diphtheria and tetanus vaccine, assay method, lethal dose method, Method A. challenge toxins in the guinea pig, Method B. challenge toxins in mice, Determination of antibodies in the guinea pig, guidelines .

1. RAGHAV DOGRA
M .PHARMA(PHARMACEUTICAL ANALYSIS)
2ND SEMESTER
Assay of Adsorbed Diptheria Vaccine
and Adsorbed Tetanus Vaccine

2. TABLE OF CONTENT
 INTRODUCTION TO ADV.
 PRINCIPLE OF ASSAY.
 LETHAL CHALLENGE METHOD.
 INTRODUCTION TO ATV.
 PRINCIPLE OF ASSAY.
 ASSAY METHOD OF ATV.
 METHOD A. CHALLENGE TOXN IN GUINEA PIG.
 METHOD B. CHALLENGE TOXIN IN MICE.
 METHOD C. DETERMINATION OF ANTIBODIES IN GUINEA PIG
 GUIDELINES

3. INTRODUCTION OF ADV:
 Adsorbed Diphtheria Vaccine (ADV) is an anti-toxin
preparation containing antitoxic globulins that have
the power of specifically neutralizing the toxin
formed by Corynebacterium diphtheria.
 It is obtained by fraction of horse or other mammal
serum, that have been immunized against
Diphtheria toxin.
 Diphtheria vaccine is generally available in the
combination with the Tetanus And Pertusis vaccine
or DPT.
 The formal Toxoid is prepared from the toxin

4. Cont…
 It is generally prepared by combining Diphtheria
formal toxoid with mineral carrier i.e. hydrated
Aluminum hydroxide, Ammonium hydroxide or
Phosphates ,Calcium Phosphates etc.
Diphtheria formal
Toxoid
Mineral Carrier such
as Aluminum,
Ammonium Hydroxide
etc
Adsorbed Diphtheria Toxin(
ADV)

6. PRINCIPLE OF ASSAY:
 The potency of Diphtheria antitoxin is
determined by comparing the dose necessary
to protect the guinea pig or rabbit against the
erythrogenic effect of a fixed dose of the
standard preparation of Diphtheria toxin
required necessary to give same protection.

7. SELECTION OF CHALLENGE TOXIN:
 Selection of the challenge toxin is based upon reacting
dose (Lr).
 The preparation containing 67-133 Lr/mL in Lime
flocculation's (lf) of Diphtheria Toxin (DT) is selected or
the preparation with 25000 to 50000 minimal reacting
doses for guinea pig skin in 1lf.
 The toxin are stored in the refrigeration 0-5˚C and
Toluene is added as antimicrobial preservatives which
does not cause rapid decline in toxicity.

8. PREPARATION OF STANDARD TOXIN:
 It is prepared in a saline solution having 1mL of
preparation having 0.1 IU of toxin followed by:
 1mL of standard preparation along with 0.2 IU test
toxin.
 1mL of standard preparation along with 0.3IU test
toxin.
 Store the preparation away from light.

9. PREPARATION OF CHALLENGE
TOXIN:
 Challenge toxin / preparation to be assayed is diluted
with phosphate buffer solution (PBS) of pH 7.4.
 The challenge toxin solution is diluted in the same
solution upto the following level:
 2LD50
 LD50
 ½LD50

10. LETHAL CHALLENGE METHOD:
 Test animal such as guinea Pig, Horses, Rabbits are
selected for this.
 If guinea pig then it should be of 250-350 gm.
 The animal are grouped into 6 groups of 16 animals
each having same sex.
 0.2 mL of each mixture should be injected
subcutaneously or intradermally into the animal.
 The animals are observed after 48 hours for specific
Diphtheria erythema.
 Mixture containing larger amount of toxin will give
severe reaction and vice versa.

