Preparation and characterization of novel PBAE/PLGA polymer blend microparticles for DNA vaccine delivery.

CONTEXT: Poly(beta-amino ester) (PBAE) with its pH sensitiveness and Poly(lactic-co-glycolic acid) (PLGA) with huge DNA cargo capacity in combination prove to be highly efficient as DNA delivery system. OBJECTIVE: To study the effectiveness of novel synthesized PBAE polymer with PLGA blend at different ratios in DNA vaccine delivery. METHODS: In the present study, multifunctional polymer blend microparticles using a combination of PLGA and novel PBAE polymers A1 (bis(3-(propionyloxy)propyl)3,3'-(propane-1,3-diyl-bis(methylazanediyl))dipropanoate) and A2 (bis(4-(propionyloxy)butyl)3,3'-(ethane-1,2-diyl-bis(isopropylazanediyl))dipropanoate) at different ratios (85:15, 75:25, and 50:50) were prepared by double emulsion solvent removal method. The microparticles were characterized for cytotoxicity, transfection efficiency, and DNA encapsulation efficiency. RESULT: It was evident from results that among the microparticles prepared with PLGA/PBAE blend the PLGA:PBAE at 85:15 ratio was found to be more effective combination than the microparticles prepared with PLGA alone in terms of transfection efficiency and better DNA integrity. Microparticles made of PLGA and PBAE A1 at 85:15 ratio, respectively, were found to be less toxic when compared with microparticles prepared with A2 polymer. CONCLUSION: The results encourage the use of the synthesized PBAE polymer in combination with PLGA as an effective gene delivery system.

Construction and immunogenic characterization of a fusion anti-caries DNA vaccine against PAc and glucosyltransferase I of Streptococcus mutans.

Glucosyltransferases (GTFs) and A cell-surface protein (PAc) are two important virulence factors of the cariogenic organism Streptococcus mutans. They may mediate sucrose-independent or sucrose-dependent attachment of Streptococcus mutans to tooth surfaces, respectively. Thus, inhibiting both virulence factors is predicted to provide better protection against caries than inhibiting a single factor. To develop a highly efficient vaccine against caries, we constructed a fusion DNA vaccine, pGLUA-P, by cloning the GLU region of GTF into a DNA vaccine, pCIA-P, which encodes two highly conservative regions of PAc. In this report, we provide evidence that fewer caries lesions were observed in rats following subcutaneous injection of pGLUA-P, compared with pCIA-P, near the submandibular gland. Our findings suggest that a multigenic DNA vaccine may be more caries-preventive than a single-gene DNA vaccine.

Development of nucleic acid vaccines: use of self-amplifying RNA in lipid nanoparticles.

Self-amplifying RNA or RNA replicon is a form of nucleic acid-based vaccine derived from either positive-strand or negative-strand RNA viruses. The gene sequences encoding structural proteins in these RNA viruses are replaced by mRNA encoding antigens of interest as well as by RNA polymerase for replication and transcription. This kind of vaccine has been successfully assayed with many different antigens as vaccines candidates, and has been shown to be potent in several animal species, including mice, nonhuman primates, and humans. A key challenge to realizing the broad potential of self-amplifying vaccines is the need for safe and effective delivery methods. Ideally, an RNA nanocarrier should provide protection from blood nucleases and extended blood circulation, which ultimately would increase the possibility of reaching the target tissue. The delivery system must then be internalized by the target cell and, upon receptor-mediated endocytosis, must be able to escape from the endosomal compartment into the cell cytoplasm, where the RNA machinery is located, while avoiding degradation by lysosomal enzymes. Further, delivery systems for systemic administration ought to be well tolerated upon administration. They should be safe, enabling the multiadministration treatment modalities required for improved clinical outcomes and, from a developmental point of view, production of large batches with reproducible specifications is also desirable. In this review, the concept of self-amplifying RNA vaccines and the most promising lipid-based delivery systems are discussed.

Ultrasonic synthetic technique to manufacture a pHEMA nanopolymeric-based vaccine against the H6N2 avian influenza virus: a preliminary investigation.

This preliminary study investigated the use of poly (2-hydroxyethyl methacrylate) (pHEMA) nanoparticles for the delivery of the deoxyribonucleic acid (DNA) vaccine pCAG-HAk, which expresses the full length hemagglutinin (HA) gene of the avian influenza A/Eurasian coot/Western Australian/2727/1979 (H6N2) virus with a Kozak sequence which is in the form of a pCAGGS vector. The loaded and unloaded nanoparticles were characterized using field-emission scanning electron microscopy. Further characterizations of the nanoparticles were made using atomic force microscopy and dynamic light scattering, which was used to investigate particle size distributions. This preliminary study suggests that using 100 µg of pHEMA nanoparticles as a nanocarrier/adjuvant produced a reduction in virus shedding and improved the immune response to the DNA vaccine pCAG-HAk.

Construction of a new fusion anti-caries DNA vaccine.

Mutans streptococci (MS) are generally considered to be the principal etiological agent of dental caries. MS have two important virulence factors: cell- surface protein PAc and glucosyltransferases (GTFs). GTFs have two functional domains: an N-terminal catalytic sucrose-binding domain (CAT) and a C-terminal glucan-binding domain (GLU). A fusion anti-caries DNA vaccine, pGJA-P/VAX, encoding two important antigenic domains, PAc and GLU, of S. mutans, was successful in reducing the levels of dental caries caused by S. mutans in gnotobiotic animals. However, its protective effect against S. sobrinus infection proved to be weak. Does the DNA vaccine need an antigen of S. sobrinus to enhance its ability to inhibit infection? To answer this question, in this study, we cloned the catalytic (cat) fragment of S. sobrinus gtf-I, which demonstrated its ability to inhibit water-insoluble glucan synthesis by S. sobrinus, into pGJA-P/VAX to produce a new anti-caries DNA vaccine.