Antibody to native human immunodeficiency virus type 1 envelope glycoproteins induced by IIIB and MN recombinant gp120 vaccines. The NIAID AIDS Vaccine Evaluation Group

A brief history of the global effort to develop a preventive HIV vaccine

Soon after HIV was discovered as the cause of AIDS in 1983-1984, there was an expectation that a preventive vaccine would be rapidly developed. In trying to achieve that goal, three successive scientific paradigms have been explored: induction of neutralizing antibodies, induction of cell mediated immunity, and exploration of combination approaches and novel concepts. Although major progress has been made in understanding the scientific basis for HIV vaccine development, efficacy trials have been critical in moving the field forward. In 2009, the field was reinvigorated with the modest results obtained from the RV144 trial conducted in Thailand. Here, we review those vaccine development efforts, with an emphasis on events that occurred during the earlier years. The goal is to provide younger generations of scientists with information and inspiration to continue the search for an HIV vaccine.

Binding of antibodies to human immunodeficiency virus type 1 (HIV-1)-infected lymphocytes elicited by vaccines and by natural infection

Binding of antibodies to oligomeric envelope glycoprotein of R5-tropic primary isolates of human immunodeficiency virus type 1 (HIV-1) was studied by flow cytometry using sera from HIV-1 vaccine recipients and clade B and C HIV-1-infected patients, and monoclonal and polyclonal antibodies to neutralizing epitopes of HIV-1. Vaccine recipients received recombinant canarypox virus vaccine expressing HIV-1 gene products, and SF-2 recombinant gp120 subunit vaccine. Anti-gp120 neutralizing antibodies including human monoclonal antibody 2G12 and goat polyclonal anti-serum to V3 loop peptide [peptide T1-SP10MN(A)] bound to HIV-1-infected cells. Sera from vaccine recipients bound to HIV-1-infected cells, but at levels lower than did infected patient sera.

QS-21 promotes an adjuvant effect allowing for reduced antigen dose during HIV-1 envelope subunit immunization in humans

Three separate studies were undertaken in HIV-1 uninfected persons to determine if the adjuvant QS-21 improves the magnitude or kinetics of immune responses induced by recombinant soluble gp120 HIV-1(MN) protein (rsgp120) immunization. The QS-21 was administered at two doses (50 and 100 microg), either alone or in combination with aluminum hydroxide (600 microg). At the highest doses of rsgp120 (100, 300, and 600 microg), QS-21 exerted no significant effect on either binding or neutralizing antibody titers. Antibody binding and neutralizing responses fell dramatically when rsgp120, formulated with alum alone, was given at low doses (3 and 30 microg). In contrast, antibody responses similar in titer to those in the high dose antigen groups were induced with the low dose rsgp120 formulated with QS-21. In addition, the lymphocyte proliferation and delayed type hypersensitivity skin testing were superior in the QS-21 recipients compared with the alum recipients at the low antigen doses. Moderate to severe pain was observed in majority of the volunteers receiving QS-21 formulations, and vasovagal episodes and hypertension were not infrequent. Thus, the use of QS-21 may provide a means to reduce the dose of a soluble protein immunogen.

Expansion of epitope cross-reactivity by anti-idiotype modulation of the primary humoral response

The primary humoral response produces antigen-specific antibodies so to clear the initial infection, and generates a population of corresponding memory cells to prevent infection by future encounters with the same pathogen. The continuous genetic modification of a pathogen's exterior, however, is one mechanism used to evade the immune defenses of its host. Here we describe a novel means, involving anti-idiotypic antibodies, by which the host can counteract such pathogen genetic alterations by modulation of its primary humoral response. An autoimmune response against primary antibodies, Ab1's, creates anti-idiotypic antibodies (Ab2's), some of which (designated Ab2alpha) are able to bind the Ab1/antigen complex. We have discovered that binding of Ab2alpha to its corresponding Ab1 can expand Ab1's ability to bind variations of its antigen. This expanded epitope cross-reactivity is shown not only to increase the binding activity of Ab1 but also its ability to neutralize a variant infectious virus. MAb M77 is an Ab1, which is highly strain-specific for the HIV-1 envelope protein gp120(IIIB). This Ab1 can be rendered cross-reactive and neutralizing for an otherwise resistant HIV strain by its interaction with a unique anti-idiotypic Ab2alpha (GV12). Furthermore, molecular characterization of this expanded cross-reactivity was accomplished using combinatorial phage display peptide libraries.