11. DETERMINATION OF POTENCY OF
THE VACCINE:
 The 3 dilutions of sample and standard vaccine are
prepared in saline solution.
 Inject into guinea pigs.
 This should protect 50% animals from lethal effect of
subcutaneous injection.
 Calculate the potency of the vaccine relative to the
potency of potency of standard preparation on the
basis of the number of animals survived in each

12. VALIDITY OF TEST:
 Vaccine under examination and standard
preparation , the 50% protective doses lies between
the largest and the smallest dose of the preparation
given to guinea pigs.
 Mortality increases when increases in toxin dose
level is there the minimum amount of toxin which
when combined should cause a local skin reaction
that is just visible and indicates the presence of
toxin.

13. INTRODUCTION TO ATV:
 Tetanus vaccine, also known as tetanus toxoid (TT), is
an inactive vaccine used to prevent tetanus.
 During childhood five doses are recommended, followed by
additional doses every ten years. After three doses almost
everyone is immune. In those who are not up to date on
their tetanus immunization a booster should be given within
48 hours of an injury.
 In those with high risk injuries who are not fully immunized
tetanus antitoxin may also be recommended. Making sure
women who are pregnant are up to date on their tetanus
immunization and, if not, immunizing them can
prevent neonatal tetanus.

14. Contd..
 Tetanus Toxoid Adsorbed USP, for intramuscular use, is
a sterile suspension of alum-precipitated (aluminum
potassium sulfate) toxoid in an
isotonic sodium chloride solution containing
sodium phosphate buffer to control pH.
 Clostridium tetani culture is grown in a peptone-based
medium and detoxified with formaldehyde. The detoxified
material is then purified by serial ammonium sulfate
fractionation, followed by sterile filtration, and the toxoid is
adsorbed to aluminum potassium sulfate (alum). The
adsorbed toxoid is diluted with physiological saline solution
0.85%.
 Each 0.5 mL dose is formulated to contain 5 Lf

15. PRINCIPLE:
• The potency of tetanus vaccine is determined by
administration of the vaccine to animals i.e. guinea-pigs or
mice followed administration of either challenge with
tetanus toxin or by determining of the titre of antibodies
against tetanus Toxoid in the serum of the guinea-pigs.
• In both cases the potency of the vaccine is calculated by
comparison with a reference vaccine, calibrated in
International Units.
 Tetanus vaccine (adsorbed) BRP is calibrated in
International Units with reference to the International
Standard.

16. ASSAY METHODS OF ATV:
ASSAY OF ADSORBED
TETANUS VACCINE
METHOD B. CHALLENGE
TEST IN MICE.
METHOD A. CHALLENGE
TEST IN GUINEA-PIGS.
METHOD C. DETERMINATION OF
ANTIBODIES IN
GUINEA-PIGS

17. METHOD A.CHALLENGE TOXIN IN
GUINEA PIG
 SELECTION AND DISTRIBUTION OF TEST ANIMALS:
 Healthy guinea pigs from the same stock should be selected of
weight 250-350 gm.
 Animals are distributed in not less than 6 equal groups
containing no. of animals sufficient to obtain results
 If the validity of the challenge toxin is to be determined 3 further
groups of the 5 animals each should be taken which are used
as unvaccinated control.
 Animals should be of same sex if both sex are included then the

18. Contd…
 SELECTION OF CHALLENGE TOXIN:
 Preparation of tetanus toxin containing not less than 50
times the 50 per cent paralytic dose per millilitre is
selected.
 If the challenge toxin preparation has been shown to be
stable, it is not necessary to verify the paralytic dose for
every assay.
PREPARATION OF CHALLENGE TOXIN SOLUTION:
 The challenge toxin is immediately diluted to 50 times the
50 per cent paralytic dose per millilitre with the, peptone
buffered saline solution pH 7.4 etc to obtain stable
challenge toxin.

