Narayan, J. IR that persisted for months, with an unusual reemergence in the blood following an initial decline but in the absence of antibody responses. The majority of vaccine-specific CD4+and CD8+T cells lacked gamma interferon production but showed high antigen-specific proliferation capacities. Proliferative CD8+T cells expressed the lytic molecule granzyme B. No integrated viral vector could be detected in mononuclear cells from immunized animals, and this high dose of DNA did not induce any detectable autoimmune responses against DNA. Taken together, our comprehensive analysis exhibited for the first time the capacity of a single high dose of HIV DNA vaccine alone to induce long-lasting and polyfunctional Tubacin T-cell responses in the nonhuman primate model, bringing new insights for the design of future HIV vaccines. The development of a vaccine that substantially decreases the viral load set points and reduces the transmission of HIV-1 appears to be the long-term solution to control the persistently growing epidemic of this virus in the world (10). In the past, vaccines against challenging infectious diseases, including smallpox, polio, measles, and yellow fever, have been the most effective strategies for fighting these human pandemics. However, and unlike these traditional vaccines that mostly rely on the production of neutralizing antibodies (Abs) for protection from pathogenic infections, the control of HIV contamination strongly depends on the development of high-frequency, broadly targeted, polyfunctional T-cell responses specific to the virus (11,28,45). Live-attenuated simian immunodeficiency virus (SIV)/HIV vaccines so far have been the best inducers of potent T-cell responses that correlate with protection against AIDS following challenge with pathogenic strains in nonhuman primate (NHP) models (24,39,47,61), although the exact correlates of such protection remain to be fully delineated. However, the persistence, integration, and possible reversion to pathogenic forms of these replication-competent vaccines comprise a risk that will not be acceptable for their use in humans. Instead, the use of DNA-based vaccines as a strategy to induce protective responses to control infectious diseases, including HIV-1/AIDS, is very attractive, based on its safety, the absence of contamination even in immunocompromised recipients, and its capacity to induce both humoral and T-cell immune responses. For many years, numerous plasmid DNAs encoding Tubacin HIV proteins have been developed and tested in animal models, and some Tubacin of them have been tested in humans (14,18,42,49). However, unlike that in rodents, the immune responses induced in humans and NHPs by these DNA vaccines were dramatically weak despite successive immunizations with multiple doses of DNA (30). To circumvent this limitation, new strategies currently are used to improve the immunogenicity of DNA vaccines, including the incorporation of signal-to-target dendritic cells (43), the codon optimization of HIV antigens (Ag) (14), the coexpression of adjuvant (15), and new tools that optimize the delivery of DNA in target cells in the muscle (34). We have developed a noninfectious DNA vaccine derived from the highly pathogenic SHIVKU2expressing seven proteins of HIV under the control of the SIV Rabbit Polyclonal to MNT 5 long terminal repeat (LTR) promoter (35). This design mimics the natural expression of the viral proteins and leads to the formation of numerous viral-like particles that are extruded out of expressing cells (4). Repeated low-dose immunizations with this vaccine without heterologous boost guarded macaques from progression to AIDS following challenge with pathogenic SHIV. However, enzyme-linked immunospot (ELISPOT) assay responses to HIV antigens before challenge were sporadic and weak (35,54). In contrast, T-cell responses specific to HIV antigens induced by our construct in immunized mice were substantially higher (21). Using the mouse model, we developed a more sensitive immunity-monitoring assay that measures proliferative capacity, cytotoxic potential, and other immune functions (gamma interferon [IFN-] and interleukin-2 [IL-2] secretion) and provides more robust indications regarding the immunogenicity induced by the vaccine. We reported that this intramuscular immunization of mice with a single dose of this HIV DNA vaccine induced long-lasting and polyfunctional CD8+T-cell responses Tubacin directed against all HIV antigens expressed by the construct. Interestingly, in the absence of any additional immunization, we observed a primary peak of immune responses (IR) within 2 to 4 weeks postinfection (p.i.), followed by a contraction phase and then the late reemergence of responses after 14 to 20 weeks p.i. and lasting until the end of the experiment (more than 63 weeks p.i.). This is a typical pattern of vaccine-specific T-cell responses induced by nonpersistent vectors that progressively elicit secondary lymphoid tissue-based memory T cells as the expressed antigen becomes rare (9,38,58). Importantly, the major proportion of these HIV-specific CD8+T cells was not producing IFN- but proliferated vigorously following antigen stimulation and produced the lytic molecule granzyme B (5). The contribution of this type of.
