Antigenic specificity of antibody-dependent cell-mediated cytotoxicity directed against human immunodeficiency virus in antibody-positive sera

Antibody-dependent cell-mediated cytotoxicity (ADCC) specific for human immunodeficiency virus (HIV) has been described for HIV-infected individuals. To determine the antigenic specificity of this immune response and to define its relationship to the disease state, an ADCC assay was developed using Epstein-Barr virus-transformed lymphoblastoid cell line targets infected with vaccinia virus vectors expressing HIV proteins. The vaccinia virus vectors induced appropriate HIV proteins (envelope glycoproteins gp160, gp120, and gp41 or gag proteins p55, p40, p24, and p17) in infected lymphoblastoid cell lines as demonstrated by radioimmunoprecipitation and syncytia formation with c8166 cells. Killer cell-mediated, HIV-specific ADCC was found in sera from HIV-seropositive but not HIV-seronegative hemophiliacs. This HIV-specific response was directed against envelope glycoprotein but was completely absent against target cells expressing the HIV gag proteins. The ADCC directed against gp160 was present at serum dilutions up to 1/316,000. There was no correlation between serum ADCC titer and the stage of HIV-related illness as determined by T-helper-cell numbers. These experiments clearly implicated gp160 as the target antigen of HIV-specific ADCC activity following natural infection. Vaccines which stimulate antibodies directed against gp160, which are capable of mediating ADCC against infected cells, could be important for protection against infection by cell-associated virus

Detection of major histocompatibility complex class I-restricted, HIV-specific cytotoxic T lymphocytes in the blood of infected hemophiliacs

Major histocompatibility (MHC)-restricted, human immunodeficiency virus type one (HIV-1)-specific, cytotoxic T lymphocytes (CTLs) were detected in the peripheral blood mononuclear cells (PBMCs) of HIV-1-infected individuals. Using a system of autologous B and T lymphoblastoid cell lines infected with recombinant vaccinia vectors (VVs) expressing HIV-1 gene products, we were able to detect HIV-1-specific cytolytic responses in the PBMCs of 88% of HIV-1-seropositive hemophiliac patients in the absence of in vitro stimulation. These cytolytic responses were directed against both HIV-1 envelope and gag gene products. The responses were resistant to natural killer (NK) cell depletion and were inhibited by monoclonal antibodies (MoAbs) to the T cell receptor, CD8 surface antigens, and MHC class I antigens, suggesting a classical MHC class I restricted, virus-specific CTL response

Mucosal Priming of Simian Immunodeficiency Virus-Specific Cytotoxic T-Lymphocyte Responses in Rhesus Macaques by the \u3ci\u3eSalmonella\u3c/i\u3e Type III Secretion Antigen Delivery System

Nearly all human immunodeficiency virus (HIV) infections are acquired mucosally, and the gut-associated lymphoid tissues are important sites for early virus replication. Thus, vaccine strategies designed to prime virus-specific cytotoxic T lymphocyte (CTL) responses that home to mucosal compartments may be particularly effective at preventing or containing HIV infection. The Salmonella type III secretion system has been shown to be an effective approach for stimulating mucosal CTL responses in mice. We therefore tested ∆phoP-phoQ attenuated strains of Salmonella enterica serovar Typhimurium and S. enterica serovar Typhi expressing fragments of the simian immunodeficiency virus (SIV) Gag protein fused to the type III-secreted SopE protein for the ability to prime virus-specific CTL responses in rhesus macaques. Mamu-A*01+ macaques were inoculated with three oral doses of recombinant Salmonella, followed by a peripheral boost with modified vaccinia virus Ankara expressing SIV Gag (MVA Gag). Transient low-level CTL responses to the Mamu-A*01 Gag181-189 epitope were detected following each dose of Salmonella. After boosting with MVA Gag, strong Gag-specific CTL responses were consistently detected, and tetramer staining revealed the expansion of Gag181-189-specific CD8+ T-cell responses in peripheral blood. A significant percentage of the Gag181-189- specific T-cell population in each animal also expressed the intestinal homing receptor α4β7. Additionally, Gag181-189-specific CD8+ T cells were detected in lymphocytes isolated from the colon. Yet, despite these responses, Salmonella-primed/MVA-boosted animals did not exhibit improved control of virus replication following a rectal challenge with SIVmac239. Nevertheless, this study demonstrates the potential of mucosal priming by the Salmonella type III secretion system to direct SIV-specific cellular immune responses to the gastrointestinal mucosa in a primate model

Broadly reactive antibody-dependent cellular cytotoxic response to HIV-1 envelope glycoproteins precedes broad neutralizing response in human infection

To determine if and when the antibody-dependent cell-mediated cytotoxic (ADCC) response of human serum exhibits broad reactivity across HIV-1 strains, multiple sera were tested for their ability to mediate ADCC against target cells infected with recombinant vaccinia vectors expressing envelope genes of HTLV-IIIB or HTLV-IIIRF. These vectors were found to express the envelope glycoproteins of the two HIV-1 strains and so were appropriate targets for ADCC assays. All the HIV-1-positive sera were able to mediate ADCC against both HTLV-IIIB and HTLV-IIIRF envelope-expressing targets at similar titer. In sera from early seroconverters, the ADCC response was again broadly reactive, even in those sera that exhibited strain-specific neutralizing antibody responses. The ADCC response to natural infection with HIV-1 is therefore broadly reactive and precedes the development of a broad neutralizing antibody response. The broad reactivity of HIV-1-specific ADCC responses may be important for protection against cell-associated virus in vaccine development

