James Robinson

• Tulane University

Antigen conformation shapes CD4+ T-cell specificity through mechanisms of antigen processing, and the consequences for immunity may rival those from conformational effects on antibody specificity. CD4+ T cells initiate and control immunity to pathogens and cancer and are at least partly responsible for immunopathology associated with infection, aut...

Spillover of sarbecoviruses from animals to humans has resulted in outbreaks of severe acute respiratory syndrome SARS-CoVs and the ongoing COVID-19 pandemic. Efforts to identify the origins of SARS-CoV-1 and -2 has resulted in the discovery of numerous animal sarbecoviruses–the majority of which are only distantly related to known human pathogens...

SARS CoV-2 in children or special populations post-infection has not been well studied. Asthma is a heterogenous disease marked by chronic airway inflammation; triggers include cockroaches (CRA), and other inhaled irritants. Asthma also has links to viral infections like respiratory syncytial virus (RSV). Additionally, some with moderate to severe...

Pregnant women and neonates are at risk for adverse SARS CoV-2 infection outcomes, but few studies have evaluated this population for adaptive immunity. Here, we utilized samples collected from pregnant women 18 years or older reporting two or more respiratory symptoms. Information about trimester of COVID positive test or history of vaccination wa...

Children (less than 19 years) account for 20% of the US population but currently represent less than 2% of coronavirus disease 2019 (COVID-19) cases. Because infected children often have few or no symptoms and may not be tested, the extent of infection in children is poorly understood. METHODS During the March 18th-May 15th 2020 Louisiana Stay At H...

Mice have been used as accepted tools for investigating complex human diseases and new drug therapies because of their shared genetics and anatomical characteristics with humans. However, the tissues in mice are different from humans in that human cells have a natural mutation in the α1,3 galactosyltransferase (α1,3GT) gene and lack α-Gal epitopes...

Serum from convalescent Lassa fever patients was previously shown to be ineffective as a source of protective antibodies in some early studies. Subsequently, monoclonal antibodies (MAbs) to the Lassa virus (LASV) glycoprotein produced by memory B cells of West African patients who survived Lassa fever were identified. Development of MAbs as potenti...

Lassa virus (LASV) causes hemorrhagic fever and is endemic in West Africa. Protective antibody responses primarily target the LASV surface glycoprotein (GPC), and GPC-B competition group antibodies often show potent neutralizing activity in humans. However, which features confer potent and broadly neutralizing antibody responses is unclear. Here, w...

Leukemia Stem Cells (LSCs) quiescence in Chronic Myeloid Leukemia (CML) plays a major role in therapeutic resistance and disease progression calling for the need for identifying and targeting such cells (1). LSCs belong to the primitive population; CD34+CD38-Lin-, which can’t distinguish normal hematopoietic stem cells (HSCs) from CML LSCs. IL1RAP...

Leukemia Stem Cells (LSCs) quiescence in Chronic Myeloid Leukemia (CML) plays a major role in therapeutic resistance and disease progression calling for the need for identifying and targeting such cells (1). LSCs belong to the primitive population; CD34+CD38-Lin-, which can’t distinguish normal hematopoietic stem cells (HSCs) from CML LSCs. IL1RAP...

The subtype C HIV-1 isolate MW965.26 is a highly neutralization-sensitive tier 1a primary isolate that is widely used in vaccine studies, but the basis for the sensitive neutralization phenotype of this isolate is not known. Substituting the MW965.26 V1/V2 domain into a neutralization-sensitive SF162 Env clone resulted in high resistance to standar...

Thomas Geisbert and colleagues show that a cocktail of monoclonal antibodies protects cynomolgus monkeys from lethal Lassa fever virus infection, including when administration is delayed by more than a week after viral challenge.

The arenavirus Lassa causes severe hemorrhagic fever and a significant disease burden in West Africa every year. The glycoprotein, GPC, is the sole antigen expressed on the viral surface and the critical target for antibody-mediated neutralization. Here we present the crystal structure of the trimeric, prefusion ectodomain of Lassa GP bound to a ne...

