2. vaccine
A vaccine is a substance containing
a harmless form of the germs that cause a
particular disease.
It is given to people, usually by injection,
to prevent them getting that disease.
3. Classification of vaccine
• Live or attenuated vaccines
Dead or inactivated vaccines
Conjugate vaccines
Recombinant vaccines
Toxoid vaccines
DNA vaccines
The two main classifications of vaccines are: live and
dead vaccines.
4. Live or attenuated vaccines
They are derived from disease-causing “wild”
bacteria or viruses.
These bacteria and viruses are weakened or
“attenuated” by culturing them in a laboratory.
After being injected, live attenuated vaccines grow
and replicate inside the vaccinated person’s body
to produce an immune response.
5. Dead or inactivated vaccines
These vaccines consist of killed or inactivated forms of
the pathogen, killed with either heat, chemicals like
formalin, or radiation.
These vaccines function when the immune system
responds to the introduction of the virus, bacteria, or
toxin produced by the germ.
6. Adsorbed Diphtheria Vaccines
Diphtheria vaccine(absorbed) is a sterile suspension prepared
by mixing purified diphtheria formol toxoid + Mineral
carries[which is hydrated aluminum hydroxide [or] calcium Po 4
] , in saline solution or other suitable solution isotonic with
blood.
The formal toxoid is prepared from the toxin, produced from the
Corynebacterium diphtheriae.
It is an active immunizing agent.
7. Dose
Dose of 0.5ml by intramuscular injection at 2 months.
2nd dose of 0.5ml after 4 weeks.
3rd dose of 0.5ml after another 4 weeks.
A reinforcing dose of 0.5ml is recommended at school
entry age(4 to 6 yrs) preferably after an interval of at
least 3yrs after completing basic course.
8. BIOLOGICAL ASSAY OF
ADSORBED DIPHTHERIA VACCINE
1.Intradermal challenge method (POTENCY
DETERMINATION)
The potency of ADV is determined by comparing the dose
necessary to protect guinea-pigs against effects of a range
of intradermal injections of diphtheria toxin with the dose
of Standard Preparation of adsorbed diphtheria toxoid
necessary to give the same protection.
For this, the Standard Preparation of adsorbed diphtheria
toxoid and a suitable preparation of diphtheria toxin, for
use as a challenge toxin, are required.
9. Standard preparation:Consist of toxoid absorbed on
aluminum hydroxide with polygeline.
TEST ANIMAL : White guinea pig weight between
250g-350g
10. SELECTION OF CHALLENGE
TOXOIN:
select a preparation of diphtheria toxin containing 67-
133 Lime Reactionis/100 in limes flocculation and
25000-50000 minimal reacting doses for guinea pig
skin in 1 LF(limes flocculation )
11. PREPARATION OF CHALLENGE
TOXOIN SOLUTION
Dilute the challenge toxin with a suitable diluents to
obtain a challenge toxin solution containing about
512×10 -4 LF in 0.2ml.
12. DETERMINATION OF POTENCY OF
VACCINE:-
Vaccine diluite with saline solution
↓
Inject guinea pig subcutaneously (5 numbers)
↓
After 28 days shave both flanks of each guinea pig
↓
0.2ml challenge toxin solution inject guinea pig-intradermally
↓
after 4 hours , record the incidence of diptheria erythema .
↓
assay limit falls between 50% and 200% of the estimated potency.
13. 2)LETHAL CHALLENGE METHOD
TEST ANIMAL: guinea pig weight between 250g-350g
divide them into 6 groups of 16animals and 4groups
containg-5 animals.
• All guinea pigs should have same sex.
CHALLENGE TOXIN: Diphtheria toxin containing not
less than 100 LD 50 in 1.0ml.
14. PREPARATION OF CHALLENGE TOXIN SOLUTION
• Challenge toxin + phaosphate buffer saline soln
(pH7.4).
• Dilute the challenge toxin soln to 2LD 50 , 1LD 50 ,
1/2LD 50 in the same solution
15. DETERMINATION OF POTENCY OF THE VACCINE:
3 dilutions of sample and standard vaccine prepared in
saline solution each dilution difference by 2.5 fold.
Intermediate conc inject subcuatneously into guinea
pigs.
This should (intermediate conc) Protect 50% animal
from lethal effect of subcutaneous injection.
16. Allocate 6 dilutions, one to each of the 6 groups of
16guinea pigs (1ml)
↓
After 28 days
↓
Test challenge toxin dilution
↓
1ml inject to 4 groups of 5-guinea pigs-
subcutaneously
↓
After 4 days count the number of survival animals.
17. Calculate the potency of the vaccine relative to the
potency of standard preparation on the basis of
number of animals survived in each group of 16
animals.
The test is not valid unless vaccine under examination
and std preparation, the 50% protective doses lie
between the largest and smallest doses.
4 groups of 5 guinea pigs ingested challenge toxin
should produce 100 LD 50
Mortality increases when increases the toxin dose
level.