S H A H A B D U L L A T I F U N I V E R S I T Y K H A I R P U R

ROLL NO. BC0113-01

NAME: ABDUL-RAHMAN SHAIKH

CLASS: BS (P-IV)

SEMESTER: 2nd

DEPARTMENT: BIOCHEMISTRY

SUBJECT: BIOTECHNOLOGY

TEACHER: RESAPECTABLE SIR MOHAMMAD SALEEM LASHARI

ASSIGNMENT TOPIC: BIOTECHNOLOGY APPLICATIONS FOR THE DISCOVERY OF VACCINES

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ContentsIntroduction to Vaccines..............................................................................................................................................3

Recombinant vaccines:................................................................................................................................................3

Recombinant protein vaccines:....................................................................................................................................4

a. Whole protein vaccines...................................................................................................................................4

b. Polypeptide vaccines:......................................................................................................................................4

DNA vaccines:.............................................................................................................................................................5

Oral vaccines:..............................................................................................................................................................5

Steps of Production of New Vaccine...........................................................................................................................7

i. Generation of the antigen................................................................................................................................7

ii. Release and isolation of the antigen................................................................................................................7

iii. Purification......................................................................................................................................................7

iv. Addition of other components.........................................................................................................................7

v. Packaging........................................................................................................................................................8

Restriction for the discovery of New Vaccines............................................................................................................8

Conclusion...................................................................................................................................................................9

References..................................................................................................................................................................10

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BIOTECHNOLOGY APPLICATIONS FOR THE

DISCOVERY OF VACCINESIntroduction to VaccinesA biological preparation, which evokes an immune response when administered into the body, is

termed as vaccines. This usually consists of parts of pathogen in its weakened state or its products.

This triggers an immune response from the body to the particular disease without actually causing

the disease. [1]

Vaccines are preparation, containing weakened or dead microbes of the kind that cause disease,

administered to stimulate the immune system to produce antibodies against the disease. Vaccine was

used by British Physician Edward Jenner at the end of 18 th century in the terms “vaccine disease”

means at that time the Sore of other disease is inoculated to immunize the person. [2]

Our discussion is about the applications of Biotechnology for production of Vaccines. So now a

days so-many vaccines are developed by applying the biotech methods. i.e:

Recombinant vaccines:Biotechnology sector has also played its part in developing vaccines against certain diseases. Such

vaccine which makes use of recombinant DNA technology is known as recombinant vaccines. It is

also known as subunit vaccines.

Recombinant vaccines can be broadly grouped into two kinds:

(i) Recombinant protein vaccines: This is based on production of recombinant DNA which is

expressed to release the specific protein used in vaccine preparation.

(ii) DNA vaccines: Here the gene encoding for immunogenic protein is isolated and used to produce

recombinant DNA which acts as vaccine to be injected into the individual.

Steps involved:

Production of recombinant vaccines involves the following steps:

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1. First and foremost, it is important that the protein which is crucial to the growth and

development of the causative organism be identified.

2. The corresponding gene is then isolated applying various techniques. Further to this, an

extensive study of the gene explains the gene expression pattern involved in the production of

corresponding protein.

3. This gene is then integrated into a suitable expression vector to produce a recombinant DNA.

4. This rDNA is used as vaccines or is introduce into another host organism to produce

immunogenic proteins which acts as vaccines.

Recombinant protein vaccines:A pathogen upon infection produces proteins, vital for its functions, which elicit an immune response

from the infected body. The gene encoding such a protein is isolated from the causative organism

and used to develop a recombinant DNA. This DNA is expressed in another host organism, like

genetically engineered microbes; animal cells; plant cells; insect larvae etc, resulting in the release of

the appropriate proteins which are then isolated and purified. These when injected into the body,

causes immunogenic response to be active against the corresponding disease providing immunity

against future attack of the pathogen.

Based on the proteins involved in evoking immune response recombinant protein vaccines are of two

types:

a. Whole protein vaccines : The whole immunogenic protein is produced in another host

organism which is isolated and purified to act as vaccines.

b. Polypeptide vaccines: It is known that in the immunogenic protein produced, the actual

immunogenic property is limited to one or two polypeptides forming the protein. The other

parts of the protein may be successful in evoking an immune response but do not actually

cause the disease. For e.g. in the case of cholera caused by Vibrio cholera, consists of three

polypeptide chains like A1, A2, and B. The A polypeptides are toxic while B is non-toxic.

Thus while producing vaccines, the polypeptide B is produced by rDNA technology and used

for vaccination.