Importance: It is not yet possible to cure HIV infection. Even after years of fully effective antiviral therapy, a persistent reservoir of virus-infected cells remains. Here we propose that a targeted conjugate, consisting of an anti-HIV antibody bound to a toxic moiety, could function to kill the HIV-infected cells that constitute this reservoir....

Importance: There is increased interest in using antibodies to treat and cure HIV infection. Antibodies can neutralize free virus and kill cells already carrying the virus. The virus envelope (Env) is the only HIV protein expressed on the surfaces of virions and infected cells. In this study we examined a panel of human anti-Env antibodies for the...

A comprehensive understanding of the regions on HIV-1 envelope trimers targeted by broadly neutralizing antibodies may contribute to rational design of an HIV-1 vaccine. We previously identified a participant in the CAPRISA cohort, CAP248, who developed trimer-specific antibodies capable of neutralizing 60% of heterologous viruses at three years po...

Comparison of IC20 and IC50 titres for weakly neutralizing HIV-1 antibodies. Three weakly neutralizing antibodies, 447-52D, 17b and HK20 were tested against a 45 virus panel. Titres at both IC20 and IC50 are shown, and coloured as in Fig 1. Percentage breadth is indicated at the bottom. (TIF)

CAP248-2B blocks the binding of 35O22, 3BC315, and PGT151 to cell surface envelope trimers. (B) Binding of labelled HIV-1 bNAbs 35O22, 3BC315, PGT151, 8ANC195, and 4E10 to cell-surface anchored HIV-1 trimers by flow cytometry, in the presence of increasing concentration of unlabeled CAP248-2B. Median fluorescence intensity (MFI) is shown on the y-a...

Conformational differences between unliganded structures of CAP248-2B explained by crystal packing. Predicted germline alleles, CDR3 lengths, and mutation frequencies for CAP248-2B from the IMGT database [88]. (TIF)

Glycan dependence of known gp120-gp41 interface targeting bNAbs. (A) Neutralization of CAP45 by broadly neutralizing antibodies that target the gp120-gp41 interface, when compared to CAP248-2B epitope proximal glycan mutants. The S613A mutant that removed the glycan at N611 but maintains the amino acid side chain properties is shown with red dashed...

Crystallographic data and refinement statistics (molecular replacement) for the antigen binding fragment of CAP248-2B. Data collection and refinement statistics for the two unliganded CAP248-2B Fab crystal structures. (TIF)

Selection pressure in conserved bNAb epitopes does not contribute to escape from CAP248-2B. (A) Alignments of five different regions in CAP248 autologous envelope sequences at nine weeks (study enrolment), 1, 2, 3 and 3.5 years post-infection, that overlap with previously described broadly neutralizing antibody epitopes in V2 (boxed in purple), C1/...

Supporting crystal structure, ELISA, and negative stain EM data. (A) Cartoon representation of neighboring asymmetric units from the 2 Å resolution dataset showing crystal packing in the antibody paratope. The heavy and light chains of Fab1 in the first unit are colored forest and olive green respectively, and in the second unit dark and light blue...

Lassa fever is a significant health threat to West African human populations with hundreds of thousands of annual cases. There are no approved medical countermeasures currently available. Compassionate use of the antiviral drug ribavirin or transfusion of convalescent serum has resulted in mixed success depending on when administered or the donor s...

Background: Kenema Government Hospital (KGH) has developed an advanced clinical and laboratory research capacity to manage the threat of Lassa fever, a viral hemorrhagic fever (VHF). The 2013-2016 Ebola virus (EBOV) disease (EVD) outbreak is the first to have occurred in an area close to a facility with established clinical and laboratory capacity...

Vaccination with SIVmac239Δnef provides robust protection against subsequent challenge with wild type SIV, but safety issues have precluded designing an HIV-1 vaccine based on a live attenuated virus concept. Safe immunogens and adjuvants that could reproduce identified immune correlates of SIVmac239Δnef protection therefore offer an alternative pa...

Although antibodies to the HIV-1 envelope glycoprotein have been studied extensively for their ability to block viral infectivity, little data is currently available on non-neutralizing functions of these antibodies, such as their ability to eliminate virus-infected cells by antibody-dependent cell-mediated cytotoxicity (ADCC). HIV-1 Env-specific a...

