Using murine IgG subclass molecules (IgG1 or IgG2a) synthetically fused to HIV-1 or influenza test antigens, we explored the potential for IgG Fc scaffolds to augment immunogenicity. Each antigen (Ag) was grafted onto a hinge-Fc scaffold containing all critical residues necessary for interaction with effector cells, thus retaining effector functions of the native IgG subclass. We hypothesized that the differential affinity of Fcγ Rs for specific IgG subclasses would influence the magnitude of immune responses elicited by immunization with an Ag-IgG Fc fusion vaccine. We demonstrate here that the antigen-specific humoral response elicited by Ag-IgG2a fusion vaccines is at least tenfold greater than that elicited by native antigen, that this response is superior to that elicited by Ag-IgG1, and that the augmented antigen-specific humoral response elicited is Fcγ receptor-dependent. © 2011 Elsevier Ltd.

Zaharatos Gerasimos J.    于建    Pace Craig    Yang Song    Vasan    何大一     Huang Yaoxing   

Vaccine

2011

Objective: To demonstrate that the use of highly active antiretroviral therapy (HAART) to interrupt transmission of HIV-1 from mother to baby is effective, safe, and feasible in a remote rural region of China. Methods: Between November 2005 and May 2009, we enrolled 279 HIV-1-infected pregnant women to receive HAART to interrupt transmission of HIV-1 to their newborns across 16 counties in Yunnan. All women were started on triple combination therapy and submitted to regular blood draws to monitor CD4 T cells and viral load in their blood plasma. Infants received a single dose of nevirapine at birth and 1 or 4 weeks of zidovudine depending on the length of the mother's regimen. Exclusive formula feeding was recommended, and families were provided with 12-month supply of formula. Mothers and infant pairs were followed for 12-18 months postdelivery. Results: Of 279 enrolled HIV-infected women, 222 (79.6%) were identified and started treatment by 28 weeks of pregnancy. Viral load was undetectable at time of delivery for 62.4% (136 of 218) at delivery, with a mean 1.76 log viral load reduction between enrollment and delivery. Two of 193 babies (1.0%) who have already been tested became infected with HIV-1. Seven of 223 babies have died. By Kaplan-Meier analysis, cumulative one-year survival was 96.3%. Conclusions: The project demonstrated that HAART for all infected pregnant women is effective with a vertical transmission rate of ∼1%. Thus, this project provides a model for China to scale up its efforts to prevent mother-to-child transmission of HIV-1. Copyright © 2010 by Lippincott Williams & Wilkins.

Zhou Zeng-Quan    Meyers Kathrine    Li Xia    Chen Qingling    Qian Haoyu    Lao Yunfei    Geng Elvin    Fan Yi-Shan    Yang Shaomin    Chiu Michael    何大一    

Journal of Acquired Immune Deficiency Syndromes

2010

Background: We conducted a Phase I dose-escalation trial of ADMVA, a Clade-B'/C-based HIV-1 candidate vaccine expressing env, gag, pol, nef, and tat in a modified vaccinia Ankara viral vector. Sequences were derived from a prevalent circulating HIV-1 recombinant form in Yunnan, China, an area of high HIV incidence. The objective was to evaluate the safety and immunogenicity of ADMVA in human volunteers. Methodology/Principal Findings: ADMVA or placebo was administered intramuscularly at months 0, 1 and 6 to 50 healthy adult volunteers not at high risk for HIV-1. In each dosage group [16107 (low), 56107 (mid), or 2.56108 pfu (high)] volunteers were randomized in a 3:1 ratio to receive ADMVA or placebo in a double-blinded design. Subjects were followed for local and systemic reactogenicity, adverse events including cardiac adverse events, and clinical laboratory parameters. Study follow up was 18 months. Humoral immunogenicity was evaluated by anti-gp120 binding ELISA, immunoflourescent staining, and HIV-1 neutralization. Cellular immunogenicity was assessed by a validated IFNc ELISpot assay and intracellular cytokine staining. Antivaccinia binding titers were measured by ELISA. ADMVA was generally well-tolerated, with no vaccine-related serious adverse events or cardiac adverse events. Local or systemic reactogenicity events were reported by 77% and 78% of volunteers, respectively. The majority of events were of mild intensity. The IFNc ELISpot response rate to any HIV antigen was 0/12 (0%) in the placebo group, 3/12 (25%) in the low dosage group, 6/12 (50%) in themid dosage group, and 8/13 (62%) in the high dosage group. Responses were often multigenic and occasionally persisted up to one year post vaccination. Antibodies to gp120 were detected in 0/12 (0%), 8/13 (62%), 6/12 (50%) and 10/13 (77%) in the placebo, low, mid, and high dosage groups, respectively. Antibodies persisted up to 12 months after vaccination, with a trend toward agreement with the ability to neutralize HIV-1 SF162 in vitro. Two volunteers mounted antibodies that were able to neutralize clade-matched viruses. Conclusions/Significance: ADMVA was well-tolerated and elicited durable humoral and cellular immune responses. Trial Registration: Clinicaltrials.gov NCT00252148. © 2010 Vasan et al.

