Toll-Like Receptor 9 Activation Rescues Impaired Antibody Response in Needle-free Intradermal DNA Vaccination.

The delivery of plasmid DNA to the skin can target distinct subsets of dermal dendritic cells to confer a superior immune response. The needle-free immunization technology offers a reliable, safe and efficient means to administer intradermal (ID) injections. We report here that the ID injection of DNA vectors using an NF device (NF-ID) elicits a superior cell-mediated immune response, at much lesser DNA dosage, comparable in magnitude to the traditional intramuscular immunization. However, the humoral response is significantly impaired, possibly at the stage of B cell isotype switching. We found that the NF-ID administration deposits the DNA primarily on the epidermis resulting in a rapid loss of the DNA as well as the synthesized antigen due to the faster regeneration rate of the skin layers. Therefore, despite the immune-rich nature of the skin, the NF-ID immunization of DNA vectors may be limited by the impaired humoral response. Additional booster injections are required to augment the antibody response. As an alternative and a viable solution, we rescued the IgG response by coadministration of a Toll-like receptor 9 agonist, among other adjuvants examined. Our work has important implication for the optimization of the emerging needle-free technology for ID immunization.

HIV-DNA Given with or without Intradermal Electroporation Is Safe and Highly Immunogenic in Healthy Swedish HIV-1 DNA/MVA Vaccinees: A Phase I Randomized Trial.

BACKGROUND: We compared safety and immunogenicity of intradermal (ID) vaccination with and without electroporation (EP) in a phase I randomized placebo-controlled trial of an HIV-DNA prime HIV-MVA boost vaccine in healthy Swedish volunteers. METHODS: HIV-DNA plasmids encoding HIV-1 genes gp160 subtypes A, B and C; Rev B; Gag A and B and RTmut B were given ID at weeks 0, 6 and 12 in a dose of 0.6 mg. Twenty-five volunteers received vaccine using a needle-free device (ZetaJet) with (n=16) or without (n=9) ID EP (Dermavax). Five volunteers were placebo recipients. Boosting with recombinant MVA-CMDR expressing HIV-1 Env, Gag, Pol of CRF01_AE (HIV-MVA) or placebo was performed at weeks 24 and 40. Nine of the vaccinees received a subtype C CN54 gp140 protein boost together with HIV-MVA. RESULTS: The ID/EP delivery was very well tolerated. After three HIV-DNA immunizations, no statistically significant difference was seen in the IFN-γ ELISpot response rate to Gag between HIV-DNA ID/EP recipients (5/15, 33%) and HIV-DNA ID recipients (1/7, 14%, p=0.6158). The first HIV-MVA or HIV-MVA+gp140 vaccination increased the IFN-γ ELISpot response rate to 18/19 (95%). CD4+ and/or CD8+ T cell responses to Gag or Env were demonstrable in 94% of vaccinees. A balanced CD4+ and CD8+ T cell response was noted, with 78% and 71% responders, respectively. IFN-γ and IL-2 dominated the CD4+ T cell response to Gag and Env. The CD8+ response to Gag was broader with expression of IFN-γ, IL-2, MIP-1ß and/or CD107. No differences were seen between DNA vaccine groups. Binding antibodies were induced after the second HIV-MVA+/-gp140 in 93% of vaccinees to subtype C Env, with the highest titers among EP/gp140 recipients. CONCLUSION: Intradermal electroporation of HIV-DNA was well tolerated. Strong cell- and antibody-mediated immune responses were elicited by the HIV-DNA prime and HIV-MVA boosting regimen, with or without intradermal electroporation use. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number (ISRCTN) 60284968.

Jet injection devices for the needle-free administration of compounds, vaccines, and other agents.

Jet injection involves the use of a needle-free device that delivers a prescribed drug, vaccine, or compound intradermally, subcutaneously, or intramuscularly via high pressure produced by either a carbon-dioxide-filled or nitrogen-filled cartridge or a spring. During that procedure, the injector is held at an angle against the patient's skin, and a very fine stream of liquid medication is forced through a tiny orifice in the device, penetrates the skin in a selected volume ranging from 0.05 mL to 1.0 mL, and is deposited in the underlying tissue. When compared with methods of injection that require a needle, jet injection offers multiple benefits. It can be less painful for the patient, and it enhances compliance, reduces risks such as needlestick injuries and cross-contamination, eliminates the need for "sharps" disposal, and enables (with minimal training) the reliable, reproducible, and accurate delivery of medication. Patient convenience is also a factor: Jet injectors are designed for self-medication as well as professional use. It must be remembered, however, that treatment via jet injection is not always painless. Because of their formulations, some medications and vaccines produce a burning or stinging sensation, whether they are administered with a jet injector or a needle. Some compounded preparations, like the formulations included in this article, can be administered by jet injection, a practice that we suggest will increase in popularity as more drugs are prescribed for administration in the home setting. Because changes in drug concentration may be required to effect the transfer of an agent or ensure the accurate reconstitution of a lyophilized drug administered with a jet injector, the skill of a compounding pharmacist will be essential in preparing customized injectates. In this article, we address the use of needle-free technology in general; present examples of carbon-dioxide, spring-powered, and novel jet injection systems; and answer questions of interest to compounders about the use of jet injectors.

Biodistribution, persistence and lack of integration of a multigene HIV vaccine delivered by needle-free intradermal injection and electroporation.