Lassa fever is a severe multisystem disease that often has haemorrhagic manifestations. The epitopes of the Lassa virus (LASV) surface glycoproteins recognized by naturally infected human hosts have not been identified or characterized. Here we have cloned 113 human monoclonal antibodies (mAbs) specific for LASV glycoproteins from memory B cells of...

Supplementary Figures 1-8, Supplementary Table 1, Supplementary Note and Supplementary References

Importance: CD4 tropism is an invariant feature of primate lentiviruses and likely plays a key role in pathogenesis by focusing viral infection onto cells that mediate adaptive immune responses and in protecting virions attached to cells from neutralizing antibodies. Although CD4-independent viruses are well described for HIV and SIV, these viruse...

Arenaviruses exist worldwide and can cause hemorrhagic fever and neurologic disease. A single glycoprotein expressed on the viral surface mediates entry into target cells. This glycoprotein, termed GPC, contains a membrane-associated signal peptide, a receptor-binding subunit termed GP1 and a fusion-mediating subunit termed GP2. Although GPC is a c...

Previous studies have shown that sera from HIV-1-infected individuals contain antibodies able to mediate antibody-dependent cellular cytotoxicity (ADCC). These antibodies preferentially recognize envelope glycoproteins (Env) epitopes induced upon CD4 binding. Here, we show that a highly conserved tryptophan at position 69 of the gp120 inner domain...

Background: Nonhuman primates (NHPs), such as rhesus macaques, are currently the best preclinical models for studying HIV vaccines. The details of how NHP Abs can mimic human Abs will be useful in evaluating NHP Ab responses to HIV vaccine candidates. The extensive knowledge of the antigen binding modes of anti-V3 Abs allows a structural comparison...

Unlabelled: Accumulating evidence indicates a role for Fc receptor (FcR)-mediated effector functions of antibodies, including antibody-dependent cell-mediated cytotoxicity (ADCC), in prevention of human immunodeficiency virus type 1 (HIV-1) acquisition and in postinfection control of viremia. Consequently, an understanding of the molecular basis f...

HIV-1 mucosal transmission begins with virus or virus-infected cells moving through mucus across mucosal epithelium to infect CD4+ T cells. Although broadly neutralizing antibodies (bnAbs) are the type of HIV-1 antibodies that are most likely protective, they are not induced with current vaccine candidates. In contrast, antibodies that do not neutr...

Unlabelled: Antibodies that can neutralize diverse viral strains are likely to be an important component of a protective human immunodeficiency virus type 1 (HIV-1) vaccine. To this end, preclinical simian immunodeficiency virus (SIV)-based nonhuman primate immunization regimens have been designed to evaluate and enhance antibody-mediated protecti...

Eliciting broad tier 2 neutralizing antibodies (nAbs) is a major goal of HIV-1 vaccine research. Here we investigated the ability of native, membrane-expressed JR-FL Env trimers to elicit nAbs. Unusually potent nAb titers developed in 2 of 8 rabbits immunized with virus-like particles (VLPs) expressing trimers (trimer VLP sera) and in 1 of 20 rabbi...

Lassa fever (LF) is a potentially fatal disease that affects an estimated 300,000-500,000 people in endemic areas of west Africa each year. Though past studies have identified fatality rates of 5-20% in patients suspected to have contracted Lassa virus (LASV), new studies using more precise clinical diagnoses and modern diagnostic assays show fatal...

Flaviviruses share significant amino acid sequence similarity in their surface E and preM proteins, resulting in antigenic overlap in immunological responses. This gives rise to the potential for original antigenic sin effects, including cross protection or enhancement effects. Here we have examined a panel of broadly neutralizing anti-dengue human...

Unlabelled: The RV144 vaccine trial implicated epitopes in the C1 region of gp120 (A32-like epitopes) as targets of potentially protective antibody-dependent cellular cytotoxicity (ADCC) responses. A32-like epitopes are highly immunogenic, as infected or vaccinated individuals frequently produce antibodies specific for these determinants. Antibody...

Background: HVTN 505, a phase 2b trial assessing if a DNA/ rAd5 HIV vaccine prime/boost regimen reduces HIV acquisition or viremia post infection, halted vaccinations in 2013 due to efficacy futility, though it induced substantial CD8 + T-cell responses. We examined whether vaccine-induced T cells in HVTN 505 were unable to inhibit virus replicatio...

