Enhanced Cellular Immune Responses Elicited by an Engineered HIV-1 Subtype B Consensus-based Envelope DNA Vaccine

Abstract

An important goal for human immunodeficiency virus (HIV) vaccines is to develop immunogens that induce broader and more potent cellular immune responses. In this study of DNA vaccine potency, we constructed a novel subtype B env gene (EY2E1-B) with the goal of increasing vaccine antigen immune potency. The vaccine cassette was designed based on subtype B-specific consensus sequence with several modifications, including codon optimization, RNA optimization, the addition of a Kozak sequence, and a substituted immunoglobulin E leader sequence. The V1 and V2 loops were shortened and the cytoplasmic tail was truncated to prevent envelope recycling. Three different strains of mice (BALB/c, C57BL/6, and HLA-A2 transgenic mice) were immunized three times with pEY2E1-B or the primary DNA immunogen pEK2P-B alone. The analysis of specific antibody responses suggested that EY2E1-B could induce a moderate subtype B-specific antibody response. Moreover, this construct was up to four times more potent at driving cellular immune responses. Epitope mapping results indicated that there is an increase in the breadth and magnitude of cross-reactive cellular responses induced by the EY2E1-B immunogen. These properties suggest that such a synthetic immunogen deserves further examination for its potential to serve as a component antigen in an HIV vaccine cocktail.

Cellular immunity induced by a novel HPV18 DNA vaccine encoding an E6/E7 fusion consensus protein in mice and rhesus macaques

“…IFN-γ ELISpot assay was performed as described previously (21). A set of peptides each containing 15 amino acid residues overlapping by 8 amino acids representing the entire consensus E6/E7 fusion protein sequence of HPV-18 was synthesized from Invitrogen.…”

“…Accordingly, improving their immuno-potency is critical. Recently, several strategies aimed at improving the magnitude of the cellular immune responses induced by DNA vaccines, such as codon optimization (16,17), RNA optimization (18,19) and the addition of immunoglobin leader sequences that have weak RNA secondary structure (20), have been studied and applied successfully to HIV and Influenza vaccine development (21,22). Improvements in delivery are also highly important to improve the magnitude of immune responses induced by DNA vaccines.…”

“…On the other hand, recent research from our lab and others have indicated that utilization of "centralized" immunogens such as consensus immunogens or ancestral immunogens could increase the breadth of cellular immune responses than native DNA immunogens (21,22,25,26). Such consensus immungens in the context of HPV may appear more foreign and thus facilitate immune stimulation, which is an important issue with a slow growth that may induce peripheral tolerance.…”

Prototype development and preclinical immunogenicity analysis of a novel minimally invasive electroporation device

“…[3][4][5][6][7] These optimization strategies can lead to improved, cross-reactive immune responses. 8,9 The addition of co-delivered gene-based molecular adjuvants is another area in which an augmentation of resulting immune responses frequently occurs. Despite the improvements in vector design and the use of molecular adjuvants, there is still a clear requirement for an efficient method of administration of DNA vaccines that results in high-level expression of the plasmid in the desired cell type of the desired tissue, most commonly, muscle, tumor or skin.…”

Combined effects of IL-12 and electroporation enhances the potency of DNA vaccination in macaques

“…The Gag4Y gene was subcloned into the expression vector, pVax (Invitrogen, Carlsbad, CA), for further study. pEY-2E1-B contains an expression cassette encoding for a consensus sequence of the envelope of HIV clade B [26]. WLV104M is a plasmid encoding a rhesus IL-12 gene [27].…”