunodeficiency Virus type-1 (HIV-1) establishes a latent viral reservoir soon after infection, which poses a major challenge for drug treatment and curative strategies. Many efforts are therefore focused on blocking infection. To this end, both viral and host factors relevant to the onset of infection need to be considered. Given that HIV-1 is most often transmitted mucosally, strategies designed to protect against infection need to be effective at mucosal portals of entry. These strategies need to contend also with cell-free and cell-associated transmitted/founder (T/F) virus forms; both can initiate and establish infection. This review will discuss how insight from the current model of HIV-1 mucosal transmission and cell entry has highlighted challenges in developing effective strategies to prevent infection. First, we examine key viral and host factors that play a role in transmission and infection. We then discuss preventive strategies based on antibody-mediated protection, with emphasis on targeting T/F viruses and mucosal immunity. Lastly, we review treatment strategies targeting viral entry, with focus on the most clinically advanced entry inhibitors.
- Published
- 2021
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31. Serum alpha-mannosidase as an additional barrier to eliciting oligomannose-specific HIV-1-neutralizing antibodies.
- Author
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Bruxelle JF, Kirilenko T, Qureshi Q, Lu N, Trattnig N, Kosma P, and Pantophlet R
- Subjects
- AIDS Vaccines immunology, Animals, Bacterial Proteins immunology, Epitopes immunology, Female, Glycoconjugates, Glycoproteins immunology, Glycoproteins metabolism, HIV Infections virology, Humans, Male, Mice, Oligosaccharides, Polysaccharides immunology, Protein Binding, Protein Multimerization, Vaccines, Conjugate, env Gene Products, Human Immunodeficiency Virus chemistry, env Gene Products, Human Immunodeficiency Virus immunology, Antibodies, Neutralizing immunology, HIV Antibodies immunology, HIV Infections blood, HIV Infections immunology, HIV-1 immunology, alpha-Mannosidase blood
- Abstract
Oligomannose-type glycans on HIV-1 gp120 form a patch that is targeted by several broadly neutralizing antibodies (bnAbs) and that therefore is of interest to vaccine design. However, attempts to elicit similar oligomannose-specific bnAbs by immunizing with oligomannosidic glycoconjugates have only been modestly successful so far. A common assumption is that eliciting oligomannose-specific bnAbs is hindered by B cell tolerance, resulting from the presented oligomannosides being sensed as self molecules. Here, we present data, along with existing scientific evidence, supporting an additional, or perhaps alternate, explanation: serum mannosidase trimming of the presented oligomannosides in vivo. Mannosidase trimming lessens the likelihood of eliciting antibodies with capacity to bind full-sized oligomannose, which typifies the binding mode of existing bnAbs to the oligomannose patch. The rapidity of the observed trimming suggests the need for immunization strategies and/or synthetic glycosides that readily avoid or resist mannosidase trimming upon immunization and can overcome possible tolerance restrictions.
- Published
- 2020
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32. Synthesis of an Undecasaccharide Featuring an Oligomannosidic Heptasaccharide and a Bacterial Kdo-lipid A Backbone for Eliciting Neutralizing Antibodies to Mammalian Oligomannose on the HIV-1 Envelope Spike.
- Author
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Trattnig N, Blaukopf M, Bruxelle JF, Pantophlet R, and Kosma P
- Subjects
- Chemistry Techniques, Synthetic, Glycoconjugates chemistry, Models, Molecular, Protein Conformation, Agrobacterium tumefaciens chemistry, Antibodies, Neutralizing immunology, Glycoconjugates chemical synthesis, HIV-1, Lipid A chemistry, Oligosaccharides chemistry, env Gene Products, Human Immunodeficiency Virus immunology
- Abstract
Lipooligosaccharides (LOS) from the bacterium Rhizobium radiobacter Rv3 are structurally related to antigenic mammalian oligomannoses on the HIV-1 envelope glycoprotein spike that are targets for broadly neutralizing antibodies. Here, we prepared a hybrid structure of viral and bacterial epitopes as part of a vaccine design strategy to elicit oligomannose-specific HIV-neutralizing antibodies using glycoconjugates based on the Rv3 LOS structure. Starting from a Kdo
2 GlcNAc2 tetrasaccharide precursor, a central orthogonally protected mannose trichloroacetimidate donor was coupled to OH-5 of the innermost Kdo residue. To assemble larger glycans, the N-acetylamino groups of the glucosamine units were converted to imides to prevent formation of unwanted imidate byproducts. Blockwise coupling of the pentasaccharide acceptor with an α-(1→2)-linked mannotriosyl trichloroacetimidate donor introduced the D1-arm fragment. Glycosylation of O-6 of the central branching mannose with an α-(1→2)-α-(1→6)-linked mannotriosyl trichloroacetimidate donor unit then furnished the undecasaccharide harboring a D3-arm extension. Global deprotection yielded the 3-aminopropyl ligand, which was activated as an isothiocyanate or adipic acid succinimidoyl ester and conjugated to CRM197 . However, representative oligomannose-specific HIV-neutralizing antibodies bound the undecasaccharide conjugates poorly. Possible reasons for this outcome are discussed herein along with paths for improvement.- Published
- 2019
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33. Comparative Antigenicity of Thiourea and Adipic Amide Linked Neoglycoconjugates Containing Modified Oligomannose Epitopes for the Carbohydrate-Specific anti-HIV Antibody 2G12.