19.  DILUTION OF THE TEST AND REFERENCE
SOLUTION:
 The vaccine to be examined and the reference preparation
are diluted with the 9g/l solution of NaCl.
 The dilution forms series which do not differ the by 2.5
folds from the alternating previous and next dilutions.
 When injected subcutaneously with dose of 1.0 mL per
guinea pig should protect approximately 50% of animals
from the paralytic effects of tetanus toxin prescribed for
test.
 IMMUNIZATION CHALLENGE AND CHALLENGE:
 Allocate the dilutions to the groups.
 Then Inject subcutaneously 1 mL allocated dilution into the
Contd..

20. Contd…
 DETERMINATION OF ACTIVITY OF THE CHALLENGE
TOXIN:
 3 dilutions made from the challenge toxin and each dilution
were allocated to 1 group of 5 guinea pigs i.e. 3 groups if
necessary.
 Subcutaneously inject 1mL of allocated solution into each
guinea pig of the group.
 The activity and stability of the challenge toxin are
determined by carrying out a suitable number of
determinations of the 50 per cent paralytic dose.

21. Contd..
 READING AND INTERPRETATION OF RESULTS:
 The guinea-pigs are examined twice daily. Remove and
humanely kill all animals showing definite signs of tetanus
paralysis.
 The number of guinea-pigs without paralysis 5 days after
injection of the challenge toxin are counted.
 Calculate the potency of the vaccine to be examined
relative to the potency of the reference preparation on the
basis of the proportion of challenged animals without
paralysis in each of the groups of vaccinated guinea-pigs,
using the usual statistical methods

22. Contd..
 REQUIREMENTS FOR A VALID ASSAY:
 The test is not valid unless, for both the vaccine to be
examined and the reference preparation the 50 per cent
protective dose lies between the largest and smallest
doses of the preparations given to the guinea-pigs,
 if applicable, the number of paralyzed animals in the 3
groups of 5 injected with the dilutions of the challenge toxin
solution indicates that the challenge was approximately 50
times the 50 per cent paralytic dose,
 the confidence limits (P = 0.95) are not less than 50 per
cent and not more than 200 per cent of the estimated
potency,
 the statistical analysis shows significant slope and no
deviation from linearity and parallelism of the dose

23. METHOD B.CHALLENGE TOXIN IN MICE:
 SELECTION AND DISTRIBUTION OF TEST ANIMALS:
 Use in the test healthy mice from the same stock, about 5
weeks old and from a strain shown to be suitable. Rest
same as guinea pig.
 SELECTION OF CHALLENGE TOXIN:
 Preparation of tetanus toxin containing not less than 100
times the 50 per cent paralytic dose per millilitre is
selected.
 PREPARATION OF CHALLENGE TOXIN SOLUTION:
 DILUTION OF THE TEST AND REFERENCE
SOLUTION:
 IMMUNIZATION CHALLENGE AND CHALLENGE:
 DETERMINATION OF ACTIVITY OF THE CHALLENGE

24. Contd..
 READING AND INTERPRETATION OF RESULTS:
 The mice are examined twice daily. Remove and humanely
kill all animals showing definite signs of tetanus paralysis.
 The number of mice without paralysis 4 days after injection
of the challenge toxin are counted.
 Calculate the potency of the vaccine to be examined
relative to the potency of the reference preparation on the
basis of the proportion of challenged animals without
paralysis in each of the groups of vaccinated guinea-pigs,
using the usual statistical methods.

25. METHOD C. DETERMINATION OF
ANTBODIES IN GUINEA PIG
 SELECTION AND DISTRIBUTION OF TEST ANIMALS:
 Healthy guinea pigs from the same stock should be selected of
weight 250-350 gm.
 Animals are distributed in not less than 6 equal groups
containing no. of animals sufficient to obtain results.
 Animals should be of same sex if both sex are included then the
should be equally distributed among groups.
 Use a further group of non-vaccinated guinea-pigs of the same
origin to provide a negative serum control. If test consistency
has been demonstrated, a reference negative serum control
may be used.

