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Scientific Publications
Risk of heterosexual HIV transmission attributable to sexually transmitted infections and non specific genital inflammation in Zambian discordant couples 1994 2012
Wall KM, Kilembe W, Vwalika B, Haddad LB, Hunter E, Lakhi S, Chavuma R, Htee Khu N, Brill I, Vwalika C, Mwananyanda L, Chomba E, Mulenga J, Tichacek A, Allen S
Risk of heterosexual HIV transmission attributable to sexually transmitted infections and non-specific genital inflammation in Zambian discordant couples, 1994-2012. Int J Epidemiol 2017;46(5):1593-1606 doi: 10.1093/ije/dyx045
Abstract
Studies have demonstrated the role of ulcerative and non-ulcerative sexually transmitted infections (STI) in HIV transmission/acquisition risk; less is understood about the role of non-specific inflammatory genital abnormalities.
Scientific Publications
Characterization of a stable HIV 1 B C recombinant soluble and trimeric envelope glycoprotein Env highly resistant to CD4 induced conformational changes
Kumar R, Ozorowski G, Kumar V, Holden LG, Shrivastava T, Patil S, Deshpande S, Ward AB, Bhattacharya J
Characterization of a stable HIV-1 B/C recombinant, soluble, and trimeric envelope glycoprotein (Env) highly resistant to CD4-induced conformational changes. J. Biol. Chem. 2017;292(38):15849-15858 doi: 10.1074/jbc.M117.803056
Abstract
The HIV-1 envelope (Env) is a glycoprotein consisting of a trimer of heterodimers containing gp120 and gp41 subunits that mediates virus entry and is a major target of broadly neutralizing antibodies (bnAbs) developed during infection in some individuals. The engagement of the HIV-1 gp120 glycoprotein to the host CD4 protein triggers conformational changes in gp120 that allow its binding to co-receptors and is necessary for virus entry to establish infection. Native-like HIV-1 Env immunogens representing distinct clades have been proposed to improve immunogenicity. In the present study, we examined the basis of resistance of an HIV-1 B/C recombinant Env (LT5.J4b12C) to non-neutralizing antibodies targeting CD4-induced Env epitopes in the presence of soluble CD4 (sCD4). Using native polyacrylamide gel shift assay and negative-stain EM, we found that the prefusion conformational state of LT5.J4b12C trimeric Env was largely unaffected in the presence of excess sCD4 with most Env trimers appearing to be in a ligand-free state. This resistance to CD4-induced conformational changes was associated with a lower affinity for CD4. Moreover, the LT5.J4b12C trimeric Env preferentially bound to the neutralizing antibodies compared with non-neutralizing antibodies. Taken together, we report on an HIV-1 B/C recombinant, native-like trimeric Env protein that is highly resistant to CD4-induced conformational changes but displays epitopes recognized by a diverse array of bnAbs. Such features make this B/C recombinant trimeric Env a useful addition to the pool of other recently identified native-like HIV-1 Env trimers suitable for use as antigenic bait for bnAb isolation, structural studies, and use as potential immunogens.
Scientific Publications
Protection against a mixed SHIV challenge by a broadly neutralizing antibody cocktail
Julg B, Liu PT, Wagh K, Fischer WM, Abbink P, Mercado NB, Whitney JB, Nkolola JP, McMahan K, Tartaglia LJ, Borducchi EN, Khatiwada S, Kamath M, LeSuer JA, Seaman MS, Schmidt SD, Mascola JR, Burton DR, Korber BT, Barouch DH
Protection against a mixed SHIV challenge by a broadly neutralizing antibody cocktail. Sci Transl Med 2017;9(408) doi: eaao4235
Abstract
HIV-1 sequence diversity presents a major challenge for the clinical development of broadly neutralizing antibodies (bNAbs) for both therapy and prevention. Sequence variation in critical bNAb epitopes has been observed in most HIV-1-infected individuals and can lead to viral escape after bNAb monotherapy in humans. We show that viral sequence diversity can limit both the therapeutic and prophylactic efficacy of bNAbs in rhesus monkeys. We first demonstrate that monotherapy with the V3 glycan-dependent antibody 10-1074, but not PGT121, results in rapid selection of preexisting viral variants containing N332/S334 escape mutations and loss of therapeutic efficacy in simian-HIV (SHIV)-SF162P3-infected rhesus monkeys. We then show that the V3 glycan-dependent antibody PGT121 alone and the V2 glycan-dependent antibody PGDM1400 alone both fail to protect against a mixed challenge with SHIV-SF162P3 and SHIV-325c. In contrast, the combination of both bNAbs provides 100% protection against this mixed SHIV challenge. These data reveal that single bNAbs efficiently select resistant viruses from a diverse challenge swarm to establish infection, demonstrating the importance of bNAb cocktails for HIV-1 prevention.