Limiting dilution analysis of cytotoxic T lymphocytes to human immunodeficiency virus gag antigens in infected persons: in vitro quantitation of effector cell populations with p17 and p24 specificities

The presence of cytotoxic T lymphocytes (CTL) to the gag antigens of human immunodeficiency virus (HIV) has been described in infected populations. We found that the majority of this immune response as measured in bulk CTL assays of unstimulated peripheral blood mononuclear cells (PBMC) is directed against the p24 component of the p55 gag precursor protein. Using limiting dilution analysis of this effector cell population we confirm that the majority of activated gag-specific CTL circulating in the PBMC of infected hemophilic patients are directed at p24 determinants and are present at frequencies of 1/36,000 to 1/86,000 lymphocytes. By performing in vitro stimulation after limiting dilution, the precursor population of gag-specific CTL are characterized and quantitated. HIV gag-specific CTL precursors are identified at frequencies of 1/1700 to 1/17,000 lymphocytes and are made up of cells with both p17 and p24 specificities. No HIV gag-specific CTL precursor cells are identified in the PBMC of HIV-uninfected individuals. These studies demonstrate that CTL directed at both p17 and p24 determinants make up the cellular immune repertoire in HIV-infected individuals but that only the p24-specific CTL are routinely found in an activated state in the circulation

Mucosal Priming of Simian Immunodeficiency Virus-Specific Cytotoxic T-Lymphocyte Responses in Rhesus Macaques by the \u3ci\u3eSalmonella\u3c/i\u3e Type III Secretion Antigen Delivery System

Nearly all human immunodeficiency virus (HIV) infections are acquired mucosally, and the gut-associated lymphoid tissues are important sites for early virus replication. Thus, vaccine strategies designed to prime virus-specific cytotoxic T lymphocyte (CTL) responses that home to mucosal compartments may be particularly effective at preventing or containing HIV infection. The Salmonella type III secretion system has been shown to be an effective approach for stimulating mucosal CTL responses in mice. We therefore tested ∆phoP-phoQ attenuated strains of Salmonella enterica serovar Typhimurium and S. enterica serovar Typhi expressing fragments of the simian immunodeficiency virus (SIV) Gag protein fused to the type III-secreted SopE protein for the ability to prime virus-specific CTL responses in rhesus macaques. Mamu-A*01+ macaques were inoculated with three oral doses of recombinant Salmonella, followed by a peripheral boost with modified vaccinia virus Ankara expressing SIV Gag (MVA Gag). Transient low-level CTL responses to the Mamu-A*01 Gag181-189 epitope were detected following each dose of Salmonella. After boosting with MVA Gag, strong Gag-specific CTL responses were consistently detected, and tetramer staining revealed the expansion of Gag181-189-specific CD8+ T-cell responses in peripheral blood. A significant percentage of the Gag181-189- specific T-cell population in each animal also expressed the intestinal homing receptor α4β7. Additionally, Gag181-189-specific CD8+ T cells were detected in lymphocytes isolated from the colon. Yet, despite these responses, Salmonella-primed/MVA-boosted animals did not exhibit improved control of virus replication following a rectal challenge with SIVmac239. Nevertheless, this study demonstrates the potential of mucosal priming by the Salmonella type III secretion system to direct SIV-specific cellular immune responses to the gastrointestinal mucosa in a primate model

Gender Differences in Human Immunodeficiency Virus Type 1-Specific CD8 Responses in the Reproductive Tract and Colon following Nasal Peptide Priming and Modified Vaccinia Virus Ankara Boosting

Induction of mucosal anti-human immunodeficiency virus type 1 (HIV-1) T-cell responses in males and females will be important for the development of a successful HIV-1 vaccine. An HIV-1 envelope peptide, DNA plasmid, and recombinant modified vaccinia virus Ankara (rMVA) expressing the H-2D(d)-restricted cytotoxic T lymphocyte P18 epitope were used as immunogens to test for their ability to prime and boost anti-HIV-1 T-cell responses at mucosal and systemic sites in BALB/c mice. We found of all prime-boost combinations tested, an HIV-1 Env peptide subunit mucosal prime followed by systemic (intradermal) boosting with rMVA yielded the maximal induction of gamma interferon (IFN-γ) spot-forming cells in the female genital tract and colon. However, this mucosal prime-systemic rMVA boost regimen was minimally immunogenic for the induction of genital, colon, or lung anti-HIV-1 T-cell responses in male mice. We determined that a mucosal Env subunit immunization could optimally prime an rMVA boost in female but not male mice, as determined by the magnitude of antigen-specific IFN-γ responses in the reproductive tracts, colon, and lung. Defective mucosal priming in male mice could not be overcome by multiple mucosal immunizations. However, rMVA priming followed by an rMVA boost was the optimal prime-boost strategy for male mice as determined by the magnitude of antigen-specific IFN-γ responses in the reproductive tract and lung. Thus, prime-boost immunization strategies able to induce mucosal antigen-specific IFN-γ responses were identified for male and female mice. Understanding the cellular and molecular basis of gender-determined immune responses will be important for optimizing induction of anti-HIV-1 mucosal immune responses in both males and females