Recombinant rubella vectors elicit SIV Gag-specific T cell responses with cytotoxic potential in rhesus macaques

AbstractLive-attenuated rubella vaccine strain RA27/3 has been demonstrated to be safe and immunogenic in millions of children. The vaccine strain was used to insert SIV gag sequences and the resulting rubella vectors were tested in rhesus macaques alone and together with SIV gag DNA in different vaccine prime-boost combinations. We previously reported that such rubella vectors induce robust and durable SIV-specific humoral immune responses in macaques. Here, we report that recombinant rubella vectors elicit robust de novo SIV-specific cellular immune responses detectable for >10 months even after a single vaccination. The antigen-specific responses induced by the rubella vector include central and effector memory CD4+ and CD8+ T cells with cytotoxic potential. Rubella vectors can be administered repeatedly even after vaccination with the rubella vaccine strain RA27/3. Vaccine regimens including rubella vector and SIV gag DNA in different prime-boost combinations resulted in robust long-lasting cellular responses with significant increase of cellular responses upon boost. Rubella vectors provide a potent platform for inducing HIV-specific immunity that can be combined with DNA in a prime-boost regimen to elicit durable cellular immunity

Altered Response Hierarchy and Increased T-Cell Breadth upon HIV-1 Conserved Element DNA Vaccination in Macaques

HIV sequence diversity and potential decoy epitopes are hurdles in the development of an effective AIDS vaccine. A DNA vaccine candidate comprising of highly conserved p24 gag elements (CE) induced robust immunity in all 10 vaccinated macaques, whereas full-length gag DNA vaccination elicited responses to these conserved elements in only 5 of 11 animals, targeting fewer CE per animal. Importantly, boosting CE-primed macaques with DNA expressing full-length p55 gag increased both magnitude of CE responses and breadth of Gag immunity, demonstrating alteration of the hierarchy of epitope recognition in the presence of pre-existing CE-specific responses. Inclusion of a conserved element immunogen provides a novel and effective strategy to broaden responses against highly diverse pathogens by avoiding decoy epitopes, while focusing responses to critical viral elements for which few escape pathways exist

HIV Env conserved element DNA vaccine alters immunodominance in macaques

ABSTRACT Sequence diversity and immunodominance are major obstacles in the design of an effective vaccine against HIV. HIV Env is a highly-glycosylated protein composed of ‘conserved’ and ‘variable’ regions. The latter contains immunodominant epitopes that are frequently targeted by the immune system resulting in the generation of immune escape variants. This work describes 12 regions in HIV Env that are highly conserved throughout the known HIV M Group sequences (Env CE), and are poorly immunogenic in macaques vaccinated with full-length Env expressing DNA vaccines. Two versions of plasmids encoding the 12 Env CE were generated, differing by 0–5 AA per CE to maximize the inclusion of commonly detected variants. In contrast to the full-length env DNA vaccine, vaccination of macaques with a combination of these 2 Env CE DNA induced robust, durable cellular immune responses with a significant fraction of CD8+ T cells with cytotoxic phenotype (Granzyme B+ and CD107a+). Although inefficient in generating primary responses to the CE, boosting of the Env CE DNA primed macaques with the intact env DNA vaccine potently augmented pre-existing immunity, increasing magnitude, breadth and cytotoxicity of the cellular responses. Fine mapping showed that 7 of the 12 CE elicited T cell responses. Env CE DNA also induced humoral responses able to recognize the full-length Env. Env CE plasmids are therefore capable of inducing durable responses to highly conserved regions of Env that are frequently absent after Env vaccination or immunologically subdominant. These modified antigens are candidates for use as prophylactic and therapeutic HIV vaccines

Long-Term Programming of Antigen-Specific Immunity from Gene Expression Signatures in the PBMC of Rhesus Macaques Immunized with an SIV DNA Vaccine