Scientific Publications
Glycans Function as Anchors for Antibodies and Help Drive HIV Broadly Neutralizing Antibody Development
Andrabi R, Su CY, Liang CH, Shivatare SS, Briney B, Voss JE, Nawazi SK, Wu CY, Wong CH, Burton DR
Glycans Function as Anchors for Antibodies and Help Drive HIV Broadly Neutralizing Antibody Development. Immunity 2017;47(3):524-537.e3 doi: S1074-7613(17)30364-3
Abstract
Apex broadly neutralizing HIV antibodies (bnAbs) recognize glycans and protein surface close to the 3-fold axis of the envelope (Env) trimer and are among the most potent and broad Abs described. The evolution of apex bnAbs from one donor (CAP256) has been studied in detail and many Abs at different stages of maturation have been described. Using diverse engineering tools, we investigated the involvement of glycan recognition in the development of the CAP256.VRC26 Ab lineage. We found that sialic acid-bearing glycans were recognized by germline-encoded and somatically mutated residues on the Ab heavy chain. This recognition provided an 'anchor' for the Abs as the core protein epitope varies, prevented complete neutralization escape, and eventually led to broadening of the response. These findings illustrate how glycan-specific maturation enables a human Ab to cope with pathogen escape mechanisms and will aid in optimization of immunization strategies to induce V2 apex bnAb responses.
Scientific Publications
Targeted N glycan deletion at the receptor binding site retains HIV Env NFL trimer integrity and accelerates the elicited antibody response
Dubrovskaya V, Guenaga J, de Val N, Wilson R, Feng Y, Movsesyan A, Karlsson Hedestam GB, Ward AB, Wyatt RT
Targeted N-glycan deletion at the receptor-binding site retains HIV Env NFL trimer integrity and accelerates the elicited antibody response. PLoS Pathog. 2017;13(9):e1006614 doi: 10.1371/journal.ppat.1006614
Abstract
Extensive shielding by N-glycans on the surface of the HIV envelope glycoproteins (Env) restricts B cell recognition of conserved neutralizing determinants. Elicitation of broadly neutralizing antibodies (bNAbs) in selected HIV-infected individuals reveals that Abs capable of penetrating the glycan shield can be generated by the B cell repertoire. Accordingly, we sought to determine if targeted N-glycan deletion might alter antibody responses to Env. We focused on the conserved CD4 binding site (CD4bs) since this is a known neutralizing determinant that is devoid of glycosylation to allow CD4 receptor engagement, but is ringed by surrounding N-glycans. We selectively deleted potential N-glycan sites (PNGS) proximal to the CD4bs on well-ordered clade C 16055 native flexibly linked (NFL) trimers to potentially increase recognition by naïve B cells in vivo. We generated glycan-deleted trimer variants that maintained native-like conformation and stability. Using a panel of CD4bs-directed bNAbs, we demonstrated improved accessibility of the CD4bs on the N-glycan-deleted trimer variants. We showed that pseudoviruses lacking these Env PNGSs were more sensitive to neutralization by CD4bs-specific bNAbs but remained resistant to non-neutralizing mAbs. We performed rabbit immunogenicity experiments using two approaches comparing glycan-deleted to fully glycosylated NFL trimers. The first was to delete 4 PNGS sites and then boost with fully glycosylated Env; the second was to delete 4 sites and gradually re-introduce these N-glycans in subsequent boosts. We demonstrated that the 16055 PNGS-deleted trimers more rapidly elicited serum antibodies that more potently neutralized the CD4bs-proximal-PNGS-deleted viruses in a statistically significant manner and strongly trended towards increased neutralization of fully glycosylated autologous virus. This approach elicited serum IgG capable of cross-neutralizing selected tier 2 viruses lacking N-glycans at residue N276 (natural or engineered), indicating that PNGS deletion of well-ordered trimers is a promising strategy to prime B cell responses to this conserved neutralizing determinant.
