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plant vaccines, fruits vaccine, vegetable vaccine, banana vaccine, potato vaccine, human diseases, AK Chhabra, CCSHAU, Hisar, chhabra61, ppt, Ashok Chhabra


By: harinayak969 (52 month(s) ago)

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(C) 2003-04 A.K. Chhabra A.K. Chhabra EDIBLE VACCINES

What is a vaccine ?:

(C) 2003-04 A.K. Chhabra What is a vaccine ? An immunization agent against infectious diseases. Originally derived from immunization against small pox using vaccinia virus (cowpox virus) Such agents could be either whole organism or its component.


(C) 2003-04 A.K. Chhabra Scarification Inhalation Variolation Vaccination Historical Developments in Vaccinology


(C) 2003-04 A.K. Chhabra ERADICATION OF SMALL POX Edward Jenner (1749-1823)


(C) 2003-04 A.K. Chhabra Global eradication of smallpox 9th Dec. 1979


(C) 2003-04 A.K. Chhabra Pasteur believed that cultivation of the pathogen in unnatural host would decrease the virulence. Rabies agent was serially passaged in rabbit brains. Louis Pasteur RABIES VACCINE

Pasteur’s Vaccine Against Anthrax: Public Demonstration:

(C) 2003-04 A.K. Chhabra Pasteur’s Vaccine Against Anthrax: Public Demonstration


(C) 2003-04 A.K. Chhabra Live vaccines Viral Bacterial Killed vaccines Whole organisms Bacterial / Viral Sub-units Conventional components Synthetic Recombinant Genetically engineered vaccines Vectored vaccines Naked DNA vaccines Edible plant vaccines Anti-idiotypic vaccines TYPES OF VACCINES


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How vaccines work ?:

(C) 2003-04 A.K. Chhabra How vaccines work ? Vaccines act as antigens/immunogens. Produce mainly two types of responses: Humoral immune response Cellular immune response


(C) 2003-04 A.K. Chhabra Antibody Mediated Immune Response


(C) 2003-04 A.K. Chhabra Antibodies are glycoprotein molecules known as immunoglobulins. They are secreted by plasma cells derived from B lymphocytes. There are five classes of antibodies (IgG, IgM, IgA, IgE & IgD) IgG is a monomer and has two important regions: 1. Constant Region & 2. Variable Region Variable region is antigen binding region What is Antibody ?


(C) 2003-04 A.K. Chhabra The serum which contains antibodies against any antigen. Polyclonal antiserum. Monospecific antiserum Monoclonal antibodies What is Antiserum ?


(C) 2003-04 A.K. Chhabra Reaction of particulate antigen with specific antibodies leads to agglutination. Reaction of soluble antigen with specific antibodies leads to precipitation. Antigen-Antibody Reaction


(C) 2003-04 A.K. Chhabra Cellular immune response is mediated by T lymphocytes. The pathogen infected cells are attacked and destroyed by cytotoxic T lymphocytes . Cellular Immune Response


(C) 2003-04 A.K. Chhabra TYPE OF ANTIGENS VACCINE EXAMPLE Living Organisms Natural Vaccinia for smallpox, Vole bacillus for TB Attenuated Polio (Sabin, oral polio vaccine Measles, Mumps, Rubella, Yellow fever, Varicella zoster, BCG for TB Intact but non-living organisms Viruses Polio (Salk), Rabies, Influenza, Hepatitis A, Typhus Bacteria Pertussis, Typhoid, Cholera, Plague Sub-cellular fragments Capsular polysaccharides Pneumocuccus, Meningococcus , Haemophilus influenzae Surface antigen Hepatitis B Toxoids Tetanus and Diphtheria Recombinant DNA-based Gene cloned & expressed Genes expressed in vectors Naked DNA Hepatitis B Experimental Experimental Anti-idiotype Experimental


(C) 2003-04 A.K. Chhabra Live Viral & Bacterial vaccines Polio Measles Mumps Rubella Yellow fever Varicella-zoster Hepatitis A Tuberculosis Present vaccines

Present vaccines:

(C) 2003-04 A.K. Chhabra Killed/ Inactivated Vaccines Viral Polio Rabies Influenza Hepatitis A Bacterial Pertussis Typhoid Cholera Plague Q fever Present vaccines

Present vaccines:

(C) 2003-04 A.K. Chhabra Toxin-based vaccines Clostridium tetani Formalin inactivated toxin Corynebacterium diphtheriae Formalin inactivated toxin Vibrio cholerae Toxin B subunit Clostridium perfringens Formalin inactivated toxin Present vaccines


(C) 2003-04 A.K. Chhabra H.influenza 1995 Why new vaccines became possible ? GENOME SEQUENCING RACE Antibody


