Interrupted CAG expansions in ATXN2 gene expand the genetic spectrum of frontotemporal dementias

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Production of human antibodies by in vitro immunization using a fusion protein containing the transcriptional transactivator of HIV-1

International audienceAntigen-specific activation of human B cells represents a key step for the production of monoclonal antibodies. Several approaches have been developed over the last thirty years in order to improve the process of lymphocyte activation in vitro. In the present study, we investigated whether the transcriptional transactivator (Tat) of human immunodeficiency virus, which possesses numerous biological activities, is able to trigger antibody secretion when incubated with human peripheral blood mononuclear cells. No such effect was observed when using Tat as a free protein. However, we found a significant IgM antibody production when Tat was previously fused to a double domain, called ZZ, derived from protein A of Staphylococcus aureus. The effect was also observed when the fusion protein, called ZZTat101, was incubated with purified B cells, indicating that the phenomenon does not require T-cell help. Antibody secretion was observed in the absence of cytokines that are usually used during in vitro immunization experiments, indicating that ZZTat101 provides the signals required for the initiation of the immune response. Antibody secretion was observed using a ZZTat mutant, containing only the Tat residues 22 to 57, called ZZTat22-57, indicating that this region is sufficient to initiate the immune response. In contrast, the effect was not found with a ZZTat22-57 mutant devoid of the seven Tat cysteines located between residues 22 and 37, demonstrating that these residues play a crucial role in the phenomenon. Our results pave the way to the development of a new in vitro immunization method based on antigens associated with ZZTat

Biocompatible Anionic Polymeric Microspheres as Priming Delivery System for Effetive HIV/AIDS Tat-Based Vaccines

Here we describe a prime-boost regimen of vaccination in Macaca fascicularis that combines priming with novel anionic microspheres designed to deliver the biologically active HIV-1 Tat protein and boosting with Tat in Alum. This regimen of immunization modulated the IgG subclass profile and elicited a balanced Th1-Th2 type of humoral and cellular responses. Remarkably, following intravenous challenge with SHIV89.6Pcy243, vaccinees significantly blunted acute viremia, as compared to control monkeys, and this control was associated with significantly lower CD4+ T cell depletion rate during the acute phase of infection and higher ability to resume the CD4+ T cell counts in the post-acute and chronic phases of infection. The long lasting control of viremia was associated with the persistence of high titers anti-Tat antibodies whose profile clearly distinguished vaccinees in controllers and viremics. Controllers, as opposed to vaccinated and viremic cynos, exhibited significantly higher pre-challenge antibody responses to peptides spanning the glutamine-rich and the RGD-integrin-binding regions of Tat. Finally, among vaccinees, titers of anti-Tat IgG1, IgG3 and IgG4 subclasses had a significant association with control of viremia in the acute and post-acute phases of infection. Altogether these findings indicate that the Tat/H1D/Alum regimen of immunization holds promise for next generation vaccines with Tat protein or other proteins for which maintenance of the native conformation and activity are critical for optimal immunogenicity. Our results also provide novel information on the role of anti-Tat responses in the prevention of HIV pathogenesis and for the design of new vaccine candidates