The effect of conjugation to gold nanoparticles on the ability of low molecular weight chitosan to transfer DNA vaccine.

Nonviral gene delivery systems based on conventional high molecular weight chitosans are efficient as DNA vaccine delivery system, but have poor physical properties such as aggregated shapes, low solubility at neutral pH, high viscosity at concentrations used for in vivo delivery and a slow onset of action. Furthermore, Chitosan oligomers shorter than 14 monomers units were recently found to form only weak complexes with DNA, resulting in physically unstable polyplexes in vitro and in vivo. Here, low molecular weight chitosans with an average molecular mass of 6kDa (Chito6) have been covalently attached to gold nanoparticles (GNPs), and the potency of the resulting Chito6-GNPs conjugates as vectors for the delivery of plasmid DNA has been investigated in vitro and in vivo. After delivery by intramuscular immunization in BALB/c mice, the Chito6-GNPs conjugates induced an enhanced serum antibody response 10 times more potent than naked DNA vaccine. Additionally, in contrast to naked DNA, the Chito6-GNPs conjugates induced potent cytotoxic T lymphocyte responses at a low dose.

Co-injection of interleukin 8 with the glycoprotein gene from viral haemorrhagic septicemia virus (VHSV) modulates the cytokine response in rainbow trout (Oncorhynchus mykiss).

Since previous results showed that interleukin 8 (IL-8) was induced in rainbow trout (Oncorhynchus mykiss) in response to viral hemorrhagic septicemia virus (VHSV) infection, we have cloned IL-8 in an expression vector (pIL8+) and studied its possible adjuvant effect on the early response to a VHSV immunization model, focusing on the early response of several cytokines induced by a vector coding for the glycoprotein of VHSV (pMCV1.4-G) in the spleen and head kidney. First, we demonstrated that the pIL8+ successfully transcribed IL-8, by induction of IL-8 transcription in the muscle and blood, and by a massive infiltration of neutrophils at the muscle inoculation site. We have studied the effect of pIL8+ co-administration on the expression of two pro-inflammatory cytokines, such as IL-1beta and tumour necrosis factor alpha (TNF-alpha); cytokines that have mainly an inhibitory role, IL-11 and transforming growth factor beta (TGF-beta); and a Th1 type cytokine, IL-18. We demonstrated that the co-administration of pIL8+ with pMCV1.4-G modulates the cytokine response that is induced, mainly by having its effect increasing pro-inflammatory cytokines (IL-1beta and TNF-alpha1), with a greater impact on the spleen, and to a lesser extent in the head kidney. All these data suggest that IL-8 is able to modulate the early cytokine immune response that is produced in response to a DNA vaccine, and therefore, might be a potential immune adjuvant in fish viral vaccination. More work should be done to determine if this modulation has a beneficial effect on protection as seen in other mammal viral models.

Enhanced CD8+ T cell immune responses and protection elicited against Plasmodium berghei malaria by prime boost immunization regimens using a novel attenuated fowlpox virus.

Sterile immunity can be provided against the pre-erythrocytic stages of malaria by IFN-gamma-secreting CD8(+) T cells that recognize parasite-infected hepatocytes. In this study, we have investigated the use of attenuated fowlpox virus (FPV) strains as recombinant vaccine vectors for eliciting CD8(+) T cells against Plasmodium berghei. The gene encoding the P. berghei circumsporozoite (PbCS) protein was inserted into an FPV vaccine strain licensed for use in chickens, Webster's FPV, and the novel FPV vaccine strain FP9 by homologous recombination. The novel FP9 strain proved more potent as a vaccine for eliciting CD8(+) T cell responses against the PbCS Ag. Sequential immunization with rFP9 and recombinant modified vaccinia virus Anakara (MVA) encoding the PbCS protein, administered by clinically acceptable routes, elicited potent CD8(+) T cell responses against the PbCS protein. This immunization regimen elicited substantial protection against a stringent liver-stage challenge with P. berghei and was more immunogenic and protective than DNA/MVA prime/boost immunization. However, further improvement was not achieved by sequential (triple) immunization with a DNA vaccine, FP9, and MVA.

Uses of granulocyte-macrophage colony-stimulating factor in vaccine development.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent cytokine capable of inducing differentiation, proliferation, and activation of a variety of immunologically active cell populations. In addition to its effects on stimulating granulocytic hematopoiesis, it also facilitates development of both humoral and cellular mediated immunity. Accordingly, strategies involving the use of GM-CSF as a vaccine adjuvant have attracted considerable attention. These strategies include the systemic administration of soluble GM-CSF with an immunogen, and also its use as part of gene therapy approaches to immunization. Because of the potency of this cytokine as an immune adjuvant, particular interest has focused on its use to overcome poorly immunogenic antigens such as those associated with intracellular infections and cancer. This review focuses on recent advances in the use of GM-CSF as a vaccine adjuvant.

Distribution fate and mechanism of immune modulation following mucosal delivery of plasmid DNA encoding IL-10.

DNA vaccination has been widely studied in several models of vaccination and in the treatment of inflammatory diseases, even though the mechanism involved is still unclear. This report demonstrates that mucosal administration of plasmid DNA leads to rapid and widespread distribution around the body. Dissemination likely occurred via the bloodstream because plasmid DNA was present in blood plasma. The plasmid DNA was also detectable in several tissues including draining lymph nodes, spleen, liver, bone marrow, and even the dermis of ear pinnae. Except for the site of administration, plasmid DNA was no longer detectable in tissues after 3 wk postadministration. RNA and protein expression was also found in the tissues and bloodstream. Animals previously primed by HSV infection and subsequently given IL-10 DNA via the nasal mucosa, showed diminished Ag-induced delayed type hypersensitivity reactions for up to 5 wk posttreatment. The mechanism of modulation involved diminished the Ag-specific proliferation and production of Th1 cytokines. The Ag-specific silencing effects persisted beyond the duration of detectable plasmid encoded protein and was maintained upon adoptive transfer of T cells into a plasmid-free environment. The silenced T cells were not a source of IL-10, and their anergic state was reversible by exposure to Ag in the presence of exogenous IL-2.