(C) 2003-04 A.K. Chhabra The DNA Double Helix (1953) Rosalyn Franklin (1921-1958) X-Ray crystallograph A tribute to The Discoverers of Double Helix


(C) 2003-04 A.K. Chhabra Recombinant subunit vaccines Genetically altered live vaccines Nucleic acid based vaccines Edible vaccines Plant virus based vaccines Vaccines of Future


(C) 2003-04 A.K. Chhabra NUCLEIC ACID VACCINES What are nucleic acid vaccines ? Nucleic acid vaccines refer to direct inoculation of plasmid DNA encoding immunogenic proteins. The concept was developed in 1993 by Ulmer and Co-workers using influenza virus mouse model.

How to Produce a DNA Vaccine ?:

(C) 2003-04 A.K. Chhabra How to Produce a DNA Vaccine ?

Advantages of DNA Vaccines:

(C) 2003-04 A.K. Chhabra Advantages of DNA Vaccines Induce cellular as well as humoral immune responses. Great ease in production and quality control. Non-integration of DNA. Lack of immunogenicity of vector. Lower cost of production. Heat stability DNA can be lyophilised & stored for long time.

Limitations of DNA Vaccines:

(C) 2003-04 A.K. Chhabra Limitations of DNA Vaccines Long term effects are unknown. Poor efficiency of uptake of DNA by target cells. Possibility of immunotolerance. Duration of protection unknown. Problem of antibiotic resistance. Stability of plasmid in the target cells.


(C) 2003-04 A.K. Chhabra   AIDS TB bacilli A number of diseases such as AIDS, TB, Malaria, Dengue, Cholera, Hepatitis, Typhoid, Rabies, Japanese encephalitis would require cost effective thermostable vaccines suitable for developing countries such as India. FUTURE CHALLENGES


(C) 2003-04 A.K. Chhabra Causes of death among children under age 5 in developing countries and developed countries, 1990 Numbers of deaths by age group in developing and developed countries, 1990 Source: World Bank (1993b). Note: Developed countries include the former socialist economies of Europe and the established market economies.


(C) 2003-04 A.K. Chhabra 1992 WHO Children/s Vaccine Initiative Goals Develop vaccines that are : Low cost Easy to store & distribute without refrigeration Easy to administer Related goal is to decrease pathogen reservoirs Solution = edible vaccines produced in plants


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What are Edible Plant Vaccines ?:

(C) 2003-04 A.K. Chhabra What are Edible Plant Vaccines ? The approach was developed in 1995 by Charles J. Arntzen and Coworkers. Transgenic fruits and vegetables capable of synthesizing protein antigens that retain immunological properties.


(C) 2003-04 A.K. Chhabra What is Molecular farming/ Pharming ? Molecular farming is defined as the production of valuable pharmaceutical or industrial proteins in organisms traditionally used in an agricultural setting. Scientists use agricultural crop plants as bioreactors to produce proteins that can be modified for safe, low-cost therapeutic use.


(C) 2003-04 A.K. Chhabra Crop plants are very flexible : can synthesize a wide variety of proteins that are free of mammalian toxins and pathogens. Crop plants produce large amounts of biomass at low cost and require limited facilities. Crops are therefore well suited for the production of safe low-cost therapeutic proteins. WHY PLANTS ?


(C) 2003-04 A.K. Chhabra Advantages of EDIBLE vaccines Multiple vaccinations per plant (in theory) Stimulates mucosal immunity More effective vs. pathogens that invade mucosal surfaces Administration is safe & painless Cost could be very low Could be produced in developing countries


(C) 2003-04 A.K. Chhabra Banana Corn Potato Tomato Soybeans Rice Lettuce Brassica Wheat Foods under study AS VECTORS


(C) 2003-04 A.K. Chhabra Genetic enhancement is used to introduce and express genes coding for the high value proteins. How is it done ?


(C) 2003-04 A.K. Chhabra 1 The plant leaf disc is dipped in a solution of bacteria. The bacterial "Trojan Horse" infects the edges of the leaf disc and in the process integrates the pharmaceutical protein gone into the plant genome. 2 & 3 After infection the discs are placed on selection media that a flows only plant cells that carry the protein gene to survive and regenerate into plantlets. After about six weeks on selection media, a large number of plantlets that carry the pharmaceutical protein gene are visible at the edges of the original leaf disc. 4 The plantlets are removed from the leaf disc and placed in clear plastic boxes that contain media that allows them to form roots. 5 The rooted plantlets are placed in pots and plants are allowed to grow and produce seed. This seed can then be used for large scale production of the pharmaceutical protein. 6 Following translation of the molecular ring gene, the protein will move through the endoplasmic reticulum and Golgi apparatus for processing, folding and glycosylation. 7 Low alkaloid plants expressing the pharmaceutical protein gone can then be produced in the field. Following harvest the tissue can be fed directly or the protein extracted for later use. Plant Transformation Protein Trafficking Field Production