- Author
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Trattnig N, Mayrhofer P, Kunert R, Mach L, Pantophlet R, and Kosma P
- Subjects
- Amides chemistry, Carbohydrate Sequence, Click Chemistry, Dendrimers chemistry, Glycoconjugates chemical synthesis, HIV Antibodies chemistry, Adipates chemistry, Epitopes chemistry, Glycoconjugates chemistry, HIV Antibodies immunology, Mannose chemistry, Thiourea chemistry
- Abstract
Novel neoglycoproteins containing oligomannosidic penta- and heptasaccharides as structural variants of oligomannose-type N-glycans found on human immunodeficiency virus type 1 gp120 have been prepared using different conjugation methods. Two series of synthetic ligands equipped with 3-aminopropyl spacer moieties and differing in the anomeric configuration of the reducing mannose residue were activated either as isothiocyanates or as adipic acid succinimidoyl esters and coupled to bovine serum albumin. Coupling efficiency for adipic acid connected neoglycoconjugates was better than for the thiourea-linked derivatives; the latter constructs, however, exhibited higher reactivity toward antibody 2G12, an HIV-neutralizing antibody with exquisite specificity for oligomannose-type glycans. 2G12 binding avidities for the conjugates, as determined by Bio-Layer Interferometry, were mostly higher for the β-linked ligands and, as expected, increased with the numbers of covalently linked glycans, leading to approximate K
D values of 10 to 34 nM for optimized ligand-to-BSA ratios. A similar correlation was observed by enzyme-linked immunosorbent assays. In addition, dendrimer-type ligands presenting trimeric oligomannose epitopes were generated by conversion of the amino-spacer group into a terminal azide, followed by triazole formation using "click chemistry". The severe steric bulk of the ligands, however, led to poor efficiency in the coupling step and no increased antibody binding by the resulting neoglycoconjugates, indicating that the low degree of substitution and the spatial orientation of the oligomannose epitopes within these trimeric ligands are not conducive to multivalent 2G12 binding.- Published
- 2019
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34. Synthesis of a Pentasaccharide Fragment Related to the Inner Core Region of Rhizobial and Agrobacterial Lipopolysaccharides.
- Author
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Trattnig N, Farcet JB, Gritsch P, Christler A, Pantophlet R, and Kosma P
- Subjects
- Disaccharides chemical synthesis, Lipopolysaccharides chemistry, Lipopolysaccharides chemical synthesis, Oligosaccharides chemistry, Rhizobium chemistry
- Abstract
The pentasaccharide fragment α-d-Man-(1 → 5)-[α-d-Kdo-(2 → 4)-]α-d-Kdo-(2 → 6)-β-d-GlcNAc-(1 → 6)-α-d-GlcNAc equipped with a 3-aminopropyl spacer moiety was prepared by a sequential assembly of monosaccharide building blocks. The glucosamine disaccharide-as a backbone surrogate of the bacterial lipid A region-was synthesized using an 1,3-oxazoline donor, which was followed by coupling with an isopropylidene-protected Kdo-fluoride donor to afford a protected tetrasaccharide intermediate. Eventually, an orthogonally protected manno-configured trichloroacetimidate donor was used to achieve the sterically demanding glycosylation of the 5-OH group of Kdo in good yield. The resulting pentasaccharide is suitably protected for further chain elongation at positions 3, 4, and 6 of the terminal mannose. Global deprotection afforded the target pentasaccharide to be used for the conversion into neoglycoconjugates and "clickable" ligands.
- Published
- 2017
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35. Bacterially derived synthetic mimetics of mammalian oligomannose prime antibody responses that neutralize HIV infectivity.
- Author
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Pantophlet R, Trattnig N, Murrell S, Lu N, Chau D, Rempel C, Wilson IA, and Kosma P
- Subjects
- Animals, Antibodies, Neutralizing chemistry, Antibodies, Neutralizing metabolism, Bacteria metabolism, CHO Cells, Carbohydrate Sequence, Cricetulus, HEK293 Cells, HIV Antibodies chemistry, HIV Antibodies metabolism, HIV Envelope Protein gp120 chemistry, HIV Envelope Protein gp120 immunology, HIV Infections virology, HIV-1 immunology, HIV-1 physiology, Humans, Mammals immunology, Mammals metabolism, Molecular Mimicry immunology, Protein Conformation, Rats, Transgenic, Antibodies, Neutralizing immunology, HIV Antibodies immunology, HIV Infections immunology, Oligosaccharides immunology
- Abstract
Oligomannose-type glycans are among the major targets on the gp120 component of the HIV envelope protein (Env) for broadly neutralizing antibodies (bnAbs). However, attempts to elicit oligomannose-specific nAbs by immunizing with natural or synthetic oligomannose have so far not been successful, possibly due to B cell tolerance checkpoints. Here we design and synthesize oligomannose mimetics, based on the unique chemical structure of a recently identified bacterial lipooligosaccharide, to appear foreign to the immune system. One of these mimetics is bound avidly by members of a family of oligomannose-specific bnAbs and their putative common germline precursor when presented as a glycoconjugate. The crystal structure of one of the mimetics bound to a member of this bnAb family confirms the antigenic resemblance. Lastly, immunization of human-antibody transgenic animals with a lead mimetic evokes nAbs with specificities approaching those of existing bnAbs. These results provide evidence for utilizing antigenic mimicry to elicit oligomannose-specific bnAbs to HIV-1.
