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Inactivated Poliomyelitis Vaccine; Poliovirus Vaccine Inactivated; Salk Vaccine; IPV

Category Active immunizing agent.

      Inactivated Poliomyelitis Vaccine is a sterile liquid preparation of suitable strains of human poliovirus types 1, 2 and 3 grown in suitable cell cultures and inactivated by a validated method.

      The vaccine complies with the requirements stated under Vaccines, with the following modifications.

Description Clear liquid; may be coloured owing to the presence of a pH indicator. 

Strength available 40 D-antigen units of type 1, 8 Dantigen units of type 2, and 32 D-antigen units of type 3 per 0.5 ml.

Dose Subcutaneous, 0.5 ml.

Contra-indication

1. It is contra-indicated in individuals with hypersensitivity to any component of the vaccine, including neomycin, streptomycin and polymyxin B.

2. Do not administer intravenously.

Warnning Defer vaccination of person with any acute, febrile illness until after recovery.

Expiration date When stored under the prescribed conditions, the expiration date is not later than 18 months from the date of the last satisfactory test for potency.

Labelling Complies with the “General Information for Biological Products”, p. 177. In addition, the label on the container states (1) the nature of the cell cultures used; (2) the types of poliovirus contained in the vaccine; (3) the nominal amount of virus of each type (1, 2 and 3), expressed in units of D-antigen, per single human dose; (4) that it is not to be frozen.

Inactivation test

      The vaccine shows the absence of any living extraneous virus when determined by one of the following methods.

          A. Inoculate the vaccine to be examined into cell cultures sensitive to human and simian viruses and incubate for a sufficient time, including sub-cultures, to detect any extraneous viruses as well as any living poliomyelitis virus.

B. Inoculate the vaccine into mice, guinea-pigs and rabbits.

Antimicrobial preservative Where applicable, determine the amount of antimicrobial preservative by a suitable chemical or physicochemical method. The amount is not less than the minimum amount shown to be effective and is not mores than 115 per cent of that stated on the label.

Protein nitrogen content Not more than 10 μg per single human dose. Carry out the determination as described in the “Determination of Nitrogen” (Method III, Appendix 6.7).

Bovine serum albumin Not more than 50 ng per single human dose, determined by a suitable immunochemical method (Appendix 14.5).

Bacterial endotoxins When tested as described in the “Test for Bacterial Endotoxins” (Appendix 8.5), it contains not more than 5 Endotoxin Units per single human dose.

Assay

      IN VITRO TEST

      D-antigen content Determine the D-antigen content for human poliovirus types 1, 2 and 3 by a suitable immunochemical method (Appendix 14.5) using a reference preparation calibrated in International Units of D-antigen. For each type, the content, expressed with reference to the amount of D-antigen stated on the label, is within the limits approved for the particular product.

      IN VIVO TEST The capacity of the vaccine to induce the formation of neutralizing antibodies is determined in vivo by one of the following methods.

      Test in chicks or guinea-pigs Prepare a suitable series of not less than three dilutions of the vaccine to be examined using a suitable buffered saline solution. Distribute either guinea-pigs weighing 250 to 350 g or 3-week-old chicks into groups of 10, and allocate a group to each dilution of the vaccine. Inject intramuscularly into each animal 0.5 ml of the dilution intended for its group. Bleed the animals after 5 to 6 days and separate the sera. Examine the sera for the presence of neutralizing antibodies, at a dilution of 1 in 4, to each of the human polioviruses 1, 2 and 3. Mix 100 CCID₅₀ of virus with the dilution of serum and incubate at 37º for 4.5 to 6 hours. Keep at a temperature between 2º and 8º for 12 to 18 hours where necessary for consistency of results. Inoculate the mixtures into cell cultures for the detection of unneutralized virus and read the results up to 7 days after inoculation. For each group of animals, note the number of sera which have neutralizing antibodies and calculate the dilution of the vaccine giving an antibody response in 50 per cent of the animals. Carry out in parallel a control test using a suitable reference preparation. The vaccine complies with the test if a dilution of 1 in 100 or more produces an antibody response for each of the three types of virus in 50 per cent of the animals.

      Test in rats Prepare a suitable series of not less than three dilutions of the vaccine to be examined and a reference vaccine. Inject each dilution intramuscularly into the hind limb(s) of a group of 10 specific pathogenfree rats of a suitable strain. Use of four dilutions is often necessary to obtain valid results for all three serotypes. The number of animals per group must be sufficient to obtain results that meet the validity criteria; groups of 10 rats are usually sufficient although valid results may be obtained with fewer animals per group. If animals of different sex are used, males and females are evenly distributed between all groups. A weight range of 175 to 250 g has been found suitable. An inoculum of 0.5 ml per rat is used. The dose range is chosen such that a dose response to all three poliovirus type is obtained. Bleed the animals after 20 to 22 days. Neutralizing titres against all three poliovirus types are measured separately using 100 CCID₅₀ of the Sabin strains as challenge viruses, Vero of Hep2 as indicator cells, and neutralization conditions of 3 hours at 35º to 37º followed by 18 hours at 2º to 8º where necessary for consistency of results. Results are read following fixation and staining after 7 days of incubation at 35º. For a valid antibody assay, the titre of each challenge virus must be shown to be within the range of 10 CCID₅₀ to 1000 CCID₅₀ and the neutralizing antibody titre of a control serum must be within two twofold dilutions of the geometric mean titre of the serum. The potency is calculated by comparison of the proportion of responders for the vaccine to be examined and the reference vaccine by the probit method or, after validation, using a parallel-line model. For the probit method it is necessary to establish a cut-off neutralizing antibody titre for each poliovirus type to define a responder. Due to interlaboratory variation, it is not possible to define cut-off values that could be applied by all laboratories. Rather, the cut-off values are determined for each laboratory based on a minimum series of three tests with the reference vaccine. The mid-point on a log2 scale of the minimum and maximum geometric mean titres of the series of three or more tests is used as the cut-off value. For each of the three poliovirus types, the potency of the vaccine is not significantly less than that of the reference preparation.

      The test is not valid unless:

      – for both the test and reference vaccines the ED₅₀ lies between the smallest and the largest doses given to the animals;

      – the statistical analysis shows no significant deviation from linearity or parallelism;

      – the confidence limits (P = 0.95) are not less than 25 per cent and not more than 400 per cent of the estimated potency.