Edible Vaccines

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edible vaccine

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Dr . Naseel Salim EDIBLE VACCINES : CURRENT STATUS AND FUTURE

What is Edible Vaccine ?:

What is Edible Vaccine ? I ntroduction of selected desired genes into plants and then inducing these altered plants to manufacture the encoded proteins. transformation transgenic plants

How it acts ?:

How it acts ? Antigen in transgenic plant Bioencapsulation -The tough outer wall of plant cells, which protects them from gastric secretions and finally break up in the intestines.

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Ingestion Taken up by M cell Pass on to the Macrophage IgG , IgE responses Local IgA response & Memory cells Neutralize the attack by the real infectious agent.

 Preparation of Edible Vaccines:

Preparation of Edible Vaccines Introduction of foreign DNA Gene-gun Agrobacterium tumefaciens - "Ti plasmid"

'Second-Generation' Edible Vaccines:

'Second-Generation' Edible Vaccines Multicomponent vaccines – Crossing two plant lines Adjuvants -co-expressed along with the antigen in the same plant. Eg . a trivalent edible vaccine against cholera, ETEC ( Enterotoxigenic E. coli ) and rotavirus.

Chimeric Viruses:

Chimeric Viruses Viruses can be redesigned to express fragments of antigenic proteins on their surface CPMV (cowpea mosaic virus), Alfalfa mosaic virus, TMV (tobacco mosaic virus), CaMV (cauliflower mosaic virus), Potato virus X and tomato bushy stunt virus

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Routes – Parenteral and nasal (purified particles) Oral (formulated leaf extracts) Whole and homogenized leaves Fruits or vegetable tissues

Overcoat and epicoat technology:

Overcoat and epicoat technology Overcoat technology :the plant to produce the entire protein. Epicoat technology: involves expression of only the foreign proteins.

Advantage and Disadvantage of different plants:

Advantage and Disadvantage of different plants Potato : Advantage Easily transformed. Easily propagated. Stored for long periods without refrigeration. Disadvantage Need cooking which denature antigen.

Advantages and Disadvantages:

Advantages and Disadvantages Banana Advantages Do not need cooking. Protein not destroyed even after cooking. Inexpensive . Grown widely in developing countries. Disadvantages Trees take 2-3 to mature years. Spoils rapidly after ripening.

Advantages and Disadvantages:

Advantages and Disadvantages Rice Advantages Commonly used in baby food. High expression of antigen. Disadvantages Grows slowly. Requires glasshouse condition.

Advantages and Disadvantages:

Advantages and Disadvantages Potato Advantage Grow quicly. Cultivate broadly. High content Vitamin-A may boost immune response. Disadvantages Spoils readily.

Clinical Trials:

Clinical Trials ETEC : Charles Arntzen at Boyce Thompson Institute, USA, 1997 11 Volunteers were feed raw transgenic Potatoes expressing LT-B. 10 (95%) of these individuals developed neutralizing antibodies and 6 (55%)develop mucosal response.

Clinical Trial on:

Clinical Trial on Norwalk Virus 20 people fed with transgenic potato . 19 (95%)of them expressing Norwalk virus antigen showed seroconversion . Bananas and powdered tomatoes

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Cholera Transgenic potato with CT-B gene of Vibrio cholerae was shown to be efficacious in mice. Eating one potato a week for a month with periodic boosters Co-expression of mutant cholera toxin subunit A ( mCT -A) and LT-B in crop seed has been shown to be effective by nasal administration.

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Measles Mice fed with tobacco expressing MV-H (measles virus haemagglutinin from Edmonston strain) MV-H edible vaccine does not cause atypical measles, which may be occasionally seen with the current vaccine. Transgenic rice, lettuce and baby food. When given with CT-B (adjuvant), 35-50 gm MV-H lettuce is enough-an increased dose would be required if given alone.

Clinical Trial on:

Clinical Trial on Hepatitis B First human trials of potato-based vaccine against Hepatitis B have reported encouraging results. The amount of HBsAg needed for one dose could be achieved in a single potato. Tomatoes, Transgenic lettuce also developed.

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Rabies Tomato plants expressing rabies antigens could induce antibodies in mice Alternatively, TMV may also be used. Transformed tomato plants using CaMV (cauliflower mosaic virus) with the glycoprotein (G-protein) gene of rabies virus (ERA strain) was shown to be immunogenic in animals.

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HIV CPMV(cowpea mosaic virus) HIV-1 (gp41), (gp120) Spinach and tomatoes

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STDs Human papilloma virus type-11 (HPV-11) recombinant VLPs produced in insect cells are immunogenic when given orally to BALB/c mice. The response is dose-dependent, conformationally -dependent and genotype-restricted. Thus, VLPs may be effective oral immunogens for the prevention of anogenital HPV disease.

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Anthrax Tobacco leaves bombarded with pag gene (anthrax protective antigen - PA) Tomato plants. spinach by inoculating it with TMV-expressing PA,

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Others Transgenic Arabidopsis thaliana plants are able to produce a fusion protein consisting of LT-B and early secretory antigen ESAT-6 of Mycobacterium tuberculosis Respiratory syncytial virus (RSV) RSV expressed in tomato and potato plants , Apple juice Rotavirus, transgenic potatoes expressing VP7 Malaria- chimeric coat proteins of CPMV expressing malarial and foot-and-mouth disease epitopes have been reported.

Veterinary Sciences:

Veterinary Sciences The first patented edible vaccine against the transmissible gastroenteritis virus (TGEV) in pigs

Passive Immunization:

Passive Immunization " plantibodies .“ Only four antibodies produced in plants IgG-IgA against Streptococcus mutans Attempts are being made to formulate these secretory antibodies into toothpaste to protect against tooth decay HBV antibodies-tobacco plants anti-HIV antibodies are under development A cream containing anti-HIV antibodies, reduce the risk of HIV transmission Monoclonal antibodies ( Mabs ) -genital herpes have been expressed in soybean

Other Potential Domains:

Other Potential Domains Cancer therapy Soybean has been genetically engineered to make MAB(BR-96) as a vehicle for targeting doxorubicin for breast, ovarian, colon and lung tumors. Non-Hodgkin's lymphoma is also being investigated.

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Birth control Autoimmune diseases Recombinant drugs/protein

Advantages of Edible Vaccine:

Advantages of Edible Vaccine Cost effective. Easy to administer. Easy to store. Acceptable to poor developing country. Fail safe Activate both mucosal and systemic immunity. Heat stable. Do not required cold chain maintenance. No fear of contamination.

Future of Edible Vaccine:

Future of Edible Vaccine Resistance to GM foods may affect future of Edible Vaccine.

Limitation:

Limitation Transgenic contamination can occur. Antibiotic resistance marker genes can spread from GM food to pathogenic Bacteria. Difficulty in dose maintenance.

Conclusion:

Conclusion Edible plant derived vaccine may lead to a future of safer and more effective immunization.