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Background and Aim: Rabies is a widespread neurological zoonotic disease causing significant mortality rates, especially in developing countries. Although a vaccine for rabies is available, its production and scheduling are costly in such countries. Advances in recombinant DNA technology have made it a good candidate for an affordable vaccine. Among the proteins of rabies virus, the Glycoprotein (RVG) has been the major target for new vaccine development which plays the principal role in providing complete protection against RV challenge. The aim of this study is to produce recombinant RVG which could be a DNA vaccine candidate and to evaluate the efficiency of this construct in a prime-boost vaccination regimen, compared to commercial vaccine., Methods: Cloning to pcDNA3.1(+) and expression of rabies virus glycoprotein gene in BSR cell  line were performed followed by SDS-PAGE and Western blot analysis of the expressed glycoprotein. The resulting genetic construct was used as a DNA vaccine by injecting 80 µg of the plasmid to MNRI mice twice. Prime-Boost vaccination strategy was performed using 80 µg plasmid construct as prime dose and the second dose of an inactivated rabies virus vaccine. Production of rabies virus neutralizing antibody (RVNA) titers of the serum samples were determined by RFFIT., Results: In comparisons between heterologous prime-boost vaccination strategy and DNA vaccinations, the potency of group D that received Prime-Boost vaccine with the second dose of pcDNA3.1(+)-Gp was enhanced significantly compared to the group C which had received pcDNA3.1(+)-Gp as first injection., Conclusion: In this study, RVGP expressing construct was used in a comparative approach between Prime-Boost vaccination strategy and DNA vaccination and compared with the standard method of rabies vaccination. It was concluded that this strategy could lead to induction of acceptable humoral immunity.

Abstract: Many approaches have so far been tried to enhance the immunogenicity of DNA vaccine. These include the use of various factors that induce apoptosis or anti-apoptosis effects when co-delivered with DNA vaccine. In the present study, the effects of pro-apoptotic Bax encoding plasmid (pBax) and anti-apoptotic Bcl-XL encoding plasmid (pBcl-xl), intradermally co-injected with glycoprotein B (gB) of Herpes Simplex Virus (HSV)-1 encoding plasmid (pgB) into the C57BL/6 mice were evaluated. Immune responses of the mice to the antigen were assessed by antibody assay, lymphoproliferative responses as well as cytokine and cytotoxic T-lymphocyte (CTL) assay. Analysis of the humoral and cellular responses showed that the mice immunized with pBax and pgB induced higher levels of antibody and Interleukin-4 as well as stronger lymphocyte proliferative responses and cytotoxic activity compared to those mice received pgB alone. pBcl-xl when intradermally co-injected with pgB showed no significant enhancement in immune responses comparing to pgB. [Copyright &y& Elsevier]

Abstract: Phage display is based on expressing peptides as a fusion to one of the phage coat proteins. To date, many vaccine researches have been conducted to display immunogenic peptides or mimotopes of various pathogens and tumors on the surface of filamentous bacteriophages. In recent years as a new approach to application of phages, recombinant bacteriophage lambda particles were used as DNA delivery vehicles to mammalian cells. In this study, recombinant filamentous phage whole particles were used for vaccination of mice. BALB/c mice were inoculated with filamentous phage particles containing expression cassette of Herpes simplex virus 1 (HSV-1) glycoprotein D that has essential roles in the virus attachment and entry. Both humoral and cellular immune responses were measured in the immunized mice and compared to conventional DNA vaccination. A dose–response relationship was observed in both arms of immune responses induced by recombinant filamentous phage inoculation. The results were similar to those from DNA vaccination. Filamentous phages can be considered as suitable alternative candidate vaccines because of easier and more cost-effective production and purification over plasmid DNA or bacteriophage lambda particles. [Copyright &y& Elsevier]

Herpes simplex virus produces primary and latent infections with periodic recurrency. The prime-boost immunization strategies were studied using a DNA vaccine carrying the full-length glycoprotein D-1 gene and a baculovirus-derived recombinant glycoprotein D, both expressing herpes simplex virus glycoprotein D-1 protein. Immunization with recombinant DNAs encoding antigenic proteins could induce cellular and humoral responses by providing antigen expression in vivo. Higher immune response, however, occurred when the recombinant proteins followed DNA inoculation. While all groups of the immunized mice and positive control group could resist virus challenge, a higher virus neutralizing antibody level was detected in the animals receiving recombinant protein following DNA vaccination. [ABSTRACT FROM AUTHOR]

Abstract: Previously, we have reported that the injection of an expression vector containing Herpes simplex virus (HSV) Glycoprotein D-1 (gD-1) generated a significant antibody response in mice and protected them against HSV lethal challenge. We tested its potential to induce antibody and cell mediated immune responses in latently infected mice. Positive control group (KOS) and HSV gD-1 vaccinated mice demonstrated protection against a lethal ocularly challenge of 105.5 plaque-forming units (pfu)/eye of wild HSV-1 versus negative control groups. For neutralizing antibody titers, delayed-type hypersensitivity (DTH), lymphocyte proliferation responses, clinical evaluation and survival following lethal challenge, no considerable difference was observed between mice vaccinated with DNA plasmid and those vaccinated with KOS. KOS-vaccinated mice demonstrated the ability to completely prevent latency whereas DNA vaccinated group showed some degree of protection and displayed less latency than negative control groups and had considerably high levels of IFN-γ and strong CTL responses versus negative control groups. It can be concluded that although immunization with the DNA vaccine is more effective in both protecting mice and induction of immune response, however it could not completely block the latent infection in sensory nerves. [Copyright &y& Elsevier]