SHAH ABDUL LATIF UNIVERSITY KHAIRPUR

Presentation Topic: Biotechnology applications for the discovery of vaccines

Presented By: Abdul-Rahman, Ali Gohar, Ayaz Ahmad, Aamir Khoso &

Ghulam Mustafa

Presented to: Respected Sir

Muhammad Saleem Lashari

Introduction 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.

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 18th century in the terms “vaccine disease” means at that

time the Sore of other disease is inoculated to immunize the person.

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.

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:

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

growth and development of the causative organism be identified.

The corresponding gene is then isolated applying various techniques. Further to

this, an extensive study of the gene explains the gene expression pattern

1. involved in the production of corresponding protein.

2. This gene is then integrated into a suitable expression vector to produce a

recombinant DNA.

3. 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:

Whole protein vaccines: The whole immunogenic protein is produced in

another host organism which is isolated and purified to act as vaccines.

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.

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.

Steps of Production of New Vaccine 

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.

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.

PurificationIn 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.

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.

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.

Restriction for the discovery of New Vaccines

According 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.

Conclusion

In 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.

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.