26. Contd…
 REFERENCE PREPARATION:
 A suitable reference preparation such as tetanus
vaccine(adsorbed) BRP or a batch of vaccine shown to be
effective in clinical studies, or a batch representative thereof,
and which has been calibrated in International Units with
reference to tetanus vaccine (adsorbed) BRP or the
International Standard for tetanus toxoid (adsorbed) are used.
 DILUTION OF THE TEST AND REFERENCE SOLUTION:
 The vaccine to be examined and the reference preparation are
diluted with the 9g/l solution of NaCl.
 The dilution forms series which do not differ the by 2.5 to 5 folds
from the alternating previous and next dilutions. Use not fewer
than 3 dilutions within the range for example 0.5-16 IU/ml for
each series. Use dilutions for immunization preferably within 1 h
of preparation. Allocate 1 dilution to each group of guinea-pigs.

27. Contd…
 IMMUNISATION:
 Inject subcutaneously in the nape of each guinea-pig 1.0
ml of the dilution allocated to its group.
 BLOOD SAMPLING:
 35-42 days after immunization, take a blood sample from
each vaccinated and control guinea-pig using a suitable
method.
 PREPARATION OF SERUM SAMPLES:
 Avoid frequent freezing and thawing of serum samples. To
avoid microbial contamination, it is preferable to carry out
manipulations in a laminar-flow cabinet.

28. Contd…
 DETERMINATION OF ANTIBODY TITRE:
 Determine the relative antibody titre or score of each
serum sample by a suitable immunochemical method . The
methods shown below (enzyme-linked immunosorbent
assay (ELISA) and toxin-binding inhibition (ToBI)) have
been found suitable.
 CALCULATION OF POTENCY:
 Calculate the potency of the vaccine to be examined in
International Units relative to the reference preparation,
using the usual statistical methods (for example 5.3).
 NOTE: International Units of potency refer to the
reference vaccine and not to the International Units of

29. Contd…
 Requirements for a valid assay. The test is not valid
unless :
 The confidence limits (P = 0.95) are not less than 50
percent and not more than 200 per cent of the estimated
potency,
 The statistical analysis shows significant slope and no
deviation from linearity and parallelism of the dose-
response lines .
 The test may be repeated but when more than 1 test is
performed the results of all valid tests must be combined in
the estimate of potency.

30. GUIDELINES…
 READING AND INTERPRETATION OF RESULTS:
 In order to minimize suffering in the test animals, it is
recommended to note the degree of paralysis on a
scale such as that shown below. The scale gives
typical signs when injection of the challenge toxin is
made mid-ventrally directly behind the sternum with
the needle pointing towards the neck of the guinea-pig
mice and . Grade T3 is taken as the end-point, but with
experience grade T2 can be used instead. Tetanus
toxin produces in at least 1 of the forelimbs paralysis
that can be recognized at an early stage. The tetanus
grades in guinea-pigs and mice are characterized by

31. Contd..
 T1: slight stiffness of 1 forelimb, but difficult to observe
 T2: paresis of 1 forelimb which still can function.
 T3: paralysis of 1 forelimb. The animal moves reluctantly,
the body is often slightly banana-shaped owing to scoliosis
;
 T4: the forelimb is completely stiff and the toes are
immovable. The muscular contraction of the forelimb is
very pronounced and usually scoliosis is observed;
 T5: tetanus seizures, continuous tonic spasm of muscles ;
 D:death.

32. Contd…
 METHOD C. DETERMINATION OF ANTIBODIES IN
GUINEA-PIGS
 PREPARATION OF SERUM SAMPLES:
 For preparation of serum samples, the following technique
has been found suitable. Invert the tubes containing blood
samples 6 times and allow to stand at 37 °C for 2 h, then at
4 °C for 2 h. Centrifuge at room temperature at 800 g for
20 min. Transfer the serum to sterile tubes and store at a
temperature below −20 °C. At least 40 per cent yield of
serum is obtained by this procedure.
 DETERMINATION OF ANTIBODY TITRE:
 The ELISA and ToBI tests shown below are given as
examples of immunochemical methods that have been
found suitable for the determination of antibody titre.