Study on Toxicity Reduction and Potency Induction in Whole-cell Pertussis Vaccine by Developing a New Optimal Inactivation Condition Processed on Bordetella pertussis.
BACKGROUND
Whooping cough is caused by Bordetella pertussis, and it remains a public health concern. Whole-cell pertussis vaccines have been commonly employed for expanded immunization. There is no doubt of the efficacy of whole cell pertussis vaccine, but it is necessary to improve the vaccine to decrease its toxicity.


OBJECTIVE
In this study, an inactivation process of dealing with pertussis bacteria is optimized in order to decrease the bacteria content in human doses of vaccines and reduce the vaccine's toxicity.


METHODS
The bacterial suspensions of pertussis strains 509 and 134 were divided into 21 sample parts from F1 to F21 and inactivated under different conditions. The inactivated suspensions of both strains were tested for opacity, non-viability, agglutination, purity, and sterility; the same formulation samples that passed quality tests were then pooled together. The pool of inactivated suspensions were analyzed for sterility, agglutination, opacity, specific toxicity, and potency.


RESULTS
The harvest of both bacterial strains showed purity. The opacity of various samples were lost under different treatment conditions by heat from 8% to 12%, formaldehyde 6% to 8%, glutaraldehyde 6% to 8%, and thimerosal 5% to 8%. Tests on suspensions after inactivation and on pooled suspensions showed inactivation conditions not degraded agglutinins of both strains. The samples of F2, F4, F8, F12, F15, and F17 passed the toxicity test. The potency (ED50) of these samples showed following order F17 > F12 > F8 > F15, F4 > F2, and F17 revealed higher potency compared to other formulations.


CONCLUSIONS
It can be concluded that F17 showed desirable outcomes in the toxicity test and good immunogenicity with a low bacterial number content. Consequently, lower adverse effects and good immunogenicity are foreseeable for vaccine preparation with this method.
Department of Human Vaccine and Serum, Razi Vaccine and Serum Research Institute, Karaj, IR Iran.
Naser
N
Mohammadpour Dounighi
Department of Mycology, Pasteur Institute of Iran, Tehran, IR Iran.
Mehdi
M
Razzaghi-Abyane
Department of Human Vaccine and Serum, Razi Vaccine and Serum Research Institute, Karaj, IR Iran.
Mojtaba
M
Nofeli
Department of Human Vaccine and Serum, Razi Vaccine and Serum Research Institute, Karaj, IR Iran.
Hossein
H
Zolfagharian
Department of Microbiology, Pasteur Institute of Iran, Tehran, IR Iran.
Fereshteh
F
Shahcheraghi
Pertussis; Potency Test; Toxicity Test; Whole-Cell Vaccines; Whooping Cough
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