Vaccine-Induced Immune Responses in Rodents and Nonhuman Primates by Use of a Humanized Human Immunodeficiency Virus Type 1 pol Gene

Abstract

A synthetic gene consisting of the reverse transcriptase (RT) and integrase (IN) domains of human immunodeficiency virus type 1 (HIV-1) pol was constructed using codons most frequently used in humans. The humanized pol gave dramatically improved levels of Rev-independent, in vitro protein production in mammalian cells and elicited much stronger cellular immunity in rodents than did virus-derived gene. Specifically, BALB/c mice were immunized with plasmids and/or recombinant vaccinia virus constructs expressing the synthetic gene. High frequencies of Pol-specific T lymphocytes were detected in these animals by the gamma interferon enzyme-linked immunospot assay against pools of short overlapping peptides. Characterization of the stimulatory peptides from these pools indicates that the optimized gene constructs are able to effectively activate both CD4 ؉ and CD8 ؉ T cells. Immunization of rhesus macaques with DNA vaccines expressing the humanized pol coupled to a human tissue plasminogen activator leader sequence led to pronounced in vitro cytotoxic T-lymphocyte killing activities and enhanced levels of circulating Pol-specific T cells, comparable to those observed in HIV-1-infected human subjects. Thus, optimizing the immunogenic properties of HIV-1 Pol at the level of the gene sequence validates it as an antigen and provides an important step toward the construction of a potent pol-based HIV-1 vaccine component.

Efficient induction of T‐cell responses to carcinoembryonic antigen by a heterologous prime‐boost regimen using DNA and adenovirus vectors carrying a codon usage optimized cDNA

“…This observation is in line with data obtained in mice and nonhuman primates with genetic vaccines for HCV, HIV and HPV, whereby vectors carrying codon sequence optimized cDNA are characterized by increased expression and enhanced immunogenicity of the viral polypeptides. [26][27][28][29][30][31][32] Although it is reasonable to assume that the higher expression of CEA will lead to enhanced presentation by the MHC of CEA-derived epitopes, an enhanced immune response can also be ascribed, at least in part, to an increase in CpG motifs in the synthetic gene administered. The role of immune modulation of unmethylated CpG in governing the immune response has been described both in rodents and in nonhuman primates.…”

“…[26][27][28][29][30][31][32] To compare the efficiency of expression of the CEAopt to that of CEA, groups of 10 C57Bl/6 mice were injected into the quadriceps with different doses of the AdCEAopt vector ranging from 1 x 10 7 to 1 3 10 4 pfu. Three days post injection, CEA protein levels in the mice sera were determined and compared to those of control groups that had been injected with the same doses of Ad-CEA.…”

“…justified by the observation that for highly expressed genes, G or C is generally preferred over A or T. In fact, in a variety of experimental systems, optimizing the codon usage of the target gene has been shown to enhance expression and increase immunogenicity. [26][27][28][29][30][31][32] In our study, the immunogenic properties of a genetic vaccine based on plasmid DNA-EP and Ad vector have been examined by monitoring the amplitude and type of immune responses to CEA. In addition, the immunogenicity of a codon usage optimized cDNA encoding CEA was examined both in C57Bl/6 and in CEA transgenic mice.…”

Genetic vaccines against Ep‐CAM break tolerance to self in a limited subset of subjects: Initial identification of predictive biomarkers

“…The response was characterized using peptides covering the entire Ep-CAM amino acid sequence. This approach allowed the responsive peptides to be identified experimentally [20]. Using these peptides, a CD4 epitope (P 177 ) and a CD8 epitope (C 66 LVMKAEM 73 ) were mapped.…”

GRA1 protein vaccine confers better immune response compared to codon-optimized GRA1 DNA vaccine

“…In order to comprehensively evaluate these variables, the present study compares cellular immune response and protection potency of a recombinant GRA1 protein vaccine adjuvanted with a strong Th1 inducer Provax [32,33], a wild type GRA1 DNA vaccine and a GRA1 DNA vaccine codon-optimized for protein expression in mammalian cells. Codon usage optimization is widely accepted as a means of increasing the level of in vivo antigen expression from DNA vaccines and improving the cellular and humoral immune responses against the expressed antigens from diverse microorganisms [34][35][36][37][38][39][40][41][42][43][44][45][46][47]. The codonoptimized GRA1 DNA vaccine used in this study is the first example of a codon-optimized gene being used as DNA vaccine candidate against T. gondii.…”