seminar edible_vaccines 2

8/2/2019 SEMINAR Edible_vaccines 2

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Edible Vaccines

Prepared by:

Rubielyn Narra



Plants as Bioreactors

Transgenic non-food GM

plant pharming;biopharming;

molecular farming;

or simply, pharming



MOLECULAR FARMING

Molecular farming is a method used tointegrate a foreign gene into plants.

Molecular farming is the term for newuse plants only (not animals) and isdifferent in that this does not affect andhas nothing to do with food.



Plants genetically engineeredto make products that are notof plant origin

Products: therapeutics,vaccines, antibodies,industrial proteins, bioplastics

Pro’s: large amounts, no

bacterial or viralcontamination, low productioncost

Con’s: different sugar

residuesThere are two types ofMolecular Farming: Medicaland non-Medical.



Medical Molecular Farming

The first synthesis of a pharmaceutically-relevant protein, human growth hormone,was described in transgenic tobacco

plants in 1986.

Now, molecular farming has becomecommercially interesting as a method for

the production of recombinantpharmaceutical proteins, in particularantibodies.



Non-Medical Molecular Farming

Non-Medical Molecular Farming includesIndustrial Enzymes and Polymers.• Industrial enzymes: for example laccase in

transgenic maize,

• Technical proteins for research purposes:for example avidin, which is also producedin maize,

• Milk proteins such as human beta casein,

which is produced in transgenic tomatoes,• Protein polymers: collagens, which are

used for medical as well as industrialpurposes.



• Potentially the biggest development in this fieldcould be the development of plants growing

biodegradable plastics.

• Other uses could be as

Industrial oils such as hydraulic oil or highyielding biodiesels,

new solid Biofuels,

new Fibers and Papers, and

as agents for Bioremediation andPhytoremediation, environmentally cleaning upcontamination.



Molecular Farming



Key processes

Transform

Express

Patenting



WHY PLANTS?Plants are also very flexible and canproduce a wide variety of proteins.Crop plants can synthesize a wide varietyof proteins that are free of mammalian

toxins and pathogens.Crop plants produce large amounts ofbiomass at low cost and require limitedfacilities.Crops are therefore well suited for theproduction of safe low-cost therapeuticproteins.



Edible VaccinesBiotech Plants Serving Human Health Needs

• Works like any vaccine• A transgenic plant with a pathogen protein gene is developed• Potato, banana, and tomato are targets• Humans eat the plant

• The body produces antibodies against pathogen protein• Humans are “immunized” against the pathogen • Examples:

RabiesNorwalk virus (cold virus)Anthrax



Rabies Virus Vaccine

Rabies is fatal in 100% of cases when no treatment is givenresulting in 60,000 deaths every year worldwide.

A specific protein of rabies virus, known as G protein, is themajor antigen that causes immunity.

Gene that codes for the G protein was significantly modifiedto facilitate a higher expression of the protein in plants.

Agrobacterium tumefaciens was used to insert the genethat encodes for the antigen as well as a gene that encodesfor herbicide resistance.



Rabies Virus Vaccine

The effect to which the plantvaccine was able to invoke animmune response wasperformed by injecting micewith the protein derived from

tobacco.

The plant made vaccineproduced a higher level ofantibodies for the rabies virusthan the commerciallyavailable rabies vaccine.

Mice from each group werethen challenged with 10LD

50

of rabies virus.

(Adapted from Ashraf S, Singh PK, Yadav DK, Shahnawaz M,Mishra S, Sawant SV, Tuli R: High level expression of surfaceglycoprotein of rabies virus in tobacco leaves and itsimmunoprotective activity in mice. Journal of Biotechnology

2005, 119:1-14.)



RABIES VIRUS G PROTEIN IN TOMATO • Gene introduced to tomatoplants by Agrobacterium- mediated transformation

• Expression of recombinant

glycoprotein in leaves andfruits

• Protein localized in golgibodies, vesicles and

plasmalemma



Norwalk virus (cold virus) capsid protein inpotato and tobacco

• Causative agent for acute epidemicgastroenteritis

•Transformation by Agrobacterium

• Expression level:

0.37% in potato tubers

0.23% in tobacco leaves



Anthrax Vaccine

The toxins PA, LF, and EF are responsible for the pathogenicityof deadly strains of Bacillus anthracis .

The PA gene was expressed in Nicotiana tabacum throughchloroplast transformation

~14% in leaves was PA, 1 acre of land=360 million doses of anthraxvaccine.

Producing proteins in chloroplasts has several advantages:

– ~10,000 copies of chloroplast DNA in every cell, 10 –25 timeshigher protein levels

– lack of gene silencing.

– reduces the risk of a transgene proliferating throughout the

environment



Anthrax Vaccine in Transgenic Tomatoes are in early

stage of development.



Tomato Callus Differentiating On Selection

Medium



Putative Transgenic Tomato Plants at

Bottle Stage



Putative Tomato Transgenic PlantsTransferred To Pots



Comparison to other VaccineProductions Methods

Transgenic plants are significantly less expensive thanother means of vaccine production.

~80% of the total production costs are attributed to

extraction and purification of the recombinant proteins – Costs can be reduced by expressing the protein inwatery tissues.

Transgenic cereal crops can be stored at room

temperature.

Plants also provide a greater degree of safety.



Comparison to other VaccineProductions Methods

Table 1Comparison of currently used vectors for recombinant proteinproduction

(Adapted from Balen B, Krsnik-Rasol M, Lt: N-glycosylation of recombinant therapeuticglycoproteins in plant systems. Food Technology and Biotechnology 2007, 45:1-10.)



Oral delivery

Edible vaccines would make massimmunization possible at extremely lowcosts.

Concern that the expressed antigenscould be broken down by proteases upon

entering the stomach.

Possible side effects of accidental

consumption of antigen containing plants.



Oral delivery

Transgenic rice has been shown to orally immunizeagainst cholera toxin even after prolonged storage.

Mice born to females that had eaten transgenicalfalfa containing an antigen for a class of rotavirusgained partial passive immunity.

A protein necessary for the production of HIV viruswas produced in transgenic tomato plants andelicited the production of antibodies in mice.



Conclusion

Plant made vaccines are safe, cheap, effective, andhighly accessible alternative to current methods ofvaccine production.

An array of pathogens, plant species, and transformationtechnology can be used to produce vaccines in plants.

The technology has shown to have numerousadvantages over current methods of vaccine productionas well as a few disadvantages.



Thank you.

seminar edible_vaccines 2

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