Mucosal Immunization with a Novel Nanoemulsion-Based Recombinant Anthrax Protective Antigen Vaccine Protects againstBacillus anthracisSpore Challenge

Abstract

The currently available commercial human anthrax vaccine requires multiple injections for efficacy and has side effects due to its alum adjuvant. These factors limit its utility when immunizing exposed populations in emergent situations. We evaluated a novel mucosal adjuvant that consists of a nontoxic, water-in-oil nanoemulsion (NE). This material does not contain a proinflammatory component but penetrates mucosal surfaces to load antigens into dendritic cells. Mice and guinea pigs were intranasally immunized with recombinant Bacillus anthracis protective antigen (rPA) mixed in NE as an adjuvant. rPA-NE immunization was effective in inducing both serum anti-PA immunoglobulin G (IgG) and bronchial anti-PA IgA and IgG antibodies after either one or two mucosal administrations. Serum anti-PA IgG2a and IgG2b antibodies and PA-specific cytokine induction after immunization indicate a Th1-polarized immune response. rPA-NE immunization also produced high titers of lethal-toxin-neutralizing serum antibodies in both mice and guinea pigs. Guinea pigs nasally immunized with rPA-NE vaccine were protected against an intradermal challenge with ϳ1,000 times the 50% lethal dose (ϳ1,000؋ LD 50 ) of B. anthracis Ames strain spores (1.38 ؋ 10 3 spores), which killed control animals within 96 h. Nasal immunization also resulted in 70% and 40% survival rates against intranasal challenge with 10؋ LD 50 and 100؋ LD 50 (1.2 ؋ 10 6 and 1.2 ؋ 10 7 ) Ames strain spores. Our results indicate that NE can effectively adjuvant rPA for intranasal immunization. This potentially could lead to a needle-free anthrax vaccine requiring fewer doses and having fewer side effects than the currently available human vaccine.

Intranasal Immunization of Ferrets with Commercial Trivalent Influenza Vaccines Formulated in a Nanoemulsion-Based Adjuvant

“…Studies with a prototype NE formulations showed that the NE can inactivate whole influenza virus and induce an immune response after nasal administration that protects mice from homologous influenza virus challenge (25). Similar protective immune responses were observed using the NE with either whole vaccinia virus (VV) (7) or purified antigens such as recombinant anthrax protective antigen (8). Immunization with recombinant HIV gp120 and NE adjuvant produced a Th1 immune response and neutralizing antibodies in mice (9).…”

“…W 80 5EC-adjuvanted vaccine induced a Th17 response that was present in addition to a significantly enhanced Th1 bias (20). In other studies, when an NE adjuvant prototype was combined with purified antigens such as recombinant anthrax protective antigen (8) and HIV gp120, it elicited a Th1 systemic response with neutralizing serum antibodies and mucosal IgA when it was administered intranasally to mice or guinea pigs (9). W 80 5EC NE combined with hepatitis B virus surface antigen and administered intranasally produced an enhanced immune response and caused no inflammation in the nasal cavity, no histopathological changes in key organs, and no abnormal laboratory findings in safety studies performed with mice, rats, guinea pigs, and dogs (23).…”

Distinct Pathways of Humoral and Cellular Immunity Induced with the Mucosal Administration of a Nanoemulsion Adjuvant

“…NE-based vaccines formulated with various viral and bacteria-derived Ags and administered intranasally (i.n.) produced protective immunity to a variety of pathogens, including anthrax, vaccinia, HIV, influenza, and hepatitis B surface Ag (32)(33)(34)(35). Recently, we also demonstrated that W 80 5EC NE increases Ag uptake and trafficking by epithelial cells and DCs, resulting in both apoptosis and DC maturation (36,37).…”

“…This NE adjuvant is simply an oil-in-water formulation of emulsified, highly refined soybean oil combined with nonionic and cationic surfactants and ethanol, and it is similar in size to many viruses that infect the nasal mucosa (32). Our studies (32)(33)(34) showed that nasal administration of the NE adjuvant mixed with Ag(s) induces robust mucosal and systemic Ab responses and unique Th-1-biased and Th-17-mediated cellular immunity without causing acute inflammation in the nasal mucosa. NE-based vaccines formulated with various viral and bacteria-derived Ags and administered intranasally (i.n.)…”

Nasal-nanotechnology: revolution for efficient therapeutics delivery

“…It has been demonstrated that the nanoemulsion-based vaccines are not altered physically or chemically and retain potency following actuation with nasal spray devices (Makidon et al, 2010). In different investigations, NEs were utilized for IN delivery of influenza A vaccine (Myc et al, 2003) and recombinant anthrax vaccine (Bielinska et al, 2007).…”