- Published
- 2017
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36. Identification of CD4-Binding Site Dependent Plasma Neutralizing Antibodies in an HIV-1 Infected Indian Individual.
- Author
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Khan L, Makhdoomi MA, Kumar S, Nair A, Andrabi R, Clark BE, Auyeung K, Bhattacharya J, Vajpayee M, Wig N, Pantophlet R, and Luthra K
- Subjects
- Adolescent, Adult, Antibodies, Neutralizing chemistry, Female, HIV Antibodies immunology, HIV-1 immunology, Humans, Male, Middle Aged, Antibodies, Neutralizing immunology, Binding Sites, Antibody, CD4 Antigens immunology, HIV Infections immunology
- Abstract
Dissecting antibody specificities in the plasma of HIV-1 infected individuals that develop broadly neutralizing antibodies (bNAbs) is likely to provide useful information for refining target epitopes for vaccine design. Several studies have reported CD4-binding site (CD4bs) antibodies as neutralization determinants in the plasma of subtype B-infected individuals; however there is little information on the prevalence of CD4bs specificities in HIV-infected individuals in India. Here, we report on the presence of CD4bs antibodies and their contribution to virus neutralization in the plasma from a cohort of HIV-1 infected Indian individuals. Plasma from 11 of the 140 HIV-1 infected individuals (7.9%) studied here exhibited cross-neutralization activity against a panel of subtype B and C viruses. Analyses of these 11 plasma samples for the presence of CD4bs antibodies using two CD4bs-selective probes (antigenically resurfaced HXB2gp120 core protein RSC3 and hyperglycosylated JRFLgp120 mutant ΔN2mCHO) revealed that five (AIIMS 617, 619, 627, 642, 660) contained RSC3-reactive plasma antibodies and only one (AIIMS 660) contained ΔN2mCHO-reactive antibodies. Plasma antibody depletion and competition experiments confirmed that the neutralizing activity in the AIIMS 660 plasma was dependent on CD4bs antibodies. To the best of our knowledge, this is the first study to report specifically on the presence of CD4bs antibodies in the plasma of a cohort of HIV-1 infected Indian donors. The identification of CD4bs dependent neutralizing antibodies in an HIV-1 infected Indian donor is a salient finding of this study and is supportive of ongoing efforts to induce similar antibodies by immunization.
- Published
- 2015
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37. Crystal structure of the HIV neutralizing antibody 2G12 in complex with a bacterial oligosaccharide analog of mammalian oligomannose.
- Author
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Stanfield RL, De Castro C, Marzaioli AM, Wilson IA, and Pantophlet R
- Subjects
- Binding Sites, Broadly Neutralizing Antibodies, Carbohydrate Conformation, Crystallography, X-Ray, HIV Antibodies, Hydrogen Bonding, Models, Molecular, Protein Structure, Tertiary, Antibodies, Monoclonal chemistry, Antibodies, Neutralizing chemistry, Mannans chemistry, Polysaccharides, Bacterial chemistry
- Abstract
Human immunodeficiency virus-1 (HIV-1) is a major public health threat that continues to infect millions of people worldwide each year. A prophylactic vaccine remains the most cost-effective way of globally reducing and eliminating the spread of the virus. The HIV envelope spike, which is the target of many vaccine design efforts, is densely mantled with carbohydrate and several potent broadly neutralizing antibodies to HIV-1 recognize carbohydrate on the envelope spike as a major part of their epitope. However, immunizing with recombinant forms of the envelope glycoprotein does not typically elicit anti-carbohydrate antibodies. Thus, studies of alternative antigens that may serve as a starting point for carbohydrate-based immunogens are of interest. Here, we present the crystal structure of one such anti-carbohydrate HIV neutralizing antibody (2G12) in complex with the carbohydrate backbone of the lipooligosaccharide from Rhizobium radiobacter strain Rv3, which exhibits a chemical structure that naturally mimics the core high-mannose carbohydrate epitope of 2G12 on HIV-1 gp120. The structure described here provides molecular evidence of the structural homology between the Rv3 oligosaccharide and highly abundant carbohydrates on the surface of HIV-1 and raises the potential for the design of novel glycoconjugates that may find utility in efforts to develop immunogens for eliciting carbohydrate-specific neutralizing antibodies to HIV., (© The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2015
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38. The presence of glutamine at position 315 but not epitope masking predominantly hinders HIV subtype C neutralization by the anti-V3 antibody B4e8.