Scientific Publications
Volunteer motivators for participating in HIV vaccine clinical trials in Nairobi Kenya
Nyaoke BA, Mutua GN, Sajabi R, Nyasani D, Mureithi MW, Anzala OA
Volunteer motivators for participating in HIV vaccine clinical trials in Nairobi, Kenya. PLoS ONE 2017;12(9):e0183788 doi: 10.1371/journal.pone.0183788
Abstract
1.5 million Kenyans are living with HIV/AIDS as per 2015 estimates. Though there is a notable decline in new HIV infections, continued effort is still needed to develop an efficacious, accessible and affordable HIV vaccine. HIV vaccine clinical trials bear risks, hence a need to understand volunteer motivators for enrolment, retention and follow-up. Understanding the factors that motivate volunteers to participate in a clinical trial can help to strategize, refine targeting and thus increase enrolment of volunteers in future HIV vaccine clinical trials. The health belief model classifies motivators into social benefits such as 'advancing research' and collaboration with science, and personal benefits such as health benefits and financial interests.
Scientific Publications
Design and crystal structure of a native like HIV 1 envelope trimer that engages multiple broadly neutralizing antibody precursors in vivo
Medina-Ramírez M, Garces F, Escolano A, Skog P, de Taeye SW, Del Moral-Sanchez I, McGuire AT, Yasmeen A, Behrens AJ, Ozorowski G, van den Kerkhof TLGM, Freund NT, Dosenovic P, Hua Y, Gitlin AD, Cupo A, van der Woude P, Golabek M, Sliepen K, Blane T, Kootstra N, van Breemen MJ, Pritchard LK, Stanfield RL, Crispin M, Ward AB, Stamatatos L, Klasse PJ, Moore JP, Nemazee D, Nussenzweig MC, Wilson IA, Sanders RW
Design and crystal structure of a native-like HIV-1 envelope trimer that engages multiple broadly neutralizing antibody precursors in vivo. J. Exp. Med. 2017;214(9):2573-2590 doi: 10.1084/jem.20161160
doi: 10.1084/jem.20161160
Abstract
Induction of broadly neutralizing antibodies (bNAbs) by HIV-1 envelope glycoprotein immunogens would be a major advance toward an effective vaccine. A critical step in this process is the activation of naive B cells expressing germline (gl) antibody precursors that have the potential to evolve into bNAbs. Here, we reengineered the BG505 SOSIP.664 glycoprotein to engage gl precursors of bNAbs that target either the trimer apex or the CD4-binding site. The resulting BG505 SOSIP.v4.1-GT1 trimer binds multiple bNAb gl precursors in vitro. Immunization experiments in knock-in mice expressing gl-VRC01 or gl-PGT121 show that this trimer activates B cells in vivo, resulting in the secretion of specific antibodies into the sera. A crystal structure of the gl-targeting trimer at 3.2-Å resolution in complex with neutralizing antibodies 35O22 and 9H+109L reveals a native-like conformation and the successful incorporation of design features associated with binding of multiple gl-bNAb precursors.
Scientific Publications
Plasma CXCL13 but Not B Cell Frequencies in Acute HIV Infection Predicts Emergence of Cross Neutralizing Antibodies
Mabuka JM, Dugast AS, Muema DM, Reddy T, Ramlakhan Y, Euler Z, Ismail N, Moodley A, Dong KL, Morris L, Walker BD, Alter G, Ndung'u T
Plasma CXCL13 but Not B Cell Frequencies in Acute HIV Infection Predicts Emergence of Cross-Neutralizing Antibodies. Front Immunol 2017;8:1104 doi: 10.3389/fimmu.2017.01104
Abstract
Immunological events in acute HIV-1 infection before peak viremia (hyperacute phase) may contribute to the development of broadly cross-neutralizing antibodies. Here, we used pre-infection and acute-infection peripheral blood mononuclear cells and plasma samples from 22 women, including 10 who initiated antiretroviral treatment in Fiebig stages I-V of acute infection to study B cell subsets and B-cell associated cytokines (BAFF and CXCL13) kinetics for up to ~90 days post detection of plasma viremia. Frequencies of B cell subsets were defined by flow cytometry while plasma cytokine levels were measured by ELISA. We observed a rapid but transient increase in exhausted tissue-like memory, activated memory, and plasmablast B cells accompanied by decline in resting memory cells in untreated, but not treated women. B cell subset frequencies in untreated women positively correlated with viral loads but did not predict emergence of cross-neutralizing antibodies measured 12 months post detection of plasma viremia. Plasma BAFF and CXCL13 levels increased only in untreated women, but their levels did not correlate with viral loads. Importantly, early CXCL13 but not BAFF levels predicted the later emergence of detectable cross-neutralizing antibodies at 12 months post detection of plasma viremia. Thus, hyperacute HIV-1 infection is associated with B cell subset changes, which do not predict emergence of cross-neutralizing antibodies. However, plasma CXCL13 levels during hyperacute infection predicted the subsequent emergence of cross-neutralizing antibodies, providing a potential biomarker for the evaluation of vaccines designed to elicit cross-neutralizing activity or for natural infection studies to explore mechanisms underlying development of neutralizing antibodies.
