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Patent Issued for Compositions and Methods for Encapsulating Vaccines for the Oral Vaccination and Boostering of Fish and Other Animals

July 30, 2014

By a News Reporter-Staff News Editor at Biotech Week -- A patent by the inventors Harel, Moti (Pikesville, MD); Carpenter, Brian (Baltimore, MD), filed on May 8, 2012, was published online on July 15, 2014, according to news reporting originating from Alexandria, Virginia, by NewsRx correspondents (see also Advanced Bionutrition Corporation).

Patent number 8778384 is assigned to Advanced Bionutrition Corporation (Columbia, MD).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a composition comprising a pharmaceutically active agent, such as, but not limited to, an immunogenic agent (e.g., a vaccine), and a bioadhesive delivery system, that allows the oral administration and delivery of the pharmaceutically active agent essentially unaltered to the intestinal mucosa.

"Orally delivered pharmaceutically active agents present a significant problem in transiting an animal's stomach, an organ whose contents represent a harsh digestive environment consisting of low pH and enzymes specifically designed to denature proteins. As a consequence, orally delivered bacterin or subunit vaccines have not been proven to be efficacious since the antigens are generally modified by the stomach prior to presentation to the immuno-responsive cells of the gut mucosa. A number of approaches have been tested to provide an oral delivery vehicle that would transit the stomach but most have been unsuccessful at the commercial scale. One approach involves the transient changing of the stomach pH, neutralizing gastric enzymes and stimulating the mucosal immune response.

"In 2003 about 200 million fish were vaccinated in Chile, primarily for Yersiniosis, Salmonid Ricketsial Septicaemia (SRS), and Infectious Pancreatic Necrosis (IPN) (Bravo, 2007). Of the more than 20 vaccines for aquacultured fish brought to the Chilean market from 1999-2003, none was an orally delivered vaccine.

"SRS is a pathology of salmonid fish caused by the intracellular bacterium Piscrickettsia salmonis and is a major infectious disease in the Chilean salmon industry with annual losses exceeding 20%. Unlike other bacterial diseases, the anti-SRS vaccination is not as effective in preventing the disease or in reducing the need for post-infection medication. This is because of a gradual diminishing of the SRS immunogenicity in the vaccinated fish. Boostering the antibody titer in the blood by vaccinating at a later stage should allow the continued protection of the animals throughout the entire commercial growing period. However, it is extremely difficult and economically impractical to provide parenteral vaccine boosters to large animals in the grow-out net pens.

"Almost all existing vaccines are delivered to aquatic animals by injection, which is traumatic, inconvenient, time consuming, expensive, has a number of side effects, and may fail to induce an appropriate immunogenic response in mucosal tissues. Thus, a method and system for delivery that avoids these disadvantages would be of great value.

"Perhaps the most well known antigen delivery systems are those derived from the linear polymeric esters of lactic acid and glycolic acid (i.e., poly DL-lactide-co-glycolide, PLGA, reviewed by Wu (Wu, 2004). In such systems, immunogenic subunit vaccine components have been captured in poly-acrylate and poly-glycolide/lactide beads or liposome-like vesicles through processes utilizing volatile organic solvents such as dichloromethane or chloroform. The solvents are used to form emulsions of polymer solutions or dried lipid films. Encapsulation of antigens into PLGA microcapsules affords a number of advantages including rapid degradation by hydrolysis and subsequent penetration of the Peyer's Patches (concentrated sites of lymphocytic tissue in the intestinal mucosa of higher vertebrates but not in fish). A major disadvantage of PLGA microcapsules is the requisite use of organic solvents. Contact with organic solvents can inactivate or reduce the efficacy of the vaccine by altering the immunogenicity of surface proteins critical to induction of humoral or cellular immune responses. Additionally, poly-acrylate and poly-glycolide/lactide processes typically result in microbeads with extremely low immunogen or antigen capture efficiency.

"Polymer microspheres and lamellar particles (e.g., liposomes) have been employed for the improved parenteral and mucosal administration of antigens. Because vaccines themselves may not be efficiently recognized and taken up by mucosal lymphocytes, they typically need to be co-administered with penetration enhancers or adjuvants. Different classes of polymer mixtures are known for potential use as Mucoadhesives (Malik et al., 2007). These include synthetic polymers such as poly (acrylic acid) (PAA), hydroxypropyl methylcellulose and poly(methylacrylate) derivatives, as well as naturally occurring polymers such as hyaluronic acid and chitosan.