- Author
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Manhas S, Chau D, Rempel C, Clark BE, Auyeung K, and Pantophlet R
- Subjects
- Amino Acid Substitution, Arginine immunology, HIV-1 genetics, env Gene Products, Human Immunodeficiency Virus genetics, Antibodies, Neutralizing immunology, Epitopes immunology, Glutamine immunology, HIV Antibodies immunology, HIV-1 immunology, env Gene Products, Human Immunodeficiency Virus immunology
- Abstract
Antibody B4e8 exhibits modest cross-neutralizing activity, with preference for HIV subtype B. This preference might be explained by B4e8׳s extensive interaction with Arg315, which occurs at the center of most subtype B V3 sequences but is replaced by Gln in subtype C. The extent to which B4e8׳s ability to neutralize subtype C strains is hindered by Gln315 and/or other factors, e.g. epitope masking, is unclear. We confirmed here that an Arg315-to-Gln substitution in a subtype B virus abrogates B4e8 neutralizing activity. Conversely, B4e8-resistant subtype C viruses were rendered sensitive upon Gln 315-to-Arg substitution. V2 region swapping between B4e8-sensitive and- resistant subtype C strains revealed a role for V2 in limiting B4e8 access, but this was less significant than the absence of Arg315. Our findings, while illustrating the importance of Arg315 for B4e8, suggest that some subtype C strains may be vulnerable to B4e8 derivatives capable of binding stronger to Gln315-containing sequences., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
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39. 2G12-expressing B cell lines may aid in HIV carbohydrate vaccine design strategies.
- Author
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Doores KJ, Huber M, Le KM, Wang SK, Doyle-Cooper C, Cooper A, Pantophlet R, Wong CH, Nemazee D, and Burton DR
- Subjects
- Animals, Antibodies, Monoclonal genetics, Broadly Neutralizing Antibodies, Cell Line, Drug Discovery methods, HIV Antibodies, Lymphocyte Activation, Mice, AIDS Vaccines immunology, Antibodies, Monoclonal immunology, B-Lymphocytes immunology, Carbohydrates immunology, Gene Expression, HIV Envelope Protein gp120 immunology, HIV-1 immunology
- Abstract
The highly conserved cluster of high-mannose glycans on the HIV-1 envelope glycoprotein, gp120, has been highlighted as a target for neutralizing antibodies. 2G12, the first HIV-1 antiglycan neutralizing antibody described, binds with an unusual domain-exchanged structure that creates a high-affinity multivalent binding surface. It is an interesting challenge for rational vaccine design to generate immunogens capable of eliciting domain-exchanged 2G12-like responses. We recently showed that di-mannose recognition by the variable domains of 2G12 is independent of domain exchange but that exchange is critical for virus neutralization. Carbohydrate-based immunogens aimed at inducing 2G12-like antibodies may need to drive both di-mannose recognition and domain exchange through interactions with B cell receptors. Here we assessed the ability of such immunogens to activate mouse B cell lines displaying domain-exchanged wild-type 2G12 (2G12 WT), a non-domain-exchanged Y-shaped variant (2G12 I19R), and germ line 2G12 (2G12 gl). We show that several immunogens, including heat-killed yeast and bacteria, can activate both 2G12 WT and 2G12 I19R B cells. However, only discrete clusters of high-mannose glycans, as on recombinant forms of the HIV-1 envelope trimer and oligodendrons, activate 2G12 WT B cells. Furthermore, no immunogen tested activated 2G12 gl cells. Our results support the hypothesis that in order to drive domain exchange of an antimannose antibody response, a boost with an immunogen displaying discrete clusters of high-mannose glycans not recognized by conventional Y-shaped antibodies will be required. Additionally, a molecule capable of activating 2G12 gl cells might also be required. The results highlight broadly neutralizing antibody-expressing mouse B cells as potentially useful tools for carbohydrate immunogen screening.
- Published
- 2013
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40. A bacterial lipooligosaccharide that naturally mimics the epitope of the HIV-neutralizing antibody 2G12 as a template for vaccine design.