Vasan    Sarah Schlesinger    Zhiwei Chen    Arlene Hurley    Lombardo Angela    Than Soe    Adesanya Phumla    Bunce Catherine    Boaz Mark    Boyle Rosanne    Sayeed    Clark    Dugin    Boente-Carrera    Schmidt Claudia    Fang Qing    LeiBa    Huang Yaoxing    Zaharatos Gerasimos J.    David Gardiner    Marina Caskey    Seamons Laura    Ho Martin    Dally Len    Smith Carol    Cox Josephine    Gill    Gilmour Jill    Keefer Michael C.    Fast Patricia    何大一    

PLoS ONE

2010

We conducted a Phase I dose-escalation trial of ADMVA, a Clade-B'/C-based HIV-1 candidate vaccine expressing env, gag, pol, nef, and tat in a modified vaccinia Ankara viral vector. Sequences were derived from a prevalent circulating HIV-1 recombinant form in Yunnan, China, an area of high HIV incidence. The objective was to evaluate the safety and immunogenicity of ADMVA in human volunteers. ADMVA or placebo was administered intramuscularly at months 0, 1 and 6 to 50 healthy adult volunteers not at high risk for HIV-1. In each dosage group [1x10(7) (low), 5x10(7) (mid), or 2.5x10(8) pfu (high)] volunteers were randomized in a 3:1 ratio to receive ADMVA or placebo in a double-blinded design. Subjects were followed for local and systemic reactogenicity, adverse events including cardiac adverse events, and clinical laboratory parameters. Study follow up was 18 months. Humoral immunogenicity was evaluated by anti-gp120 binding ELISA, immunoflourescent staining, and HIV-1 neutralization. Cellular immunogenicity was assessed by a validated IFNgamma ELISpot assay and intracellular cytokine staining. Anti-vaccinia binding titers were measured by ELISA. ADMVA was generally well-tolerated, with no vaccine-related serious adverse events or cardiac adverse events. Local or systemic reactogenicity events were reported by 77% and 78% of volunteers, respectively. The majority of events were of mild intensity. The IFNgamma ELISpot response rate to any HIV antigen was 0/12 (0%) in the placebo group, 3/12 (25%) in the low dosage group, 6/12 (50%) in the mid dosage group, and 8/13 (62%) in the high dosage group. Responses were often multigenic and occasionally persisted up to one year post vaccination. Antibodies to gp120 were detected in 0/12 (0%), 8/13 (62%), 6/12 (50%) and 10/13 (77%) in the placebo, low, mid, and high dosage groups, respectively. Antibodies persisted up to 12 months after vaccination, with a trend toward agreement with the ability to neutralize HIV-1 SF162 in vitro. Two volunteers mounted antibodies that were able to neutralize clade-matched viruses. ADMVA was well-tolerated and elicited durable humoral and cellular immune responses. Clinicaltrials.gov NCT00252148.

Vasan    Sarah Schlesinger    Zhiwei Chen    Arlene Hurley    Lombardo Angela    Than Soe    Adesanya Phumla    Bunce Catherine    Boaz Mark    Boyle Rosanne    Sayeed    Clark    Dugin    Boente-Carrera    Schmidt Claudia    Fang Qing    LeiBa    Huang Yaoxing    Zaharatos Gerasimos J.    David Gardiner    Marina Caskey    Seamons Laura    Ho Martin    Dally Len    Smith Carol    Cox Josephine    Gill    Gilmour Jill    Keefer Michael C.    Fast Patricia    何大一    

