Download Zol 4 - Government Degree College Pulwama

GOVERNMENT DEGREE COLLEGE (BOYS) PULWAMA
SUBJECT
Zoology
TOPIC
Vaccine
CLASS
B Sc 3rd year
LECTURER
Mr. Sawjid Habib Bhat
INTRODUCTION:
A vaccine is a preparation containing a pathogen either in attenuated or
inactivated state. This preparation is introduced into an individual to induce
adequate antibody production against the pathogen in question so that the
individual becomes protected against infection, at a later stage. The
introduction of a vaccine in an individual is called “Vaccination” or
Immunization’.
The process of vaccination was first developed by Dr. Edward-Jenner in 1796.
Later, it was Louis Pasteur who discovered the vaccine against Rabies or
Hydrophobia.
“Features of an ideal –Vaccine”
1. It should not be tumerogenic or toxic or pathogenic.
2. It should have very low level of side effects in normal individuals.
3. It should be effective in producing long lasting humoral and cellular
immunities.
4. The technique of vaccination should be simple.
5. An ideal vaccine should be cheap.
“Types of vaccines”
1. Conventional Vaccines:-These vaccines contain the whole organism
which may either be killed or live but attenuated e.g.
a) Influenza virus, inactivated by formalin.
b) Rabies vaccine (Rabies virus, inactivated by Phenol or 𝛽 -propio Lactone)
c) Small pox Vaccine, anthrax vaccine (attenuated viruses)
Attenuation of the pathogen can be achieved as follows:1. Several consecutive passages through an animal which is not the usual
host of the pathogen e.g., small pox virus in calf.
2. Treatment of pathogens with some chemicals e.g. B.C.G vaccine is produced
by culturing the bacteria on a medium containing Bile.
3. Culture of Bacteria at 40-500C for attenuation (Anthrax).
Disadvantage:
Conventional vaccines carry risk of disease development due to inactivation
of vaccine.
2. Purified antigen vaccine:-These vaccines are based on purified antigens
isolated from the concerned pathogens. These vaccines don’t contain whole
organism.
Many bacteria produce exotoxins, which don’t have toxicity but retain the
immunogenicity. These are called toxoids. These are used as effective vaccines
e.g. Tetanus, Diphtheria vaccines etc.
3. Recombinant Vaccines:-A recombinant vaccine contains either a protein or
gene encoding a protein of a pathogen origin that is immunogenic. The vaccine is
produced using DNA, Recombinant DNA technology. The vaccines based on
recombinant proteins are also sub–unit vaccines e.g. Hepatitis-B surface antigen
vaccines for Hepatitis -B virus.
4. Recombinant Polypeptide Vaccine:-Generally, the whole protein is not
necessary for immunogenicity. The immunogenic property is usually confined to
a small portion of the protein molecules e.g., the Immunogenicity Foot & mouth
disease virus coat protein is due to its amino acids 114-160 & also 201-213.
5. DNA Vaccines:-Recently, Vaccines based on DNA are being developed &
the result obtained with influenza virus is quite exciting. There are regarded as
Third revolution Vaccines. This preparation is introduced into the individual to
be immunized. The use of DNA for Immunization is known as Genetic
Immunization.
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Advantages of DNA Vaccine
The protein expressed by the DNA vaccine is exactly similar to that of the
pathogen.
DNAs of many pathogens can be injected by a single dose.
Temperature stable.
Easy storage and transport.
Polio, Rabies & Rubella Vaccine is manufactured in India.
The vaccines produced from conventional methods are called first generation
vaccine, those through genetic engineering 2nd generation vaccines.
Importance of Vaccines
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Vaccine primes the body to attack an infecting pathogen.
The body develops immunity.
Infectious diseases are prevented.
Smallpox, polio, etc. are eradicated from humans by vaccines.