- Author
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Clark BE, Auyeung K, Fregolino E, Parrilli M, Lanzetta R, De Castro C, and Pantophlet R
- Subjects
- AIDS Vaccines immunology, Animals, Antibodies, Monoclonal immunology, Antibodies, Monoclonal metabolism, Antibodies, Neutralizing immunology, Carbohydrate Sequence, Epitopes immunology, HIV Envelope Protein gp120 immunology, HIV Envelope Protein gp120 metabolism, HIV Infections immunology, Humans, Lipopolysaccharides immunology, Mice, Molecular Sequence Data, Protein Binding, AIDS Vaccines metabolism, Antibodies, Neutralizing metabolism, HIV Infections prevention & control, Lipopolysaccharides metabolism, Rhizobium metabolism
- Abstract
The broadly neutralizing antibody 2G12 binds a fairly conserved cluster of oligomannose sugars on the HIV surface glycoprotein gp120, which has led to the hypothesis that these sugars pose potential vaccine targets. Here, we present the chemical analysis, antigenicity, and immunogenicity of a bacterial lipooligosaccharide (LOS) comprised of a manno-oligosaccharide sequence analogous to the 2G12 epitope. Antigenic similarity of the LOS to oligomannose was evidenced by 2G12 binding to the LOS and the inability of sera elicited against synthetic oligomannosides, but incapable of binding natural oligomannose, to bind the LOS. Immunization with heat-killed bacteria yielded epitope-specific serum antibodies with the capacity to bind soluble gp120. Although these sera did not exhibit specific anti-HIV activity, our data suggest that this LOS may find utility as a template for the design of glycoconjugates to target HIV., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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41. Complex binding sites made to order.
- Author
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Scott JK, Pantophlet R, and Craig L
- Subjects
- Algorithms, Humans, Protein Conformation, Binding Sites, Antibody immunology, Computational Biology, Epitopes immunology, Viral Vaccines immunology
- Published
- 2012
- Full Text
- View/download PDF
42. An engineered mutant of HIV-1 gp120 formulated with adjuvant Quil A promotes elicitation of antibody responses overlapping the CD4-binding site.
- Author
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Ahmed FK, Clark BE, Burton DR, and Pantophlet R
- Subjects
- AIDS Vaccines administration & dosage, AIDS Vaccines genetics, Animals, Antibodies, Neutralizing blood, Antibodies, Neutralizing metabolism, Binding Sites, Female, HIV Antibodies metabolism, HIV Envelope Protein gp120 genetics, Lipid A administration & dosage, Lipid A analogs & derivatives, Mice, Mice, Inbred BALB C, Neutralization Tests, Quillaja Saponins, Vaccines, Synthetic administration & dosage, Vaccines, Synthetic genetics, Vaccines, Synthetic immunology, AIDS Vaccines immunology, Adjuvants, Immunologic administration & dosage, HIV Antibodies blood, HIV Envelope Protein gp120 immunology, Saponins administration & dosage
- Abstract
A major priority in HIV vaccine research is the development of an immunogen to elicit broadly neutralizing antibodies (NAbs). Monoclonal antibody (mAb) b12 is one of now several broadly neutralizing mAbs that bind epitopes overlapping the CD4-binding site (CD4bs) on HIV-1 gp120 and that serve as templates to engineer effective immunogens. We are exploring a strategy whereby extra glycans are incorporated onto gp120 to occlude the epitopes of non-neutralizing mAbs while maintaining exposure of the b12 site. Immunizing with these so-called hyperglycosylated gp120s is hypothesized to preferentially elicit b12-like NAbs. Here, the effects of two adjuvants, monophosphoryl lipid A (MPL) and Quil A, on eliciting b12-like responses when formulated with a new hyperglycosylated mutant, ΔN2mCHO(Q105N), is presented. Sera from ΔN2mCHO(Q105N)_MPL immunized animals bound the homologous antigen ΔN2mCHO(Q105N) with greater preference than sera from ΔN2mCHO(Q105N)_QuilA immunized animals, demonstrating the modulation of antibody fine specificity by these two adjuvants. We also found that sera from ΔN2mCHO(Q105N)_QuilA immunized animals bound best to a resurfaced HIV gp120 core protein on which non-CD4bs epitopes are substituted with non-HIV residues, suggesting that these sera contain a relatively larger fraction of CD4bs-specific antibodies. Consistent with these data, inhibition assays revealed epitope overlap with the binding sites of the CD4bs-specific antibodies b12, b13 and VRC03. Unexpectedly, these sera did not exhibit significant neutralizing activity against a set of HIV-1 primary strains. Our results show that although formulating mutant ΔN2mCHO(Q105N) with Quil A promotes the elicitation of CD4bs-directed antibodies relative to wild-type gp120, tweaking of the immunization regimen is needed to yield robust, CD4bs-focused NAbs., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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43. Binding of the mannose-specific lectin, griffithsin, to HIV-1 gp120 exposes the CD4-binding site.