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DNA vaccines:It refers to the recombinant vaccines in which the DNA is used as a vaccine. The gene responsible

for the immunogenic protein is identified, isolated and cloned with corresponding expression vector.

Upon introduction into the individuals to be immunized, it produces a recombinant DNA. This DNA

when expressed triggers an immune response and the person becomes successfully vaccinated. The

mode of delivery of DNA vaccines include: direct injection into muscle; use of vectors like

adenovirus, retrovirus etc; in vitro transfer of the gene into autologous cells and re-implantation of

the same and particle gun delivery of the DNA.

In certain cases, the responsible gene is integrated into live vectors which are introduced into

individuals as vaccines. This is known as live recombinant vaccines. E.g. vaccinia virus. Live

vaccinia virus vaccine (VV vaccine) with genes corresponding to several diseases, when introduced

into the body elicit an immune response but does not actually cause the diseases.

Advantages:

(i) Since it does not involve actual pathogen, recombinant vaccines is considered to be safe than the

conventional vaccines.

(ii) It induces both humoral and cellular immune response resulting in effective vaccination.

Risks involved:

(i) High cost of production.

(ii) Have to be stored at low temperature since heat destabilizes protein. Hence storage and

transportation is tedious.

(iii) Individuals with immunodeficiency may elicit poor immune response.

Oral vaccines:The latest hot spot in the field of vaccine research is the development of vaccine which can be taken

orally. Immunogenic protein of certain pathogens is found to be active when administered orally.

The gene corresponding to such proteins is isolated and a gene construct is produced. This is

introduced and expressed in a plant genome which results in production of such immunogenic

proteins in the parts of the plant where it is expressed. These when fed into animals or mainly

humans, the person becomes vaccinated against certain pathogen. Such vaccines are also known as

edible vaccines. An exciting invention is production of ‘melt in the mouth’ vaccines that can be

administered by placing them under your tongue which delivers it into the blood stream. The most

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important example is the production of flu vaccine by Bacillus which melts in the mouth. The

tremendous benefit of such vaccines is the comfort of administration, low cost and ease of storage.

Live genetically modified vaccines can be bacteria or viruses, generally with two or more genes

inactivated or deleted. They can also be vaccines carrying a foreign gene from a different disease

agent, referred to as vaccine vectors. These vaccines are developed to attenuate the infectious agent.

An additional recent technique of creating a live genetically modified vaccine is to utilize an

infectious clone of the disease causing agent. An infectious clone is produced by isolating the

complete genome of the disease agent in the lab. This isolated or cloned genome can be purposefully

and specifically altered in the lab and then utilized to re-create the live genetically modified

organism.

Recombinant inactivated vaccines are the subunit vaccines consisting of only a part of the entire

organism. Subunit vaccines can be synthetic peptides produced in the lab. It can also be whole

proteins extracted from the disease agent or the one that is expressed from the cloned genes.

Numerous systems can be utilized to express a recombinant protein and the expression systems can

be cell free or use entire cells. The expression systems that use entire cells includes prokaryotic such

as Escherichia coli (bacteria based) and eukaryotic such as yeast, mammalian, avian or insect based

systems. An additional type of recombinant subunit vaccines, referred to as virus-like particles or

VLPs, can be generated when one or more cloned genes that characterize the structural proteins of a

virus are expressed at the same time and self-assemble to form VLPs.

Genetic or DNA vaccines are generally plasmids, which contain a foreign gene from an infectious

agent and a promoter to initiate its expression in the target animal. These plasmids can be maintained

in bacteria such as E. coli .The plasmids are purified from the bacteria and the DNA is injected

directly into the animal by intramuscular means or into the skin. The cells of the animal take up the

naked DNA, and as a result the immune response is induced to the protein that is expressed from the

foreign gene. [1]

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Steps of Production of New Vaccine

i. Generation of the antigen The first step in order to produce a vaccine is generating the antigen that will trigger the immune

response. For this purpose the pathogen’s proteins or DNA need to be grown and harvested using the

following mechanisms:

Viruses are grown on primary cells such as cells from chicken embryos or using fertilised

eggs (e.g. influenza vaccine) or cell lines that reproduce repeatedly (e.g. hepatitis A)

Bacteria are grown in bioreactors which are devices that use a particular growth medium that

optimizes the production of the antigens

Recombinant proteins derived from the pathogen can be generated either in yeast, bacteria or

cell cultures.

ii. Release and isolation of the antigen

The aim of this second step is to release as much virus or bacteria as possible. To achieve this, the

antigen will be separated from the cells and isolated from the proteins and other parts of the growth

medium that are still present.

iii. Purification In a third step the antigen will need to be purified in order to produce a high purity/quality product.