Scientific Publications
Hidden Lineage Complexity of Glycan Dependent HIV 1 Broadly Neutralizing Antibodies Uncovered by Digital Panning and Native Like gp140 Trimer
He L, Lin X, de Val N, Saye-Francisco KL, Mann CJ, Augst R, Morris CD, Azadnia P, Zhou B, Sok D, Ozorowski G, Ward AB, Burton DR, Zhu J
Hidden Lineage Complexity of Glycan-Dependent HIV-1 Broadly Neutralizing Antibodies Uncovered by Digital Panning and Native-Like gp140 Trimer. Front Immunol 2017;8:1025 doi: 10.3389/fimmu.2017.01025
Abstract
Germline precursors and intermediates of broadly neutralizing antibodies (bNAbs) are essential to the understanding of humoral response to HIV-1 infection and B-cell lineage vaccine design. Using a native-like gp140 trimer probe, we examined antibody libraries constructed from donor-17, the source of glycan-dependent PGT121-class bNAbs recognizing the N332 supersite on the HIV-1 envelope glycoprotein. To facilitate this analysis, a digital panning method was devised that combines biopanning of phage-displayed antibody libraries, 900 bp long-read next-generation sequencing, and heavy/light (H/L)-paired antibodyomics. In addition to single-chain variable fragments resembling the wild-type bNAbs, digital panning identified variants of PGT124 (a member of the PGT121 class) with a unique insertion in the heavy chain complementarity-determining region 1, as well as intermediates of PGT124 exhibiting notable affinity for the native-like trimer and broad HIV-1 neutralization. In a competition assay, these bNAb intermediates could effectively compete with mouse sera induced by a scaffolded BG505 gp140.681 trimer for the N332 supersite. Our study thus reveals previously unrecognized lineage complexity of the PGT121-class bNAbs and provides an array of library-derived bNAb intermediates for evaluation of immunogens containing the N332 supersite. Digital panning may prove to be a valuable tool in future studies of bNAb diversity and lineage development.
Scientific Publications
Improving the Immunogenicity of Native like HIV 1 Envelope Trimers by Hyperstabilization
Torrents de la Peña A, Julien JP, de Taeye SW, Garces F, Guttman M, Ozorowski G, Pritchard LK, Behrens AJ, Go EP, Burger JA, Schermer EE, Sliepen K, Ketas TJ, Pugach P, Yasmeen A, Cottrell CA, Torres JL, Vavourakis CD, van Gils MJ, LaBranche C, Montefiori DC, Desaire H, Crispin M, Klasse PJ, Lee KK, Moore JP, Ward AB, Wilson IA, Sanders RW
Improving the Immunogenicity of Native-like HIV-1 Envelope Trimers by Hyperstabilization. Cell Rep 2017;20(8):1805-1817 doi: S2211-1247(17)31072-0
Abstract
The production of native-like recombinant versions of the HIV-1 envelope glycoprotein (Env) trimer requires overcoming the natural flexibility and instability of the complex. The engineered BG505 SOSIP.664 trimer mimics the structure and antigenicity of native Env. Here, we describe how the introduction of new disulfide bonds between the glycoprotein (gp)120 and gp41 subunits of SOSIP trimers of the BG505 and other genotypes improves their stability and antigenicity, reduces their conformational flexibility, and helps maintain them in the unliganded conformation. The resulting next-generation SOSIP.v5 trimers induce strong autologous tier-2 neutralizing antibody (NAb) responses in rabbits. In addition, the BG505 SOSIP.v6 trimers induced weak heterologous NAb responses against a subset of tier-2 viruses that were not elicited by the prototype BG505 SOSIP.664. These stabilization methods can be applied to trimers from multiple genotypes as components of multivalent vaccines aimed at inducing broadly NAbs (bNAbs).
