Assessment of In Vitro Immunostimulatory Activity of an Adjuvanted Whole-Cell Inactivated Neisseria gonorrhoeae Microparticle Vaccine Formulation

The emergence of drug-resistant gonorrhea infections worldwide combined with the lack of a vaccine is alarming. We prepared a novel microparticulate (MP) vaccine formulation using whole-cell inactivated Neisseria gonorrhoeae as the vaccine antigen, with Alum and AddaVax™ as vaccine adjuvants. The adjuvanted vaccine MP formulation was assessed for in vitro immunostimulatory activity, autophagy, and antigen presentation ability. The data shows that the adjuvanted gonococci vaccine MP enhanced autophagy induction in antigen presenting cells (APCs) compared to gonococci vaccine MP without adjuvants, which is important for enhancing antigen presentation. In addition, the adjuvanted vaccine formulation increased the surface expression of antigen presenting molecules MHCI and MHCII as well as co-stimulatory molecules CD40 and CD86 on the surface of dendritic cells. In addition, the gonococci vaccine microparticles at lower doses did not significantly increase the expression of the death receptor CD95 in APCs, which when elevated leads to suboptimal antigen presentation and reduced immune responses. The adjuvanted whole-cell inactivated gonococci microparticle vaccine formulation enhanced antigen uptake, processing, and antigen presentation.

Buccal and Sublingual Vaccines: A Review on Oral Mucosal Immunization and Delivery Systems

Currently, most vaccines available on the market are for parental use; however, this may not be the best option on several occasions. Mucosal routes of administration such as intranasal, sublingual, and buccal generate great interest due to the benefits they offer. These range from increasing patient compliance to inducing a more effective immune response than that achieved through conventional routes. Due to the activation of the common mucosal immune system, it is possible to generate an effective systemic and local immune response, which is not achieved through parenteral administration. Protection against pathogens that use mucosal entry routes is provided by an effective induction of mucosal immunity. Mucosal delivery systems are being developed, such as films and microneedles, which have proven to be effective, safe, and easy to administer. These systems have multiple advantages over commonly used injections, which are simple to manufacture, stable at room temperature, painless for the patient since they do not require puncture. Therefore, these delivery systems do not require to be administered by medical personnel; in fact, they could be self-administered.

Novel ablative laser mediated transdermal immunization for microparticulate measles vaccine

With the need for safe and efficacious vaccines which could be administered via non-invasive procedure, alternatives to traditional injectables vaccines are sought after. The present study aimed to develop the microparticulate formulation of measles vaccine and explore the feasibility of transdermal delivery via ablative laser mediated skin microporation. Transdermal route offers several advantages including painless immunization and ease of administration. We propose to use P.L.E.A.S.E. ablative laser for transdermal immunization of the microparticulate measles vaccine. This laser emits energy at 2940 µm, enabling cold ablation. This creates the micropores of defined size for delivery of vaccines into the skin. We compared the efficacy of transdermal immunization using the particulate formulation of the vaccine to that of traditional subcutaneous immunization using soluble and particulate vaccine. The microparticles were formulated using the biocompatible and biodegradable bovine serum albumin (BSA)-based polymer matrix. These vaccine microparticles were non-cytotoxic to the antigen presenting cells (APCs) and could effectively stimulate the innate immune response, confirmed by release of nitric oxide (NO) from the Griess's assay. The APCs when exposed to vaccine microparticles also showed a significantly higher expression of antigen-presenting molecules, MHC I and MHC II, and their co-stimulatory molecules, CD80 and CD40 as compared to the blank microparticles. The microparticulate measles vaccine was evaluated in vivo in the murine model. We compared the serum IgG and IgM levels in the mice receiving the vaccine subcutaneously and transdermally post-immunization. The results revealed that transdermal immunization with microparticulate vaccine is as efficient as the traditional subcutaneous administration.

Physicochemical and Preclinical Evaluation of a Novel Buccal Measles Vaccine

The aim of this study is to develop an orally disintegrating film (ODF) containing a microparticulate measles vaccine formulation for buccal delivery. The measles vaccine microparticles were made with biocompatible and biodegradable bovine serum albumin (BSA) and processed by spray drying. These vaccine microparticles were incorporated in the ODF, consisting of Lycoat RS720®, Neosorb P60W® and Tween 80. The yield of the microparticles was approximately 85-95%, w/w. The mean size of the vaccine microparticles was 3.65 ± 1.89 μm and had a slightly negative surface charge of 32.65 ± 2.4 mV. The vaccine particles were nontoxic to normal cells at high concentrations (500 μg/2.5 × 10⁵ cells) of vaccine particles. There was a significant induction of innate immune response by vaccine microparticles which was observed in vitro when compared to blank microparticles (P < 0.05). The vaccine microparticles also significantly increased the antigen presentation and co-stimulatory molecules expression on antigen presenting cells, which is a prerequisite for Th1 and Th2 immune responses. When the ODF vaccine formulation was dosed in juvenile pigs, significantly higher antibody titers were observed after week 2, with a significant increase at week 4 and plateauing through week 6 comparative to naïve predose titers. The results suggest that the ODF measles vaccine formulation is a viable dosage form alternative to noninvasive immunization that may increase patient compliance and commercial distribution.

