Strong antibody responses induced by protein antigens conjugated onto the surface of lecithin-based nanoparticles

Abstract

An accumulation of research over the years has demonstrated the utility of nanoparticles as antigen carriers with adjuvant activity. Herein we defined the adjuvanticity of a novel lecithin-based nanoparticle engineered from emulsions. The nanoparticles were spheres of around 200 nm. Model protein antigens, bovine serum albumin (BSA) or Bacillus anthracis protective antigen (PA) protein, were covalently conjugated onto the nanoparticles. Mice immunized with the BSA-conjugated nanoparticles developed strong anti-BSA antibody responses comparable to that induced by BSA adjuvanted with incomplete Freund's adjuvant and 6.5-fold stronger than that induced by BSA adsorbed onto aluminum hydroxide. Immunization of mice with the PA-conjugated nanoparticles elicited a quick, strong, and durable anti-PA antibody response that afforded protection of the mice against a lethal dose of anthrax lethal toxin challenge. The potent adjuvanticity of the nanoparticles was likely due to their ability to move the antigens into local draining lymph nodes, to enhance the uptake of the antigens by antigen-presenting cells (APCs), and to activate APCs. This novel nanoparticle system has the potential to serve as a universal protein-based vaccine carrier capable of inducing strong immune responses.

Carbon nanotube-protein carriers enhance size-dependent self-adjuvant antibody response to haptens

“…[27][28][29] This way, the particles can easily reach cytosol, where they are degraded, thus releasing the antigen. The other approach consists of attaching the antigen (covalently or not) to the functionalized surface of 75 biocompatible and non-biodegradable particulate materials, such as lecithin NPs, [30] gold NPs,[31-33] quantum dots, [34] or MPs/NPs based on diverse organic polymers like polystyrene, [35,36] polypropylene sulfide, [37] or polyacrylate. [38] Carbon nanotubes (CNTs) are nanomaterials of tubular shape with promising applications in biological and medicinal chemistry.…”

Permeation of antigen protein-conjugated nanoparticles and live bacteria through microneedle-treated mouse skin

“…27,28 Briefly, soy lecithin 3.5 mg and glyceryl monostearate 0.5 mg were placed into a 7 mL glass vial. One milliliter of deionized filtrated (0.22 µm) water was added into the vial, followed by heating on a hot plate to 70-75°C, with stirring and brief intermittent periods of sonication (Ultrasonic Cleaner Model 150T, VWR International, West Chester, PA).…”

“…27,29 To label the nanoparticles fluorescently, DOPE-fluorescein (5%, m/m of total lipids) was included in the lecithin and glyceryl monostearate mixture during nanoparticle preparation. 27,29 conjugation of ovalbumin onto the nanoparticles…”

“…[27][28][29] Prior to conjugation, ovalbumin was thiolated using Traut's reagent. Ovalbumin was diluted in carbonate buffer (0.1 M, pH 9.6), followed by addition of Traut's reagent (20× molar excess) and a 60-minute incubation at room temperature.…”

“…27,28 It was shown that subcutaneous injection of protein antigens conjugated onto the nanoparticles induced strong functional antibody and cellular immune responses. 27,29 In the present study, the antibody responses induced by ovalbumin nanoparticles or ovalbumin alone when applied onto a mouse skin area pretreated with microneedle rollers were evaluated and compared, using ovalbumin as a model antigen chemically conjugated onto nanoparticles (mean diameter 230 nm) and three different microneedle rollers with different-sized microneedles. Prior to an in vivo animal immunization study, permeation of the ovalbumin nanoparticles through mouse skin treated with microneedle rollers was evaluated in vitro.…”