For comparative purposes, we used the replication-competent WR strain. the expression of IFN- and IFN-/-inducible genes. In a DNA prime/MVA boost immunization protocol in mice, flow cytometry analysis revealed that MVA-B C6L enhanced the magnitude and polyfunctionality of the HIV-1-specific CD4+ and CD8+ T-cell memory immune responses, with most of the HIV-1 responses mediated by the CD8+ T-cell compartment with an effector phenotype. Significantly, while MVA-B induced preferentially Env- and Gag-specific CD8+ T-cell responses, MVA-B C6L induced more Gag-Pol-Nef-specific CD8+ T-cell responses. Furthermore, MVA-B Liraglutide C6L enhanced the levels of antibodies against Env in comparison with MVA-B. These findings revealed that C6 can be considered as an immunomodulator and that deleting gene in MVA-B confers an immunological benefit by enhancing IFN–dependent responses and increasing the magnitude and quality Liraglutide of the T-cell memory immune responses to HIV-1 antigens. Our observations are relevant for the improvement of MVA vectors as HIV-1 vaccines. Introduction Poxvirus vectors express numerous genes encoding for immunomodulatory proteins that interfere with host anti-viral response [1]. The VACV gene is present in the genome of VACV strains Western Reserve (WR) (is presumably an immediate-early gene based on the analysis of the promoter (www.poxvirus.org) and a genome-wide transcriptome analysis that detected C6 mRNA 30 minutes post-infection [2]. encodes a 157 amino acid protein with a predicted molecular weight of 18.2 kDa (www.poxvirus.org). Bioinformatic analyses clustered to the poxvirus BCL-2-like gene family that includes (named in WR) and and peptides [15]. All these characteristics suggest that C6 may have an important immunomodulatory function by antagonizing with the TLR signalling pathway. The highly attenuated VACV strain MVA is one of the most promising vectors to be used as an effective vaccine against HIV-1 [16]. MVA has an excellent safety profile, and MVA recombinants expressing HIV-1 antigens induce protection after simian/human immunodeficiency virus (SHIV) challenge, and elicit strong, broad, polyfunctional and durable immune responses to HIV-1 antigens in different animal models and humans trials [[17], [18], [19], [20], [21], [22], for a review [23]]. We have previously constructed a recombinant MVA expressing codon-optimized Env as monomeric gp120 and the polyprotein Gag-Pol-Nef of HIV-1 from clade B (referred as MVA-B), that in DNA prime/MVA boost protocols in mice induced strong immune responses to HIV-1 antigens [17], [18], [20]. In macaques, a similar MVA construct expressing Env (gp120 from SHIV89.6P) and Gag-Pol-Nef (from SIVmac239) showed strong specific CD4+ and CD8+ T-cell immune responses with a bias for CD8+, and high protection after challenge with SHIV89.6P [22]. Furthermore, the expression of HIV-1 antigens from MVA-B selectively induced in human dendritic cells (DCs) the expression of different cellular genes that might act as regulators of immune responses to HIV-1 antigens [24] and MVA-B-infected DCs co-cultured with autologous T Liraglutide lymphocytes induced a highly functional HIV-1-specific CD8+ T-cell responses including proliferation, secretion of IFN-, IL-2, TNF-, MIP1, MIP1, RANTES and IL-6, and strong cytotoxic activity against autologous HIV-1-infected CD4+ T lymphocytes [25]. Based on these previous results, MVA-B has recently entered a phase I clinical trial in healthy volunteers in Spain. However, more efficient poxvirus Liraglutide MVA-B vectors that enhance the magnitude, breath, polyfunctionality and durability of the immune responses to HIV-1 antigens are desirable. This is particularly relevant when a single immunogen is desirable for mass vaccination purposes to simplify the immunization protocols and reduce manufacturing cost. Deletion in the vector backbone of MVA-B of known or suggested immunomodulatory VACV genes, which antagonize host specific immune responses, is a general strategy that could Rabbit Polyclonal to Potassium Channel Kv3.2b enhance immunogenicity of the vector against HIV-1 antigens. In this study, we have generated a new HIV-1 vaccine candidate, termed MVA-B C6L, which contains a deletion in the vector backbone of MVA-B of the VACV.