Evaluation of various adjuvant nanoparticulate formulations for meningococcal capsular polysaccharide-based vaccine

Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis and its capsular polysaccharides (CPS) are a major virulence factor in meningococcal infections and form the basis for serogroup designation and preventive vaccines. We have formulated a novel meningococcal nanoparticulate vaccine formulation that does not require chemical conjugation, but encapsulates meningococcal CPS polymers in a biodegradable material that slowly release antigens, thereby has antigen depot effect to enhance antigenicity. The novel vaccine formulation is inexpensive and can be stored as a dry powder with extended shelf life that does not require the cold-chain which facilitates storage and distribution. In order to enhance the antigenicity of meningococcal nanoparticulate vaccine, we screened various adjuvants formulated in nanoparticles, for their ability to potentiate antigen presentation by dendritic cells. Here, we report that MF59 and Alum are superior to TLR-based adjuvants in enhancing dendritic cell maturation and antigen presentation markers MHC I, MHC II, CD40, CD80 and CD86 in dendritic cells pulsed with meningococcal CPS nanoparticulate vaccine.

A comprehensive production method of self-cryoprotected nano-liposome powders

This study provided a convenient approach for large scale production of hydrogenated soya phosphatidylcholine nano-liposome powders using beclometasone dipropionate as a model drug and sucrose as proliposome carrier. Fluid-bed coating was employed to manufacture proliposomes by coating sucrose with the phospholipid (5%, 10%, 15% and 20% weight gains), followed by hydration, size reduction using high pressure homogenization, and freeze-drying to yield stable nano-vesicles. High pressure homogenization was compared with probe-sonication in terms of liposome size, zeta potential and drug entrapment. Furthermore, the effect of freeze-drying on vesicle properties generated using both size reduction methods was evaluated. Results have shown that high-pressure homogenization followed by freeze-drying and rehydration tended to yield liposomes smaller than the corresponding vesicles downsized via probe-sonication, and all size measurements were in the range of 72.64-152.50 nm, indicating that freeze-drying was appropriate, regardless of the size reduction technique. The liposomes, regardless of size reduction technique and freeze drying had slightly negative zeta potential values or were almost neutral in surface charge. The entrapment efficiency of BDP in homogenized liposomes was found to increase following freeze-drying, hence the drug entrapment efficiency values in rehydrated liposomes were 64.9%, 57%, 69.5% and 64.5% for 5%, 10%, 15% and 20% weight gains respectively. In this study, we have reported a reliable production method of nano-liposomes based on widely applicable industrial technologies such as fluid-bed coating, high pressure homogenization and freeze-drying. Moreover, sucrose played a dual role as a carrier in the proliposome formulations and as a cryoprotectant during freeze-drying.

Induction of death receptor CD95 and co-stimulatory molecules CD80 and CD86 by meningococcal capsular polysaccharide-loaded vaccine nanoparticles

Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis, and its capsular polysaccharides (CPS) are a major virulence factor in meningococcal infections and form the basis for serogroup designation and protective vaccines. We formulated a novel nanovaccine containing meningococcal CPS as an antigen encapsulated in albumin-based nanoparticles (NPs) that does not require chemical conjugation to a protein carrier. These nanoparticles are taken up by antigen-presenting cells and act as antigen depot by slowly releasing the antigen. In this study, we determined the ability of CPS-loaded vaccine nanoparticles to induce co-stimulatory molecules, namely CD80, CD86, and CD95 that impact effective antigen presentation. Co-stimulatory molecule gene induction and surface expression on macrophages and dendritic cells pulsed with meningococcal CPS-loaded nanoparticles were investigated using gene array and flow cytometry methods. Meningococcal CPS-loaded NP significantly induced the surface protein expression of CD80 and CD86, markers of dendritic cell maturation, in human THP-1 macrophages and in murine dendritic cells DC2.4 in a dose-dependent manner. The massive upregulation was also observed at the gene expression. However, high dose of CPS-loaded NP, but not empty NP, induced the expression of death receptor CD95 (Fas) leading to reduced TNF-α release and reduction in cell viability. The data suggest that high expression of CD95 may lead to death of antigen-presenting cells and consequently suboptimal immune responses to vaccine. The CPS-loaded NP induces the expression of co-stimulatory molecules and acts as antigen depot and can spare antigen dose, highly desirable criteria for vaccine formulations.