Principles to guide design of an effective vaccine against HIV are greatly needed, particularly to protect women in the pandemic's epicenter in Africa. We have been seeking these principles by identifying correlates of the robust protection associated with SIVmac239Δnef vaccination in the SIV-rhesus macaque animal model of HIV-1 transmission to wom...

We sought design principles for a vaccine to prevent HIV transmission to women by identifying correlates of protection conferred by a highly effective live attenuated SIV vaccine in the rhesus macaque animal model. We show that SIVmac239Δnef vaccination recruits plasma cells and induces ectopic lymphoid follicle formation beneath the mucosal epithe...

Approaches to prevent human immunodeficiency virus (HIV-1) transmission are urgently needed. Difficulties in eliciting antibodies that bind conserved epitopes exposed on the unliganded conformation of the HIV-1 envelope glycoprotein (Env) trimer represent barriers to vaccine development. During HIV-1 entry, binding of the gp120 Env to the initial r...

Virus-like particles (VLPs) offer a platform to test the hypothesis that, since antibody binding to native envelope glycoprotein (Env) trimers results in HIV-1 neutralization, that native Env trimers presented in membranes may be useful for inducing neutralizing antibodies (nAbs) in a vaccine setting. So far, VLPs have not fulfilled this potential....

Lassa fever (LF), an often-fatal hemorrhagic disease caused by Lassa virus (LASV), is a major public health threat in West Africa. When the violent civil conflict in Sierra Leone (1991 to 2002) ended, an international consortium assisted in restoration of the LF program at Kenema Government Hospital (KGH) in an area with the world's highest inciden...

Unlabelled: Anti-HIV-1 envelope glycoprotein (Env) antibodies without broadly neutralizing activity correlated with protection in the RV144 clinical trial, stimulating interest in other protective mechanisms involving antibodies, such as antibody-dependent cell-mediated cytotoxicity (ADCC). Env epitopes targeted by many antibodies effective at med...

Methods and compositions are provided for the use of an envelope polypeptide or a functional variant thereof from a lentivirus that is not HIV-1 as a molecular scaffold for HIV-1 epitopes. The HIV-1 epitopes can be recognized by HIV-1 binding antibodies, HIV-1 neutralizing antibodies and/or CD4-induced antibodies. Thus, methods are provided for det...

Primary HIV-1 isolates are relatively resistant to neutralization by antibodies commonly induced after infection or vaccination. This is generally attributed to masking of sensitive epitopes by the V1/V2 domain and/or glycans situated at various positions in Env. Here we identified a novel masking effect mediated by subtype C-specific V3 sequences...

In natural infection, antibodies interact with HIV-1 primarily through non-functional forms of envelope glycoproteins (Env), including uncleaved (UNC) gp160 and gp41 stumps. These antigens are important to fully characterize, as they may be decoys that promote non-neutralizing responses, and may also be targets for non-neutralizing effector respons...

Reactivity of serum samples (diluted 1∶100) determined by ELISA on plates coated with control peptide. Serum from the Control-primed animals reacted with the Control peptide. (PDF)

Peptide-specific T-cell and B-cell responses (Excel file). (XLSX)

Evidence of immune priming was examined in a preliminary study of mice that were treated with only peptide 2, peptide 29, or control peptide. The peptides emulsified in incomplete Freund’s adjuvant (IFA) were administered to groups of four BALB/c mice in the peritoneal cavity over a period of six days (day -9 to day -3, following the scheme in A),...

Variation in peptide-specific IL-2 responses (A) and antibody reactions (B) of individual mice in the same group (peptide-29 primed). In both A and B, a different mouse yields the largest response (oval) to a given peptide, suggesting that the variation in responses is not related to the overall strength of immunization. (PDF)

Thirty-eight peptides spanning the sequence of HIV89.6 gp120, except V1–V2. Peptide sequences including cysteines as the carbamidomethyl derivatives were as described by Dai, G., Steede, N.K., and Landry, S.J. (2001), Allocation of helper T-cell epitope immunodominance according to three-dimensional structure in the human immunodeficiency virus typ...