While HIV-1-specific cellular immunity is thought to be critical for the suppression of viral replication, the correlates of protection have not yet been determined. Rhesus macaques (RM) are an important animal model for the study and development of vaccines against HIV/AIDS. Our laboratory has helped to develop and study DNA-based vaccines in which recent technological advances, including genetic optimization and in vivo electroporation (EP), have helped to dramatically boost their immunogenicity. In this study, RMs were immunized with a DNA vaccine including individual plasmids encoding SIV gag, env, and pol alone, or in combination with a molecular adjuvant, plasmid DNA expressing the chemokine ligand 5 (RANTES), followed by EP. Along with standard immunological assays, flow-based activation analysis without ex vivo restimulation and high-throughput gene expression analysis was performed. Strong cellular immunity was induced by vaccination which was supported by all assays including PBMC microarray analysis that identified the up-regulation of 563 gene sequences including those involved in interferon signaling. Furthermore, 699 gene sequences were differentially regulated in these groups at peak viremia following SIVmac251 challenge. We observed that the RANTES-adjuvanted animals were significantly better at suppressing viral replication during chronic infection and exhibited a distinct pattern of gene expression which included immune cell-trafficking and cell cycle genes. Furthermore, a greater percentage of vaccine-induced central memory CD8+ T-cells capable of an activated phenotype were detected in these animals as measured by activation analysis. Thus, co-immunization with the RANTES molecular adjuvant followed by EP led to the generation of cellular immunity that was transcriptionally distinct and had a greater protective efficacy than its DNA alone counterpart. Furthermore, activation analysis and high-throughput gene expression data may provide better insight into mechanisms of viral control than may be observed using standard immunological assays

A DNA Vaccine against Chikungunya Virus Is Protective in Mice and Induces Neutralizing Antibodies in Mice and Nonhuman Primates

Chikungunya virus (CHIKV) is an emerging mosquito-borne alphavirus indigenous to tropical Africa and Asia. Acute illness is characterized by fever, arthralgias, conjunctivitis, rash, and sometimes arthritis. Relatively little is known about the antigenic targets for immunity, and no licensed vaccines or therapeutics are currently available for the pathogen. While the Aedes aegypti mosquito is its primary vector, recent evidence suggests that other carriers can transmit CHIKV thus raising concerns about its spread outside of natural endemic areas to new countries including the U.S. and Europe. Considering the potential for pandemic spread, understanding the development of immunity is paramount to the development of effective counter measures against CHIKV. In this study, we isolated a new CHIKV virus from an acutely infected human patient and developed a defined viral challenge stock in mice that allowed us to study viral pathogenesis and develop a viral neutralization assay. We then constructed a synthetic DNA vaccine delivered by in vivo electroporation (EP) that expresses a component of the CHIKV envelope glycoprotein and used this model to evaluate its efficacy. Vaccination induced robust antigen-specific cellular and humoral immune responses, which individually were capable of providing protection against CHIKV challenge in mice. Furthermore, vaccine studies in rhesus macaques demonstrated induction of nAb responses, which mimicked those induced in convalescent human patient sera. These data suggest a protective role for nAb against CHIKV disease and support further study of envelope-based CHIKV DNA vaccines

Rhodium intercalators as novel peptide delivery systems to the major groove of DNA : towards the design of artificial repressors

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Phenanthrenequinone diimine (phi) complexes of rhodium(III) bearing tethered peptides have been designed to serve as metallointercalating anchors to deliver peptide side chain functionalities for DNA recognition in the major groove. Metal-peptide complexes containing 11-15 amino acid residues were prepared using two complementary synthetic strategies: by direct coupling of a pendant carboxylate on the coordinatively saturated rhodium complex, [...] (phen'=5-amidoglutaryl-1, 10-phenanthroline), to the N-terminus of a resin-bound peptide in a manner analogous to the chain-elongation step in solid phase peptide synthesis; or by coupling phen' containing the pendant carboxylate to the resin-bound peptide, followed by coordination of [...] to the bidentate chelator attached to the peptide. With coordination complexes which are stable to peptide deprotection and cleavage conditions from the resin, the solid phase synthetic strategies prove convenient to apply. The metal-peptide complexes have been characterized by amino acid analysis, electronic spectroscopy, circular dichroism and mass spectrometry, where a novel pattern of peptide fragmentation facilitates the detailed sequence analysis of the appended peptide. All the metal-peptide complexes bind and, with photoactivation, cleave DNA with evidence of major groove chemistry. Significantly, the DNA site-specificity is seen to depend on the peptide side-chain functional groups. In one series, a single glutamate at position 10 is found to be essential in directing DNA site-recognition to the sequence 5'-CCA-3'. Methylation of the glutamate side chain or single ElOQ, E1OD, E1OA mutations abolish this selectivity. The glutamate is essential to maintain [...]-helicity in the peptide and make base specific contacts, thereby providing a glutamate switch for site-specific DNA recognition. A second series, based on the recognition helix of the phage 434 repressor, reproduces operator binding. Photocleavage and MPE-Fe footprint analysis indicates that these metal-peptide complexes bind to the 5'-ACAA-3' operator sequences as monomers at 10 nM concentration and differentiate between operator site variants. These studies represent a new strategy to create an array of metal-peptide complexes with differing sequence specificity for DNA and suggest a route to the construction of small molecules that function as artificial repressors

