Influence of temperature on D-antigen and potency in chickens of inactivated poliomyelitis vaccines

Summary

Monovalent inactivated poliomyelitis vaccines were exposed to 40° and 45°C for different times. Two pools of each of the three poliotypes were tested. It could be shown, that the decrease of the D-antigen value upon heating was slower than the decrease of the antigenic potency as determined in chickens. A difference between the three poliotypes existed, type II and type III showing a more thermostable D-antigen than type I. This was confirmed by immunoelectrophoresis experiments. A difference in thermostability between the three types was not detected in the chicken test.

Three other pools, one of each poliotype, were submitted to a prolonged inactivation (Formalin 1/4000, 36°–37°C, pH 7.0) after the usual 12 days. Again the same discrepancy between the behaviour of the D-antigen and the antigenic potency appeared.

Besides some theoretical implications which are briefly discussed, these results lead us to the practical conclusion, that for testing inactivated poliovaccines, especially expired vaccines, the D-antigen determination is not reliable. However, this method can be very helpful as a guide during the production of the vaccine.

To make sure that the precipitation lines found with the vaccines which were exposed to the two temperatures were D-lines some tests were performed, in one of which we used anti D-sera of a different origin. No indication was found, which could give rise to doubt about the nature of the lines under these conditions.