It is likely that gene-based vaccines will enter the human vaccine area soon. A few veterinary vaccines employing this concept have already been licensed, and a multitude of clinical trials against infectious diseases or different forms of cancer are ongoing. Highly important when developing novel vaccines are the safety aspects and also new adjuvants and delivery techniques needs to be carefully investigated so that they meet all short- and long-term safety requirements. One novel in vivo delivery method for plasmid vaccines is electroporation, which is the application of short pulses of electric current immediately after, and at the site of, an injection of a genetic vaccine. This method has been shown to significantly augment the transfection efficacy and the subsequent vaccine-specific immune responses. However, the dramatic increase in delivery efficacy offered by electroporation has raised concerns of potential increase in the risk of integration of plasmid DNA into the host genome. Here, we demonstrate the safety and lack of integration after immunization with a high dose of a multigene HIV-1 vaccine delivered intradermally using the needle free device Biojector 2000 together with electroporation using Derma Vax™ DNA Vaccine Skin Delivery System. We demonstrate that plasmids persist in the skin at the site of injection for at least four months after immunization. However, no association between plasmid DNA and genomic DNA could be detected as analyzed by qPCR following field inversion gel electrophoresis separating heavy and light DNA fractions. We will shortly initiate a phase I clinical trial in which healthy volunteers will be immunized with this multiplasmid HIV-1 vaccine using a combination of the delivery methods jet-injection and intradermal electroporation.

An alternative method for preparation of pandemic influenza strain-specific antibody for vaccine potency determination.

The traditional assay used to measure potency of inactivated influenza vaccines is a single-radial immunodiffusion (SRID) assay that utilizes an influenza strain-specific antibody to measure the content of virus hemagglutinin (HA) in the vaccine in comparison to a homologous HA reference antigen. Since timely preparation of potency reagents by regulatory authorities is challenging and always a potential bottleneck in influenza vaccine production, it is extremely important that additional approaches for reagent development be available, particularly in the event of an emerging pandemic influenza virus. An alternative method for preparation of strain-specific antibody that can be used for SRID potency assay is described. The approach does not require the presence or purification of influenza virus, and furthermore, is not limited by the success of the traditional technique of bromelain digestion and purification of virus HA. Multiple mammalian expression vectors, including plasmid and modified vaccinia virus Ankara (MVA) vectors expressing the HAs of two H5N1 influenza viruses and the HA of the recently emerging pandemic H1N1 (2009) virus, were developed. An immunization scheme was designed for the sequential immunization of animals by direct vector injection followed by protein booster immunization using influenza HA produced in vitro from MVA vector infection of cells in culture. Each HA antibody was highly specific as shown by hemagglutination inhibition assay and the ability to serve as a capture antibody in ELISA. Importantly, each H5N1 antibody and the pandemic H1N1 (2009) antibody preparation were suitable for use in SRID assays for determining the potency of pandemic influenza virus vaccines. The results demonstrate a feasible approach for addressing one of the potential bottlenecks in inactivated pandemic influenza vaccine production and are particularly important in light of the difficulties in preparation of potency reagent antibody for pandemic H1N1 (2009) virus vaccines.

Protection of mice against rotavirus challenge following intradermal DNA immunization by Biojector needle-free injection.

Mucosal administration (intranasal or oral) of a VP6 rotavirus vaccine to mice consistently elicits high levels of protection after rotavirus challenge (93->99% reductions in fecal rotavirus shedding) but only when co-administered with an effective adjuvant such as LT(R192G). Here, we showed that Biojector needle-free injection of VP6-encoded plasmids also induced protection (85-93%) when they were co-administrated with LT(R192G)-encoded plasmids. A reduction in the amount of VP6 plasmid from 50 to 10 microg reduced protection from 93 to 70%, but the immunized mice remained significantly (P<0.05) protected. Intramuscular needle injection of VP6/LT(R192G)-plasmids also induced significant protection (66%).

Evaluation of a needle-free delivery platform for prime-boost immunization with DNA and modified vaccinia virus ankara vectors expressing herpes simplex virus 2 glycoprotein D.

A previous report described a prime-boost immunization strategy using plasmid and modified vaccinia virus Ankara (MVA) vectors expressing herpes simplex virus 2 glycoprotein D (gD). Enhanced humoral and cellular immune responses were elicited by the prime-boost combination compared to plasmid DNA immunization alone. Surprisingly, a more diverse antibody isotype response, and a greater antibody and cellular immune response, was obtained if the gD MVA vector was used as the priming immunization rather than the gD plasmid vector. The present report evaluates the use of a needle-free delivery platform (Biojector) for delivery of plasmid and MVA gD-expressing vectors in a prime-boost immunization strategy. Needle-free delivery of both plasmid and MVA gD expression vectors was efficient, reproducible, and elicited a strong immune response in immunized mice. Biojector delivery of plasmid DNA was able to evoke a broader isotype response and cellular immune response than that obtained by gene gun delivered plasmid DNA. Further, DNA priming by Biojector delivery as part of a prime-boost procedure with MVA-gD2 resulted in a diverse antibody isotype distribution and enhanced cellular immune responses, similar to the responses obtained when MVA-gD2 was used as the priming immunization. Thus, needle-free delivery of plasmid DNA may provide additional flexibility and options for effective prime-boost vaccination.