Scientific Publications
HIV 1 neutralizing antibody induced by simian adenovirus and poxvirus MVA vectored BG505 native like envelope trimers
Capucci S, Wee EG, Schiffner T, LaBranche CC, Borthwick N, Cupo A, Dodd J, Dean H, Sattentau Q, Montefiori D, Klasse PJ, Sanders RW, Moore JP, Hanke T
HIV-1-neutralizing antibody induced by simian adenovirus- and poxvirus MVA-vectored BG505 native-like envelope trimers. PLoS ONE 2017;12(8):e0181886 doi: 10.1371/journal.pone.0181886
Abstract
Rabbits and monkeys immunized with HIV type 1 (HIV-1) native-like BG505 SOSIP.664 (BG505s) glycoprotein trimers are known to induce antibodies that can neutralize the autologous tier-2 virus. Here, we assessed the induction of HIV-1 trimer binding and neutralizing antibody (nAb) titres when BG505s trimers were also delivered by non-replicating simian (chimpanzee) adenovirus and non-replicating poxvirus modified vaccinia virus Ankara (MVA) vaccine vectors. First, we showed that approximately two-thirds and one-third of the trimers secreted from the ChAdOx1.BG505s (C) and MVA.BG505s (M) vaccine-infected cells, respectively, were cleaved and in a native-like conformation. Rabbits were immunized intramuscularly with these vaccine vectors and in some cases boosted with ISCOMATRIX™-adjuvanted BG505s protein trimer (P), using CCC, MMM, PPP, CPP, MPP and CMP vaccine regimens. We found that the peak trimer-binding antibody and tier-1A and autologous tier-2 nAb responses induced by the CC, CM, PPP, CPP, MPP and CMP regimens were comparable, although only PPP induced autologous tier-2 nAbs in all the immunized animals. Three animals developed weak heterologous tier-2 nAbs. These results demonstrate that ChAdOx1 and MVA vectors are useful delivery modalities for not only T-cell, but also antibody vaccine development.
Scientific Publications
Rapid elicitation of broadly neutralizing antibodies to HIV by immunization in cows
Sok D, Le KM, Vadnais M, Saye-Francisco KL, Jardine JG, Torres JL, Berndsen ZT, Kong L, Stanfield R, Ruiz J, Ramos A, Liang CH, Chen PL, Criscitiello MF, Mwangi W, Wilson IA, Ward AB, Smider VV, Burton DR
Rapid elicitation of broadly neutralizing antibodies to HIV by immunization in cows. Nature 2017;548(7665):108-111 doi: 10.1038/nature23301
doi: 10.1038/nature23301
Abstract
No immunogen to date has reliably elicited broadly neutralizing antibodies to HIV in humans or animal models. Advances in the design of immunogens that antigenically mimic the HIV envelope glycoprotein (Env), such as the soluble cleaved trimer BG505 SOSIP, have improved the elicitation of potent isolate-specific antibody responses in rabbits and macaques, but so far failed to induce broadly neutralizing antibodies. One possible reason for this failure is that the relevant antibody repertoires are poorly suited to target the conserved epitope regions on Env, which are somewhat occluded relative to the exposed variable epitopes. Here, to test this hypothesis, we immunized four cows with BG505 SOSIP. The antibody repertoire of cows contains long third heavy chain complementary determining regions (HCDR3) with an ultralong subset that can reach more than 70 amino acids in length. Remarkably, BG505 SOSIP immunization resulted in rapid elicitation of broad and potent serum antibody responses in all four cows. Longitudinal serum analysis for one cow showed the development of neutralization breadth (20%, n = 117 cross-clade isolates) in 42 days and 96% breadth (n = 117) at 381 days. A monoclonal antibody isolated from this cow harboured an ultralong HCDR3 of 60 amino acids and neutralized 72% of cross-clade isolates (n = 117) with a potent median IC of 0.028 μg ml. Breadth was elicited with a single trimer immunogen and did not require additional envelope diversity. Immunization of cows may provide an avenue to rapidly generate antibody prophylactics and therapeutics to address disease agents that have evolved to avoid human antibody responses.
Scientific Publications
Lack of decline in hepatitis C virus incidence among HIV positive men who have sex with men during 1990 2014
van Santen DK, van der Helm JJ, Del Amo J, Meyer L, D'Arminio Monforte A, Price M, Béguelin CA, Zangerle R, Sannes M, Porter K, Geskus RB, Prins M
Lack of decline in hepatitis C virus incidence among HIV-positive men who have sex with men during 1990-2014. J. Hepatol. 2017;67(2):255-262 doi: S0168-8278(17)30209-X
Abstract
Hepatitis C virus (HCV) incidence among HIV-positive men who have sex with men (MSM) has increased since 2000, although there are regional differences. We aimed to 1) estimate trends in HCV incidence among HIV-positive MSM, 2) assess the association between incidence and geographical region, age and HIV-related measurements and, 3) assess temporal changes from HIV seroconversion to HCV infection.