MN and IIIB recombinant glycoprotein 120 vaccine-induced binding antibodies to native envelope glycoprotein of human immunodeficiency virus type 1 primary isolates. National Institute of Allergy and Infectious Disease Aids Vaccine Evaluation Group

The ability of antibody induced by MN and IIIB recombinant gp120 (rgp120) human immunodeficiency virus type 1 (HIV-1) vaccines to bind to oligomeric native HIV-1 envelope glycoproteins of primary isolates of HIV-1 was measured by flow cytometric indirect immunofluorescence assay (FIFA) in 25 uninfected, healthy adults. After three immunizations, MN rgp120 HIV-1 vaccine given alone and coadministered with IIIB rgp120 HIV-1 vaccine elicited antibody that bound to cells infected with each of a panel of six subtype B strains of HIV-1. Lower levels of vaccine-induced binding antibody were detected against envelope subtype A, D, and (EA) strains of HIV-1 than against subtype B strains. Priming immunization with IIIB rgp120 HIV-1 vaccine alone induced low levels of antibody capable of binding to envelope glycoprotein of primary isolate strains of HIV-1, and booster immunizations with MN rgp120 HIV-1 vaccine resulted in much higher antibody levels. We conclude that MN rgp120 HIV-1 vaccine was an effective inducer of antibody to native envelope glycoproteins of antigenically diverse primary isolates of HIV-1.

HIV-1MN recombinant glycoprotein 160 vaccine-induced cellular and humoral immunity boosted by HIV-1MN recombinant glycoprotein 120 vaccine. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group

We evaluated prime-boost immunization with two recombinant envelope glycoprotein subunit vaccines (HIV-1MN recombinant gp160 vaccine in alum adjuvant [MN rgp160] and HIV-1MN recombinant gp120 vaccine in alum adjuvant [MN rgp120]) for safety and immunogenicity in healthy, HIV-1-uninfected adults. The rationale was to combine the helper T cell memory and binding antibody responses typically induced by rgp160 vaccines with the superior neutralizing antibody responses induced by rgp120 vaccines. In a double-blinded, controlled trial, volunteers were randomly assigned to receive MN rgp160 or adjuvant placebo, and a subset later received MN rgp120. The two vaccines were safe, but reactions to MN rgp160 and its adjuvant placebo exceeded those to MN rgp120. MN rgp160 induced IgG binding antibodies, including all IgG subclasses, to MN rgp160 in all vaccine recipients. HIV-1MN-neutralizing and anti-V3 MN peptide-binding antibodies were observed in a majority of volunteers after the fourth MN rgp160 immunization, but at lower levels compared with immunization with MN rgp120 in historical controls. HIV-1-binding, neutralizing, and fusion inhibition antibodies were boosted to the highest levels among MN rgp160 recipients after MN rgp120 booster injections. MN rgp120 boosting appeared to alter the distribution of MN rgp160 vaccine-induced, anti-MN rgp160 IgG subclass antibodies. MN rgp160 induced helper T cell memory, measured by lymphocyte proliferation, Thl and Th2 cytokine production, and skin testing. Strategies including both subunit vaccines may help maximize antibody and helper T cell memory responses to HIV-1 envelope glycoprotein.

Modulation of immunologic responses to HIV-1MN recombinant gp160 vaccine by dose and schedule of administration. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group

The safety and immunogenicity of HIV-1MN recombinant gp160 (MN rgp160) vaccine in healthy, uninfected volunteers was tested in a double-blind study with a factorial design. By random assignment, 20 volunteers received three 200 micrograms doses of MN rgp160 and four volunteers received placebo at days 0, 28, and 168 or 0, 56, and 224. Of the 24 volunteers, 16 received 200 micrograms or 800 micrograms of MN rgp160 and two received placebo at day 532 (month 18). The vaccine was safe. It induced T cell memory measured by Th1 cytokine production and lymphocyte proliferation, and serum anti-MN rgp160 IgG (all subclasses) and IgA antibodies. Fifteen of 20 vaccinees developed neutralizing antibody. The regimen including immunizations on days 0, 28, and 168 followed by the 800 micrograms fourth dose was most immunogenic.