Profiles of cytokine secretion log[cytokine(pg/ml)] in response to individual peptides. Data are presented as mean +/− SEM for groups of ten mice. Individual mouse responses are available in Table S2. (PDF)

Approximately one quarter of HIV-1 infected individuals will generate broadly neutralizing antibodies, but the exact mechanisms for triggering and maturation of these responses are presently undefined. We consequently investigated the roots of neutralization breadth. In a subtype A HIV-1 infected Rwandan seroconverter, we pinpointed the primary neu...

Profound vascular leakage in conjunction with elevated viremia is the hallmark of Dengue Hemorrhagic Fever/Dengue Shock Syndrome (DHF/DSS). Antibody (Ab)-dependent enhancement (ADE), in which pre-existing, cross-reactive Ab enhance virus infectivity, is thought to be responsible for increased viremia, while loss of endothelial cell (EC) barrier int...

The sooty mangabey-derived SIV strain E660 (SIVsmE660) is a genetically heterogeneous, pathogenic isolate that is commonly used as a vaccine challenge strain in the non-human primate (NHP) model of HIV-1 infection. Though it is often employed to assess antibody-based vaccine strategies, its sensitivity to antibody-mediated neutralization has not be...

We recently have characterized a comprehensive panel of human mAbs isolated from HIV-1 infected individuals based on a modified antibody-dependent cell-mediated cytotoxicity (ADCC) assay that detects epitopes exposed on the target cell surface during viral entry. Among the epitopes that constituted the best ADCC targets were those exposed on trimer...

Specificity of R880F VH and VL pairing. 19.3H-HC, a common R880F heavy chain shared by the two R880F mAbs, was stochastically paired and co-transfected with two unrelated R880F light chains, 15.1B-LC2 (A) and 15.10G-LC2 (B). Similarly, the wild-type 19.3H-L3 light chain was matched with a random R880F heavy chain, 3.11A-HC1 (C). All chimeric mAbs w...

Full-length R880F Env gp160 alignment. The complete Env gp160 amino acid sequences of twenty longitudinal R880F humoral escape variants have been aligned in comparison to the founder Envs 0-A6/B24 and examined using Sequencher v5.0 and Geneious v5.0.3 software. Dashes represent conserved positions; dots represent gaps. Significant structural domain...

Fab crystal structure data collection and refinement statistics. Fab fragments of R880F mAbs 19.3H-L1 (PDB code 4F57) and 19.3H-L3 (PDB code 4F58) were crystallized with the hanging drop method after papain digestion, affinity and size exclusion chromatography purification, and concentration. X-ray diffraction data were collected, processed using H...

Antibodies that neutralize (nAbs) genetically diverse HIV-1 strains have been recovered from a subset of HIV-1 infected subjects during chronic infection. Exact mechanisms that expand the otherwise narrow neutralization capacity observed during early infection are, however, currently undefined. Here we characterized the earliest nAb responses in a...

Background The impact of extended use of ART in developing countries has been enormous. A thorough understanding of all factors contributing to the success of antiretroviral therapy is required. The current study aims to investigate the value of cross-sectional drug resistance monitoring using DNA and RNA oligonucleotide ligation assays (OLA) in tr...

There are no available vaccines for dengue, the most important mosquito-transmitted viral disease. Mechanistic studies with anti-dengue virus (DENV) human monoclonal antibodies (hMAbs) provide a rational approach to identify and characterize neutralizing epitopes on DENV structural proteins that can serve to inform vaccine strategies. Here we repor...

The HIV-1 envelope glycoprotein (Env) undergoes conformational transitions consequent to CD4 binding and coreceptor engagement during viral entry. The physical steps in this process are becoming defined, but less is known about their significance as targets of antibodies potentially protective against HIV-1 infection. Here we probe the functional s...

Recent studies have shown that natural infection by HIV-2 leads to the elicitation of high titers of broadly neutralizing antibodies (NAbs) against primary HIV-2 strains (T. I. de Silva, et al., J. Virol. 86:930-946, 2012; R. Kong, et al., J. Virol. 86:947-960, 2012; G. Ozkaya Sahin, et al., J. Virol. 86:961-971, 2012). Here, we describe the envelo...