PloS one

2010

BACKGROUND: We conducted a Phase I dose escalation trial of ADVAX, a DNA-based candidate HIV-1 vaccine expressing Clade C/B' env, gag, pol, nef, and tat genes. Sequences were derived from a prevalent circulating recombinant form in Yunnan, China, an area of high HIV-1 incidence. The objective was to evaluate the safety and immunogenicity of ADVAX in human volunteers. METHODOLOGY/PRINCIPAL FINDINGS: ADVAX or placebo was administered intramuscularly at months 0, 1 and 3 to 45 healthy volunteers not at high risk for HIV-1. Three dosage levels [0.2 mg (low), 1.0 mg (mid), and 4.0 mg (high)] were tested. Twelve volunteers in each dosage group were assigned to receive ADVAX and three to receive placebo in a double-blind design. Subjects were followed for local and systemic reactogenicity, adverse events, and clinical laboratory parameters. Study follow up was 18 months. Humoral immunogenicity was evaluated by anti-gp120 binding ELISA. Cellular immunogenicity was assessed by a validated IFNgamma ELISpot assay and intracellular cytokine staining. ADVAX was safe and well-tolerated, with no vaccine-related serious adverse events. Local and systemic reactogenicity events were reported by 64% and 42% of vaccine recipients, respectively. The majority of events were mild. The IFNgamma ELISpot response rates to any HIV antigen were 0/9 (0%) in the placebo group, 3/12 (25%) in the low-dosage group, 4/12 (33%) in the mid-dosage group, and 2/12 (17%) in the high-dosage group. Overall, responses were generally transient and occurred to each gene product, although volunteers responded to single antigens only. Binding antibodies to gp120 were not detected in any volunteers, and HIV seroconversion did not occur. CONCLUSIONS/SIGNIFICANCE: ADVAX delivered intramuscularly is safe, well-tolerated, and elicits modest but transient cellular immune responses. TRIAL REGISTRATION: Clinicaltrials.gov NCT00249106.

Vasan    Sarah Schlesinger    Huang Yaoxing    Arlene Hurley    Lombardo Angela    Zhiwei Chen    Than Soe    Adesanya Phumla    Bunce Catherine    Boaz Mark    Boyle Rosanne    Sayeed    Clark    Dugin    Schmidt Claudia    Yang Song    Seamons Laura    Dally Len    Ho Martin    Smith Carol    Markowitz Martin    Cox Josephine    Gill    Gilmour Jill    Keefer Michael C.    Fast Patricia    何大一    

PloS one

2010

Ibalizumab is a humanized monoclonal antibody that binds human CD4, the primary receptor for human immunodeficiency virus type 1 (HIV-1). With its unique specificity for domain 2 of CD4, this antibody potently and broadly blocks HIV-1 infection in vitro by inhibiting a postbinding step required for viral entry but without interfering with major histocompatibility complex class II (MHC-II)-mediated immune function. In clinical trials, ibalizumab has demonstrated anti-HIV-1 activity in patients without causing immunosuppression. Thus, a characterization of the ibalizumab epitope was conducted in an attempt to gain insight into the underlying mechanism of its antiviral activity as well as its safety profile. By studying mouse/human chimeric CD4 molecules and site-directed point mutants of CD4, amino acids L96, P121, P122, and Q163 in domain 2 were found to be important for ibalizumab binding, with E77 and S79 in domain 1 also contributing. All these residues appear to cluster on the interface between domains 1 and 2 of human CD4 on a surface opposite the site where gp120 and the MHC-II molecule bind on domain 1. Separately, the epitope of M-T441, a weakly neutralizing mouse monoclonal antibody that competes with ibalizumab, was localized entirely within domain 2 on residues 123 to 125 and 138 to 140. The results reported herein not only provide an appreciation for why ibalizumab has not had significant adverse immunological consequences in infected patients to date but also raise possible steric hindrance mechanisms by which this antibody blocks HIV-1 entry into a CD4-positive cell. Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Song Ruijiang    Franco David    Kao Chia-Ying    Yu Faye    Huang Yaoxing    何大一    

Journal of Virology

2010

The failure to develop an effective vaccine against HIV-1 infection has led the research community to seek new ways of raising qualitatively different antibody and cellular immune responses. Towards this goal, we investigated the yellow fever 17D vaccine strain (YF17D), one of the most effective vaccines ever made, as a platform for HIV-1 vaccine development. A test antigen, HIV-1 p24 (clade B consensus), was inserted near the 5' end of YF17D, in frame and upstream of the polyprotein (YF-5'/p24), or between the envelope and the first non-structural protein (YF-E/p24/NS1). In vitro characterization of these recombinants indicated that the gene insert was more stable in the context of YF-E/p24/NS1. This was confirmed in immunogenicity studies in mice. CD8 IFN-γ T-cell responses against p24 were elicited by the YF17D recombinants, as were specific CD4 T cells expressing IFN-γ and IL-2. A balanced CD4 and CD8 T-cell response was notable, as was the polyfunctionality of the responding cells. Finally, the protective efficacy of the YF17D recombinants, particularly YF-E/p24/NS1, in mice challenged with a vaccinia expressing HIV-1 Gag was demonstrated. These results suggest that YF17D warrants serious consideration as a live-attenuated vector for HIV-1 vaccine development. © 2010 Elsevier Ltd.