- Author
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Alexandre KB, Gray ES, Pantophlet R, Moore PL, McMahon JB, Chakauya E, O'Keefe BR, Chikwamba R, and Morris L
- Subjects
- Antibodies, Neutralizing metabolism, Binding Sites, CD4 Antigens metabolism, Humans, Neutralization Tests, Plant Lectins, Protein Binding, Algal Proteins metabolism, HIV Antibodies metabolism, HIV Envelope Protein gp120 metabolism, Lectins metabolism, Mannose-Binding Lectins metabolism
- Abstract
The glycans on HIV-1 gp120 play an important role in shielding neutralization-sensitive epitopes from antibody recognition. They also serve as targets for lectins that bind mannose-rich glycans. In this study, we investigated the interaction of the lectin griffithsin (GRFT) with HIV-1 gp120 and its effects on exposure of the CD4-binding site (CD4bs). We found that GRFT enhanced the binding of HIV-1 to plates coated with anti-CD4bs antibodies b12 and b6 or the CD4 receptor mimetic CD4-IgG2. The average enhancement of b12 or b6 binding was higher for subtype B viruses than for subtype C, while for CD4-IgG2, it was similar for both subtypes, although lower than observed with antibodies. This GRFT-mediated enhancement of HIV-1 binding to b12 was reflected in synergistic neutralization for 2 of the 4 viruses tested. The glycan at position 386, which shields the CD4bs, was involved in both GRFT-mediated enhancement of binding and neutralization synergism between GRFT and b12. Although GRFT enhanced CD4bs exposure, it simultaneously inhibited ligand binding to the coreceptor binding site, suggesting that GRFT-dependent enhancement and neutralization utilize independent mechanisms. This study shows for the first time that GRFT interaction with gp120 exposes the CD4bs through binding the glycan at position 386, which may have implications for how to access this conserved site.
- Published
- 2011
- Full Text
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44. Defining criteria for oligomannose immunogens for HIV using icosahedral virus capsid scaffolds.
- Author
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Astronomo RD, Kaltgrad E, Udit AK, Wang SK, Doores KJ, Huang CY, Pantophlet R, Paulson JC, Wong CH, Finn MG, and Burton DR
- Subjects
- AIDS Vaccines immunology, Allolevivirus chemistry, Animals, Broadly Neutralizing Antibodies, Capsid chemistry, Carbohydrate Sequence, Comovirus chemistry, HIV Antibodies, HIV Infections prevention & control, Mannose chemistry, Molecular Sequence Data, Oligosaccharides chemistry, Oligosaccharides immunology, Rabbits, AIDS Vaccines chemistry, Allolevivirus immunology, Antibodies, Monoclonal immunology, Capsid immunology, Comovirus immunology, HIV immunology, Mannose immunology
- Abstract
The broadly neutralizing antibody 2G12 recognizes a conserved cluster of high-mannose glycans on the surface envelope spike of HIV, suggesting that the "glycan shield" defense of the virus can be breached and may, under the right circumstances, serve as a vaccine target. In an attempt to recreate features of the glycan shield semisynthetically, oligomannosides were coupled to surface lysines on the icosahedral capsids of bacteriophage Q beta and cowpea mosaic virus (CPMV). The Q beta glycoconjugates, but not CPMV, presented oligomannose clusters that bind the antibody 2G12 with high affinity. However, antibodies against these 2G12 epitopes were not detected in immunized rabbits. Rather, alternative oligomannose epitopes on the conjugates were immunodominant and elicited high titers of anti-mannose antibodies that do not crossreact with the HIV envelope. The results presented reveal important design considerations for a carbohydrate-based vaccine component for HIV., ((c) 2010 Elsevier Ltd. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
45. Antibody epitope exposure and neutralization of HIV-1.
- Author
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Pantophlet R
- Subjects
- Animals, Antibodies, Neutralizing chemistry, Antibodies, Neutralizing immunology, Epitopes chemistry, HIV Envelope Protein gp120 chemistry, HIV Envelope Protein gp120 immunology, HIV Envelope Protein gp41 chemistry, HIV Envelope Protein gp41 immunology, HIV-1 metabolism, Humans, Protein Conformation, AIDS Vaccines immunology, Epitopes immunology, HIV Infections prevention & control, HIV-1 immunology, env Gene Products, Human Immunodeficiency Virus chemistry, env Gene Products, Human Immunodeficiency Virus immunology
- Abstract
Formulating an effective HIV vaccine remains a formidable challenge despite nearly 3 decades of intense research since the virus was first isolated. One of the obstacles that need to be surmounted is the design of a preparation that elicits a potent and broadly neutralizing antibody (nAb) response, i.e. antibodies with the capacity to block infectivity of the genetically diverse pool of HIV strains that circulate globally. The primary target for nAbs on HIV-1 is the envelope glycoprotein spike (Env). Early work on elucidating the exposure of antibody epitopes on Env suggested highly restricted accessibility of antibodies to epitopes that are conserved among otherwise diverse virus isolates. Crystal structures of Env-derived antigens, most in complex with antibodies, along with structure-function studies and molecular modeling, have provided significant further insight into features of Env that limit broad antibody recognition. Despite these challenges, recent progress on various fronts has led to a growing sense that Env is not as impenetrable to nAbs as might have been believed in the past. Increased understanding of antibody epitope exposure on Env should provide new impulses for efforts to elicit nAbs that can protect against HIV-1 infection.
