VACCINES

VACCINES

(ARTIFICIAL ACTIVE IMMUNITY)

Edward Jenner performed vaccination in 1798 against small pox using cowpox virus. The term vaccine was originally used to designate a suspension of killed or attenuated. Currently the term is used to include all antigenic substances such as toxoid, venoms or any other biological products.

Function

ý            Provide an antigenic stimulus that does not cause disease but can produce    

          long lasting, protective immunity.

Principle

ý            Basic principle behind vaccination is to stimulate a primary and secondary anamnestic response that primes the immune system for future exposure to a virulent pathogen. If the pathogen enters the body, the immune response will be immediate, powerful, and sustained.

Types of vaccine

The vaccines are classified into broad groups

1. replicative vaccines
2. Non-replicative vaccines
3. acellular or subcellular vaccines
4. Toxoid

1. Replicative Vaccines

ý            Contain live or attenuated bacteria or viruses that are able to reproduce but  

          have lost virulence.

ý            Immunological potential is related to their ability to increase their number

ý            Confer long-lasting protection

ý            Usually require fewer doses and boosters than other types of vaccines

ý            Require special storage facilities, can be transmitted to other people, and can mutate back to a virulent strain.

Used against

Yellow Fever,     Small pox,    mumps, measles, rubella (MMR)

Tuberculosis (BCG= bacilli calmette Guerin)

2. Non-replicative vaccines

ý            Contain killed or inactivated pathogenic cells or their products.

ý            Microbes do not multiply

ý            Often require a larger dose and more boosters to be effective.

Used Against

Diphtheria, tetanus, pertussis (DTP), polio e.t.c

3. A CELLULAR OR SUBCELLULAR VACCINE

ý            For viruses, they are called subunit vaccines.

ý            The antigens used in these vaccines may be taken from cultures of the microbes, produced by rDNA technology, or synthesized chemically.

EXAMPLE

ý            Capsules of the pneumococcus and meningococcus

ý            The protein surface antigen of anthrax

ý            Surface proteins of hepatitis B virus

TOXOIDS

ý            An inactivated toxin

ý            Many of the microbes that infect people are not themselves harmful. It is the  

          powerful toxins they produce that can cause illness.

ý            Formalin, a solution of formaldehyde and sterile water, is most often used to

          inactivate toxins and produce toxoids.

Used Against

Tetanus, botulism and  diphtheria.

                                                                      Edward Jenner and vaccination

CURRENTLY APPROVED VACCINES

S.NO

DISEASE/PREPARATION

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Contain killed Whole Bacteria Cholera Typhoid Plague Contain Live,Attenuated Bacteria Tuberculosis (BCG) A cellular vaccines (capsular polysaccharides) Meningitis(meningococcal) Meningitis(haemophilus influenzae) Pneumococcal pneumonia Pertussis Toxoids (Formaldehyde-Inactivated Bacterial Exotoxins) Diphtheria Tetanus Botulism Contain Inactivated Whole Viruses Poliomyelitis (salk) Rabies Influenza Hepatitis A Contain Live, Attenuated Viruses adenovirus infection measles mumps poliomyelitis rubella chickenpox yellow fever Subunit Viral Vaccines hepatitis B Influenza Recombinant Vaccines Hepatitis B Pertussis Lyme disease