Systemic Immunization with an ALVAC-HIV-1/Protein Boost Vaccine Strategy Protects Rhesus Macaques from CD4 + T-Cell Loss and Reduces both Systemic and Mucosal Simian-Human Immunodeficiency Virus SHIV KU2 RNA Levels

Autor: Jim Tartaglia, Genoveffa Franchini, Nicolas Rose, Marcin Moniuszko, Lindsey Hocker, Janos Nacsa, Vaniambadi S. Kalyanaraman, Igor M. Belyakov, Sampa Santra, Yvette Edghill-Smith, Norman L. Letvin, Lauren Hudacik, Ranajit Pal, David C. Montefiori, Zdeněk Hel, David Venzon, Jay A. Berzofsky, Phillip D. Markham, Robyn Washington Parks
Rok vydání: 2006
Předmět:
Zdroj: Journal of Virology. 80:3732-3742
ISSN: 1098-5514
0022-538X
Popis: Due to the alarming spread of human immunodeficiency virus type 1 (HIV-1) infection worldwide, the development of a prophylactic vaccine is critical. Vaccine strategies for AIDS have included the use of structural and nonstructural HIV subunit proteins or peptides, naked DNA, bacterial and viral live vectors, or combinations of the above. Most of the vaccines developed thus far induce T-cell responses but are unable to induce neutralizing antibodies to the Env of primary HIV-1 isolates. The fact that a decrease in plasma viremia (9, 41) is concomitant with the appearance of virus-specific cytotoxic T lymphocytes (CTLs) and depletion of CD8+ T cells in simian immunodeficiency virus (SIV)-infected macaques or HIV-infected chimpanzees suggests that CD8+ T cells are able to partially control HIV-1/SIV replication (15, 36, 43, 52). Indeed, several “T-cell vaccines” based on DNA and live vectors confer protection from high-level replication of challenge viruses in rhesus macaques (2, 4, 8, 30, 31, 48). The extent of the decrease in viral replication induced by these vaccines is variable in nonhuman primates, and protection from disease appears to be dependent on the virulence of the virus used in the challenge experiments (28). The relative efficacy of poxvirus-based vaccine candidates with various degrees of attenuation has been extensively studied in rhesus macaques after challenge with SIV, SHIV, and HIV-2 isolates (1, 3, 8, 24, 25, 29-31, 48). These vaccine modalities elicit variable levels of cell-mediated immune response and prevent infection after challenge exposure to viruses with low virulence, such as HIV-2 (3, 25), and to other somewhat-attenuated SIV isolates (34, 35). Importantly, these vaccine modalities were also able to significantly reduce virus load after challenge with highly pathogenic SIV isolates (8, 29, 32, 48). An ALVAC-SIV vaccine encoding the gag, pol, and env genes of the SIVmac251 isolate was able to reduce plasma virus load during primary infection and conferred protection from CD4+ loss during both acute and chronic phases of infection after rectal exposure to a highly pathogenic SIVmac251 isolate (50). Among the pox vector-based vaccines, several ALVAC-based HIV-1 vaccines have been tested in phase I and II clinical trials and have been shown to be safe and immunogenic in humans (10, 14, 18, 21, 27). Whether the immunogenicity of these vaccine candidates will be sufficient to protect humans from HIV-1 remains unknown (5, 11, 44). The ongoing human phase III trial in Thailand will provide key information in this regard. Here, we designed a study to assess whether systemic immunization with recombinant canarypox expressing either HIV-1 gp120 or gp160 followed by a boost with either purified gp120 or gp140 proteins would confer protection after mucosal challenge with the pathogenic SHIVKU2. We also investigated whether the addition of the Tat protein of HIV-1 as an immunogen could provide better protection, since a few studies have demonstrated that immunization of macaques with Tat protein either alone or as a Nef-Tat fusion protein in a multicomponent subunit vaccine confers an advantage in a SHIV89.6P model (12, 13, 56) but not in other studies (53). Here, we found that immunization of macaques with this type of ALVAC-based vaccine formulation elicited both antibody and cellular responses and significantly decreased plasma viremia and CD4+ T-cell loss after rectal exposure to the SHIVKU2 isolate. Tat protein immunization had no additive effect on the reduction of virus load in vaccinated rhesus macaques, as also observed by others (42, 46, 53).
Databáze: OpenAIRE
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