Human immunodeficiency virus type 1 (HIV-1) infection can spread efficiently from infected to uninfected T cells through adhesive contacts called virological synapses (VSs). In this process, cell-surface envelope glycoprotein (Env) initiates adhesion and viral transfer into an uninfected recipient cell. Previous studies have found some HIV-1-neutra...

We have been studying the magnitude, breadth, kinetics and epitope specificity of the neutralizing antibody (nAb) response in early and chronic HIV-1 infection. The earliest nAb response was highly specific for the early autologous virus but within 1-2 years of infection, low titers of broadly neutralizing activity were detected in a subset of subj...

Compared with human immunodeficiency virus type 1 (HIV-1), little is known about the susceptibility of HIV-2 to antibody neutralization. We characterized the potency and breadth of neutralizing antibody (NAb) responses in 64 subjects chronically infected with HIV-2 against three primary HIV-2 strains: HIV-2(7312A), HIV-2(ST), and HIV-2(UC1). Surpri...

Few studies have explored the role of neutralizing antibody (NAb) responses in controlling HIV-2 viremia and disease progression. Using a TZM-bl neutralization assay, we assessed heterologous and autologous NAb responses from a community cohort of HIV-2-infected individuals with a broad range of disease outcomes in rural Guinea-Bissau. All subjects...

ABSTRACT: Correction After publication of this work [Branco et al: Virology Journal 2011, 8:404], we noted that we inadvertently failed to include the complete list of all coauthors. The full list of authors has now been added and the Authors' contributions and Competing interests section modified accordingly. Competing interests The authors declar...

A series of potently neutralizing monoclonal antibodies (MAbs) that target quaternary epitopes on the native Env trimer have recently been described. A common feature shared by these antibodies is the critical involvement of sites in both the V2 and V3 variable domains in antibody recognition. In this study the gp120 variable-region determinants we...

Studies using live attenuated virus vaccines in the simian immunodeficiency virus (SIV) rhesus macaque model have demonstrated broad protection against experimental challenge. Protection in these studies was found to be critically dependent on the length of time postvaccination, suggesting that protective immunity involves a necessary maturation of...

Epitopes that drive the initial autologous neutralizing antibody response in HIV-1-infected individuals could provide insights for vaccine design. Although highly strain specific, these epitopes are immunogenic, vulnerable to antibody attack on infectious virus, and could be involved in the ontogeny of broadly neutralizing antibody responses. To de...

Table 2. Metabolic, cytokine, LASV Ag, IgG, and IgM profiles for five patients who succumbed to LF at the KGH LFW in recent months, and in two healthy controls. Thirteen metabolic indicators, 11 cytokines, LASV NP Ag, IgM, and IgG status were compared between 5 representative recent fatal cases of LF (G-1209, G-1220, G-1380, G-1401), including one...

Table 1. Urinalysis profile for patient G-1442 during the course of admission at the KGH LFW. Urine samples were collected from patient G-1442 daily (days 7-18) and tested for 10 metabolites as outlined in Methods. The first day of ribavirin administration (7) and still birth delivery (13) are noted. Abbreviations and codes: moderate (mod.); negati...

Vital signs for G-1442 during hospitalization at KGH LFW. Core temperature (°C) [green triangle], pulse [red circle], respiratory rate [blue diamond], and blood pressure purple [square = systolic, yellow square = diastolic] were measured at regular intervals, usually every 4 hours at the onset, and every 12 hours at later times, throughout the hosp...

Additional Piccolo metabolites analyzed in G-1442. Patient G-1442 presented with low serum Cl- and albumin, normal K+, Na+, Ca2+ (corrected for albumin levels), TCO2, and total protein levels. Over the course of disease management the patient developed hyponatremia, hypochloremia, and slight hypokalemia. Total protein and albumin levels remained lo...

Map of Sierra Leone and expanded view of relevant localities and routes travelled by patient G-1442. Maps of Sierra Leone outlining Districts (A) and Provinces (B) [http://commons.wikimedia.org/wiki/Atlas_of_Sierra_Leone], with an inset map (C) [http://maps.google.com] displaying the location of Mabineh 1 [red star], where the suspected LF case in...