Abstract

FAJARDO, Esther María; ALVAREZ, Eduardo; RUIZ, Boris  and  MUNOZ, Pedro. Evaluation of two different Biological Methods (Subcutaneous and Intradermal) for detecting Diphtheria Toxin. Vaccimonitor [online]. 2004, vol.13, n.2, pp.17-21. ISSN 1025-028X.

The World Health Organization Requirements establish tests to determine both specific toxicity and reversion to toxicity of the purified diphtheria anatoxin as mandatory controls for the production process. The proposed method to evaluate the specific toxicity consists in the subcutaneous inoculation (subcutaneous method) of Guinea pigs with 1 mL of the product containing 500 Lf/mL; other suggested possible methods are those using cell-cultures and the intradermal inoculation (intradermal method) of 20 Lf in Guinea pigs or rabbits. No specific method is proposed for the reversion to toxicity test; it only should be approved by the National Regulatory Authority and be sufficiently sensitive to detect small amounts of toxin. Due to the importance of those tests for supporting the safety of the product, both methods were evaluated, mainly in terms of their detection limits (by using known concentrations of a reference diphtheria toxin), but also related to the fulfilment of the ethical “3 Rs” principle (Replace,Reduction, Refinement) and the overall time required for the results. The intradermal method resulted more sensitive than the subcutaneous one (detection limit 0.0067 x 10-4 Lf/mL vs 4.17 x 10-4 Lf/mL), requires less animals (2 vs 5 per sample), its end-point is a local reaction (erythema) instead of death (meets 2 “Rs”) and it is shorter in time (48 h vs 6) weeks and therefore more economic. It is recommended to carry out the corresponding studies for its introduction in the routine specific toxicity and reversion to toxicity tests performed on the purified diphtheria anatoxin produced at Finlay Institute.

Keywords : Diphtheria; Anatoxin; Specific Toxicity; Reversion.

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