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(C) 2003-04 A.K. Chhabra Figure 1. A schematic diagram showing the steps needed to create transgenic banana plants that express immunogenic proteins. A. A well studied antigen with potential value as a vaccine is identified. B. The gene encoding the antigen is isolated. C. The gene is ligated into a plant transformation vector. D. The gene is transfered into the chromosomes of the banana cells. E. Plants are regenerated from transformed cells. F. and G. Immunogenicity is determined by extracting the foreign protein, or by feeding the banana to animals.


(C) 2003-04 A.K. Chhabra Banana(s) : can be grown in the developing world (worldwide); production and transport technology are available in the developing world; are readily eaten by children; are eaten raw/ uncooked; can be grown locally and cheaply; are tasty and can be used as weaning food; donot require refrigeration for storage. Limitations: Time for transformation to evaluation of fuuit is 2 years or more. Bananas offer several advantages for edible vaccines.


(C) 2003-04 A.K. Chhabra VACCINE


(C) 2003-04 A.K. Chhabra “Delicious Vaccines” “A Banana A Day Will Keep A Virus Away” “ You Say Potato, I Say Good Health” “A Salad With Antibodies on the Side” “Fruit or vegetable instead of a Jab”


(C) 2003-04 A.K. Chhabra Examples of Edible Vaccines-Plant Expression Systems Enterotoxigenic E .coli [LT-B] (humans)- Tobacco/Maize – Immunogenic when administered orally. Enterotoxigenic E .coli (humans)- Potato – Immunogenic & protective when administered orally . (Human trials successful) Cholera toxin B-subunit - Tobacco and Potato - Mice immunized with transgenic potato by oral feeding produced toxin specific antibodies. Hepatitis B surface antigen –Tobacco/ Banana /Potato/Lupin/ lettuce– Immunized mice produced anti-hepatitis antibodies. Norwalk Like virus capsid proteins- Tobacco and Potato- Immunogenic when administered orally. Rabies virus protein (G) – Tomato - Immunogenic when administered orally- Intact glycoprotein. FMD – Arabidopsis/ Alfalfa - Immunogenic & protective when administered orally


(C) 2003-04 A.K. Chhabra Questions remaining: Evaluation of dosage requirements Survival in gut Possible plant cell interference with antigen presentation Possible induction of immune tolerance Stability in stored fruit Possible cost to plant of multiple transgenes What food plant is best Banana Avocado Tomato Is need for increased oral dose a problem? Prevention of mis- or over-use


(C) 2003-04 A.K. Chhabra Would the antigens survive the hostile, acidic conditions of the human stomach and if they did, would they always trigger the immune system in the right way? Some early trials have found an immune response in human subjects, but it is not clear what would happen if people were exposed to the actual virus. How could the vaccine dose be controlled ? There seems to be a danger that too high a dose could provoke 'oral tolerance' of a invading bacteria or virus, instead of an immune response. Some researchers have suggested the food would always have to processed into pills or capsules. In addition, the current controversy over GM food means edible vaccines will continue to encounter some serious resistance, particularly in Europe.


(C) 2003-04 A.K. Chhabra Regulatory issues How will edible vaccines be regulated? Food Drugs Agricultural products What component of the vaccine would be licensed? The antigen itself Genetically-engineered fruit The transgenic seeds


(C) 2003-04 A.K. Chhabra WE STILL KNOW VERY LITTLE


(C) 2003-04 A.K. Chhabra “Evolution will continue to generate new highly virulent pathogens. Therefore, continuous monitoring and surveillance for the genetic variants is international imperative for effective control of infectious diseases”


(C) 2003-04 A.K. Chhabra “ Relationship between host and the parasite can range from complete compatibility to fatal divergence depending on the extent to which they share their agendas for survival.” Will Homo sapiens and Microbes co-exist, or will one side win ?


(C) 2003-04 A.K. Chhabra WILL WE SUCCEED?


(C) 2003-04 A.K. Chhabra I think we will…


(C) 2003-04 A.K. Chhabra “F eeling good predisposes one to respond to beauty, warmth of feeling or cerebral challenge in a positive way”.


(C) 2003-04 A.K. Chhabra Discoveries and Success are hidden in dark Don't stop yourself from learning...

Thank You:

(C) 2003-04 A.K. Chhabra Thank You Thank You


(C) 2003-04 A.K. Chhabra

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