Franco David    Li Wenjing    Qing Fang    Stoyanov Cristina T.    Thomas Moran    Charles Rice    何大一    

Vaccine

2010

The glycolipid α-galactosylceramide (α-GalCer) has been shown to bind CD1d molecules to activate invariant natural killer T (iNKT) cells, and subsequently induce activation of various immune-competent cells, including dendritic cells, thereby providing a significant adjuvant effect for various vaccines. However, in phase I clinical trials, α-GalCer was shown to display only marginal biological activity. In our search for a glycolipid that can exert more potent stimulatory activity against iNKT cells and dendritic cells and produce an adjuvant effect superior to α-GalCer, we performed step-wise screening assays on a focused library of 25 α-GalCer analogues. Assays included quantification of the magnitude of stimulatory activity against human iNKT cells in vitro, binding affinity to human and murine CD1d molecules, and binding affinity to the invariant t cell receptor of human iNKT cells. Through this rigorous and iterative screening process, we have identified a lead candidate glycolipid, 7DW8-5, that exhibits a superior adjuvant effect than α-GalCer on HIV and malaria vaccines in mice.

Xiangming Li    Fujio Masakazu    Imamura Masakazu    Wu Douglass    Vasan    翁启惠    何大一     Tsuji Moriya   

Proceedings of the National Academy of Sciences of the United States of America

2010

During immune responses, antibodies are selected for their ability to bind to foreign antigens with high affinity, in part by their ability to undergo homotypic bivalent binding. However, this type of binding is not always possible. For example, the small number of gp140 glycoprotein spikes displayed on the surface of the human immunodeficiency virus (HIV) disfavours homotypic bivalent antibody binding. Here we show that during the human antibody response to HIV, somatic mutations that increase antibody affinity also increase breadth and neutralizing potency. Surprisingly, the responding naive and memory B cells produce polyreactive antibodies, which are capable of bivalent heteroligation between one high-affinity anti-HIV-gp140 combining site and a second low-affinity site on another molecular structure on HIV. Although cross-reactivity to self-antigens or polyreactivity is strongly selected against during B-cell development, it is a common serologic feature of certain infections in humans, including HIV, Epstein-Barr virus and hepatitis C virus. Seventy-five per cent of the 134 monoclonal anti-HIV-gp140 antibodies cloned from six patients with high titres of neutralizing antibodies are polyreactive. Despite the low affinity of the polyreactive combining site, heteroligation demonstrably increases the apparent affinity of polyreactive antibodies to HIV. © 2010 Macmillan Publishers Limited. All rights reserved.

Hugo Mouquet    Johannes Scheid    Zoller Markus J.    Krogsgaard Michelle    Ott Rene G.    Shukair Shetha    Artyomov Maxim N.    John Pietzsch    Connors Mark    Pereyra Florencia    Bruce Walker    何大一     Patrick Wilson    Michael Seaman    Herman Eisen    Arup Chakraborty    Thomas Hope    Jeffrey Ravetch    Wardemann Hedda    Michel Nussenzweig   

Nature

2010

Ibalizumab is a humanized, anti-CD4 monoclonal antibody. It potently blocks HIV-1 infection and targets an epitope in the second domain of CD4 without interfering with immune functions mediated by interaction of CD4 with major histocompatibility complex (MHC) class II molecules. We report here the crystal structure of ibalizumab Fab fragment in complex with the first two domains (D1-D2) of CD4 at 2.2 resolution. Ibalizumab grips CD4 primarily by the BC-loop (residues 121-125) of D2, sitting on the opposite side of gp120 and MHC-II binding sites. No major conformational change in CD4 accompanies binding to ibalizumab. Both monovalent and bivalent forms of ibalizumab effectively block viral infection, suggesting that it does not need to crosslink CD4 to exert antiviral activity. While gp120-induced structural rearrangements in CD4 are probably minimal, CD4 structural rigidity is dispensable for ibalizumab inhibition. These results could guide CD4-based immunogen design and lead to a better understanding of HIV-1 entry. © 2010 Elsevier Ltd. All rights reserved.

Freeman Michael M.    Michael Seaman    Rits-Volloch Sophia    Hong Xinguo    Kao Chia-Ying    何大一     Chen Bing   

Structure

2010