Comparison of the Efficacy of HIV-1 Nef-Tat-Gp160-p24 Polyepitope Vaccine Candidate with Nef Protein in Different Immunization Strategies.

OBJECTIVES: One of the promising strategies for effective HIV-1 vaccine design involves finding the polyepitope immunogens using T cell epitopes. METHODS: Herein, an HIV-1 polyepitope construct (i.e., Nef-Tat-Gp160-P24) comprising of several epitopes from Nef, Tat, Gp160, and P24 proteins was designed. To improve its immunogenicity in BALB/c mice, cell-penetrating peptides (HR9 and MPG for DNA delivery, and LDP-NLS and Cy- LoP-1 for protein transfer), Montanide adjuvant, and heterologous DNA prime/polypeptide boost strategy were used. To compare the immunogenicity, Nef was utilized as a vaccine candidate. The levels of total IgG and its subclasses, cytokines, and Granzyme B were assessed using ELISA. RESULTS: Immunological studies showed that heterologous prime-boost regimens for both antigens could considerably augment the levels of IgG2a, IgG2b, IFN-γ, and Granzyme B directed toward Th1 and CTL immune responses in comparison with homologous prime-boost strategies. The levels of IFN-γ, IL-10, total IgG, IgG1, and IgG2b were drastically higher in groups immunized with Nef-Tat-Gp160-P24 in heterologous prime-boost regimens than those in groups immunized with Nef. CONCLUSION: The use of the Nef-Tat-Gp160-P24 polyepitope immunogen in heterologous primeboost strategy could generate the mixture of Th1 and Th2 responses directed further toward Th1 response as a hopeful method for improvement of HIV-1 vaccine.

In vivo delivery of a multiepitope peptide and Nef protein using novel cell-penetrating peptides for development of HIV-1 vaccine candidate.

OBJECTIVES: A potent HIV vaccine should overcome some limitations such as polymorphism of human HLA, the diversity of HIV-1 virus, and the lack of an effective delivery system. In this study, a DNA construct encoding Nef60-84, Nef126-144, Vpr34-47, Vpr60-75, Gp16030-53, Gp160308-323, and P248-151 epitopes was designed using bioinformatics tools. The pcDNA3.1-nef-vpr-gp160-p24 and pcDNA3.1-nef constructs were prepared in large scale as endotoxin-free form. Moreover, the recombinant Nef-Vpr-Gp160-p24 polypeptide and Nef protein were generated inE. coli. These constructs were delivered using cell penetrating peptides (CPPs) in vivo, and immune responses were assessed for different modalities in BALB/c mice. RESULTS: The recombinant DNA constructs were confirmed as the ~ 867 bp and ~ 648 bp bands related tonef-vpr-gp160-p24 andnef genes on agarose gel. Moreover, the purified Nef-Vpr-Gp160-p24 polypeptide and Nef protein showed the ~ 32 kDa and ~ 30 kDa bands on SDS-PAGE, respectively. The results of immune responses indicated that the heterologous prime/boost regimens using both Nef-Vpr-Gp160-P24 and Nef antigens induced significantly the secretion of IgG2a, IgG2b, IFN-γ and Granzyme B compared to other groups. The levels of Granzyme B in mice immunized with Nef antigen were higher than those immunized with Nef-Vpr-Gp160-P24 antigen. The CPPs showed the same potency with Montanide adjuvant for eliciting immune responses. CONCLUSIONS: The heterologous prime/boost regimens for both antigens could significantly direct immune responses toward Th1 and CTL activity compared to other regimens. Comparing the efficiency of Nef-Vpr-Gp160-P24 and Nef constructs, the Nef-Vpr-Gp160-P24 constructs delivered by CPPs showed promising results as an HIV vaccine candidate.

Design and in vitro delivery of HIV-1 multi-epitope DNA and peptide constructs using novel cell-penetrating peptides.

OBJECTIVES: Developing an effective HIV vaccine that stimulates the humoral and cellular immune responses is still challenging because of the diversity of HIV-1 virus, polymorphism of human HLA and lack of a suitable delivery system. RESULTS: Using bioinformatics tools, we designed a DNA construct encoding multiple epitopes. These epitopes were highly conserved within prevalent HIV-1 subtypes and interacted with prevalent class I and II HLAs in Iran and the world. The designed DNA construct included Nef60-84, Nef126-144, Vpr34-47, Vpr60-75, Gp16030-53, Gp160308-323 and P248-151 epitopes (i.e., nef-vpr-gp160-p24 DNA) which was cloned into pET-24a(+) and pEGFP-N1 vectors. The recombinant polyepitope peptide (rNef-Vpr-Gp160-P24; ~ 32 kDa) was successfully generated in E. coli expression system. The pEGFP-nef-vpr-gp160-p24 and rNef-Vpr-Gp160-P24 polyepitope peptide were delivered into HEK-293 T cells using cell-penetrating peptides (CPPs). The MPG and HR9 CPPs, as well as the novel LDP-NLS and CyLoP-1 CPPs, were utilized for DNA and peptide delivery into the cells, respectively. SEM results confirmed the formation of stable MPG/pEGFP-N1-nef-vpr-gp160-p24, HR9/pEGFP-N1-nef-vpr-gp160-p24, LDP-NLS/rNef-Vpr-Gp160-P24 and CyLoP-1/rNef-Vpr-Gp160-P24 nanoparticles with a diameter of < 200 nm through non-covalent bonds. MTT assay results indicated that these nanoparticles did not have any major toxicity in vitro. Fluorescence microscopy, flow cytometry and western blot data demonstrated that these CPPs could significantly deliver the DNA and peptide constructs into HEK-293 T cells. CONCLUSION: The use of these CPPs can be considered as an approach in HIV vaccine development for in vitro and in vivo delivery of DNA and peptide constructs into mammalian cells.

Detection of VIM- and IMP-type Metallo-Beta-Lactamase Genes in Acinetobacter baumannii Isolates from Patients in Two Hospitals in Tehran.

BACKGROUND: Acinetobacter baumannii, is an opportunistic pathogen and is responsible for numerous nosocomial infections. In recent years, this microorganism has been resistant to a wide range of antibiotics. One of the most important mechanisms of resistance in this microorganism is production of metallo-beta-lactamases (MBLs). OBJECTIVES: The aim of this study was to detect VIM- and IMP-type metallo-beta-lactamase genes in Acinetobacter baumanniiisolates from patients in two Hospitals in Tehran. MATERIALS AND METHODS: 104 isolates were tested using the PCR method for the identification of VIM- and IMP-type genes. RESULTS: vim1, vim2, imp1 and imp2 genes were detected in 6.7%, 41.7%, 50% and 1.7% of the isolates from Tehran Heart Center, and in 29.5%, 38.6%, 4.5% and 4.5% of the isolates from Shahid Mutahhari Hospital respectively. DISCUSSIONS: Our analysis revealed that the majority of the isolates had at least one of these genes, indicating that MBLs production is an important resistance mechanism in Acinetobacter baumannii.