In previous studies of whooping cough vaccines, most showed protection but a few did not, and it wasn't really clear why these studies were negative. One hypothesis was that while preparing the vaccine for these negative studies, a washing step was included that made the vaccine ineffective. So this study investigated this question by trying different preparation methods and testing the results on mice.
The three preparations were unwashed, washed with distilled water, or washed with saline. The protein observed in the washing liquid was similar between the two kinds, and didn't seem to have much toxicity or antigenicity, at least not for mice.
So then they tested the vaccines themselves with mice. It took a few trials before they got a really good protocol for mouse protection trials, with the unwashed vaccine giving good protection and the infection challenge being strong enough to kill most of the controls. Eventually they succeeded though. But none of the trials seemed to consistently show a significant difference between types of washing, or washed vs. unwashed.
So the reason the negative trials were negative is still a mystery, sadly. But at least future studies had a decent protocol for testing pertussis vaccines with mice, which seems to be the main reason they cite this study.
Reference:
The three preparations were unwashed, washed with distilled water, or washed with saline. The protein observed in the washing liquid was similar between the two kinds, and didn't seem to have much toxicity or antigenicity, at least not for mice.
So then they tested the vaccines themselves with mice. It took a few trials before they got a really good protocol for mouse protection trials, with the unwashed vaccine giving good protection and the infection challenge being strong enough to kill most of the controls. Eventually they succeeded though. But none of the trials seemed to consistently show a significant difference between types of washing, or washed vs. unwashed.
So the reason the negative trials were negative is still a mystery, sadly. But at least future studies had a decent protocol for testing pertussis vaccines with mice, which seems to be the main reason they cite this study.
Reference:
Miller, Jr., J. J. & Silverberg, R. J. H. pertussis Vaccines: The Effect of Washing and the Use of Mouse Protection Tests. The Journal of Infectious Diseases 65, 16–23 (1939).
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