- Published
- 2010
- Full Text
- View/download PDF
46. Report on the AIDS Vaccine 2008 Conference.
- Author
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Alter G, Ananworanich J, Pantophlet R, Rybicki EP, and Buonaguro L
- Subjects
- AIDS Vaccines adverse effects, Acquired Immunodeficiency Syndrome epidemiology, Humans, South Africa, AIDS Vaccines immunology, Acquired Immunodeficiency Syndrome immunology, Acquired Immunodeficiency Syndrome prevention & control
- Abstract
The "AIDS Vaccine 2008" Conference was held in Cape Town, South Africa (October 13 to 16, 2008) and organized, under the aegis of the Global HIV Vaccine Enterprise, by Dr. Lynn Morris (Chair of the Conference) National Institute of Communicable Diseases; Dr. Koleka Mlisana from CAPRISA, University KwaZulu-Natal, Durban, Dr. Glenda Gray from Perinatal HIV Research Unit, University Witwatersrand, Johannesburg and Dr. Carolyn Williamson from Institute of Infectious Diseses. and Molecular Medicine, UCT, Cape Town (Co-Chairs of the Conference). Since the first AIDS Vaccine conference, organized in Paris in 2000, this was the first time it was held outside of the U.S. and Europe, and involved nearly 1,000 participants. Besides three Plenary Sessions with ten state-of-the-art plenary lectures and one Keynote Lecture given by Dr. A.S. Fauci (Director of NIAID, NIH, USA), the Conference was organized in nine oral sessions, four poster discussion groups covering a wide spectrum of scientific information relating to HIV vaccine research and development. Moreover three Symposia, two Special Sessions, one Roundtable as well as two Debates were held, the latter focusing on current controversial topics. The conference opening was memorable for a number of reasons: among these was the presence of South Africa's new Minister of Health, Barbara Hogan who, in her first speech in a major forum as a senior member of the SA Government, affirmed that HIV causes AIDS, and that the search for a vaccine is of paramount importance to SA and the rest of the world. A scientific summary of the Conference is reported in the present article, divided into four major topics: (1) vaccine concepts and design; (2) T-cell immunology and innate immunity; (3) B-cell immunology, neutralizing antibodies and mucosal immunology; and (4) clinical trials.
- Published
- 2009
- Full Text
- View/download PDF
47. The human immunodeficiency virus type 1 envelope spike of primary viruses can suppress antibody access to variable regions.
- Author
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Pantophlet R, Wang M, Aguilar-Sino RO, and Burton DR
- Subjects
- Amino Acid Sequence, Epitopes genetics, Epitopes immunology, HIV-1 genetics, Humans, Models, Molecular, Molecular Sequence Data, Protein Structure, Quaternary, env Gene Products, Human Immunodeficiency Virus genetics, HIV Antibodies immunology, HIV-1 immunology, env Gene Products, Human Immunodeficiency Virus immunology
- Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope spike is a heavily glycosylated trimeric structure in which protein surfaces conserved between different HIV-1 isolates are particularly well hidden from antibody recognition. However, even variable regions on the spike tend to be less antigenic and immunogenic than one might have anticipated for external structures. Here we show that the envelope spike of primary viruses has an ability to restrict antibody recognition of variable regions. We show that access to an artificial epitope, introduced at multiple positions across the spike, is frequently limited, even though the epitope has been inserted at surface-exposed regions on the spike. Based on the data, we posit that restricted antibody access may be the result, at least in part, of a rigidification of the epitope sequence in the context of the spike and/or a highly effective flexible arrangement of the glycan shield on primary viruses. Evolution of the HIV envelope structure to incorporate extra polypeptide sequences into nominally accessible regions with limited antibody recognition may contribute to reducing the magnitude of antibody responses during infection and allow the virus to replicate unhindered by antibody pressure for longer periods.
- Published
- 2009
- Full Text
- View/download PDF
48. Neutralizing activity of antibodies to the V3 loop region of HIV-1 gp120 relative to their epitope fine specificity.
- Author
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Pantophlet R, Wrin T, Cavacini LA, Robinson JE, and Burton DR
- Subjects
- Alanine analysis, Amino Acid Motifs immunology, Amino Acid Sequence, Antibodies, Monoclonal immunology, Cell Line, Cross Reactions immunology, Epitopes chemistry, HIV Envelope Protein gp120 chemistry, Models, Molecular, Neutralization Tests, Peptide Fragments chemistry, Peptide Fragments immunology, Protein Structure, Tertiary, Sequence Alignment, Antibody Specificity, Epitopes immunology, HIV Antibodies immunology, HIV Envelope Protein gp120 immunology, HIV-1
- Abstract
The V3 loop of HIV-1 gp120 is considered occluded on many primary viruses. However, virus sensitivity to neutralization by different V3 mAbs often varies, indicating that access to V3 is not restricted equally for all antibodies. Here, we have sought to gain a better understanding of these restrictions by determining the neutralizing activities of 7 V3 mAbs (19b, 39F, CO11, F2A3, F530, LA21, and LE311) against 15 subtype B primary isolates and relating these activities to the fine specificity of the mAbs. Not surprisingly, we found that most mAbs neutralized the same 2-3 viruses, with only mAb F530 able to neutralize 2 additional viruses not neutralized by the other mAbs. Epitope mapping revealed that positively-charged residues in or near the V3 stem are important for the binding of all the mAbs and that most mAbs seem to require the Pro residue that forms the GPGR beta hairpin turn in the V3 tip for binding. Based on the mapping, we determined that V3 sequence variation accounted for neutralization resistance of approximately half the viruses tested. Comparison of these results to those of select V3 mAbs with overall better neutralizing activities in the light of structural information illustrates how an antibody's mode of interaction with V3, driven by contact residue requirements, may restrict the antibody from accessing its epitope on different viruses. Based on the data we propose an angle of interaction with V3 that is less stringent on access for antibodies with cross-neutralizing activity compared to antibodies that neutralize relatively fewer viruses.