DNA Recognition by Peptide Complexes of Rhodium(III): Example of a Glutamate Switch

A family of metal-peptide complexes has been synthesized by coupling short oligopeptides (13 residues) onto the metallointercalating [Rh(phi)_2(phen’)]^(3+) (phi = 9,10-phenanthrenequinone diimine; phen’ = 5-(amidoglutaryl)-1,10-phenanthroline). These complexes were prepared to explore whether the side-chain functionalities of small peptides may be used to augment metal complex recognition. The metal-peptide complexes bind and, with photoactivation, cleave DNA. The DNA site-specificity is seen to depend on the peptide side-chain functional groups. In particular, a single glutamate at position 10 is found to be essential in directing DNA site-recognition to the sequence 5’-CCA-3’. Methylation of the glutamate side chain or direct substitution of glutamine for glutamate abolishes the 5’-CCA-3’ selectivity, while substitutions at other likely DNA-binding residues show no appreciable change in selectivity. Significantly, the 5’-CCA-3’ selectivity is even sensitive to a highly conservative E10D substitution. DNA photocleavage of oligonucleotides by the metal-peptide complexes and HPLC analysis of DNA products provide evidence for major groove chemistry. Circular dichroism indicates significant α-helical content in the peptide, which depends upon the presence of the glutamate. A model for the glutamate-dependent site-selectivity is presented using shape-selective intercalation of the metal complex and base-specific contacts of the ancillary peptide. These monomeric metal-peptide complexes appear to serve as particularly useful mimics for larger site-specific DNA-binding proteins and may provide a basis for the design of an array of small, sequence-specific DNA-binding metal complexes

DNA Recognition by Peptide Complexes of Rhodium(III): Example of a Glutamate Switch

A family of metal-peptide complexes has been synthesized by coupling short oligopeptides (13 residues) onto the metallointercalating [Rh(phi)_2(phen’)]^(3+) (phi = 9,10-phenanthrenequinone diimine; phen’ = 5-(amidoglutaryl)-1,10-phenanthroline). These complexes were prepared to explore whether the side-chain functionalities of small peptides may be used to augment metal complex recognition. The metal-peptide complexes bind and, with photoactivation, cleave DNA. The DNA site-specificity is seen to depend on the peptide side-chain functional groups. In particular, a single glutamate at position 10 is found to be essential in directing DNA site-recognition to the sequence 5’-CCA-3’. Methylation of the glutamate side chain or direct substitution of glutamine for glutamate abolishes the 5’-CCA-3’ selectivity, while substitutions at other likely DNA-binding residues show no appreciable change in selectivity. Significantly, the 5’-CCA-3’ selectivity is even sensitive to a highly conservative E10D substitution. DNA photocleavage of oligonucleotides by the metal-peptide complexes and HPLC analysis of DNA products provide evidence for major groove chemistry. Circular dichroism indicates significant α-helical content in the peptide, which depends upon the presence of the glutamate. A model for the glutamate-dependent site-selectivity is presented using shape-selective intercalation of the metal complex and base-specific contacts of the ancillary peptide. These monomeric metal-peptide complexes appear to serve as particularly useful mimics for larger site-specific DNA-binding proteins and may provide a basis for the design of an array of small, sequence-specific DNA-binding metal complexes