"Chitosan and various chitosan derivatives have been used for a variety of applications as a biomaterial for tissue engineering, wound healing, and as an excipient for drug delivery (Chopra et al., 2006; Dang and Leong, 2006). Chitosan has occasionally been tested as an adjuvant for mucosal application (Kim et al., 2007), but it is typically applied directly to a mucosal surface such as intranasal application in order to obtain IgA response in the nasopharyngeal mucosa of terrestrial animals (Kang et al., 2007). However, the use of chitosan and various chitosan derivatives in vaccine delivery remains very limited due to poor physicochemical characteristics such as a high transition temperature and interfacial free energy, resulting in a suboptimal interaction with mucosal surfaces and loose interpenetration and interdiffusion of the polymer. This problem is further compounded when used for poikilothermic lower vertebrates like salmonid fish. Chitosan also has the additional disadvantage of a low mechanical strength and solubility.

"Thus, there remains a need for effective systems and processes for microencapsulation of immunogenic substances with polymers having superior adhesive and cohesive properties."

In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventors' summary information for this patent: "The present invention overcomes the shortcomings of the above-discussed encapsulation systems, wherein the present invention discloses a composition designed for an oral delivery of a primary and or booster vaccination that can be used for animals housed not only in a hatchery but also in grow-out pens. The exceptional mucoadhesive properties of compositions of the present invention provide a successful method of transmucosal drug delivery, especially for lower vertebrates with less developed digestive systems and no Peyer's Patches, such as fish.

"One aspect of the present invention provides for a method of producing a bioadhesive delivery vehicle for vaccination of animals, such as aquatic animals, wherein the delivery vehicle is in a form of dry microparticles comprising an immunogenic agent embedded or impregnated in a composite matrix of cross-linked chitosan, and at least one oligosaccharide or short chain polysaccharide. Any applicable oligosaccharides or short chain polysaccharides may be used in the composition. Common short chain polysaccharides include maltodextrins and cyclodextrins. The oligosaccharides may include fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS) or inulin. Additionally, the dry microparticles include and selected from the group consisting of a beta glucan, squalene, and squalane.

"In one embodiment, the composition comprises or consists of at least one pharmaceutically active agent in an amount from about 0.05% to about 10% w/w of composition, at least one bio-adhesive polymer in an amount from about 0.05% to about 10% w/w of composition, at least one short chain polysaccharide or oligosaccharide in an amount from about 0.05% to about 30% w/w of composition and at least one adjuvant selected from the group consisting of a beta glucan, squalene, and squalane in an amount from about 0.1% to about 20% w/w of composition.

"In one particular embodiment of the invention, the method comprises producing a bioadhesive delivery vehicle containing an SRS vaccine for use in salmonid fish.

"Another aspect of the present invention provides for a feeding regime wherein animals are fed a standard feed containing a bioadhesive delivery vehicle comprising a cationic polysaccharide, in combination with a pharmaceutically active agent, for the oral vaccination of animals. In a particular embodiment, the vaccinated animal is a fish.

"Another aspect of the present invention provides for a method of preparing a composition for oral delivery of a pharmaceutically active agent comprising: a. preparing an acidic aqueous solution comprising at least one bioadhesive polymer, wherein the bioadhesive polymer is chitosan and the acidic solution has a pH low enough to solubilize the chitosan; b. combining an oligosaccharide/short chain polysaccharide selected from the group consisting of inulin, maltodextrin and cyclodextrin into the solution with the solubilized chitosan to form an oligosaccharide/short chain polysaccharide-chitosan solution; c. introducing a sugar/emulsifier complex into the oligosaccharide/short chain polysaccharide-chitosan solution to form a smooth emulsion while maintaining the acidic pH of the solution; d. combining or emulsifying the pharmaceutically active agent with an adjuvant selected from the group consisting of beta-glucan, shark liver oil and squalane in a solution; e. adding the solution of pharmaceutically active agent and the adjuvant into the smooth bioadhesive emulsion; f. forming microparticles, beads or hydrogel by precipitating the emulsion into a cross-linking solution; and g. drying the microparticles, beads or hydrogel by any conventional means.

"The dried microparticles may be further milled to obtain particle size lower than 500 micron.

"Preferably, the crosslinking solution comprises from about 1% to about 20% of phosphate or carbonate anions. The crosslinking solution may further comprise about 1% to 30% of a sugar and/or alcohol.

"Other aspects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims."

URL and more information on this patent, see: Harel, Moti; Carpenter, Brian. Compositions and Methods for Encapsulating Vaccines for the Oral Vaccination and Boostering of Fish and Other Animals. U.S. Patent Number 8778384, filed May 8, 2012, and published online on July 15, 2014. Patent URL:

Keywords for this news article include: Advanced Bionutrition Corporation, Antigens, Biological Factors, Immunology.

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Source: Biotech Week

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