- Published
- 2008
- Full Text
- View/download PDF
49. An aptamer that neutralizes R5 strains of HIV-1 binds to core residues of gp120 in the CCR5 binding site.
- Author
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Cohen C, Forzan M, Sproat B, Pantophlet R, McGowan I, Burton D, and James W
- Subjects
- Aptamers, Nucleotide, Binding Sites, Cells, Cultured, HIV Envelope Protein gp120 drug effects, HIV Envelope Protein gp120 genetics, HIV-1 genetics, HIV-1 metabolism, Humans, Anti-HIV Agents pharmacology, HIV Envelope Protein gp120 metabolism, HIV Infections metabolism, HIV-1 drug effects, RNA pharmacology, Receptors, CCR5 metabolism
- Abstract
We have previously isolated nucleic acid ligands (aptamers) that bind the surface envelope glycoprotein, gp120, of HIV-1, and neutralize infection of diverse sub-types of virus. Our earlier studies have identified the overall structure of one of these aptamers, B40, and have indicated that it binds to gp120 in a manner that competes with that of the HIV-1 coreceptor, CCR5, and select "CD4i" antibodies with epitopes overlapping this region. Here, we sought to map the B40 binding site on gp120 more precisely by analysing its interaction with a panel of alanine substitution mutants of gp120. Furthermore, we tested our hypothesis concerning the structure of the 40 nucleotide functional core of the aptamer by the solid-phase synthesis of truncated and chemically modified derivatives. The results confirm our structural predictions and demonstrate that aptamer B40 neutralizes a diverse range of HIV-1 isolates as a result of binding to relatively conserved residues on gp120 at the heart of the CCR5-binding site. These structural insights may provide the basis for the development of potential anti-viral agents with high specificity and robustness.
- Published
- 2008
- Full Text
- View/download PDF
50. A glycoconjugate antigen based on the recognition motif of a broadly neutralizing human immunodeficiency virus antibody, 2G12, is immunogenic but elicits antibodies unable to bind to the self glycans of gp120.
- Author
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Astronomo RD, Lee HK, Scanlan CN, Pantophlet R, Huang CY, Wilson IA, Blixt O, Dwek RA, Wong CH, and Burton DR
- Subjects
- Amino Acid Motifs genetics, Antibodies, Monoclonal genetics, Broadly Neutralizing Antibodies, Enzyme-Linked Immunosorbent Assay, HIV Antibodies, Microarray Analysis, Oligosaccharides metabolism, Polysaccharides immunology, Antibodies, Monoclonal immunology, Antigens immunology, Glycoconjugates immunology, HIV Envelope Protein gp120 immunology, HIV-1 immunology, Oligosaccharides immunology
- Abstract
The glycan shield of human immunodeficiency virus type 1 (HIV-1) gp120 contributes to viral evasion from humoral immune responses. However, the shield is recognized by the HIV-1 broadly neutralizing antibody (Ab), 2G12, at a relatively conserved cluster of oligomannose glycans. The discovery of 2G12 raises the possibility that a carbohydrate immunogen may be developed that could elicit 2G12-like neutralizing Abs and contribute to an AIDS vaccine. We have previously dissected the fine specificity of 2G12 and reported that the synthetic tetramannoside (Man(4)) that corresponds to the D1 arm of Man(9)GlcNAc(2) inhibits 2G12 binding to gp120 as efficiently as Man(9)GlcNAc(2) itself, indicating the potential use of Man(4) as a building block for creating immunogens. Here, we describe the development of neoglycoconjugates displaying variable copy numbers of Man(4) on bovine serum albumin (BSA) molecules by conjugation to Lys residues. The increased valency enhances the apparent affinity of 2G12 for Man(4) up to a limit which is achieved at approximately 10 copies per BSA molecule, beyond which no further enhancement is observed. Immunization of rabbits with BSA-(Man(4))(14) elicits significant serum Ab titers to Man(4). However, these Abs are unable to bind gp120. Further analysis reveals that the elicited Abs bind a variety of unbranched and, to a lesser extent, branched Man(9) derivatives but not natural N-linked oligomannose containing the chitobiose core. These results suggest that Abs can be readily elicited against the D1 arm; however, potential differences in the presentation of Man(4) on neoglycoconjugates, compared to glycoproteins, poses challenges for eliciting anti-mannose Abs capable of cross-reacting with gp120 and HIV-1.
- Published
- 2008
- Full Text
- View/download PDF
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