An estimate 6,800 new HIV-1 infections daily dramatically underscores the desperate need for the development of an HIV-1 vaccine. Despite significant advances in our understanding of both the humoral and cellular immune response in HIV-1 infection, the correlates of protection have still not been defined. The recent failure of the Merck vaccine trial and the unexpected modest success of the RV144 HIV vaccine trial using ALVAC-HIV (vCP1521) in a prime boost combination with AIDSVAX B/E, have challenged our notion of what constitutes a protective vaccine. Strikingly, the vaccine induced not only strong antibody responses, but also a robust HIV-1-specific CD4+ T cell response. Approaches to induce HIV-1-specific CD4+ T cell responses have been met with skepticism thus far as these attempts may expand the pool of HIV-1 specific CD4+ T cells targets. However, compelling studies in the lymphochoriomeningitis virus (LCMV) mouse model suggest that virus-specific Interleukin-21 (IL21) secreting CD4+ T cell responses are a critical key factor to establish effective and long-lived virus-specific immunity. Mice lacking IL21 or IL21 receptor (IL21R) were more susceptible to chronic LCMV infection. IL21+CD4+ T cell responses have been shown to enhance cytotoxicity of virus-specific CD8+ T cells and direct antibody class switching and activation of B cells. Thus, IL21+CD4+ T cell responses play a central role in the coordination of virus-specific immunity. Surprisingly little is known about the role of IL21+ CD4+ T cells in human viral infections. Our preliminary data suggest that robust HIV-1- specific IL21+CD4+ T cell responses exist in HIV-1 elite controllers with a preferential targeting of epitopes within the Gag protein. In contrast, in subjects with chronic-progressive HIV-1 infection virtually no IL21+CD4+ T cell responses are detectable. Moreover, we have evidence that IL21 signals can transform non-controlling CD8+ T cell responses into CD8+ T cell responses with strong inhibitory activity. Thus, our preliminary data suggest that IL21+CD4+ T cell responses might be a critical factor for the generation of an effective CD8+ T cell or B cell based vaccine. Specifically we propose to: 1) Determine the presence and specificity of HIV-1-specific IL21+CD4+ T cells as well as their role in the control of viral replication. 2) Determine whether early antiretroviral treatment in primary HIV-1 infection preserves these particular responses. 3.) Assess how HIV-1-specific IL21+CD4+ T responses modulate HIV-1-specific CD8+ T cells and enhance their capacity to inhibit viral replication. 4.) Investigate whether therapeutic CD4-targeted vaccination can induce such responses and finally 5.) assess how IL21+CD4+ T cells modulate HIV-1-specific B cell functions. The underlying hypotheses of this proposal are that HIV-1-specific IL21+ CD4+ T cells have a key function in the control of viral replication by modulating HIV-1-specific B cell function and increasing the inhibitory activity of HIV-1-specific CD8+ T cells. The induction and propagation of these responses in a prophylactic or therapeutic vaccine will be essential for long-lived effective virus-specific immunity.
With 33 million HIV-1 infected individuals world-wide an HIV-1 vaccine is urgently needed. The recent failure of the Merck vaccine trial and the unexpected modest success of a vaccine consisting of a combination of two vaccine candidates (ALVAC/AIDSVAX;"Thai trial") drastically demonstrate our poor understanding how to develop an effective vaccine. Strikingly, the used vaccine not only induced antibodies, but also a robust HIV-1-specific CD4+ T cell response. Recent data from the mouse model suggest that virus-specific Interleukin-21 (IL21)-secreting CD4+ T cell responses are critical to support virus-specific CD8+ T cell and B cell immunity. Thus in this proposal we aim to define the role of HIV-1-specific IL21+CD4+ T cell responses in the control of HIV-1 infection to determine whether the induction of these responses should be a key component of a prophylactic and therapeutic vaccine.
|Schultz, Bruce T; Teigler, Jeffrey E; Pissani, Franco et al. (2016) Circulating HIV-Specific Interleukin-21(+)CD4(+) T Cells Represent Peripheral Tfh Cells with Antigen-Dependent Helper Functions. Immunity 44:167-78|
|Johnson, Susan; Eller, Michael; Teigler, Jeffrey E et al. (2015) Cooperativity of HIV-Specific Cytolytic CD4 T Cells and CD8 T Cells in Control of HIV Viremia. J Virol 89:7494-505|
|Streeck, Hendrik; Lu, Richard; Beckwith, Noor et al. (2014) Emergence of individual HIV-specific CD8 T cell responses during primary HIV-1 infection can determine long-term disease outcome. J Virol 88:12793-801|
|Schieffer, Miriam; Jessen, Heiko K; Oster, Alexander F et al. (2014) Induction of Gag-specific CD4 T cell responses during acute HIV infection is associated with improved viral control. J Virol 88:7357-66|
|Pissani, Franco; Streeck, Hendrik (2014) Emerging concepts on T follicular helper cell dynamics in HIV infection. Trends Immunol 35:278-86|
|Jessen, Heiko; Allen, Todd M; Streeck, Hendrik (2014) How a single patient influenced HIV research--15-year follow-up. N Engl J Med 370:682-3|
|Ranasinghe, Srinika; Cutler, Sam; Davis, Isaiah et al. (2013) Association of HLA-DRB1-restricted CD4âº T cell responses with HIV immune control. Nat Med 19:930-3|
|Streeck, Hendrik; D'Souza, M Patricia; Littman, Dan R et al. (2013) Harnessing CD4Ã½Ã½Ã½ T cell responses in HIV vaccine development. Nat Med 19:143-9|
|Soghoian, Damien Z; Jessen, Heiko; Flanders, Michael et al. (2012) HIV-specific cytolytic CD4 T cell responses during acute HIV infection predict disease outcome. Sci Transl Med 4:123ra25|
|Angin, Mathieu; Streeck, Hendrik; Wen, Fang et al. (2012) Regulatory T cell frequencies do not correlate with breadth or magnitude of HIV-1-specific T cell responses. AIDS Res Hum Retroviruses 28:749-51|
Showing the most recent 10 out of 17 publications