This will be accomplished using different techniques for protein purification. For this purpose

several separation steps will be carried out using the differences in for instance protein size, physio-

chemical properties, binding affinity or biological activity.

iv. Addition of other components

The fourth step may include the addition of an adjuvant, which is a material that enhances the

recipient’s immune response to a supplied antigen. The vaccine is then formulated by adding

stabilizers to prolong the storage life or preservatives to allow multi-dose vials to be used safely as

needed. Due to potential incompatibilities and interactions between antigens and other ingredients,

combination vaccines will be more challenging to develop. Finally, all components that constitute

the final vaccine are combined and mixed uniformly in a single vial or syringe.

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v. Packaging

Once the vaccine is put in recipient vessel (either a vial or a syringe), it is sealed with sterile

stoppers. All the processes described above will have to comply with the standards defined for Good

Manufacturing Practices that will involve several quality controls and an adequate infrastructure and

separation of activities to avoid cross-contamination, as shown in the diagram below. Finally, the

vaccine is labelled and distributed worldwide. [3]

Restriction for the discovery of New VaccinesAccording to the Vaccination point of view the various species cause different diseases such as HIV

(Human immune deficiency Virus), Influenza virus which causes the Cold, Hepatitis-C are not

vaccinated because there is no vaccine for these diseases. Researchers have made so many struggles

to produce a vaccine for these type of diseases but they have to face the restrictions i.e. about 200

species of influenza virus have been detected. So how many types of vaccines will be prepared for

the influenza virus.

Different vaccines are produced in different periods of time and estimated time for the production is

given by the researchers. It had taken 105 years after the discovery of the typhoid bacterium to

develop a vaccine for typhoid. For whooping cough (pertussis) it had taken 89 years; for polio and

measles 47 and 42 years respectively. But the time lag was getting shorter. It had only taken 16 years

from the discovery of the hepatitis B virus to the development of a vaccine.

The biotechnology era has experienced significant changes in the number of companies involved in

vaccine manufacturing as well as in the production systems they use. Nevertheless, challenges in this

area are multiple. In the current vaccine-manufacturing environment, time to market and cost

effectiveness are key issues that need to be addressed.

One important difference between the production of vaccines and other biopharmaceuticals is the

risk-safety consideration related to working with pathogens and pathogenic antigens. As with all

biomolecules purified from crude biological material, the removal of contaminants (e.g., derivatives

from host cell such as DNA, protein, or leachable), must be documented. However, the removal or

inactivation of adventitious viruses remains a unique challenge. [4]

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ConclusionIn simple words, Biotechnology play a major role in the production of new vaccines, which will be

Tested, Measured, cheaper and Nanotechnology based Vaccines. The Multiple vaccines of Tetanus,

Typhoid, Hepatitis and Tuberculosis. [4]

Vaccinology has been very effective in preventing infectious diseases. However, in several cases, the

conventional approach to identify protective antigens, based on biochemical, immunological and

microbiological methods, has failed to deliver successful vaccine candidates against major bacterial

pathogens. The recent development of powerful biotechnological tools applied to genome-based

approaches has revolutionized vaccine development, biological research and clinical diagnostics. The

availability of a genome provides an inclusive virtual catalogue of all the potential antigens from

which it is possible to select the molecules that are likely to be more effective. [5]

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References1. Directly searched from WWW.Google.Com2. Lectures of Immunology By Sir Khalid Bhatti Sahib

3. How to produce vaccine with steps direct search from WWW.Google.Com4. Own concepts

5. Shilts R and the Band Played On: politics, people, and the AIDS epidemic. New

York: St. Martin’s Press, 1987

- Esparza J Vaccines: State-of-the-art and future directions. 15th International

AIDS Conference, Bangkok. Plenary address, abstract ThPl15, 2004

- Desrosiers R Scientific obstacles to an effective HIV vaccine. Fifteenth

Conference on Retroviruses and Opportunistic Infections, Boston. Plenary

presentation 91, 2008

- Casimiro DR et al. Attenuation of simian immunodeficiency virus SIVmac239

infection by prophylactic immunization with DNA and recombinant

adenoviral vaccine vectors expressing gag. Journal of Virology 79(24): 15547-

15555, 2005

- Gallo RB The end or the beginning of the drive to an HIV-preventive vaccine:

a view from over 20 years. Lancet. 366(9500):1894-8, 2005

- Yang O CTL and the control of HIV-1 replication. Or: lessons learned from

mixing HIV-1 and CTL. HVTN conference, 2007

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